Article

The requisites of government are that there be sufficiency of food, sufficiency of military equipment, and the confidence of the people in their ruler.

Analects by Confucius¹

From ancient festivals to modern holidays, autumn has long been associated with the gathering of the harvest. Friends and families come together around tables laden with delicious food to enjoy the pleasures of peace and plenty. During these celebrations, we must never forget that without the strength of the nation’s military and the service of its veterans, this freedom and abundance would not be possible. Our debt of gratitude to the current and former members of the armed services makes the fact that a substantial minority experiences food insecurity not only a human tragedy, but a travesty of the nation’s promise to support those who wear or have worn the uniform.

The National Defense Authorization Act for Fiscal Year 2020 charged the Secretary of Defense to investigate food insecurity among active-duty service members and their dependents.² The RAND Corporation conducted the assessment and, based on the results of its analysis, made recommendations to reduce hunger among armed forces members and their families.³

The RAND study found that 10% of active-duty military met US Department of Agriculture (USDA) criteria for very low food security; another 15% were classified as having low food security. The USDA defines food insecurity with hunger as “reports of multiple indications of disrupted eating patterns and reduced food intake.” USDA defines low food security as “reports of reduced quality, variety, or desirability of diet. Little or no indication of reduced food intake.”⁴

As someone who grew up on an Army base with the commissary a short trip from military housing, I was unpleasantly surprised that food insecurity was more common among in-service members living on post. I was even more dismayed to read that a variety of factors constrained 14% of active-duty military experiencing food insecurity to seek public assistance to feed themselves and their families. As with so many health care and social services, (eg, mental health care), those wearing the uniform were concerned that participating in a food assistance program would damage their career or stigmatize them. Others did not seek help, perhaps because they believed they were not eligible, and in many cases were correct: they did not qualify for food banks or food stamps due to receiving other benefits. A variety of factors contribute to periods of food insecurity among military families, including remote or rural bases that lack access to grocery stores or jobs for partners or other family members, and low base military pay.⁵

Food insecurity is an even more serious concern among veterans who are frequently older and have more comorbidities, often leading to unemployment and homelessness. Feeding America, the nation’s largest organization of community food banks, estimates that 1 in 9 working-age veterans are food insecure.⁵ US Department of Veterans Affairs (VA) statistics indicate that veterans are 7% more likely to experience food insecurity than other sectors of the population.⁶ The Veterans Health Administration has recognized that food insecurity is directly related to medical problems already common among veterans, including diabetes, obesity, and depression. Women and minority veterans are the most at risk of food insecurity.⁷

Recognizing that many veterans are at risk of food insecurity, the US Department of Defense and VA have taken steps to try and reduce hunger among those who serve. In response to the shocking statistic that food insecurity was found in 27% of Iraq and Afghanistan veterans, the VA and Rockefeller Foundation are partnering on the Food as Medicine initiative to improve veteran nutrition as a means of improving nutrition-related health consequences of food insecurity.⁸

Like many federal practitioners, I was unaware of the food insecurity assistance available to active-duty service members or veterans, or how to help individuals access it. In addition to the resources outlined in the Table, there are many community-based options open to anyone, including veterans and service members. 

I have written columns on many difficult issues in my years as the Editor-in-Chief of Federal Practitioner, but personally this is one of the most distressing editorials I have ever published. That individuals dedicated to defending our rights and protecting our safety should be compelled to go hungry or not know if they have enough money at the end of the month to buy food is manifestly unjust. It is challenging when faced with such a large-scale injustice to think we cannot make a difference, but that resignation or abdication only magnifies this inequity. I have a friend who kept giving back even after they retired from federal service: they volunteered at a community garden and brought produce to the local food bank and helped distribute it. That may seem too much for those still working yet almost anyone can pick up a few items on their weekly shopping trip and donate them to a food drive. 

As we approach Veterans Day, let’s not just express our gratitude to our military and veterans in words but in deeds like feeding the hungry and urging elected representatives to fulfill their commitment to ensure that service members and veterans and their families do not experience food insecurity. Confucian wisdom written in a very distant time and vastly dissimilar context still rings true: there are direct and critical links between food and trust and between hunger and the military.¹

The requisites of government are that there be sufficiency of food, sufficiency of military equipment, and the confidence of the people in their ruler.

Analects by Confucius¹

From ancient festivals to modern holidays, autumn has long been associated with the gathering of the harvest. Friends and families come together around tables laden with delicious food to enjoy the pleasures of peace and plenty. During these celebrations, we must never forget that without the strength of the nation’s military and the service of its veterans, this freedom and abundance would not be possible. Our debt of gratitude to the current and former members of the armed services makes the fact that a substantial minority experiences food insecurity not only a human tragedy, but a travesty of the nation’s promise to support those who wear or have worn the uniform.

The National Defense Authorization Act for Fiscal Year 2020 charged the Secretary of Defense to investigate food insecurity among active-duty service members and their dependents.² The RAND Corporation conducted the assessment and, based on the results of its analysis, made recommendations to reduce hunger among armed forces members and their families.³

The RAND study found that 10% of active-duty military met US Department of Agriculture (USDA) criteria for very low food security; another 15% were classified as having low food security. The USDA defines food insecurity with hunger as “reports of multiple indications of disrupted eating patterns and reduced food intake.” USDA defines low food security as “reports of reduced quality, variety, or desirability of diet. Little or no indication of reduced food intake.”⁴

As someone who grew up on an Army base with the commissary a short trip from military housing, I was unpleasantly surprised that food insecurity was more common among in-service members living on post. I was even more dismayed to read that a variety of factors constrained 14% of active-duty military experiencing food insecurity to seek public assistance to feed themselves and their families. As with so many health care and social services, (eg, mental health care), those wearing the uniform were concerned that participating in a food assistance program would damage their career or stigmatize them. Others did not seek help, perhaps because they believed they were not eligible, and in many cases were correct: they did not qualify for food banks or food stamps due to receiving other benefits. A variety of factors contribute to periods of food insecurity among military families, including remote or rural bases that lack access to grocery stores or jobs for partners or other family members, and low base military pay.⁵

Food insecurity is an even more serious concern among veterans who are frequently older and have more comorbidities, often leading to unemployment and homelessness. Feeding America, the nation’s largest organization of community food banks, estimates that 1 in 9 working-age veterans are food insecure.⁵ US Department of Veterans Affairs (VA) statistics indicate that veterans are 7% more likely to experience food insecurity than other sectors of the population.⁶ The Veterans Health Administration has recognized that food insecurity is directly related to medical problems already common among veterans, including diabetes, obesity, and depression. Women and minority veterans are the most at risk of food insecurity.⁷

Recognizing that many veterans are at risk of food insecurity, the US Department of Defense and VA have taken steps to try and reduce hunger among those who serve. In response to the shocking statistic that food insecurity was found in 27% of Iraq and Afghanistan veterans, the VA and Rockefeller Foundation are partnering on the Food as Medicine initiative to improve veteran nutrition as a means of improving nutrition-related health consequences of food insecurity.⁸

Like many federal practitioners, I was unaware of the food insecurity assistance available to active-duty service members or veterans, or how to help individuals access it. In addition to the resources outlined in the Table, there are many community-based options open to anyone, including veterans and service members. 

I have written columns on many difficult issues in my years as the Editor-in-Chief of Federal Practitioner, but personally this is one of the most distressing editorials I have ever published. That individuals dedicated to defending our rights and protecting our safety should be compelled to go hungry or not know if they have enough money at the end of the month to buy food is manifestly unjust. It is challenging when faced with such a large-scale injustice to think we cannot make a difference, but that resignation or abdication only magnifies this inequity. I have a friend who kept giving back even after they retired from federal service: they volunteered at a community garden and brought produce to the local food bank and helped distribute it. That may seem too much for those still working yet almost anyone can pick up a few items on their weekly shopping trip and donate them to a food drive. 

As we approach Veterans Day, let’s not just express our gratitude to our military and veterans in words but in deeds like feeding the hungry and urging elected representatives to fulfill their commitment to ensure that service members and veterans and their families do not experience food insecurity. Confucian wisdom written in a very distant time and vastly dissimilar context still rings true: there are direct and critical links between food and trust and between hunger and the military.¹

The requisites of government are that there be sufficiency of food, sufficiency of military equipment, and the confidence of the people in their ruler.

Analects by Confucius¹

From ancient festivals to modern holidays, autumn has long been associated with the gathering of the harvest. Friends and families come together around tables laden with delicious food to enjoy the pleasures of peace and plenty. During these celebrations, we must never forget that without the strength of the nation’s military and the service of its veterans, this freedom and abundance would not be possible. Our debt of gratitude to the current and former members of the armed services makes the fact that a substantial minority experiences food insecurity not only a human tragedy, but a travesty of the nation’s promise to support those who wear or have worn the uniform.

The National Defense Authorization Act for Fiscal Year 2020 charged the Secretary of Defense to investigate food insecurity among active-duty service members and their dependents.² The RAND Corporation conducted the assessment and, based on the results of its analysis, made recommendations to reduce hunger among armed forces members and their families.³

The RAND study found that 10% of active-duty military met US Department of Agriculture (USDA) criteria for very low food security; another 15% were classified as having low food security. The USDA defines food insecurity with hunger as “reports of multiple indications of disrupted eating patterns and reduced food intake.” USDA defines low food security as “reports of reduced quality, variety, or desirability of diet. Little or no indication of reduced food intake.”⁴

As someone who grew up on an Army base with the commissary a short trip from military housing, I was unpleasantly surprised that food insecurity was more common among in-service members living on post. I was even more dismayed to read that a variety of factors constrained 14% of active-duty military experiencing food insecurity to seek public assistance to feed themselves and their families. As with so many health care and social services, (eg, mental health care), those wearing the uniform were concerned that participating in a food assistance program would damage their career or stigmatize them. Others did not seek help, perhaps because they believed they were not eligible, and in many cases were correct: they did not qualify for food banks or food stamps due to receiving other benefits. A variety of factors contribute to periods of food insecurity among military families, including remote or rural bases that lack access to grocery stores or jobs for partners or other family members, and low base military pay.⁵

Food insecurity is an even more serious concern among veterans who are frequently older and have more comorbidities, often leading to unemployment and homelessness. Feeding America, the nation’s largest organization of community food banks, estimates that 1 in 9 working-age veterans are food insecure.⁵ US Department of Veterans Affairs (VA) statistics indicate that veterans are 7% more likely to experience food insecurity than other sectors of the population.⁶ The Veterans Health Administration has recognized that food insecurity is directly related to medical problems already common among veterans, including diabetes, obesity, and depression. Women and minority veterans are the most at risk of food insecurity.⁷

Recognizing that many veterans are at risk of food insecurity, the US Department of Defense and VA have taken steps to try and reduce hunger among those who serve. In response to the shocking statistic that food insecurity was found in 27% of Iraq and Afghanistan veterans, the VA and Rockefeller Foundation are partnering on the Food as Medicine initiative to improve veteran nutrition as a means of improving nutrition-related health consequences of food insecurity.⁸

Like many federal practitioners, I was unaware of the food insecurity assistance available to active-duty service members or veterans, or how to help individuals access it. In addition to the resources outlined in the Table, there are many community-based options open to anyone, including veterans and service members. 

I have written columns on many difficult issues in my years as the Editor-in-Chief of Federal Practitioner, but personally this is one of the most distressing editorials I have ever published. That individuals dedicated to defending our rights and protecting our safety should be compelled to go hungry or not know if they have enough money at the end of the month to buy food is manifestly unjust. It is challenging when faced with such a large-scale injustice to think we cannot make a difference, but that resignation or abdication only magnifies this inequity. I have a friend who kept giving back even after they retired from federal service: they volunteered at a community garden and brought produce to the local food bank and helped distribute it. That may seem too much for those still working yet almost anyone can pick up a few items on their weekly shopping trip and donate them to a food drive. 

As we approach Veterans Day, let’s not just express our gratitude to our military and veterans in words but in deeds like feeding the hungry and urging elected representatives to fulfill their commitment to ensure that service members and veterans and their families do not experience food insecurity. Confucian wisdom written in a very distant time and vastly dissimilar context still rings true: there are direct and critical links between food and trust and between hunger and the military.¹

Multiple sclerosis (MS) is a complex, chronic immune-mediated disease of the central nervous system characterized by focal inflammation, demyelination, and neurodegeneration. Magnetic resonance imaging (MRI), first incorporated into the McDonald Criteria for the diagnosis of MS in 2001, is an integral tool in the diagnosis, prognosis, and therapeutic monitoring of people with MS (PwMS).¹

MRI research in MS is rapidly expanding and offers insights into the pathophysiology of MS with important implications for the routine clinical care of PwMS. At the Consortium of Multiple Sclerosis Centers 2024 Annual Meeting, the US Department of Veterans Affairs (VA) MS Centers of Excellence hosted an educational symposium highlighting MRI biomarkers in MS, including T2-lesions, chronic black holes (cBHs), brain atrophy, paramagnetic rim lesions (PRLs), and the central vein sign (CVS). The symposium also provided a brief overview of quantitative MRI techniques used to characterize MS lesion severity and research applications of these techniques. This clinical review summarizes the main points of that symposium with the goal of introducing key concepts to federal health care practitioners caring for PwMS.

MRI Biomarkers in MS

T2-lesions, Chronic Black Holes, and Brain Atrophy

Focal immune-mediated inflammation and demyelination in MS may be detected by MRI as hyperintense foci on T2-weighted (T2-w) imaging (eg, T2-w turbo spin echo or T2-w fluid attenuated inversion recovery sequences). These T2-lesions, critical for diagnosing MS, are typically ovoid and occur in the periventricular, juxtacortical, infratentorial spinal cord white matter (Figure 1A). T2-lesion number and volume show some association with disability and optic nerve.

Wattjes et al highlight 2 cases to demonstrate this point: a man aged 52 years with MS for 23 years and a woman aged 50 years with MS for 11 years. Despite having MS for a much shorter duration, the woman had worse disability due to a higher lesion number and volume.² T2-lesion volume also impacts disability progression in PwMS. Gauthier et al compared the probability of progression in 3 women, all of whom were aged 39 years and had MS for 6 years. The profile with highest probability of disability progression had the highest quartile of T2-lesion volume.³ T2-lesion volume over 2 years correlates with worse scores on disability metrics such as the MS functional composite, paced auditory serial addition task, and brain volume.⁴ A 2024 systematic review and meta-analysis demonstrated that T2-lesion volume is significantly correlated with clinical disability in PwMS.⁵

 

Select T2-lesions are also hypointense on T1-w spin echo images and are known as cBHs (Figure 1B). Histologically, T2-lesions with cBHs have more severe architectural disruption than those without cBHs.⁶ cBH number and volume are significantly correlated with disability, regardless of the degree of hypointensity on T1-w imaging.^5,7 A 10-year longitudinal study demonstrated that cBHs were associated with disease progression after 5 years while T2-lesion volume was not, indicating that cBHs may be a more accurate predictor of disability.⁸

Brain atrophy, another imaging biomarker of MS, affects both the cerebral white and gray matter. White matter fraction (the volume of white matter relative to the intracranial compartment volume) and gray matter fraction (the volume of gray matter relative to the intracranial compartment) are significantly lower among PwMS compared with healthy controls. In addition, gray matter fraction is lower among patients with primary and secondary progressive MS compared with those with relapsing-remitting MS, clinically isolated syndrome (CIS), and radiologically isolated syndrome (RIS). Gray matter fraction is also correlated with several motor and cognitive disability indices.⁹

Paramagnetic Rim Lesions

Neurologic worsening in PwMS occurs by 2 distinct mechanisms: relapse-associated worsening, a stepwise worsening of symptoms due to incomplete recovery following a relapse; and progression independent of relapse activity (PIRA), which is an irreversible neurologic deterioration in the absence of clinical or radiological relapses.¹⁰ PIRA is associated with neurodegeneration and predominates in both primary and secondary progressive MS. However, recent data demonstrated that PIRA may contribute to as much as 50% of disability worsening in relapsing MS and occurs early in the RMS disease course.^10,11 Current high-efficacy disease modifying therapy, such as ocrelizumab, are extraordinarily successful at preventing focal inflammation and relapses but are less effective for preventing the slow march of disability progression characterizing PIRA.^12,13 The prevention of PIRA is therefore an unmet treatment need.

Chronic active lesions (CALs) are an important driver of PIRA. When an acute gadolinium-enhancing lesion develops in PwMS, there are 3 possible fates of this lesion. The lesion may become chronically inactive, remyelinate, or transition to CALs.¹⁴ The histopathologic signature of CALs is compartmentalized, low-grade inflammation behind an intact blood-brain barrier with evidence of both active and chronic components.¹⁵ CALs may be found not only in cerebral white matter but also in the cerebral cortex and spinal cord.^16,17 Combined MRI and histopathological studies have shown that iron-laden microglia/macrophages can be detected by susceptibility-based MRI as a rim of paramagnetic signal surrounding select T2-lesions.¹⁹ These PRLs represent an in vivo imaging biomarker of CAL (Figure 1C). According to the North American Imaging in MS Cooperative (NAIMS) consensus criteria, a PRL must surround at least two-thirds of the outer edge of a T2-lesion, be visible in ≥ 2 consecutive MRI slices, and cannot be contrast enhancing.²⁰

PRLs can be visualized on multiple susceptibility-based imaging methods, including multiecho derived R2*/T2*, phase maps, susceptibility-weighted imaging, and quantitative susceptibility mapping.^21-23 Retrospective analyses have shown no significant differences in sensitivity across these imaging modalities.²⁴ Although first visualized with 7T MRI, PRLs may also be detected by 1.5T and 3T MRI with comparable sensitivities.^25-27 However, there remains a significant knowledge gap regarding the accuracy of each imaging modality. Systematic, prospectively designed studies are needed to ascertain the comparative value of each method.

The presence of PRL is a poor prognostic indicator. PwMS without PRLs have higher levels of disability, are more likely to progress, and demonstrate greater gray matter atrophy and cognitive dysfunction when compared with PwMS with PRLs.^27-29 Lesions with PRL tend to slowly expand, exhibit greater demyelination, and have diminished white matter integrity.^21,22,30

PRLs may also be used as a diagnostic tool. PRLs are highly specific for MS/CIS with a 99.7% specificity and 98.4% positive predictive value, although the sensitivity is limited to 24%.³¹ Taken together, these data indicate that the presence of a PRL substantially increases the likelihood of an MS/CIS diagnosis, whereas the absence of a PRL does not exclude these diagnoses. 

Several unanswered questions remain: Why do select acute MS lesions transition to CALs? How may investigators utilize PRLs as outcome measures in future clinical trials? How should PRLs be incorporated into the routine care of PwMS? As the role of this imaging biomarker is clarified both in the research and clinical settings, clinicians caring for PwMS can expect to increasingly encounter the topic of PRLs in the near future.

Central Vein Sign

A CVS is defined by the presence of a central vessel within a demyelinating plaque (Figure 1D). As early as the 1820s, MS plaques on gross pathology were noted to follow the course of a vessel. Early histological studies reported that up to 91% of MS plaques had a central vessel present.³² Lesion formation is dependent on the movement of lymphocytes and other inflammatory cells from the systemic circulation across the blood brain barrier into the perivascular space, a privileged site where immune cells interact with antigen presenting cells to launch an inflammatory cascade and eventual demyelinating lesion.³³

CVS can be visualized on 1.5T, 3T and 7T MRI. However, 7T MRI is superior to 3T in the detection of CVS, with 85% of MS lesions having CVS visible compared with 45% on 3T.³⁴ With advances in 7T MRI, fluid attenuated inversion recovery and T2* susceptibility, weighted sequences can be overlaid, allowing simultaneous visualization of the vessel and the demyelinating lesion. With higher density of parenchymal veins in the periventricular regions, the CVS is most seen in lesions of this territory but can also be present in juxtacortical, thalamic and infratentorial lesions with decreasing prevalence as these approach the cortex.³⁵

MS lesions are more likely to have CVS than T2 hyperintense white matter lesions of other causes, with a large study reporting 78% of MS lesions were CVS positive. Further, CVS positive lesions can be found across all MS phenotypes including relapsing remitting, primary progressive, and secondary progressive.³⁵ The CVS is also specific to MS lesions and is an effective tool for differentiating MS lesions from other common causes of T2 hyperintense lesions including chronic ischemic white matter disease,³⁶ migraines,³⁷ neuromyelitis optica spectrum disorders,^38,39 Susac syndrome,⁴⁰ and systemic autoimmune diseases (Behcet disease, systemic lupus erythematosus, and antiphospholipid syndrome).⁴¹

With CVS emerging as a promising radiographic biomarker for MS, NAIMS issued a consensus statement on necessary properties of a CVS. These criteria included appearance of a thin hypointense line or small dot, visualized in ≥ 2 perpendicular planes, with diameter < 2 mm, and running partially or entirely through the center of the lesion. They also clarified that lesions < 3 mm, confluent lesions, lesions with multiple vessels present or poorly visualized lesions were excluded.⁴²

A shared CVS definition was a necessary step toward routine use of CVS as a radiographic biomarker and its incorporation in the 2024 revised McDonald criteria.⁴³ Remaining limitations including 7T MRI is primarily available in research settings and the lack of consensus on a diagnostic threshold. There have been many proposed methods, including a 40% cut off,⁴⁴ 60% cut off,⁴⁵ and Select 3* or Select 6* methods.⁴⁶ The goal of each method is to optimize sensitivity and specificity while not compromising efficiency of MRI review for both neurologists and radiologists.

The CVS has significant potential as a radiographic biomarker for MS and may allow the early stages of MS to be differentiated from other common causes of white matter lesions on MRI. However, it remains unclear whether CVS holds prognostic value for patients, if CVS is suggestive of differing underlying pathology, or if the presence of a CVS is dynamic over time. Progress in these areas is anticipated as CVS is incorporated into routine clinical practice.

Quantitative MRI Techniques

In the research setting, several imaging modalities can be used to quantify the degree of microstructural injury in PwMS. The goal of these methods is to identify and quantify myelin and axonal damage, the major drivers of neurodegeneration. Among these methods, diffusion-based imaging is a measure of the amount of diffusion or fluid mobility across the tissues of the brain.⁴⁷ Diffusion-weighted imaging (DWI) yields several parametric maps including axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (Figure 2 A, B, and C). These parametric maps provide information on different directions of water molecules’ movements. Myelin surrounds the axons preventing water molecules diffusion perpendicular to axons (RD) while axonal content prevents water diffusion horizontal to the axons (AD).Thus, AD is considered more specific to axonal injury, whereas RD is specific to myelin content.⁴⁸ A higher value of any of these metrics is associated with a higher degree of tissue injury.

Although sensitive to axonal and myelin injury, AD and RD computed from single b-shell DWI experience several limitations including being affected by nonpathologic factors such as fiber orientation, distribution, and crossing, and by various nonmyelin specific pathologies including fluid accumulation during inflammation, myelin sheath thickness, and axonal intactness.⁴⁸ Several multi b-shell methods have been developed to overcome diffusion imaging limitations. For example, work at the Nashville VA MS Center of Excellence has focused on the use of the multicompartment diffusion MRI with spherical mean technique (SMT). This method removes the orientation dependency of the diffusion MRI signal, increasing the signal-to-noise ratio and reducing biases from fiber undulation, crossing, and dispersion.⁴⁹ SMT generates the apparent axonal volume fraction (V_ax), which is a direct measure of axonal integrity with lower values indicating lower axonal content and higher tissue destruction (Figure 2D). V_ax was previously validated in MS as a measure of axonal integrity.⁴⁹

In terms of myelin, several other specific measures have been developed. Magnetization transfer ratio (MTR) is another measure of tissue integrity that has been validated as a measure of tissue injury in MS (Figure 2E).^50,51 Zheng et al found that the percentage of lesions with low MTR was significantly higher among patients whose disease disability progressed compared with patients who did not.⁵²Selective inversion recovery with quantitative magnetization transfer (SIR-qMT) was developed to account for the limitations of MTR, including its sensitivity to edema and axonal density.⁵² Germane to myelin measurements, SIR-qMT generates the macromolecular to free size ratio (PSR). PSR represents the ratio of protons bound to macromolecules (myelin) to free protons (Figure 2F). PSR is considered a marker of myelin integrity, with lower values correlating with disability severity and indicating higher tissue damage and lower myelin content. Previous studies from the Nashville VA MS Center of Excellence validated the use of SIR-qMT among patients with MS, CIS, RIS, and healthy controls.⁵³

Quantitative MRI has several research applications in the field of MS. We demonstrated that PRL harbor a higher degree of myelin injury indicated by PSR compared with rimless lesions.⁵⁴ These MRI techniques are also helpful to investigate tissues surrounding the lesions, called normal appearing white matter (NAWM). Using quantitative MRI techniques such as MTR,⁵² PSR,⁵³ and V_ax,⁴⁹ investigators have demonstrated that NAWM is injured in PwMS, and proximal NAWM may have higher degree of tissue damage compared with distant NAWM.⁵⁵

Anticipated Innovations and Challenges

In the field of quantitative MRI, several new techniques are being adopted. Researchers are developing techniques such as myelin water fraction which evaluates the interaction between water and protons to measure myelin content. This is considered an advancement as it takes into account edema resulting from MS injury.⁵⁶ Another example is multicompartment diffusion imaging, such as standard model imaging,⁵⁷ and neurite orientation dispersion and density imaging,⁵⁸ which considers water as an additional compartment compared with the SMT derived V_ax. For PRL identification, more advanced methodologic techniques are developing such quantitative susceptibility mapping (QSM), which can detect iron deposits that surround the lesions with relatively high sensitivity and specificity of identifying PRL.⁵⁹

Despite these innovations, several challenges remain before possible incorporation into the clinical setting. These limitations include longer scan time, familiarity of clinicians in using these maps, higher financial cost, and the necessity of advanced imaging processing skills. Artificial intelligence is a promising tool that may overcome these challenges through creating automated processing pipelines and developing synthetic maps without the need for additional acquisition.⁶⁰

Conclusions

MRI is the most important tool for diagnosing and treating PwMS. Imaging biomarkers such as T2-lesions, cBHs, brain atrophy, PRLs, and CVS provide insight into the disease’s pathogenesis and are invaluable for the accurate diagnosis and prognostication of MS. Quantitative MRI techniques, while not available in the clinical setting, are important tools for translational research that may help direct the development of future therapeutics. In the near future, clinicians caring for PwMS should expect to encounter these imaging biomarkers more frequently in the clinical setting, especially with the inclusion of PRLs and CVS in the next iteration of the McDonald diagnostic criteria.

Multiple sclerosis (MS) is a complex, chronic immune-mediated disease of the central nervous system characterized by focal inflammation, demyelination, and neurodegeneration. Magnetic resonance imaging (MRI), first incorporated into the McDonald Criteria for the diagnosis of MS in 2001, is an integral tool in the diagnosis, prognosis, and therapeutic monitoring of people with MS (PwMS).¹

MRI research in MS is rapidly expanding and offers insights into the pathophysiology of MS with important implications for the routine clinical care of PwMS. At the Consortium of Multiple Sclerosis Centers 2024 Annual Meeting, the US Department of Veterans Affairs (VA) MS Centers of Excellence hosted an educational symposium highlighting MRI biomarkers in MS, including T2-lesions, chronic black holes (cBHs), brain atrophy, paramagnetic rim lesions (PRLs), and the central vein sign (CVS). The symposium also provided a brief overview of quantitative MRI techniques used to characterize MS lesion severity and research applications of these techniques. This clinical review summarizes the main points of that symposium with the goal of introducing key concepts to federal health care practitioners caring for PwMS.

MRI Biomarkers in MS

T2-lesions, Chronic Black Holes, and Brain Atrophy

Focal immune-mediated inflammation and demyelination in MS may be detected by MRI as hyperintense foci on T2-weighted (T2-w) imaging (eg, T2-w turbo spin echo or T2-w fluid attenuated inversion recovery sequences). These T2-lesions, critical for diagnosing MS, are typically ovoid and occur in the periventricular, juxtacortical, infratentorial spinal cord white matter (Figure 1A). T2-lesion number and volume show some association with disability and optic nerve.

Wattjes et al highlight 2 cases to demonstrate this point: a man aged 52 years with MS for 23 years and a woman aged 50 years with MS for 11 years. Despite having MS for a much shorter duration, the woman had worse disability due to a higher lesion number and volume.² T2-lesion volume also impacts disability progression in PwMS. Gauthier et al compared the probability of progression in 3 women, all of whom were aged 39 years and had MS for 6 years. The profile with highest probability of disability progression had the highest quartile of T2-lesion volume.³ T2-lesion volume over 2 years correlates with worse scores on disability metrics such as the MS functional composite, paced auditory serial addition task, and brain volume.⁴ A 2024 systematic review and meta-analysis demonstrated that T2-lesion volume is significantly correlated with clinical disability in PwMS.⁵

 

Select T2-lesions are also hypointense on T1-w spin echo images and are known as cBHs (Figure 1B). Histologically, T2-lesions with cBHs have more severe architectural disruption than those without cBHs.⁶ cBH number and volume are significantly correlated with disability, regardless of the degree of hypointensity on T1-w imaging.^5,7 A 10-year longitudinal study demonstrated that cBHs were associated with disease progression after 5 years while T2-lesion volume was not, indicating that cBHs may be a more accurate predictor of disability.⁸

Brain atrophy, another imaging biomarker of MS, affects both the cerebral white and gray matter. White matter fraction (the volume of white matter relative to the intracranial compartment volume) and gray matter fraction (the volume of gray matter relative to the intracranial compartment) are significantly lower among PwMS compared with healthy controls. In addition, gray matter fraction is lower among patients with primary and secondary progressive MS compared with those with relapsing-remitting MS, clinically isolated syndrome (CIS), and radiologically isolated syndrome (RIS). Gray matter fraction is also correlated with several motor and cognitive disability indices.⁹

Paramagnetic Rim Lesions

Neurologic worsening in PwMS occurs by 2 distinct mechanisms: relapse-associated worsening, a stepwise worsening of symptoms due to incomplete recovery following a relapse; and progression independent of relapse activity (PIRA), which is an irreversible neurologic deterioration in the absence of clinical or radiological relapses.¹⁰ PIRA is associated with neurodegeneration and predominates in both primary and secondary progressive MS. However, recent data demonstrated that PIRA may contribute to as much as 50% of disability worsening in relapsing MS and occurs early in the RMS disease course.^10,11 Current high-efficacy disease modifying therapy, such as ocrelizumab, are extraordinarily successful at preventing focal inflammation and relapses but are less effective for preventing the slow march of disability progression characterizing PIRA.^12,13 The prevention of PIRA is therefore an unmet treatment need.

Chronic active lesions (CALs) are an important driver of PIRA. When an acute gadolinium-enhancing lesion develops in PwMS, there are 3 possible fates of this lesion. The lesion may become chronically inactive, remyelinate, or transition to CALs.¹⁴ The histopathologic signature of CALs is compartmentalized, low-grade inflammation behind an intact blood-brain barrier with evidence of both active and chronic components.¹⁵ CALs may be found not only in cerebral white matter but also in the cerebral cortex and spinal cord.^16,17 Combined MRI and histopathological studies have shown that iron-laden microglia/macrophages can be detected by susceptibility-based MRI as a rim of paramagnetic signal surrounding select T2-lesions.¹⁹ These PRLs represent an in vivo imaging biomarker of CAL (Figure 1C). According to the North American Imaging in MS Cooperative (NAIMS) consensus criteria, a PRL must surround at least two-thirds of the outer edge of a T2-lesion, be visible in ≥ 2 consecutive MRI slices, and cannot be contrast enhancing.²⁰

PRLs can be visualized on multiple susceptibility-based imaging methods, including multiecho derived R2*/T2*, phase maps, susceptibility-weighted imaging, and quantitative susceptibility mapping.^21-23 Retrospective analyses have shown no significant differences in sensitivity across these imaging modalities.²⁴ Although first visualized with 7T MRI, PRLs may also be detected by 1.5T and 3T MRI with comparable sensitivities.^25-27 However, there remains a significant knowledge gap regarding the accuracy of each imaging modality. Systematic, prospectively designed studies are needed to ascertain the comparative value of each method.

The presence of PRL is a poor prognostic indicator. PwMS without PRLs have higher levels of disability, are more likely to progress, and demonstrate greater gray matter atrophy and cognitive dysfunction when compared with PwMS with PRLs.^27-29 Lesions with PRL tend to slowly expand, exhibit greater demyelination, and have diminished white matter integrity.^21,22,30

PRLs may also be used as a diagnostic tool. PRLs are highly specific for MS/CIS with a 99.7% specificity and 98.4% positive predictive value, although the sensitivity is limited to 24%.³¹ Taken together, these data indicate that the presence of a PRL substantially increases the likelihood of an MS/CIS diagnosis, whereas the absence of a PRL does not exclude these diagnoses. 

Several unanswered questions remain: Why do select acute MS lesions transition to CALs? How may investigators utilize PRLs as outcome measures in future clinical trials? How should PRLs be incorporated into the routine care of PwMS? As the role of this imaging biomarker is clarified both in the research and clinical settings, clinicians caring for PwMS can expect to increasingly encounter the topic of PRLs in the near future.

Central Vein Sign

A CVS is defined by the presence of a central vessel within a demyelinating plaque (Figure 1D). As early as the 1820s, MS plaques on gross pathology were noted to follow the course of a vessel. Early histological studies reported that up to 91% of MS plaques had a central vessel present.³² Lesion formation is dependent on the movement of lymphocytes and other inflammatory cells from the systemic circulation across the blood brain barrier into the perivascular space, a privileged site where immune cells interact with antigen presenting cells to launch an inflammatory cascade and eventual demyelinating lesion.³³

CVS can be visualized on 1.5T, 3T and 7T MRI. However, 7T MRI is superior to 3T in the detection of CVS, with 85% of MS lesions having CVS visible compared with 45% on 3T.³⁴ With advances in 7T MRI, fluid attenuated inversion recovery and T2* susceptibility, weighted sequences can be overlaid, allowing simultaneous visualization of the vessel and the demyelinating lesion. With higher density of parenchymal veins in the periventricular regions, the CVS is most seen in lesions of this territory but can also be present in juxtacortical, thalamic and infratentorial lesions with decreasing prevalence as these approach the cortex.³⁵

MS lesions are more likely to have CVS than T2 hyperintense white matter lesions of other causes, with a large study reporting 78% of MS lesions were CVS positive. Further, CVS positive lesions can be found across all MS phenotypes including relapsing remitting, primary progressive, and secondary progressive.³⁵ The CVS is also specific to MS lesions and is an effective tool for differentiating MS lesions from other common causes of T2 hyperintense lesions including chronic ischemic white matter disease,³⁶ migraines,³⁷ neuromyelitis optica spectrum disorders,^38,39 Susac syndrome,⁴⁰ and systemic autoimmune diseases (Behcet disease, systemic lupus erythematosus, and antiphospholipid syndrome).⁴¹

With CVS emerging as a promising radiographic biomarker for MS, NAIMS issued a consensus statement on necessary properties of a CVS. These criteria included appearance of a thin hypointense line or small dot, visualized in ≥ 2 perpendicular planes, with diameter < 2 mm, and running partially or entirely through the center of the lesion. They also clarified that lesions < 3 mm, confluent lesions, lesions with multiple vessels present or poorly visualized lesions were excluded.⁴²

A shared CVS definition was a necessary step toward routine use of CVS as a radiographic biomarker and its incorporation in the 2024 revised McDonald criteria.⁴³ Remaining limitations including 7T MRI is primarily available in research settings and the lack of consensus on a diagnostic threshold. There have been many proposed methods, including a 40% cut off,⁴⁴ 60% cut off,⁴⁵ and Select 3* or Select 6* methods.⁴⁶ The goal of each method is to optimize sensitivity and specificity while not compromising efficiency of MRI review for both neurologists and radiologists.

The CVS has significant potential as a radiographic biomarker for MS and may allow the early stages of MS to be differentiated from other common causes of white matter lesions on MRI. However, it remains unclear whether CVS holds prognostic value for patients, if CVS is suggestive of differing underlying pathology, or if the presence of a CVS is dynamic over time. Progress in these areas is anticipated as CVS is incorporated into routine clinical practice.

Quantitative MRI Techniques

In the research setting, several imaging modalities can be used to quantify the degree of microstructural injury in PwMS. The goal of these methods is to identify and quantify myelin and axonal damage, the major drivers of neurodegeneration. Among these methods, diffusion-based imaging is a measure of the amount of diffusion or fluid mobility across the tissues of the brain.⁴⁷ Diffusion-weighted imaging (DWI) yields several parametric maps including axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (Figure 2 A, B, and C). These parametric maps provide information on different directions of water molecules’ movements. Myelin surrounds the axons preventing water molecules diffusion perpendicular to axons (RD) while axonal content prevents water diffusion horizontal to the axons (AD).Thus, AD is considered more specific to axonal injury, whereas RD is specific to myelin content.⁴⁸ A higher value of any of these metrics is associated with a higher degree of tissue injury.

Although sensitive to axonal and myelin injury, AD and RD computed from single b-shell DWI experience several limitations including being affected by nonpathologic factors such as fiber orientation, distribution, and crossing, and by various nonmyelin specific pathologies including fluid accumulation during inflammation, myelin sheath thickness, and axonal intactness.⁴⁸ Several multi b-shell methods have been developed to overcome diffusion imaging limitations. For example, work at the Nashville VA MS Center of Excellence has focused on the use of the multicompartment diffusion MRI with spherical mean technique (SMT). This method removes the orientation dependency of the diffusion MRI signal, increasing the signal-to-noise ratio and reducing biases from fiber undulation, crossing, and dispersion.⁴⁹ SMT generates the apparent axonal volume fraction (V_ax), which is a direct measure of axonal integrity with lower values indicating lower axonal content and higher tissue destruction (Figure 2D). V_ax was previously validated in MS as a measure of axonal integrity.⁴⁹

In terms of myelin, several other specific measures have been developed. Magnetization transfer ratio (MTR) is another measure of tissue integrity that has been validated as a measure of tissue injury in MS (Figure 2E).^50,51 Zheng et al found that the percentage of lesions with low MTR was significantly higher among patients whose disease disability progressed compared with patients who did not.⁵²Selective inversion recovery with quantitative magnetization transfer (SIR-qMT) was developed to account for the limitations of MTR, including its sensitivity to edema and axonal density.⁵² Germane to myelin measurements, SIR-qMT generates the macromolecular to free size ratio (PSR). PSR represents the ratio of protons bound to macromolecules (myelin) to free protons (Figure 2F). PSR is considered a marker of myelin integrity, with lower values correlating with disability severity and indicating higher tissue damage and lower myelin content. Previous studies from the Nashville VA MS Center of Excellence validated the use of SIR-qMT among patients with MS, CIS, RIS, and healthy controls.⁵³

Quantitative MRI has several research applications in the field of MS. We demonstrated that PRL harbor a higher degree of myelin injury indicated by PSR compared with rimless lesions.⁵⁴ These MRI techniques are also helpful to investigate tissues surrounding the lesions, called normal appearing white matter (NAWM). Using quantitative MRI techniques such as MTR,⁵² PSR,⁵³ and V_ax,⁴⁹ investigators have demonstrated that NAWM is injured in PwMS, and proximal NAWM may have higher degree of tissue damage compared with distant NAWM.⁵⁵

Anticipated Innovations and Challenges

In the field of quantitative MRI, several new techniques are being adopted. Researchers are developing techniques such as myelin water fraction which evaluates the interaction between water and protons to measure myelin content. This is considered an advancement as it takes into account edema resulting from MS injury.⁵⁶ Another example is multicompartment diffusion imaging, such as standard model imaging,⁵⁷ and neurite orientation dispersion and density imaging,⁵⁸ which considers water as an additional compartment compared with the SMT derived V_ax. For PRL identification, more advanced methodologic techniques are developing such quantitative susceptibility mapping (QSM), which can detect iron deposits that surround the lesions with relatively high sensitivity and specificity of identifying PRL.⁵⁹

Despite these innovations, several challenges remain before possible incorporation into the clinical setting. These limitations include longer scan time, familiarity of clinicians in using these maps, higher financial cost, and the necessity of advanced imaging processing skills. Artificial intelligence is a promising tool that may overcome these challenges through creating automated processing pipelines and developing synthetic maps without the need for additional acquisition.⁶⁰

Conclusions

MRI is the most important tool for diagnosing and treating PwMS. Imaging biomarkers such as T2-lesions, cBHs, brain atrophy, PRLs, and CVS provide insight into the disease’s pathogenesis and are invaluable for the accurate diagnosis and prognostication of MS. Quantitative MRI techniques, while not available in the clinical setting, are important tools for translational research that may help direct the development of future therapeutics. In the near future, clinicians caring for PwMS should expect to encounter these imaging biomarkers more frequently in the clinical setting, especially with the inclusion of PRLs and CVS in the next iteration of the McDonald diagnostic criteria.

Multiple sclerosis (MS) is a complex, chronic immune-mediated disease of the central nervous system characterized by focal inflammation, demyelination, and neurodegeneration. Magnetic resonance imaging (MRI), first incorporated into the McDonald Criteria for the diagnosis of MS in 2001, is an integral tool in the diagnosis, prognosis, and therapeutic monitoring of people with MS (PwMS).¹

MRI research in MS is rapidly expanding and offers insights into the pathophysiology of MS with important implications for the routine clinical care of PwMS. At the Consortium of Multiple Sclerosis Centers 2024 Annual Meeting, the US Department of Veterans Affairs (VA) MS Centers of Excellence hosted an educational symposium highlighting MRI biomarkers in MS, including T2-lesions, chronic black holes (cBHs), brain atrophy, paramagnetic rim lesions (PRLs), and the central vein sign (CVS). The symposium also provided a brief overview of quantitative MRI techniques used to characterize MS lesion severity and research applications of these techniques. This clinical review summarizes the main points of that symposium with the goal of introducing key concepts to federal health care practitioners caring for PwMS.

MRI Biomarkers in MS

T2-lesions, Chronic Black Holes, and Brain Atrophy

Focal immune-mediated inflammation and demyelination in MS may be detected by MRI as hyperintense foci on T2-weighted (T2-w) imaging (eg, T2-w turbo spin echo or T2-w fluid attenuated inversion recovery sequences). These T2-lesions, critical for diagnosing MS, are typically ovoid and occur in the periventricular, juxtacortical, infratentorial spinal cord white matter (Figure 1A). T2-lesion number and volume show some association with disability and optic nerve.

Wattjes et al highlight 2 cases to demonstrate this point: a man aged 52 years with MS for 23 years and a woman aged 50 years with MS for 11 years. Despite having MS for a much shorter duration, the woman had worse disability due to a higher lesion number and volume.² T2-lesion volume also impacts disability progression in PwMS. Gauthier et al compared the probability of progression in 3 women, all of whom were aged 39 years and had MS for 6 years. The profile with highest probability of disability progression had the highest quartile of T2-lesion volume.³ T2-lesion volume over 2 years correlates with worse scores on disability metrics such as the MS functional composite, paced auditory serial addition task, and brain volume.⁴ A 2024 systematic review and meta-analysis demonstrated that T2-lesion volume is significantly correlated with clinical disability in PwMS.⁵

 

Select T2-lesions are also hypointense on T1-w spin echo images and are known as cBHs (Figure 1B). Histologically, T2-lesions with cBHs have more severe architectural disruption than those without cBHs.⁶ cBH number and volume are significantly correlated with disability, regardless of the degree of hypointensity on T1-w imaging.^5,7 A 10-year longitudinal study demonstrated that cBHs were associated with disease progression after 5 years while T2-lesion volume was not, indicating that cBHs may be a more accurate predictor of disability.⁸

Brain atrophy, another imaging biomarker of MS, affects both the cerebral white and gray matter. White matter fraction (the volume of white matter relative to the intracranial compartment volume) and gray matter fraction (the volume of gray matter relative to the intracranial compartment) are significantly lower among PwMS compared with healthy controls. In addition, gray matter fraction is lower among patients with primary and secondary progressive MS compared with those with relapsing-remitting MS, clinically isolated syndrome (CIS), and radiologically isolated syndrome (RIS). Gray matter fraction is also correlated with several motor and cognitive disability indices.⁹

Paramagnetic Rim Lesions

Neurologic worsening in PwMS occurs by 2 distinct mechanisms: relapse-associated worsening, a stepwise worsening of symptoms due to incomplete recovery following a relapse; and progression independent of relapse activity (PIRA), which is an irreversible neurologic deterioration in the absence of clinical or radiological relapses.¹⁰ PIRA is associated with neurodegeneration and predominates in both primary and secondary progressive MS. However, recent data demonstrated that PIRA may contribute to as much as 50% of disability worsening in relapsing MS and occurs early in the RMS disease course.^10,11 Current high-efficacy disease modifying therapy, such as ocrelizumab, are extraordinarily successful at preventing focal inflammation and relapses but are less effective for preventing the slow march of disability progression characterizing PIRA.^12,13 The prevention of PIRA is therefore an unmet treatment need.

Chronic active lesions (CALs) are an important driver of PIRA. When an acute gadolinium-enhancing lesion develops in PwMS, there are 3 possible fates of this lesion. The lesion may become chronically inactive, remyelinate, or transition to CALs.¹⁴ The histopathologic signature of CALs is compartmentalized, low-grade inflammation behind an intact blood-brain barrier with evidence of both active and chronic components.¹⁵ CALs may be found not only in cerebral white matter but also in the cerebral cortex and spinal cord.^16,17 Combined MRI and histopathological studies have shown that iron-laden microglia/macrophages can be detected by susceptibility-based MRI as a rim of paramagnetic signal surrounding select T2-lesions.¹⁹ These PRLs represent an in vivo imaging biomarker of CAL (Figure 1C). According to the North American Imaging in MS Cooperative (NAIMS) consensus criteria, a PRL must surround at least two-thirds of the outer edge of a T2-lesion, be visible in ≥ 2 consecutive MRI slices, and cannot be contrast enhancing.²⁰

PRLs can be visualized on multiple susceptibility-based imaging methods, including multiecho derived R2*/T2*, phase maps, susceptibility-weighted imaging, and quantitative susceptibility mapping.^21-23 Retrospective analyses have shown no significant differences in sensitivity across these imaging modalities.²⁴ Although first visualized with 7T MRI, PRLs may also be detected by 1.5T and 3T MRI with comparable sensitivities.^25-27 However, there remains a significant knowledge gap regarding the accuracy of each imaging modality. Systematic, prospectively designed studies are needed to ascertain the comparative value of each method.

The presence of PRL is a poor prognostic indicator. PwMS without PRLs have higher levels of disability, are more likely to progress, and demonstrate greater gray matter atrophy and cognitive dysfunction when compared with PwMS with PRLs.^27-29 Lesions with PRL tend to slowly expand, exhibit greater demyelination, and have diminished white matter integrity.^21,22,30

PRLs may also be used as a diagnostic tool. PRLs are highly specific for MS/CIS with a 99.7% specificity and 98.4% positive predictive value, although the sensitivity is limited to 24%.³¹ Taken together, these data indicate that the presence of a PRL substantially increases the likelihood of an MS/CIS diagnosis, whereas the absence of a PRL does not exclude these diagnoses. 

Several unanswered questions remain: Why do select acute MS lesions transition to CALs? How may investigators utilize PRLs as outcome measures in future clinical trials? How should PRLs be incorporated into the routine care of PwMS? As the role of this imaging biomarker is clarified both in the research and clinical settings, clinicians caring for PwMS can expect to increasingly encounter the topic of PRLs in the near future.

Central Vein Sign

A CVS is defined by the presence of a central vessel within a demyelinating plaque (Figure 1D). As early as the 1820s, MS plaques on gross pathology were noted to follow the course of a vessel. Early histological studies reported that up to 91% of MS plaques had a central vessel present.³² Lesion formation is dependent on the movement of lymphocytes and other inflammatory cells from the systemic circulation across the blood brain barrier into the perivascular space, a privileged site where immune cells interact with antigen presenting cells to launch an inflammatory cascade and eventual demyelinating lesion.³³

CVS can be visualized on 1.5T, 3T and 7T MRI. However, 7T MRI is superior to 3T in the detection of CVS, with 85% of MS lesions having CVS visible compared with 45% on 3T.³⁴ With advances in 7T MRI, fluid attenuated inversion recovery and T2* susceptibility, weighted sequences can be overlaid, allowing simultaneous visualization of the vessel and the demyelinating lesion. With higher density of parenchymal veins in the periventricular regions, the CVS is most seen in lesions of this territory but can also be present in juxtacortical, thalamic and infratentorial lesions with decreasing prevalence as these approach the cortex.³⁵

MS lesions are more likely to have CVS than T2 hyperintense white matter lesions of other causes, with a large study reporting 78% of MS lesions were CVS positive. Further, CVS positive lesions can be found across all MS phenotypes including relapsing remitting, primary progressive, and secondary progressive.³⁵ The CVS is also specific to MS lesions and is an effective tool for differentiating MS lesions from other common causes of T2 hyperintense lesions including chronic ischemic white matter disease,³⁶ migraines,³⁷ neuromyelitis optica spectrum disorders,^38,39 Susac syndrome,⁴⁰ and systemic autoimmune diseases (Behcet disease, systemic lupus erythematosus, and antiphospholipid syndrome).⁴¹

With CVS emerging as a promising radiographic biomarker for MS, NAIMS issued a consensus statement on necessary properties of a CVS. These criteria included appearance of a thin hypointense line or small dot, visualized in ≥ 2 perpendicular planes, with diameter < 2 mm, and running partially or entirely through the center of the lesion. They also clarified that lesions < 3 mm, confluent lesions, lesions with multiple vessels present or poorly visualized lesions were excluded.⁴²

A shared CVS definition was a necessary step toward routine use of CVS as a radiographic biomarker and its incorporation in the 2024 revised McDonald criteria.⁴³ Remaining limitations including 7T MRI is primarily available in research settings and the lack of consensus on a diagnostic threshold. There have been many proposed methods, including a 40% cut off,⁴⁴ 60% cut off,⁴⁵ and Select 3* or Select 6* methods.⁴⁶ The goal of each method is to optimize sensitivity and specificity while not compromising efficiency of MRI review for both neurologists and radiologists.

The CVS has significant potential as a radiographic biomarker for MS and may allow the early stages of MS to be differentiated from other common causes of white matter lesions on MRI. However, it remains unclear whether CVS holds prognostic value for patients, if CVS is suggestive of differing underlying pathology, or if the presence of a CVS is dynamic over time. Progress in these areas is anticipated as CVS is incorporated into routine clinical practice.

Quantitative MRI Techniques

In the research setting, several imaging modalities can be used to quantify the degree of microstructural injury in PwMS. The goal of these methods is to identify and quantify myelin and axonal damage, the major drivers of neurodegeneration. Among these methods, diffusion-based imaging is a measure of the amount of diffusion or fluid mobility across the tissues of the brain.⁴⁷ Diffusion-weighted imaging (DWI) yields several parametric maps including axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (Figure 2 A, B, and C). These parametric maps provide information on different directions of water molecules’ movements. Myelin surrounds the axons preventing water molecules diffusion perpendicular to axons (RD) while axonal content prevents water diffusion horizontal to the axons (AD).Thus, AD is considered more specific to axonal injury, whereas RD is specific to myelin content.⁴⁸ A higher value of any of these metrics is associated with a higher degree of tissue injury.

Although sensitive to axonal and myelin injury, AD and RD computed from single b-shell DWI experience several limitations including being affected by nonpathologic factors such as fiber orientation, distribution, and crossing, and by various nonmyelin specific pathologies including fluid accumulation during inflammation, myelin sheath thickness, and axonal intactness.⁴⁸ Several multi b-shell methods have been developed to overcome diffusion imaging limitations. For example, work at the Nashville VA MS Center of Excellence has focused on the use of the multicompartment diffusion MRI with spherical mean technique (SMT). This method removes the orientation dependency of the diffusion MRI signal, increasing the signal-to-noise ratio and reducing biases from fiber undulation, crossing, and dispersion.⁴⁹ SMT generates the apparent axonal volume fraction (V_ax), which is a direct measure of axonal integrity with lower values indicating lower axonal content and higher tissue destruction (Figure 2D). V_ax was previously validated in MS as a measure of axonal integrity.⁴⁹

In terms of myelin, several other specific measures have been developed. Magnetization transfer ratio (MTR) is another measure of tissue integrity that has been validated as a measure of tissue injury in MS (Figure 2E).^50,51 Zheng et al found that the percentage of lesions with low MTR was significantly higher among patients whose disease disability progressed compared with patients who did not.⁵²Selective inversion recovery with quantitative magnetization transfer (SIR-qMT) was developed to account for the limitations of MTR, including its sensitivity to edema and axonal density.⁵² Germane to myelin measurements, SIR-qMT generates the macromolecular to free size ratio (PSR). PSR represents the ratio of protons bound to macromolecules (myelin) to free protons (Figure 2F). PSR is considered a marker of myelin integrity, with lower values correlating with disability severity and indicating higher tissue damage and lower myelin content. Previous studies from the Nashville VA MS Center of Excellence validated the use of SIR-qMT among patients with MS, CIS, RIS, and healthy controls.⁵³

Quantitative MRI has several research applications in the field of MS. We demonstrated that PRL harbor a higher degree of myelin injury indicated by PSR compared with rimless lesions.⁵⁴ These MRI techniques are also helpful to investigate tissues surrounding the lesions, called normal appearing white matter (NAWM). Using quantitative MRI techniques such as MTR,⁵² PSR,⁵³ and V_ax,⁴⁹ investigators have demonstrated that NAWM is injured in PwMS, and proximal NAWM may have higher degree of tissue damage compared with distant NAWM.⁵⁵

Anticipated Innovations and Challenges

In the field of quantitative MRI, several new techniques are being adopted. Researchers are developing techniques such as myelin water fraction which evaluates the interaction between water and protons to measure myelin content. This is considered an advancement as it takes into account edema resulting from MS injury.⁵⁶ Another example is multicompartment diffusion imaging, such as standard model imaging,⁵⁷ and neurite orientation dispersion and density imaging,⁵⁸ which considers water as an additional compartment compared with the SMT derived V_ax. For PRL identification, more advanced methodologic techniques are developing such quantitative susceptibility mapping (QSM), which can detect iron deposits that surround the lesions with relatively high sensitivity and specificity of identifying PRL.⁵⁹

Despite these innovations, several challenges remain before possible incorporation into the clinical setting. These limitations include longer scan time, familiarity of clinicians in using these maps, higher financial cost, and the necessity of advanced imaging processing skills. Artificial intelligence is a promising tool that may overcome these challenges through creating automated processing pipelines and developing synthetic maps without the need for additional acquisition.⁶⁰

Conclusions

MRI is the most important tool for diagnosing and treating PwMS. Imaging biomarkers such as T2-lesions, cBHs, brain atrophy, PRLs, and CVS provide insight into the disease’s pathogenesis and are invaluable for the accurate diagnosis and prognostication of MS. Quantitative MRI techniques, while not available in the clinical setting, are important tools for translational research that may help direct the development of future therapeutics. In the near future, clinicians caring for PwMS should expect to encounter these imaging biomarkers more frequently in the clinical setting, especially with the inclusion of PRLs and CVS in the next iteration of the McDonald diagnostic criteria.

In 2020, the US Multi-Society Task Force (USMSTF) on Colorectal Cancer (CRC) increased the recommended colon polyp surveillance interval for 1 to 2 subcentimeter tubular adenomas from 5 to 10 years to 7 to 10 years.¹ This change was prompted by emerging research indicating that rates of CRC and advanced neoplasia among patients with a history of only 1 to 2 subcentimeter tubular adenomas are lower than initially estimated.^2,3 This extension provides an opportunity to increase endoscopy capacity and improve access to colonoscopies by retroactively applying the 2020 guidelines to surveillance interval recommendations made before their introduction. For example, based on the updated guidelines, patients previously recommended to undergo colon polyp surveillance colonoscopy 5 years after an index colonoscopy could extend their surveillance interval by 2 to 5 years. Increasing endoscopic capacity could address the growing demand for colonoscopies from new screening guidelines that reduced the age of initial CRC screening from 50 years to 45 years and the backlog of procedures due to COVID-19 restrictions.⁴

As part of a project to increase endoscopic capacity at the US Department of Veterans Affairs (VA) Pittsburgh Healthcare System (VAPHS), this study assessed the potential impact of retroactively applying the 2020 USMSTF polyp surveillance guidelines on endoscopic capacity. These results may be informative for other VA and private-sector health care systems seeking to identify strategies to improve endoscopy capacity.

Methods

VAPHS is an integrated health care system in the Veterans Health Administration (VHA) serving 85,000 patients across 8 health care institutions in Pennsylvania, Ohio, and West Virginia. VAPHS manages colorectal screening recommendations for patients receiving medical care in the health care system regardless of whether their prior colonoscopy was performed at VAPHS or external facilities. The VA maintains a national CRC screening and surveillance electronic medical record reminder that prompts health care practitioners to order colon polyp surveillance based on interval recommendations from the index colonoscopy. This study reviewed all patients from the VAPHS panel with a reminder to undergo colonoscopy for screening for CRC or surveillance of colon polyps within 12 months from September 1, 2022.

Among patients with a reminder, 3 investigators reviewed index colonoscopy and pathology reports to identify CRC risk category, colonoscopy indication, procedural quality, and recommended repeat colonoscopy interval. Per the USMSTF guidelines, patients with incomplete colonoscopy or pathology records, high-risk indications (ie, personal history of inflammatory bowel disease, personal history of CRC, or family history of CRC), or inadequate bowel preparation (Boston Bowel Preparation Score < 6) were excluded. Additionally, patients who had CRC screening or surveillance discontinued due to age or comorbidities, had completed a subsequent follow-up colonoscopy, or were deceased at the time of review were excluded.

Retroactive Interval Reclassification

Among eligible patients, this study compared the repeat colonoscopy interval recommended by the prior endoscopist with those from the 2020 USMSTF guidelines. In cases where the interval was documented as a range of years, the lower end was considered the recommendation. Similarly, the lower end of the range from the 2020 USMSTF guidelines was used for the reclassified surveillance interval. Years extended per patient were quantified relative to September 1, 2023 (ie, 1 year after the review date). For example, if the index colonoscopy was completed on September 1, 2016, the initial surveillance recommendation was 5 years, and the reclassified recommendation was 7 years, the interval extension beyond September 1, 2023, was 0 years.

Furthermore, because index surveillance recommendations are not always guideline concordant, the years extended per patient were calculated by harmonizing the index endoscopist’s recommendations with the guidelines at the time of the index colonoscopy.⁵ For example, if the index colonoscopy was completed on September 1, 2018, and the endoscopist recommended a 5-year follow-up for a patient with average risk for CRC, adequate bowel preparation, and no colorectal polyps, that patient is eligible to extend their colonoscopy to September 1, 2028, based on guideline recommendations at the time of index endoscopy recommending that the next colonoscopy occur in 10 years. In this analysis the 2012 USMSTF guidelines were applied to all index colonoscopies completed in 2021 or earlier to allow time for adoption of the 2020 guidelines. 

This project fulfilled a facility mandate to increase capacity to conduct endoscopic procedures. Institutional review board approval was not required by VAPHS policy relating to clinical operations projects. Approval for publication of clinical operations activity was obtained from the VAPHS facility director.

Results

Within 1 year of the September 1, 2022, review date, 637 patients receiving care at VAPHS had clinical reminders for an upcoming colonoscopy. Of these, 54 (8.4%) were already up to date or were deceased at the time of review. Of the 583 eligible patients, 96% were male, the median age was 74 years, the median index colonoscopy year was 2016, and 178 (30.5%) had an average-risk CRC screening indication at the index colonoscopy (Table).

Of the 583 patients due for colonoscopy, 331 (56.7%) had both colonoscopy and pathology reports available. The majority of those with incomplete records had the index colonoscopy completed outside VAPHS. Among these patients, 222 (67.0%) had adequate bowel preparation. Of those with adequate bowel preparation, 43 were not eligible for interval extension because of high-risk conditions and 13 were not eligible because there was no index surveillance interval recommendation from the index endoscopist. Of the patients due for colonoscopy, 166 (28.4%) were potentially eligible for surveillance interval extension (Figure).  

Sixty-five (39.2%) of the 166 patients had 1 to 2 subcentimeter tubular adenomas on their index colonoscopy. Sixty-two patients were eligible for interval extension to 7 years, but this only resulted in ≥ 1 year of extension beyond the review date for 36 (6% of all 583 patients due for colonoscopy). The 36 patients were extended 63 years. By harmonizing the index endoscopists’ surveillance interval recommendation with the guideline at the time of the index colonoscopy, 29 additional patients could have their colonoscopy extended by ≥ 1 year. Harmonization extended colonoscopy intervals by 93 years. Retroactively applying the 2020 USMSTF polyp surveillance guidelines and harmonizing recommendations to guidelines extended the time of index colonoscopy by 153 years.

Discussion

With retroactive application of the 2020 USMSTF polyp surveillance guidelines, 6% of patients due for an upcoming colonoscopy could extend their follow-up by ≥ 1 year by extending the surveillance interval for 1 to 2 subcentimeter tubular adenomas to 7 years. An additional 5% of patients could extend their interval by harmonizing the index endoscopist’s interval recommendation with polyp surveillance guidelines at the time of the index colonoscopy. These findings are consistent with the results of 2 studies that demonstrated that about 14% of patients due for colonoscopy could have their interval extended.^6,7 The current study enhances those insights by separating the contribution of 2020 USMSTF polyp surveillance guidelines from the contribution of harmonizing surveillance intervals with guidelines for other polyp histologies. This study found that there is an opportunity to improve endoscopic capacity by harmonizing recommendations with guidelines. This complements a 2023 study showing that even when knowledgeable about guidelines, clinicians do not necessarily follow recommendations.⁸ While this and previous research have identified that 11% to 14% of patients are eligible for extension, these individuals would also have to be willing to have their polyp surveillance intervals extended for there to be a real-world impact on endoscopic capacity. A 2024 study found that only 19% to 37% of patients with 1 to 2 small tubular adenomas were willing to have polyps surveillance interval extension.⁹ This suggests the actual effect on capacity may be even lower than reported.

Limitations

The overall impact of the 2020 USMSTF polyp surveillance guidelines on endoscopic capacity was blunted by the high prevalence of incomplete index colonoscopy records among the study population. Without data on bowel preparation quality or procedure indications, this study could not assess whether 43% of patients were eligible for surveillance interval extension. Most index colonoscopies with incomplete documentation were completed at community-care gastroenterology facilities. This high rate of incomplete documentation is likely generalizable to other VA health care systems—especially in the era of the Veterans Access, Choice, and Accountability Act of 2014, which increased veteran access to non-VA community care.¹⁰ Veterans due for colon polyp surveillance colonoscopies are more likely to have had their prior colonoscopy in community care compared with prior eras.¹¹ Furthermore, because the VHA is among the most established integrated health care systems offering primary and subspecialty care in the US, private sector health care systems may have even greater rates of care fragmentation for longitudinal CRC screening and colon polyp surveillance, as these systems have only begun to regionally integrate recently.^12,13

Another limitation is that nearly one-third of the individuals with documentation had inadequate bowel preparation for surveillance recommendations. This results in shorter surveillance follow-up colonoscopies and increases downstream demand for future colonoscopies. The low yield of extending colon polyp surveillance interval in this study emphasizes that improved efforts to obtain colonoscopy and pathology reports from community care, right-sizing the colon polyp surveillance intervals recommended by endoscopists, and improving quality of bowel preparation could have downstream health care system benefits in the future. These efforts could increase colonoscopy capacity at VA health care systems, thereby shortening colonoscopy wait times, decreasing fragmentation of care, and increasing the number of veterans who receive high-quality colonoscopies at VA health care systems.¹⁴

Conclusions

Eleven percent of patients in this study due for a colonoscopy could extend their follow-up by ≥ 1 year. About half of these extensions were directly due to the 2020 USMSTF polyp surveillance interval extension for 1 to 2 subcentimeter tubular adenomas. The rest resulted from harmonizing recommendations with guidelines at the time of the procedure. To determine whether retroactively applying polyp surveillance guidelines to follow-up interval recommendations will result in improved endoscopic capacity, health care system administrators should consider the degree of CRC screening care fragmentation in their patient population. Greater long-term gains in endoscopic capacity may be achieved by proactively supporting endoscopists in making guideline-concordant screening recommendations at the time of colonoscopy.

In 2020, the US Multi-Society Task Force (USMSTF) on Colorectal Cancer (CRC) increased the recommended colon polyp surveillance interval for 1 to 2 subcentimeter tubular adenomas from 5 to 10 years to 7 to 10 years.¹ This change was prompted by emerging research indicating that rates of CRC and advanced neoplasia among patients with a history of only 1 to 2 subcentimeter tubular adenomas are lower than initially estimated.^2,3 This extension provides an opportunity to increase endoscopy capacity and improve access to colonoscopies by retroactively applying the 2020 guidelines to surveillance interval recommendations made before their introduction. For example, based on the updated guidelines, patients previously recommended to undergo colon polyp surveillance colonoscopy 5 years after an index colonoscopy could extend their surveillance interval by 2 to 5 years. Increasing endoscopic capacity could address the growing demand for colonoscopies from new screening guidelines that reduced the age of initial CRC screening from 50 years to 45 years and the backlog of procedures due to COVID-19 restrictions.⁴

As part of a project to increase endoscopic capacity at the US Department of Veterans Affairs (VA) Pittsburgh Healthcare System (VAPHS), this study assessed the potential impact of retroactively applying the 2020 USMSTF polyp surveillance guidelines on endoscopic capacity. These results may be informative for other VA and private-sector health care systems seeking to identify strategies to improve endoscopy capacity.

Methods

VAPHS is an integrated health care system in the Veterans Health Administration (VHA) serving 85,000 patients across 8 health care institutions in Pennsylvania, Ohio, and West Virginia. VAPHS manages colorectal screening recommendations for patients receiving medical care in the health care system regardless of whether their prior colonoscopy was performed at VAPHS or external facilities. The VA maintains a national CRC screening and surveillance electronic medical record reminder that prompts health care practitioners to order colon polyp surveillance based on interval recommendations from the index colonoscopy. This study reviewed all patients from the VAPHS panel with a reminder to undergo colonoscopy for screening for CRC or surveillance of colon polyps within 12 months from September 1, 2022.

Among patients with a reminder, 3 investigators reviewed index colonoscopy and pathology reports to identify CRC risk category, colonoscopy indication, procedural quality, and recommended repeat colonoscopy interval. Per the USMSTF guidelines, patients with incomplete colonoscopy or pathology records, high-risk indications (ie, personal history of inflammatory bowel disease, personal history of CRC, or family history of CRC), or inadequate bowel preparation (Boston Bowel Preparation Score < 6) were excluded. Additionally, patients who had CRC screening or surveillance discontinued due to age or comorbidities, had completed a subsequent follow-up colonoscopy, or were deceased at the time of review were excluded.

Retroactive Interval Reclassification

Among eligible patients, this study compared the repeat colonoscopy interval recommended by the prior endoscopist with those from the 2020 USMSTF guidelines. In cases where the interval was documented as a range of years, the lower end was considered the recommendation. Similarly, the lower end of the range from the 2020 USMSTF guidelines was used for the reclassified surveillance interval. Years extended per patient were quantified relative to September 1, 2023 (ie, 1 year after the review date). For example, if the index colonoscopy was completed on September 1, 2016, the initial surveillance recommendation was 5 years, and the reclassified recommendation was 7 years, the interval extension beyond September 1, 2023, was 0 years.

Furthermore, because index surveillance recommendations are not always guideline concordant, the years extended per patient were calculated by harmonizing the index endoscopist’s recommendations with the guidelines at the time of the index colonoscopy.⁵ For example, if the index colonoscopy was completed on September 1, 2018, and the endoscopist recommended a 5-year follow-up for a patient with average risk for CRC, adequate bowel preparation, and no colorectal polyps, that patient is eligible to extend their colonoscopy to September 1, 2028, based on guideline recommendations at the time of index endoscopy recommending that the next colonoscopy occur in 10 years. In this analysis the 2012 USMSTF guidelines were applied to all index colonoscopies completed in 2021 or earlier to allow time for adoption of the 2020 guidelines. 

This project fulfilled a facility mandate to increase capacity to conduct endoscopic procedures. Institutional review board approval was not required by VAPHS policy relating to clinical operations projects. Approval for publication of clinical operations activity was obtained from the VAPHS facility director.

Results

Within 1 year of the September 1, 2022, review date, 637 patients receiving care at VAPHS had clinical reminders for an upcoming colonoscopy. Of these, 54 (8.4%) were already up to date or were deceased at the time of review. Of the 583 eligible patients, 96% were male, the median age was 74 years, the median index colonoscopy year was 2016, and 178 (30.5%) had an average-risk CRC screening indication at the index colonoscopy (Table).

Of the 583 patients due for colonoscopy, 331 (56.7%) had both colonoscopy and pathology reports available. The majority of those with incomplete records had the index colonoscopy completed outside VAPHS. Among these patients, 222 (67.0%) had adequate bowel preparation. Of those with adequate bowel preparation, 43 were not eligible for interval extension because of high-risk conditions and 13 were not eligible because there was no index surveillance interval recommendation from the index endoscopist. Of the patients due for colonoscopy, 166 (28.4%) were potentially eligible for surveillance interval extension (Figure).  

Sixty-five (39.2%) of the 166 patients had 1 to 2 subcentimeter tubular adenomas on their index colonoscopy. Sixty-two patients were eligible for interval extension to 7 years, but this only resulted in ≥ 1 year of extension beyond the review date for 36 (6% of all 583 patients due for colonoscopy). The 36 patients were extended 63 years. By harmonizing the index endoscopists’ surveillance interval recommendation with the guideline at the time of the index colonoscopy, 29 additional patients could have their colonoscopy extended by ≥ 1 year. Harmonization extended colonoscopy intervals by 93 years. Retroactively applying the 2020 USMSTF polyp surveillance guidelines and harmonizing recommendations to guidelines extended the time of index colonoscopy by 153 years.

Discussion

With retroactive application of the 2020 USMSTF polyp surveillance guidelines, 6% of patients due for an upcoming colonoscopy could extend their follow-up by ≥ 1 year by extending the surveillance interval for 1 to 2 subcentimeter tubular adenomas to 7 years. An additional 5% of patients could extend their interval by harmonizing the index endoscopist’s interval recommendation with polyp surveillance guidelines at the time of the index colonoscopy. These findings are consistent with the results of 2 studies that demonstrated that about 14% of patients due for colonoscopy could have their interval extended.^6,7 The current study enhances those insights by separating the contribution of 2020 USMSTF polyp surveillance guidelines from the contribution of harmonizing surveillance intervals with guidelines for other polyp histologies. This study found that there is an opportunity to improve endoscopic capacity by harmonizing recommendations with guidelines. This complements a 2023 study showing that even when knowledgeable about guidelines, clinicians do not necessarily follow recommendations.⁸ While this and previous research have identified that 11% to 14% of patients are eligible for extension, these individuals would also have to be willing to have their polyp surveillance intervals extended for there to be a real-world impact on endoscopic capacity. A 2024 study found that only 19% to 37% of patients with 1 to 2 small tubular adenomas were willing to have polyps surveillance interval extension.⁹ This suggests the actual effect on capacity may be even lower than reported.

Limitations

The overall impact of the 2020 USMSTF polyp surveillance guidelines on endoscopic capacity was blunted by the high prevalence of incomplete index colonoscopy records among the study population. Without data on bowel preparation quality or procedure indications, this study could not assess whether 43% of patients were eligible for surveillance interval extension. Most index colonoscopies with incomplete documentation were completed at community-care gastroenterology facilities. This high rate of incomplete documentation is likely generalizable to other VA health care systems—especially in the era of the Veterans Access, Choice, and Accountability Act of 2014, which increased veteran access to non-VA community care.¹⁰ Veterans due for colon polyp surveillance colonoscopies are more likely to have had their prior colonoscopy in community care compared with prior eras.¹¹ Furthermore, because the VHA is among the most established integrated health care systems offering primary and subspecialty care in the US, private sector health care systems may have even greater rates of care fragmentation for longitudinal CRC screening and colon polyp surveillance, as these systems have only begun to regionally integrate recently.^12,13

Another limitation is that nearly one-third of the individuals with documentation had inadequate bowel preparation for surveillance recommendations. This results in shorter surveillance follow-up colonoscopies and increases downstream demand for future colonoscopies. The low yield of extending colon polyp surveillance interval in this study emphasizes that improved efforts to obtain colonoscopy and pathology reports from community care, right-sizing the colon polyp surveillance intervals recommended by endoscopists, and improving quality of bowel preparation could have downstream health care system benefits in the future. These efforts could increase colonoscopy capacity at VA health care systems, thereby shortening colonoscopy wait times, decreasing fragmentation of care, and increasing the number of veterans who receive high-quality colonoscopies at VA health care systems.¹⁴

Conclusions

Eleven percent of patients in this study due for a colonoscopy could extend their follow-up by ≥ 1 year. About half of these extensions were directly due to the 2020 USMSTF polyp surveillance interval extension for 1 to 2 subcentimeter tubular adenomas. The rest resulted from harmonizing recommendations with guidelines at the time of the procedure. To determine whether retroactively applying polyp surveillance guidelines to follow-up interval recommendations will result in improved endoscopic capacity, health care system administrators should consider the degree of CRC screening care fragmentation in their patient population. Greater long-term gains in endoscopic capacity may be achieved by proactively supporting endoscopists in making guideline-concordant screening recommendations at the time of colonoscopy.

In 2020, the US Multi-Society Task Force (USMSTF) on Colorectal Cancer (CRC) increased the recommended colon polyp surveillance interval for 1 to 2 subcentimeter tubular adenomas from 5 to 10 years to 7 to 10 years.¹ This change was prompted by emerging research indicating that rates of CRC and advanced neoplasia among patients with a history of only 1 to 2 subcentimeter tubular adenomas are lower than initially estimated.^2,3 This extension provides an opportunity to increase endoscopy capacity and improve access to colonoscopies by retroactively applying the 2020 guidelines to surveillance interval recommendations made before their introduction. For example, based on the updated guidelines, patients previously recommended to undergo colon polyp surveillance colonoscopy 5 years after an index colonoscopy could extend their surveillance interval by 2 to 5 years. Increasing endoscopic capacity could address the growing demand for colonoscopies from new screening guidelines that reduced the age of initial CRC screening from 50 years to 45 years and the backlog of procedures due to COVID-19 restrictions.⁴

As part of a project to increase endoscopic capacity at the US Department of Veterans Affairs (VA) Pittsburgh Healthcare System (VAPHS), this study assessed the potential impact of retroactively applying the 2020 USMSTF polyp surveillance guidelines on endoscopic capacity. These results may be informative for other VA and private-sector health care systems seeking to identify strategies to improve endoscopy capacity.

Methods

VAPHS is an integrated health care system in the Veterans Health Administration (VHA) serving 85,000 patients across 8 health care institutions in Pennsylvania, Ohio, and West Virginia. VAPHS manages colorectal screening recommendations for patients receiving medical care in the health care system regardless of whether their prior colonoscopy was performed at VAPHS or external facilities. The VA maintains a national CRC screening and surveillance electronic medical record reminder that prompts health care practitioners to order colon polyp surveillance based on interval recommendations from the index colonoscopy. This study reviewed all patients from the VAPHS panel with a reminder to undergo colonoscopy for screening for CRC or surveillance of colon polyps within 12 months from September 1, 2022.

Among patients with a reminder, 3 investigators reviewed index colonoscopy and pathology reports to identify CRC risk category, colonoscopy indication, procedural quality, and recommended repeat colonoscopy interval. Per the USMSTF guidelines, patients with incomplete colonoscopy or pathology records, high-risk indications (ie, personal history of inflammatory bowel disease, personal history of CRC, or family history of CRC), or inadequate bowel preparation (Boston Bowel Preparation Score < 6) were excluded. Additionally, patients who had CRC screening or surveillance discontinued due to age or comorbidities, had completed a subsequent follow-up colonoscopy, or were deceased at the time of review were excluded.

Retroactive Interval Reclassification

Among eligible patients, this study compared the repeat colonoscopy interval recommended by the prior endoscopist with those from the 2020 USMSTF guidelines. In cases where the interval was documented as a range of years, the lower end was considered the recommendation. Similarly, the lower end of the range from the 2020 USMSTF guidelines was used for the reclassified surveillance interval. Years extended per patient were quantified relative to September 1, 2023 (ie, 1 year after the review date). For example, if the index colonoscopy was completed on September 1, 2016, the initial surveillance recommendation was 5 years, and the reclassified recommendation was 7 years, the interval extension beyond September 1, 2023, was 0 years.

Furthermore, because index surveillance recommendations are not always guideline concordant, the years extended per patient were calculated by harmonizing the index endoscopist’s recommendations with the guidelines at the time of the index colonoscopy.⁵ For example, if the index colonoscopy was completed on September 1, 2018, and the endoscopist recommended a 5-year follow-up for a patient with average risk for CRC, adequate bowel preparation, and no colorectal polyps, that patient is eligible to extend their colonoscopy to September 1, 2028, based on guideline recommendations at the time of index endoscopy recommending that the next colonoscopy occur in 10 years. In this analysis the 2012 USMSTF guidelines were applied to all index colonoscopies completed in 2021 or earlier to allow time for adoption of the 2020 guidelines. 

This project fulfilled a facility mandate to increase capacity to conduct endoscopic procedures. Institutional review board approval was not required by VAPHS policy relating to clinical operations projects. Approval for publication of clinical operations activity was obtained from the VAPHS facility director.

Results

Within 1 year of the September 1, 2022, review date, 637 patients receiving care at VAPHS had clinical reminders for an upcoming colonoscopy. Of these, 54 (8.4%) were already up to date or were deceased at the time of review. Of the 583 eligible patients, 96% were male, the median age was 74 years, the median index colonoscopy year was 2016, and 178 (30.5%) had an average-risk CRC screening indication at the index colonoscopy (Table).

Of the 583 patients due for colonoscopy, 331 (56.7%) had both colonoscopy and pathology reports available. The majority of those with incomplete records had the index colonoscopy completed outside VAPHS. Among these patients, 222 (67.0%) had adequate bowel preparation. Of those with adequate bowel preparation, 43 were not eligible for interval extension because of high-risk conditions and 13 were not eligible because there was no index surveillance interval recommendation from the index endoscopist. Of the patients due for colonoscopy, 166 (28.4%) were potentially eligible for surveillance interval extension (Figure).  

Sixty-five (39.2%) of the 166 patients had 1 to 2 subcentimeter tubular adenomas on their index colonoscopy. Sixty-two patients were eligible for interval extension to 7 years, but this only resulted in ≥ 1 year of extension beyond the review date for 36 (6% of all 583 patients due for colonoscopy). The 36 patients were extended 63 years. By harmonizing the index endoscopists’ surveillance interval recommendation with the guideline at the time of the index colonoscopy, 29 additional patients could have their colonoscopy extended by ≥ 1 year. Harmonization extended colonoscopy intervals by 93 years. Retroactively applying the 2020 USMSTF polyp surveillance guidelines and harmonizing recommendations to guidelines extended the time of index colonoscopy by 153 years.

Discussion

With retroactive application of the 2020 USMSTF polyp surveillance guidelines, 6% of patients due for an upcoming colonoscopy could extend their follow-up by ≥ 1 year by extending the surveillance interval for 1 to 2 subcentimeter tubular adenomas to 7 years. An additional 5% of patients could extend their interval by harmonizing the index endoscopist’s interval recommendation with polyp surveillance guidelines at the time of the index colonoscopy. These findings are consistent with the results of 2 studies that demonstrated that about 14% of patients due for colonoscopy could have their interval extended.^6,7 The current study enhances those insights by separating the contribution of 2020 USMSTF polyp surveillance guidelines from the contribution of harmonizing surveillance intervals with guidelines for other polyp histologies. This study found that there is an opportunity to improve endoscopic capacity by harmonizing recommendations with guidelines. This complements a 2023 study showing that even when knowledgeable about guidelines, clinicians do not necessarily follow recommendations.⁸ While this and previous research have identified that 11% to 14% of patients are eligible for extension, these individuals would also have to be willing to have their polyp surveillance intervals extended for there to be a real-world impact on endoscopic capacity. A 2024 study found that only 19% to 37% of patients with 1 to 2 small tubular adenomas were willing to have polyps surveillance interval extension.⁹ This suggests the actual effect on capacity may be even lower than reported.

Limitations

The overall impact of the 2020 USMSTF polyp surveillance guidelines on endoscopic capacity was blunted by the high prevalence of incomplete index colonoscopy records among the study population. Without data on bowel preparation quality or procedure indications, this study could not assess whether 43% of patients were eligible for surveillance interval extension. Most index colonoscopies with incomplete documentation were completed at community-care gastroenterology facilities. This high rate of incomplete documentation is likely generalizable to other VA health care systems—especially in the era of the Veterans Access, Choice, and Accountability Act of 2014, which increased veteran access to non-VA community care.¹⁰ Veterans due for colon polyp surveillance colonoscopies are more likely to have had their prior colonoscopy in community care compared with prior eras.¹¹ Furthermore, because the VHA is among the most established integrated health care systems offering primary and subspecialty care in the US, private sector health care systems may have even greater rates of care fragmentation for longitudinal CRC screening and colon polyp surveillance, as these systems have only begun to regionally integrate recently.^12,13

Another limitation is that nearly one-third of the individuals with documentation had inadequate bowel preparation for surveillance recommendations. This results in shorter surveillance follow-up colonoscopies and increases downstream demand for future colonoscopies. The low yield of extending colon polyp surveillance interval in this study emphasizes that improved efforts to obtain colonoscopy and pathology reports from community care, right-sizing the colon polyp surveillance intervals recommended by endoscopists, and improving quality of bowel preparation could have downstream health care system benefits in the future. These efforts could increase colonoscopy capacity at VA health care systems, thereby shortening colonoscopy wait times, decreasing fragmentation of care, and increasing the number of veterans who receive high-quality colonoscopies at VA health care systems.¹⁴

Conclusions

Eleven percent of patients in this study due for a colonoscopy could extend their follow-up by ≥ 1 year. About half of these extensions were directly due to the 2020 USMSTF polyp surveillance interval extension for 1 to 2 subcentimeter tubular adenomas. The rest resulted from harmonizing recommendations with guidelines at the time of the procedure. To determine whether retroactively applying polyp surveillance guidelines to follow-up interval recommendations will result in improved endoscopic capacity, health care system administrators should consider the degree of CRC screening care fragmentation in their patient population. Greater long-term gains in endoscopic capacity may be achieved by proactively supporting endoscopists in making guideline-concordant screening recommendations at the time of colonoscopy.

Tracheal deviation mostly occurs from mechanical compression of the trachea, and can be caused by a variety of clinical conditions, including trauma,¹ pharyngeal abscess,² neck hematoma,³ thyroid enlargement,⁴ and kyphoscoliosis.⁵ These conditions often result in lateral tracheal deviation, which can be associated with tracheal compression and reduction in tracheal caliber.

Anterior-posterior (A-P) tracheal deviation has rarely been reported. Kyphoscoliosis, scarring after a tracheostomy, or innominate vein compression are probable causes of A-P tracheal deviation and can be associated with tracheal narrowing and vascular fistula formation. This report describes a case of difficult endotracheal tube (ETT) advancement secondary to unexpected acute posterior tracheal deviation encountered during cardiopulmonary resuscitation (CPR). A waiver of patient consent was obtained from the Human Research Protection Program at the US Department of Veterans Affairs (VA) Puget Sound Health Care System.

Case Presentation

A 50-year-old male with a history of chronic cerebral venous sinus thrombosis and taking enoxaparin, presented to the emergency department for recurrent headaches. He experienced sudden cardiac arrest, and CPR in the form of chest compression and bag mask ventilation was immediately initiated. With the patient's head in an extended position and using a video laryngoscope, a Cormack–Lehane grade 1 view of the glottic opening was obtained and the trachea was intubated with an 8 mm (internal diameter) polyvinyl chloride ETT. Tracheal intubation was confirmed by utilizing continuous EtCO₂ monitoring. The ETT was secured at 22 cm measured at the teeth.

After about 40 minutes of CPR, spontaneous circulation restarted and a portable A-P chest X-ray with the head in a neutral position indicated the ETT tip was at the level of the first rib (Figure 1). This finding, along with a persistent air leak, prompted blind advancement of the ETT to 26 cm at the teeth, but resistance to advancement was noted. A subsequent chest computed tomography (CT) with the head in a neutral position revealed the ETT remained inappropriately positioned with the tip measured 8.2 cm above the carina (Figure 2A). Concurrently, a sagittal CT view demonstrated significant posterior deviation of the mid and lower trachea. This deviation was determined to be the most likely cause of the difficulty encountered in advancing the ETT. No masses or lesions contributing to the acute tracheal angulation could be identified. Comparing CT imaging from 2 months prior, the trachea was of normal caliber and ordinarily aligned with the vertebral column (Figure 2B).

With the patient in Fowler position with the head midline, a flexible fiber-optic bronchoscopy was performed. Acute, almost 90-degree tracheal angulation was encountered and navigated by retroflexion of the flexible bronchoscope. Once the posterior tracheal wall was encountered, retroflexion was relaxed and the carina was visualized. The bronchoscope tip was placed near the carina, and the ETT was advanced over the fiber-optic bronchoscope to terminate 3 cm above the carina. A subsequent chest X-ray confirmed appropriate ETT position (Figure 3).

Discussion

Tracheal deviation in the A-P dimension resulting in difficult tracheal intubation has rarely been reported. Previous reports have described anatomical lesions contributing to similar tracheal deviation, such as retro-tracheal thyroid tissue, pronounced cervical lordosis, and severe kyphoscoliosis with destructive cervical fusion.^5-8 In a study of the anatomical correlation of double lumen tube placement while using positron emission tomography CT, Cameron et al evaluated the size and angulation of the glottis and proximal trachea using calibrated CT measurements and an online digital protractor and note nearly perfect alignment of the pharynx and glottis.⁹ However, the trachea turned posteriorly relative to the glottis, resulting in an overall posterior angle of the proximal trachea compared to the glottis of 30.4 to 50.1 degrees, with no sex differences. The need to maneuver similar proximal tracheal angulation during endotracheal intubation has been reported as a cause of difficult intubation.¹⁰

In this case, the posterior angulation was not encountered in the proximal trachea but rather in the more distal trachea. The extreme A-P tracheal deviation was not associated with any identifiable masses or lesions. A CT performed 2 months prior demonstrated normal tracheal anatomy, and there was no interval history of neck trauma or tracheal obstruction suggestive of a likely cause for this deviation. This change in the patient’s tracheal anatomy was only discovered after CPR had been performed and as part of the workup for cardiac arrest. Iatrogenic injuries are known to occur during CPR. Common CPR-related airway injuries include tracheal mucosal injury from traumatic intubation and bony injuries to the chest wall from compressions.¹¹ Laryngeal cartilage damage from intubation may also occur, but tracheal displacement following CPR has not been previously reported.¹¹

This case of tracheal deviation is unlikely to be related to patient positioning, as the A-P deviation persisted in 3 separate head and neck alignments. First, during indirect laryngoscopy, performed in a standard sniffing position. Second, during the CT, performed in the supine position, with no head support. The acute A-P deviation seen in Figure 2 was clearly noted in this position. Lastly, flexible fiber-optic bronchoscopy was performed in a semiupright position with the head supported on a pillow. A-P deviation was encountered and navigated in this position during flexible fiber-optic guided ETT repositioning. 

Using magnetic resonance imaging, alterations in the alignment of pharyngeal and tracheal axes have been described with changes in neck positioning; however, tracheal deviation has not been described with changes in head and neck alignment.¹² Although the clinical presentation in this case was consistent with prior reports, we were unable to identify any previously reported anatomic cause for the tracheal deviation.^5,6,8 Initial glottic visualization with a video laryngoscope was unremarkable, but resistance to sufficient ETT advancement past the vocal cords and a persistent air leak due to cuff herniation through the glottic opening was noticeable. The ETT was maneuvered to an appropriate position in the trachea using a flexible fiber-optic bronchoscope. The acute angulation of the trachea that was appreciated on bronchoscopy did not result in kinking of the ETT both initially and after in-situ thermosoftening of the polyvinyl chloride tube.¹³ Previously reported instances of A-P tracheal deviation have outlined the necessity of using alternative techniques to establish a patent airway, including the use of a laryngeal mask airway and a cuffless ETT with saline-soaked gauze packing.^5,8 In 1 reported case, awake fiber-optic intubation was performed when difficult tracheal intubation was anticipated due to known A-P tracheal deviation.⁶

Failure of ETT advancement can be due to obstruction from the arytenoids and at the level of the vocal cords.¹⁴ When the ETT has been visualized to have traversed the vocal cords, tracheal A-P deviation should be considered as a cause of difficult ETT advancement. If an adequate endotracheal airway cannot be established, prompt consideration should be given to placement of a supraglottic airway. Early fiber-optic bronchoscopy should be used to establish the diagnosis and assist with proper ETT positioning.

Conclusions

This case illustrates the rare occurrence of A-P tracheal deviation leading to difficult intubation during CPR. The findings underscore the importance of considering A-P deviation as a potential cause of airway complications in emergency settings, especially in patients with previously normal tracheal anatomy. The successful use of flexible fiber-optic bronchoscopy in this case provides a valuable technique for addressing acute tracheal angulation. This report contributes to the limited literature on A-P tracheal deviation and serves as a reminder for clinicians to maintain a high index of suspicion for unusual airway challenges during critical interventions.

Tracheal deviation mostly occurs from mechanical compression of the trachea, and can be caused by a variety of clinical conditions, including trauma,¹ pharyngeal abscess,² neck hematoma,³ thyroid enlargement,⁴ and kyphoscoliosis.⁵ These conditions often result in lateral tracheal deviation, which can be associated with tracheal compression and reduction in tracheal caliber.

Anterior-posterior (A-P) tracheal deviation has rarely been reported. Kyphoscoliosis, scarring after a tracheostomy, or innominate vein compression are probable causes of A-P tracheal deviation and can be associated with tracheal narrowing and vascular fistula formation. This report describes a case of difficult endotracheal tube (ETT) advancement secondary to unexpected acute posterior tracheal deviation encountered during cardiopulmonary resuscitation (CPR). A waiver of patient consent was obtained from the Human Research Protection Program at the US Department of Veterans Affairs (VA) Puget Sound Health Care System.

Case Presentation

A 50-year-old male with a history of chronic cerebral venous sinus thrombosis and taking enoxaparin, presented to the emergency department for recurrent headaches. He experienced sudden cardiac arrest, and CPR in the form of chest compression and bag mask ventilation was immediately initiated. With the patient's head in an extended position and using a video laryngoscope, a Cormack–Lehane grade 1 view of the glottic opening was obtained and the trachea was intubated with an 8 mm (internal diameter) polyvinyl chloride ETT. Tracheal intubation was confirmed by utilizing continuous EtCO₂ monitoring. The ETT was secured at 22 cm measured at the teeth.

After about 40 minutes of CPR, spontaneous circulation restarted and a portable A-P chest X-ray with the head in a neutral position indicated the ETT tip was at the level of the first rib (Figure 1). This finding, along with a persistent air leak, prompted blind advancement of the ETT to 26 cm at the teeth, but resistance to advancement was noted. A subsequent chest computed tomography (CT) with the head in a neutral position revealed the ETT remained inappropriately positioned with the tip measured 8.2 cm above the carina (Figure 2A). Concurrently, a sagittal CT view demonstrated significant posterior deviation of the mid and lower trachea. This deviation was determined to be the most likely cause of the difficulty encountered in advancing the ETT. No masses or lesions contributing to the acute tracheal angulation could be identified. Comparing CT imaging from 2 months prior, the trachea was of normal caliber and ordinarily aligned with the vertebral column (Figure 2B).

With the patient in Fowler position with the head midline, a flexible fiber-optic bronchoscopy was performed. Acute, almost 90-degree tracheal angulation was encountered and navigated by retroflexion of the flexible bronchoscope. Once the posterior tracheal wall was encountered, retroflexion was relaxed and the carina was visualized. The bronchoscope tip was placed near the carina, and the ETT was advanced over the fiber-optic bronchoscope to terminate 3 cm above the carina. A subsequent chest X-ray confirmed appropriate ETT position (Figure 3).

Discussion

Tracheal deviation in the A-P dimension resulting in difficult tracheal intubation has rarely been reported. Previous reports have described anatomical lesions contributing to similar tracheal deviation, such as retro-tracheal thyroid tissue, pronounced cervical lordosis, and severe kyphoscoliosis with destructive cervical fusion.^5-8 In a study of the anatomical correlation of double lumen tube placement while using positron emission tomography CT, Cameron et al evaluated the size and angulation of the glottis and proximal trachea using calibrated CT measurements and an online digital protractor and note nearly perfect alignment of the pharynx and glottis.⁹ However, the trachea turned posteriorly relative to the glottis, resulting in an overall posterior angle of the proximal trachea compared to the glottis of 30.4 to 50.1 degrees, with no sex differences. The need to maneuver similar proximal tracheal angulation during endotracheal intubation has been reported as a cause of difficult intubation.¹⁰

In this case, the posterior angulation was not encountered in the proximal trachea but rather in the more distal trachea. The extreme A-P tracheal deviation was not associated with any identifiable masses or lesions. A CT performed 2 months prior demonstrated normal tracheal anatomy, and there was no interval history of neck trauma or tracheal obstruction suggestive of a likely cause for this deviation. This change in the patient’s tracheal anatomy was only discovered after CPR had been performed and as part of the workup for cardiac arrest. Iatrogenic injuries are known to occur during CPR. Common CPR-related airway injuries include tracheal mucosal injury from traumatic intubation and bony injuries to the chest wall from compressions.¹¹ Laryngeal cartilage damage from intubation may also occur, but tracheal displacement following CPR has not been previously reported.¹¹

This case of tracheal deviation is unlikely to be related to patient positioning, as the A-P deviation persisted in 3 separate head and neck alignments. First, during indirect laryngoscopy, performed in a standard sniffing position. Second, during the CT, performed in the supine position, with no head support. The acute A-P deviation seen in Figure 2 was clearly noted in this position. Lastly, flexible fiber-optic bronchoscopy was performed in a semiupright position with the head supported on a pillow. A-P deviation was encountered and navigated in this position during flexible fiber-optic guided ETT repositioning. 

Using magnetic resonance imaging, alterations in the alignment of pharyngeal and tracheal axes have been described with changes in neck positioning; however, tracheal deviation has not been described with changes in head and neck alignment.¹² Although the clinical presentation in this case was consistent with prior reports, we were unable to identify any previously reported anatomic cause for the tracheal deviation.^5,6,8 Initial glottic visualization with a video laryngoscope was unremarkable, but resistance to sufficient ETT advancement past the vocal cords and a persistent air leak due to cuff herniation through the glottic opening was noticeable. The ETT was maneuvered to an appropriate position in the trachea using a flexible fiber-optic bronchoscope. The acute angulation of the trachea that was appreciated on bronchoscopy did not result in kinking of the ETT both initially and after in-situ thermosoftening of the polyvinyl chloride tube.¹³ Previously reported instances of A-P tracheal deviation have outlined the necessity of using alternative techniques to establish a patent airway, including the use of a laryngeal mask airway and a cuffless ETT with saline-soaked gauze packing.^5,8 In 1 reported case, awake fiber-optic intubation was performed when difficult tracheal intubation was anticipated due to known A-P tracheal deviation.⁶

Failure of ETT advancement can be due to obstruction from the arytenoids and at the level of the vocal cords.¹⁴ When the ETT has been visualized to have traversed the vocal cords, tracheal A-P deviation should be considered as a cause of difficult ETT advancement. If an adequate endotracheal airway cannot be established, prompt consideration should be given to placement of a supraglottic airway. Early fiber-optic bronchoscopy should be used to establish the diagnosis and assist with proper ETT positioning.

Conclusions

This case illustrates the rare occurrence of A-P tracheal deviation leading to difficult intubation during CPR. The findings underscore the importance of considering A-P deviation as a potential cause of airway complications in emergency settings, especially in patients with previously normal tracheal anatomy. The successful use of flexible fiber-optic bronchoscopy in this case provides a valuable technique for addressing acute tracheal angulation. This report contributes to the limited literature on A-P tracheal deviation and serves as a reminder for clinicians to maintain a high index of suspicion for unusual airway challenges during critical interventions.

Tracheal deviation mostly occurs from mechanical compression of the trachea, and can be caused by a variety of clinical conditions, including trauma,¹ pharyngeal abscess,² neck hematoma,³ thyroid enlargement,⁴ and kyphoscoliosis.⁵ These conditions often result in lateral tracheal deviation, which can be associated with tracheal compression and reduction in tracheal caliber.

Anterior-posterior (A-P) tracheal deviation has rarely been reported. Kyphoscoliosis, scarring after a tracheostomy, or innominate vein compression are probable causes of A-P tracheal deviation and can be associated with tracheal narrowing and vascular fistula formation. This report describes a case of difficult endotracheal tube (ETT) advancement secondary to unexpected acute posterior tracheal deviation encountered during cardiopulmonary resuscitation (CPR). A waiver of patient consent was obtained from the Human Research Protection Program at the US Department of Veterans Affairs (VA) Puget Sound Health Care System.

Case Presentation

A 50-year-old male with a history of chronic cerebral venous sinus thrombosis and taking enoxaparin, presented to the emergency department for recurrent headaches. He experienced sudden cardiac arrest, and CPR in the form of chest compression and bag mask ventilation was immediately initiated. With the patient's head in an extended position and using a video laryngoscope, a Cormack–Lehane grade 1 view of the glottic opening was obtained and the trachea was intubated with an 8 mm (internal diameter) polyvinyl chloride ETT. Tracheal intubation was confirmed by utilizing continuous EtCO₂ monitoring. The ETT was secured at 22 cm measured at the teeth.

After about 40 minutes of CPR, spontaneous circulation restarted and a portable A-P chest X-ray with the head in a neutral position indicated the ETT tip was at the level of the first rib (Figure 1). This finding, along with a persistent air leak, prompted blind advancement of the ETT to 26 cm at the teeth, but resistance to advancement was noted. A subsequent chest computed tomography (CT) with the head in a neutral position revealed the ETT remained inappropriately positioned with the tip measured 8.2 cm above the carina (Figure 2A). Concurrently, a sagittal CT view demonstrated significant posterior deviation of the mid and lower trachea. This deviation was determined to be the most likely cause of the difficulty encountered in advancing the ETT. No masses or lesions contributing to the acute tracheal angulation could be identified. Comparing CT imaging from 2 months prior, the trachea was of normal caliber and ordinarily aligned with the vertebral column (Figure 2B).

With the patient in Fowler position with the head midline, a flexible fiber-optic bronchoscopy was performed. Acute, almost 90-degree tracheal angulation was encountered and navigated by retroflexion of the flexible bronchoscope. Once the posterior tracheal wall was encountered, retroflexion was relaxed and the carina was visualized. The bronchoscope tip was placed near the carina, and the ETT was advanced over the fiber-optic bronchoscope to terminate 3 cm above the carina. A subsequent chest X-ray confirmed appropriate ETT position (Figure 3).

Discussion

Tracheal deviation in the A-P dimension resulting in difficult tracheal intubation has rarely been reported. Previous reports have described anatomical lesions contributing to similar tracheal deviation, such as retro-tracheal thyroid tissue, pronounced cervical lordosis, and severe kyphoscoliosis with destructive cervical fusion.^5-8 In a study of the anatomical correlation of double lumen tube placement while using positron emission tomography CT, Cameron et al evaluated the size and angulation of the glottis and proximal trachea using calibrated CT measurements and an online digital protractor and note nearly perfect alignment of the pharynx and glottis.⁹ However, the trachea turned posteriorly relative to the glottis, resulting in an overall posterior angle of the proximal trachea compared to the glottis of 30.4 to 50.1 degrees, with no sex differences. The need to maneuver similar proximal tracheal angulation during endotracheal intubation has been reported as a cause of difficult intubation.¹⁰

In this case, the posterior angulation was not encountered in the proximal trachea but rather in the more distal trachea. The extreme A-P tracheal deviation was not associated with any identifiable masses or lesions. A CT performed 2 months prior demonstrated normal tracheal anatomy, and there was no interval history of neck trauma or tracheal obstruction suggestive of a likely cause for this deviation. This change in the patient’s tracheal anatomy was only discovered after CPR had been performed and as part of the workup for cardiac arrest. Iatrogenic injuries are known to occur during CPR. Common CPR-related airway injuries include tracheal mucosal injury from traumatic intubation and bony injuries to the chest wall from compressions.¹¹ Laryngeal cartilage damage from intubation may also occur, but tracheal displacement following CPR has not been previously reported.¹¹

This case of tracheal deviation is unlikely to be related to patient positioning, as the A-P deviation persisted in 3 separate head and neck alignments. First, during indirect laryngoscopy, performed in a standard sniffing position. Second, during the CT, performed in the supine position, with no head support. The acute A-P deviation seen in Figure 2 was clearly noted in this position. Lastly, flexible fiber-optic bronchoscopy was performed in a semiupright position with the head supported on a pillow. A-P deviation was encountered and navigated in this position during flexible fiber-optic guided ETT repositioning. 

Using magnetic resonance imaging, alterations in the alignment of pharyngeal and tracheal axes have been described with changes in neck positioning; however, tracheal deviation has not been described with changes in head and neck alignment.¹² Although the clinical presentation in this case was consistent with prior reports, we were unable to identify any previously reported anatomic cause for the tracheal deviation.^5,6,8 Initial glottic visualization with a video laryngoscope was unremarkable, but resistance to sufficient ETT advancement past the vocal cords and a persistent air leak due to cuff herniation through the glottic opening was noticeable. The ETT was maneuvered to an appropriate position in the trachea using a flexible fiber-optic bronchoscope. The acute angulation of the trachea that was appreciated on bronchoscopy did not result in kinking of the ETT both initially and after in-situ thermosoftening of the polyvinyl chloride tube.¹³ Previously reported instances of A-P tracheal deviation have outlined the necessity of using alternative techniques to establish a patent airway, including the use of a laryngeal mask airway and a cuffless ETT with saline-soaked gauze packing.^5,8 In 1 reported case, awake fiber-optic intubation was performed when difficult tracheal intubation was anticipated due to known A-P tracheal deviation.⁶

Failure of ETT advancement can be due to obstruction from the arytenoids and at the level of the vocal cords.¹⁴ When the ETT has been visualized to have traversed the vocal cords, tracheal A-P deviation should be considered as a cause of difficult ETT advancement. If an adequate endotracheal airway cannot be established, prompt consideration should be given to placement of a supraglottic airway. Early fiber-optic bronchoscopy should be used to establish the diagnosis and assist with proper ETT positioning.

Conclusions

This case illustrates the rare occurrence of A-P tracheal deviation leading to difficult intubation during CPR. The findings underscore the importance of considering A-P deviation as a potential cause of airway complications in emergency settings, especially in patients with previously normal tracheal anatomy. The successful use of flexible fiber-optic bronchoscopy in this case provides a valuable technique for addressing acute tracheal angulation. This report contributes to the limited literature on A-P tracheal deviation and serves as a reminder for clinicians to maintain a high index of suspicion for unusual airway challenges during critical interventions.

The introduction of extended reality (XR) to the operating room (OR) has proved promising for enhancing surgical precision and improving patient outcomes. In the field of orthopedic surgery, precise alignment of implants is integral to maintaining functional range of motion and preventing impingement of adjacent neurovascular structures. XR systems have shown promise in arthroplasty including by improving precision and streamlining surgery by allowing surgeons to create 3D preoperative plans that are accessible intraoperatively. This article explores the current applications of XR in arthroplasty, highlights recent advancements and benefits, and describes limitations in comparison to traditional techniques.

Methods

A literature search identified studies involving the use of XR in arthroplasty and current US Food and Drug Administration (FDA)-approved XR systems. Multiple electronic databases were used, including PubMed, Google Scholar, and IEEE Xplore. Search terms included: extended reality, augmented reality, virtual reality, arthroplasty, joint replacement, total knee arthroplasty, total shoulder arthroplasty, and total hip arthroplasty. The study design, intervention details, outcomes, and comparisons with traditional surgical techniques were thematically analyzed, with identification of common ideas associated with XR use in arthroplasty. This narrative report highlights the integration of XR in arthroplasty.

Extended Reality Fundamentals

XR encompasses augmented reality (AR), virtual reality (VR), and mixed reality (MR). AR involves superimposing digitally rendered information and images onto the surgeon’s view of the real world, typically through the use of a headset and smart glasses.¹ AR allows the surgeon to move and interact freely within the OR, removing the need for additional screens or devices to display patient information or imaging. VR is a fully immersive simulation using a headset that obstructs the view of the real world but allows the user to move freely within this virtual setting, often with audio or other sensory stimuli. MR combines AR and VR to create a digital model that allows for real-world interaction, with the advantage of adapting information and models in real time.² Whereas in AR the surgeon can view the data projected from the headset, MR provides the ability to interact with and manipulate the digital content (Figure). Both AR and MR have been adapted for use in the OR, while VR has been adapted for use in surgical planning and training.

Extended Reality Use in Orthopedics

The HipNav system was introduced in 1995 to create preoperative plans that assist surgeons in accurately implanting the acetabular cup during total hip arthroplasty (THA).³ Although not commercially successful, this system spurred surgeons to experiment with XR to improve the accuracy and alignment of orthopedic implants. Systems capable of displaying the desired intraoperative implant placement have flourished, with applications in fracture reduction, arthroplasty, solid tumor resection, and hardware placement.^4-7 Accurate alignment has been linked to improvements in patient outcomes.^8-10 XR has great potential within the field of arthroplasty, with multiple new systems approved by the FDA and currently available in the US (Table).

Hip Arthroplasty

Orientation of the acetabular cup is a technically challenging part of THA. Accuracy in the anteversion and inclination angles of the acetabular cup is required to maintain implant stability, preserve functional range of motion (ROM), and prevent precocious wear.^11,12 Despite preoperative planning, surgeons often overestimate the inclination angle and underestimate anteversion.¹³ Improper implantation of the acetabular cup can lead to joint instability caused by aseptic loosening, increasing the risk of dislocation and the need for revision surgery.^14,15 Dislocations typically present to the emergency department, but primary care practitioners may encounter patients with pain or diminished sensation due to impingement or instability.¹⁶

The introduction of XR into the OR has provided the opportunity for real-time navigation and adjustment of the acetabular cup to maximize anteversion and inclination angles. Currently, 2 FDA-approved systems are available for THA: the Zimmer and Surgical Planning Associates HipInsight system, and the Insight Augmented Reality Visualization and Information System (ARVIS). The HipInsight system consists of a hologram projection using the Microsoft HoloLens2 device and optimizes preoperative planning, producing accuracy of anteversion and inclination angles within 3°.¹⁷ ARVIS employs existing surgical helmets and 2 mounted tracking cameras to provide navigation intraoperatively. ARVIS has also been approved for use in total knee arthroplasty (TKA) and unicompartmental knee arthroplasty.¹⁸

HipInsight has shown utility in increasing the accuracy of acetabular cup placement along with the use of biplanar radiographic scans.¹⁹ However, there are no studies validating the efficacy of ARVIS and HipInsight and assessing long-term disease-oriented or patient-oriented outcomes.

Knee Arthroplasty

In the setting of TKA, XR is most effective in ensuring accurate resection of the tibial and femoral components. Achieving the planned femoral coronal, axial, and sagittal angles allows the prosthesis to be on the femoral axis of rotation, improving functional outcomes. XR systems for TKA have been shown to increase the accuracy of distal femoral resection with a limited increase in surgery duration.^20,21 For TKA in particular, patients are often less satisfied with the result than surgeons expect.²² Accurate alignment can improve patient satisfaction and reduce return-to-clinic rates for postoperative pain management, a factor that primary care practitioners should consider when recommending a patient for TKA.²³

Along with ARVIS, 3 additional XR systems are FDA-approved for use in TKA. The Pixee Medical Knee+ system uses smart glasses and trackers to aid in the positioning of instruments for improved accuracy while allowing real-time navigation.²⁴ The Medacta NextAR Knee’s single-use tracking system allows for intraoperative navigation with the use of AR glasses.²⁵ The Polaris STELLAR Knee uses MR and avoids the need for preoperative imaging by capturing real-time anatomic data.²⁶

The Pixee Medical Knee+ system was commercially available in Europe for several years prior to FDA approval, so more research exists on its efficacy. One study found that the Pixee Medical Knee+ system initially demonstrated an inferior clinical outcome, attributed to the learning curve associated with using the system.²⁷ However, more recent studies have shown its utility in improving alignment, regardless of implant specifications.^28,29 The Medacta NextAR Knee system has been shown to improve accuracy of tibial rotation and soft tissue balance and even increase OR efficiency.^30,31 The Polaris STELLAR Knee system received FDA approval in 2023; no published research exists on its accuracy and outcomes.²⁶

Shoulder Arthroplasty

Minimally invasive techniques are favored in total shoulder arthroplasty (TSA) due to the vitality of maintaining the surrounding soft tissue to maximize preservation of motility and strength.³² However, this complicates the procedure by decreasing the ability to effectively access and visualize key structures of the shoulder. Accordingly, issues with implant positioning and alignment are more common with TSA than other joint arthroplasties, making XR particularly promising.³³ Some studies report that up to 67% of patients experience glenohumeral instability, which can clinically present as weakness, decreased range of motion, and persistent shoulder pain.^34,35 The use of preoperative computed tomography to improve understanding of glenoid anatomy and glenohumeral subluxation is becoming increasingly common, and it can be combined with XR to improve accuracy.^36,37

Two FDA-approved systems are available. The Stryker Blueprint MR system is used for intraoperative guidance and integration for patient imaging used for preoperative planning. The Medacta NextAR Shoulder system is a parallel of the company’s TKA system. The Stryker Blueprint MR system combines the Microsoft HoloLens 2 headset to display preoperative plans with a secondary display for coordination with the rest of the surgical team.³⁸ Similar to the Medacta NextAR Knee, the Medacta NextAR Shoulder system uses the same single-use tracking system and AR glasses for intraoperative guidance.³⁹

Data on the long-term outcomes of using these systems are still limited, but the Stryker Blueprint MR system has not been shown to accurately predict postoperative ROM.⁴⁰ Cadaveric studies have demonstrated that the Medacta NextAR Shoulder system can provide accurate inclination, retroversion, entry point, depth, and rotation values based on the preoperative planned values.^41,42 However, this accuracy has yet to be confirmed in vivo, and the impact of using XR in TSA on long-term outcomes is still unknown.

Challenges and Limitations

Though XR has proven to be promising in arthroplasty, several limitations regarding widespread implementation exist. In particular, there is a steep learning curve associated with the use of XR systems, which can cause increased operative time and even initial inferior outcomes, as demonstrated with the Pixee Medical Knee+ system. The need for extensive practice and training prior to use could delay widespread adoption and may cause discrepancies in surgical outcomes. Unfamiliarity with the system and technological difficulties that may require troubleshooting can also increase operative time, particularly for surgeons new to using the XR system. Though intraoperative navigation is expected to improve accuracy of implant alignment, its added complexity may also result in longer surgeries.

In addition to the steep learning curve and increased operative time, there is a high upfront cost associated with XR systems. Exact costs of XR systems are not typically disclosed, but available estimates suggest an average sales price of about $1000 per case. Given the proprietary nature of these technologies, publicly available cost data are limited, making it challenging to fully assess the financial burden on health care institutions. Though some systems, such as ARVIS, can be integrated with existing surgical helmets, many require the purchase of AR glasses and secondary displays. This can cause further variation in the total expense for each system. In low-resource settings, this represents a significant challenge to widespread implementation. To justify this cost, additional research on long-term patient outcomes is needed to ensure the benefits of XR systems outweigh the cost. 

Although early studies on XR systems in arthroplasty have shown improvements in precision and short-term outcomes, long-term data regarding effectiveness remains. Even systems such as ARVIS and HipInsight have limited long-term follow-up, making it difficult to assess whether the improved accuracy with these XR systems translates into improved patient outcomes compared with traditional arthroplasty.

CONCLUSIONS

XR technologies have shown significant potential in enhancing precision and patient outcomes. Through the integration of XR in the OR, surgeons can visualize preoperative plans and even make intraoperative changes, with the benefit of improving implant alignment.

There are some disadvantages to its use, however, including high cost and increased operative time. Despite this, the integration of XR into surgical practice can deliver more precise implant alignment and address other challenges faced with conventional techniques. As these technologies evolve and studies on long-term outcomes validate their utility, XR has the potential to transform the field of arthroplasty.

The introduction of extended reality (XR) to the operating room (OR) has proved promising for enhancing surgical precision and improving patient outcomes. In the field of orthopedic surgery, precise alignment of implants is integral to maintaining functional range of motion and preventing impingement of adjacent neurovascular structures. XR systems have shown promise in arthroplasty including by improving precision and streamlining surgery by allowing surgeons to create 3D preoperative plans that are accessible intraoperatively. This article explores the current applications of XR in arthroplasty, highlights recent advancements and benefits, and describes limitations in comparison to traditional techniques.

Methods

A literature search identified studies involving the use of XR in arthroplasty and current US Food and Drug Administration (FDA)-approved XR systems. Multiple electronic databases were used, including PubMed, Google Scholar, and IEEE Xplore. Search terms included: extended reality, augmented reality, virtual reality, arthroplasty, joint replacement, total knee arthroplasty, total shoulder arthroplasty, and total hip arthroplasty. The study design, intervention details, outcomes, and comparisons with traditional surgical techniques were thematically analyzed, with identification of common ideas associated with XR use in arthroplasty. This narrative report highlights the integration of XR in arthroplasty.

Extended Reality Fundamentals

XR encompasses augmented reality (AR), virtual reality (VR), and mixed reality (MR). AR involves superimposing digitally rendered information and images onto the surgeon’s view of the real world, typically through the use of a headset and smart glasses.¹ AR allows the surgeon to move and interact freely within the OR, removing the need for additional screens or devices to display patient information or imaging. VR is a fully immersive simulation using a headset that obstructs the view of the real world but allows the user to move freely within this virtual setting, often with audio or other sensory stimuli. MR combines AR and VR to create a digital model that allows for real-world interaction, with the advantage of adapting information and models in real time.² Whereas in AR the surgeon can view the data projected from the headset, MR provides the ability to interact with and manipulate the digital content (Figure). Both AR and MR have been adapted for use in the OR, while VR has been adapted for use in surgical planning and training.

Extended Reality Use in Orthopedics

The HipNav system was introduced in 1995 to create preoperative plans that assist surgeons in accurately implanting the acetabular cup during total hip arthroplasty (THA).³ Although not commercially successful, this system spurred surgeons to experiment with XR to improve the accuracy and alignment of orthopedic implants. Systems capable of displaying the desired intraoperative implant placement have flourished, with applications in fracture reduction, arthroplasty, solid tumor resection, and hardware placement.^4-7 Accurate alignment has been linked to improvements in patient outcomes.^8-10 XR has great potential within the field of arthroplasty, with multiple new systems approved by the FDA and currently available in the US (Table).

Hip Arthroplasty

Orientation of the acetabular cup is a technically challenging part of THA. Accuracy in the anteversion and inclination angles of the acetabular cup is required to maintain implant stability, preserve functional range of motion (ROM), and prevent precocious wear.^11,12 Despite preoperative planning, surgeons often overestimate the inclination angle and underestimate anteversion.¹³ Improper implantation of the acetabular cup can lead to joint instability caused by aseptic loosening, increasing the risk of dislocation and the need for revision surgery.^14,15 Dislocations typically present to the emergency department, but primary care practitioners may encounter patients with pain or diminished sensation due to impingement or instability.¹⁶

The introduction of XR into the OR has provided the opportunity for real-time navigation and adjustment of the acetabular cup to maximize anteversion and inclination angles. Currently, 2 FDA-approved systems are available for THA: the Zimmer and Surgical Planning Associates HipInsight system, and the Insight Augmented Reality Visualization and Information System (ARVIS). The HipInsight system consists of a hologram projection using the Microsoft HoloLens2 device and optimizes preoperative planning, producing accuracy of anteversion and inclination angles within 3°.¹⁷ ARVIS employs existing surgical helmets and 2 mounted tracking cameras to provide navigation intraoperatively. ARVIS has also been approved for use in total knee arthroplasty (TKA) and unicompartmental knee arthroplasty.¹⁸

HipInsight has shown utility in increasing the accuracy of acetabular cup placement along with the use of biplanar radiographic scans.¹⁹ However, there are no studies validating the efficacy of ARVIS and HipInsight and assessing long-term disease-oriented or patient-oriented outcomes.

Knee Arthroplasty

In the setting of TKA, XR is most effective in ensuring accurate resection of the tibial and femoral components. Achieving the planned femoral coronal, axial, and sagittal angles allows the prosthesis to be on the femoral axis of rotation, improving functional outcomes. XR systems for TKA have been shown to increase the accuracy of distal femoral resection with a limited increase in surgery duration.^20,21 For TKA in particular, patients are often less satisfied with the result than surgeons expect.²² Accurate alignment can improve patient satisfaction and reduce return-to-clinic rates for postoperative pain management, a factor that primary care practitioners should consider when recommending a patient for TKA.²³

Along with ARVIS, 3 additional XR systems are FDA-approved for use in TKA. The Pixee Medical Knee+ system uses smart glasses and trackers to aid in the positioning of instruments for improved accuracy while allowing real-time navigation.²⁴ The Medacta NextAR Knee’s single-use tracking system allows for intraoperative navigation with the use of AR glasses.²⁵ The Polaris STELLAR Knee uses MR and avoids the need for preoperative imaging by capturing real-time anatomic data.²⁶

The Pixee Medical Knee+ system was commercially available in Europe for several years prior to FDA approval, so more research exists on its efficacy. One study found that the Pixee Medical Knee+ system initially demonstrated an inferior clinical outcome, attributed to the learning curve associated with using the system.²⁷ However, more recent studies have shown its utility in improving alignment, regardless of implant specifications.^28,29 The Medacta NextAR Knee system has been shown to improve accuracy of tibial rotation and soft tissue balance and even increase OR efficiency.^30,31 The Polaris STELLAR Knee system received FDA approval in 2023; no published research exists on its accuracy and outcomes.²⁶

Shoulder Arthroplasty

Minimally invasive techniques are favored in total shoulder arthroplasty (TSA) due to the vitality of maintaining the surrounding soft tissue to maximize preservation of motility and strength.³² However, this complicates the procedure by decreasing the ability to effectively access and visualize key structures of the shoulder. Accordingly, issues with implant positioning and alignment are more common with TSA than other joint arthroplasties, making XR particularly promising.³³ Some studies report that up to 67% of patients experience glenohumeral instability, which can clinically present as weakness, decreased range of motion, and persistent shoulder pain.^34,35 The use of preoperative computed tomography to improve understanding of glenoid anatomy and glenohumeral subluxation is becoming increasingly common, and it can be combined with XR to improve accuracy.^36,37

Two FDA-approved systems are available. The Stryker Blueprint MR system is used for intraoperative guidance and integration for patient imaging used for preoperative planning. The Medacta NextAR Shoulder system is a parallel of the company’s TKA system. The Stryker Blueprint MR system combines the Microsoft HoloLens 2 headset to display preoperative plans with a secondary display for coordination with the rest of the surgical team.³⁸ Similar to the Medacta NextAR Knee, the Medacta NextAR Shoulder system uses the same single-use tracking system and AR glasses for intraoperative guidance.³⁹

Data on the long-term outcomes of using these systems are still limited, but the Stryker Blueprint MR system has not been shown to accurately predict postoperative ROM.⁴⁰ Cadaveric studies have demonstrated that the Medacta NextAR Shoulder system can provide accurate inclination, retroversion, entry point, depth, and rotation values based on the preoperative planned values.^41,42 However, this accuracy has yet to be confirmed in vivo, and the impact of using XR in TSA on long-term outcomes is still unknown.

Challenges and Limitations

Though XR has proven to be promising in arthroplasty, several limitations regarding widespread implementation exist. In particular, there is a steep learning curve associated with the use of XR systems, which can cause increased operative time and even initial inferior outcomes, as demonstrated with the Pixee Medical Knee+ system. The need for extensive practice and training prior to use could delay widespread adoption and may cause discrepancies in surgical outcomes. Unfamiliarity with the system and technological difficulties that may require troubleshooting can also increase operative time, particularly for surgeons new to using the XR system. Though intraoperative navigation is expected to improve accuracy of implant alignment, its added complexity may also result in longer surgeries.

In addition to the steep learning curve and increased operative time, there is a high upfront cost associated with XR systems. Exact costs of XR systems are not typically disclosed, but available estimates suggest an average sales price of about $1000 per case. Given the proprietary nature of these technologies, publicly available cost data are limited, making it challenging to fully assess the financial burden on health care institutions. Though some systems, such as ARVIS, can be integrated with existing surgical helmets, many require the purchase of AR glasses and secondary displays. This can cause further variation in the total expense for each system. In low-resource settings, this represents a significant challenge to widespread implementation. To justify this cost, additional research on long-term patient outcomes is needed to ensure the benefits of XR systems outweigh the cost. 

Although early studies on XR systems in arthroplasty have shown improvements in precision and short-term outcomes, long-term data regarding effectiveness remains. Even systems such as ARVIS and HipInsight have limited long-term follow-up, making it difficult to assess whether the improved accuracy with these XR systems translates into improved patient outcomes compared with traditional arthroplasty.

CONCLUSIONS

XR technologies have shown significant potential in enhancing precision and patient outcomes. Through the integration of XR in the OR, surgeons can visualize preoperative plans and even make intraoperative changes, with the benefit of improving implant alignment.

There are some disadvantages to its use, however, including high cost and increased operative time. Despite this, the integration of XR into surgical practice can deliver more precise implant alignment and address other challenges faced with conventional techniques. As these technologies evolve and studies on long-term outcomes validate their utility, XR has the potential to transform the field of arthroplasty.

The introduction of extended reality (XR) to the operating room (OR) has proved promising for enhancing surgical precision and improving patient outcomes. In the field of orthopedic surgery, precise alignment of implants is integral to maintaining functional range of motion and preventing impingement of adjacent neurovascular structures. XR systems have shown promise in arthroplasty including by improving precision and streamlining surgery by allowing surgeons to create 3D preoperative plans that are accessible intraoperatively. This article explores the current applications of XR in arthroplasty, highlights recent advancements and benefits, and describes limitations in comparison to traditional techniques.

Methods

A literature search identified studies involving the use of XR in arthroplasty and current US Food and Drug Administration (FDA)-approved XR systems. Multiple electronic databases were used, including PubMed, Google Scholar, and IEEE Xplore. Search terms included: extended reality, augmented reality, virtual reality, arthroplasty, joint replacement, total knee arthroplasty, total shoulder arthroplasty, and total hip arthroplasty. The study design, intervention details, outcomes, and comparisons with traditional surgical techniques were thematically analyzed, with identification of common ideas associated with XR use in arthroplasty. This narrative report highlights the integration of XR in arthroplasty.

Extended Reality Fundamentals

XR encompasses augmented reality (AR), virtual reality (VR), and mixed reality (MR). AR involves superimposing digitally rendered information and images onto the surgeon’s view of the real world, typically through the use of a headset and smart glasses.¹ AR allows the surgeon to move and interact freely within the OR, removing the need for additional screens or devices to display patient information or imaging. VR is a fully immersive simulation using a headset that obstructs the view of the real world but allows the user to move freely within this virtual setting, often with audio or other sensory stimuli. MR combines AR and VR to create a digital model that allows for real-world interaction, with the advantage of adapting information and models in real time.² Whereas in AR the surgeon can view the data projected from the headset, MR provides the ability to interact with and manipulate the digital content (Figure). Both AR and MR have been adapted for use in the OR, while VR has been adapted for use in surgical planning and training.

Extended Reality Use in Orthopedics

The HipNav system was introduced in 1995 to create preoperative plans that assist surgeons in accurately implanting the acetabular cup during total hip arthroplasty (THA).³ Although not commercially successful, this system spurred surgeons to experiment with XR to improve the accuracy and alignment of orthopedic implants. Systems capable of displaying the desired intraoperative implant placement have flourished, with applications in fracture reduction, arthroplasty, solid tumor resection, and hardware placement.^4-7 Accurate alignment has been linked to improvements in patient outcomes.^8-10 XR has great potential within the field of arthroplasty, with multiple new systems approved by the FDA and currently available in the US (Table).

Hip Arthroplasty

Orientation of the acetabular cup is a technically challenging part of THA. Accuracy in the anteversion and inclination angles of the acetabular cup is required to maintain implant stability, preserve functional range of motion (ROM), and prevent precocious wear.^11,12 Despite preoperative planning, surgeons often overestimate the inclination angle and underestimate anteversion.¹³ Improper implantation of the acetabular cup can lead to joint instability caused by aseptic loosening, increasing the risk of dislocation and the need for revision surgery.^14,15 Dislocations typically present to the emergency department, but primary care practitioners may encounter patients with pain or diminished sensation due to impingement or instability.¹⁶

The introduction of XR into the OR has provided the opportunity for real-time navigation and adjustment of the acetabular cup to maximize anteversion and inclination angles. Currently, 2 FDA-approved systems are available for THA: the Zimmer and Surgical Planning Associates HipInsight system, and the Insight Augmented Reality Visualization and Information System (ARVIS). The HipInsight system consists of a hologram projection using the Microsoft HoloLens2 device and optimizes preoperative planning, producing accuracy of anteversion and inclination angles within 3°.¹⁷ ARVIS employs existing surgical helmets and 2 mounted tracking cameras to provide navigation intraoperatively. ARVIS has also been approved for use in total knee arthroplasty (TKA) and unicompartmental knee arthroplasty.¹⁸

HipInsight has shown utility in increasing the accuracy of acetabular cup placement along with the use of biplanar radiographic scans.¹⁹ However, there are no studies validating the efficacy of ARVIS and HipInsight and assessing long-term disease-oriented or patient-oriented outcomes.

Knee Arthroplasty

In the setting of TKA, XR is most effective in ensuring accurate resection of the tibial and femoral components. Achieving the planned femoral coronal, axial, and sagittal angles allows the prosthesis to be on the femoral axis of rotation, improving functional outcomes. XR systems for TKA have been shown to increase the accuracy of distal femoral resection with a limited increase in surgery duration.^20,21 For TKA in particular, patients are often less satisfied with the result than surgeons expect.²² Accurate alignment can improve patient satisfaction and reduce return-to-clinic rates for postoperative pain management, a factor that primary care practitioners should consider when recommending a patient for TKA.²³

Along with ARVIS, 3 additional XR systems are FDA-approved for use in TKA. The Pixee Medical Knee+ system uses smart glasses and trackers to aid in the positioning of instruments for improved accuracy while allowing real-time navigation.²⁴ The Medacta NextAR Knee’s single-use tracking system allows for intraoperative navigation with the use of AR glasses.²⁵ The Polaris STELLAR Knee uses MR and avoids the need for preoperative imaging by capturing real-time anatomic data.²⁶

The Pixee Medical Knee+ system was commercially available in Europe for several years prior to FDA approval, so more research exists on its efficacy. One study found that the Pixee Medical Knee+ system initially demonstrated an inferior clinical outcome, attributed to the learning curve associated with using the system.²⁷ However, more recent studies have shown its utility in improving alignment, regardless of implant specifications.^28,29 The Medacta NextAR Knee system has been shown to improve accuracy of tibial rotation and soft tissue balance and even increase OR efficiency.^30,31 The Polaris STELLAR Knee system received FDA approval in 2023; no published research exists on its accuracy and outcomes.²⁶

Shoulder Arthroplasty

Minimally invasive techniques are favored in total shoulder arthroplasty (TSA) due to the vitality of maintaining the surrounding soft tissue to maximize preservation of motility and strength.³² However, this complicates the procedure by decreasing the ability to effectively access and visualize key structures of the shoulder. Accordingly, issues with implant positioning and alignment are more common with TSA than other joint arthroplasties, making XR particularly promising.³³ Some studies report that up to 67% of patients experience glenohumeral instability, which can clinically present as weakness, decreased range of motion, and persistent shoulder pain.^34,35 The use of preoperative computed tomography to improve understanding of glenoid anatomy and glenohumeral subluxation is becoming increasingly common, and it can be combined with XR to improve accuracy.^36,37

Two FDA-approved systems are available. The Stryker Blueprint MR system is used for intraoperative guidance and integration for patient imaging used for preoperative planning. The Medacta NextAR Shoulder system is a parallel of the company’s TKA system. The Stryker Blueprint MR system combines the Microsoft HoloLens 2 headset to display preoperative plans with a secondary display for coordination with the rest of the surgical team.³⁸ Similar to the Medacta NextAR Knee, the Medacta NextAR Shoulder system uses the same single-use tracking system and AR glasses for intraoperative guidance.³⁹

Data on the long-term outcomes of using these systems are still limited, but the Stryker Blueprint MR system has not been shown to accurately predict postoperative ROM.⁴⁰ Cadaveric studies have demonstrated that the Medacta NextAR Shoulder system can provide accurate inclination, retroversion, entry point, depth, and rotation values based on the preoperative planned values.^41,42 However, this accuracy has yet to be confirmed in vivo, and the impact of using XR in TSA on long-term outcomes is still unknown.

Challenges and Limitations

Though XR has proven to be promising in arthroplasty, several limitations regarding widespread implementation exist. In particular, there is a steep learning curve associated with the use of XR systems, which can cause increased operative time and even initial inferior outcomes, as demonstrated with the Pixee Medical Knee+ system. The need for extensive practice and training prior to use could delay widespread adoption and may cause discrepancies in surgical outcomes. Unfamiliarity with the system and technological difficulties that may require troubleshooting can also increase operative time, particularly for surgeons new to using the XR system. Though intraoperative navigation is expected to improve accuracy of implant alignment, its added complexity may also result in longer surgeries.

In addition to the steep learning curve and increased operative time, there is a high upfront cost associated with XR systems. Exact costs of XR systems are not typically disclosed, but available estimates suggest an average sales price of about $1000 per case. Given the proprietary nature of these technologies, publicly available cost data are limited, making it challenging to fully assess the financial burden on health care institutions. Though some systems, such as ARVIS, can be integrated with existing surgical helmets, many require the purchase of AR glasses and secondary displays. This can cause further variation in the total expense for each system. In low-resource settings, this represents a significant challenge to widespread implementation. To justify this cost, additional research on long-term patient outcomes is needed to ensure the benefits of XR systems outweigh the cost. 

Although early studies on XR systems in arthroplasty have shown improvements in precision and short-term outcomes, long-term data regarding effectiveness remains. Even systems such as ARVIS and HipInsight have limited long-term follow-up, making it difficult to assess whether the improved accuracy with these XR systems translates into improved patient outcomes compared with traditional arthroplasty.

CONCLUSIONS

XR technologies have shown significant potential in enhancing precision and patient outcomes. Through the integration of XR in the OR, surgeons can visualize preoperative plans and even make intraoperative changes, with the benefit of improving implant alignment.

There are some disadvantages to its use, however, including high cost and increased operative time. Despite this, the integration of XR into surgical practice can deliver more precise implant alignment and address other challenges faced with conventional techniques. As these technologies evolve and studies on long-term outcomes validate their utility, XR has the potential to transform the field of arthroplasty.

To the Editor:

Necrobiotic xanthogranuloma (NXG) is classified as a cutaneous non–Langerhans cell histiocytosis, often seen with monoclonal gammopathy of undetermined significance or multiple myeloma.¹ Clinically, it appears as a red or yellow plaque with occasional ulceration and telangiectasias, most commonly seen periorbitally and on the trunk. On pathology, NXG appears as necrobiosis, giant cells, and various inflammatory cells extending into the subcutaneous tissue.² In this article, we describe a rare presentation of NXG in location and skin type.

A 52-year-old woman with a history of systemic lupus erythematosus (SLE) presented with alopecia and a tender lesion on the scalp of 5 years’ duration (Figure 1). The patient had no history of a similar lesion, and no other lesions were present. A biopsy performed at an outside clinic a few weeks to months prior to the initial presentation to our clinic showed NXG (Figure 2). Evaluation at our clinic revealed a 4x4-cm orange-brown annular plaque on the left parietal scalp. Serum and urine protein electrophoresis studies were negative. The patient reported she was up to date with recommended screenings such as mammography and colonoscopy. 

We started the patient on topical triamcinolone and topical ruxolitinib and administered intralesional triamcinolone. She was already taking hydroxychloroquine and leflunomide for SLE. Three weeks later, she returned with improved symptoms and appearance (Figure 1). She remained on intralesional triamcinolone and ruxolitinib and continues to experience improvement.

Necrobiotic xanthogranuloma is rare and typically is associated with monoclonal gammopathy.² In one study, 83 of 100 of patients with NXG presented with or were found to have a monoclonal gammopathy.² In another study, paraproteinemia was detected in 82.1% of patients.³ The majority of case reports and systematic reviews detail periorbital or thoracic lesions.⁴ The location on the scalp and lack of association with paraproteinemia make this a rare presentation of NXG. Studies may be warranted to explore any association of SLE with NXG if more cases present.

In a multicenter cross-sectional study and systematic review of 235 patients with NXG, 87% were White, 12% were Asian, and only 1% were Black or African American.³ The limited representation of skin of color raises concern for the possibility of missed diagnoses and delays in care. 

Treatment of NXG often is multimodal with use of intravenous immunoglobulin, oral steroids, chlorambucil, melphalan, and other alkylating agents, and response is variable.^3-6 Recent studies show treatment effectiveness with Janus kinase inhibitors in granulomatous dermatitides.^7-9 As our patient was not responding to prior treatments, we decided to try ruxolitinib, and she has continued to improve with it.^10,11 Interestingly, the patient experienced continued improvement with intralesional triamcinolone, which is not often reported in the literature.^2-6 Overall, NXG is an extremely rare condition that requires special care in workup to rule out paraproteinemia and a thoughtful approach to treatment modalities.

To the Editor:

Necrobiotic xanthogranuloma (NXG) is classified as a cutaneous non–Langerhans cell histiocytosis, often seen with monoclonal gammopathy of undetermined significance or multiple myeloma.¹ Clinically, it appears as a red or yellow plaque with occasional ulceration and telangiectasias, most commonly seen periorbitally and on the trunk. On pathology, NXG appears as necrobiosis, giant cells, and various inflammatory cells extending into the subcutaneous tissue.² In this article, we describe a rare presentation of NXG in location and skin type.

A 52-year-old woman with a history of systemic lupus erythematosus (SLE) presented with alopecia and a tender lesion on the scalp of 5 years’ duration (Figure 1). The patient had no history of a similar lesion, and no other lesions were present. A biopsy performed at an outside clinic a few weeks to months prior to the initial presentation to our clinic showed NXG (Figure 2). Evaluation at our clinic revealed a 4x4-cm orange-brown annular plaque on the left parietal scalp. Serum and urine protein electrophoresis studies were negative. The patient reported she was up to date with recommended screenings such as mammography and colonoscopy. 

We started the patient on topical triamcinolone and topical ruxolitinib and administered intralesional triamcinolone. She was already taking hydroxychloroquine and leflunomide for SLE. Three weeks later, she returned with improved symptoms and appearance (Figure 1). She remained on intralesional triamcinolone and ruxolitinib and continues to experience improvement.

Necrobiotic xanthogranuloma is rare and typically is associated with monoclonal gammopathy.² In one study, 83 of 100 of patients with NXG presented with or were found to have a monoclonal gammopathy.² In another study, paraproteinemia was detected in 82.1% of patients.³ The majority of case reports and systematic reviews detail periorbital or thoracic lesions.⁴ The location on the scalp and lack of association with paraproteinemia make this a rare presentation of NXG. Studies may be warranted to explore any association of SLE with NXG if more cases present.

In a multicenter cross-sectional study and systematic review of 235 patients with NXG, 87% were White, 12% were Asian, and only 1% were Black or African American.³ The limited representation of skin of color raises concern for the possibility of missed diagnoses and delays in care. 

Treatment of NXG often is multimodal with use of intravenous immunoglobulin, oral steroids, chlorambucil, melphalan, and other alkylating agents, and response is variable.^3-6 Recent studies show treatment effectiveness with Janus kinase inhibitors in granulomatous dermatitides.^7-9 As our patient was not responding to prior treatments, we decided to try ruxolitinib, and she has continued to improve with it.^10,11 Interestingly, the patient experienced continued improvement with intralesional triamcinolone, which is not often reported in the literature.^2-6 Overall, NXG is an extremely rare condition that requires special care in workup to rule out paraproteinemia and a thoughtful approach to treatment modalities.

To the Editor:

Necrobiotic xanthogranuloma (NXG) is classified as a cutaneous non–Langerhans cell histiocytosis, often seen with monoclonal gammopathy of undetermined significance or multiple myeloma.¹ Clinically, it appears as a red or yellow plaque with occasional ulceration and telangiectasias, most commonly seen periorbitally and on the trunk. On pathology, NXG appears as necrobiosis, giant cells, and various inflammatory cells extending into the subcutaneous tissue.² In this article, we describe a rare presentation of NXG in location and skin type.

A 52-year-old woman with a history of systemic lupus erythematosus (SLE) presented with alopecia and a tender lesion on the scalp of 5 years’ duration (Figure 1). The patient had no history of a similar lesion, and no other lesions were present. A biopsy performed at an outside clinic a few weeks to months prior to the initial presentation to our clinic showed NXG (Figure 2). Evaluation at our clinic revealed a 4x4-cm orange-brown annular plaque on the left parietal scalp. Serum and urine protein electrophoresis studies were negative. The patient reported she was up to date with recommended screenings such as mammography and colonoscopy. 

We started the patient on topical triamcinolone and topical ruxolitinib and administered intralesional triamcinolone. She was already taking hydroxychloroquine and leflunomide for SLE. Three weeks later, she returned with improved symptoms and appearance (Figure 1). She remained on intralesional triamcinolone and ruxolitinib and continues to experience improvement.

Necrobiotic xanthogranuloma is rare and typically is associated with monoclonal gammopathy.² In one study, 83 of 100 of patients with NXG presented with or were found to have a monoclonal gammopathy.² In another study, paraproteinemia was detected in 82.1% of patients.³ The majority of case reports and systematic reviews detail periorbital or thoracic lesions.⁴ The location on the scalp and lack of association with paraproteinemia make this a rare presentation of NXG. Studies may be warranted to explore any association of SLE with NXG if more cases present.

In a multicenter cross-sectional study and systematic review of 235 patients with NXG, 87% were White, 12% were Asian, and only 1% were Black or African American.³ The limited representation of skin of color raises concern for the possibility of missed diagnoses and delays in care. 

Treatment of NXG often is multimodal with use of intravenous immunoglobulin, oral steroids, chlorambucil, melphalan, and other alkylating agents, and response is variable.^3-6 Recent studies show treatment effectiveness with Janus kinase inhibitors in granulomatous dermatitides.^7-9 As our patient was not responding to prior treatments, we decided to try ruxolitinib, and she has continued to improve with it.^10,11 Interestingly, the patient experienced continued improvement with intralesional triamcinolone, which is not often reported in the literature.^2-6 Overall, NXG is an extremely rare condition that requires special care in workup to rule out paraproteinemia and a thoughtful approach to treatment modalities.

As the health care landscape continues to shift, direct care (also known as direct pay) models have emerged as attractive alternatives to traditional insurance-based practice. For dermatology residents poised to enter the workforce, the direct care model offers potential advantages in autonomy, patient relationships, and work-life balance, but not without considerable risks and operational challenges. This article explores the key benefits and drawbacks of starting a direct care dermatology practice, providing a framework to help early-career dermatologists determine whether this path aligns with their personal and professional goals.

The transition from dermatology residency to clinical practice allows for a variety of paths, from large academic institutions to private practice to corporate entities (private equity–owned groups). In recent years, the direct care model has gained traction, particularly among physicians seeking greater autonomy and a more sustainable pace of practice.

Direct care dermatology practices operate outside the constraints of third-party payers, offering patients transparent pricing and direct access to care in exchange for fees paid out of pocket. By eliminating insurance companies as the middleman, it allows for less overhead, longer visits with patients, and increased access to care; however, though this model may seem appealing, direct care practices are not without their own set of challenges, especially amid rising concerns over physician burnout and administrative burden. 

This article explores the key benefits and drawbacks of starting a direct care dermatology practice, providing a framework to help early-career dermatologists determine whether this path aligns with their personal and professional goals.

The Case for Direct Care Dermatology

Autonomy and Control—Perhaps the most compelling advantage of the direct care model is clinical and operational autonomy. Without insurance contracts dictating codes, coverage limitations, and documentation demands, physicians regain full control over their practice—how much time they spend with each patient, what treatments they offer, and how they structure their schedules. This option is ideal for those who want to practice medicine the way they were trained—thoroughly, thoughtfully, and without rushing.

Improved Work-Life Balance—The direct care model allows for smaller patient panels, longer visits, and more flexible hours. In contrast to the high patient volumes required to maintain profitability in insurance-based models, direct care dermatologists often can sustain their practice with a smaller number of daily appointments. This results in reduced administrative overhead and the potential for substantial reduction in burnout, a concern that has been well documented among dermatologists in high-volume settings.^1-3 As a result, physicians are less likely to rush through patient visits or be consumed by concerns of falling behind, ultimately causing them to question their career choice.

Closer Patient Relationships—With fewer patients and longer visits, dermatologists often find the direct care model fosters a stronger therapeutic alliance that can improve treatment adherence, outcomes, and overall patient satisfaction. Additionally, patients often appreciate transparent pricing, the ability to reach their dermatologist more directly, and a sense of being truly seen and heard. This, in turn, can make dermatology more rewarding for the provider.

Entrepreneurial Opportunity—Direct care offers entrepreneurial individuals the chance to build a brand and shape a niche. It also provides the flexibility to explore complementary or alternative practice models.

The Challenges of Going Direct

Despite its appeal, starting a direct care practice is not without substantial risks and hurdles—particularly for residents just out of training. These challenges include financial risks and startup costs, market uncertainty, lack of mentorship or support, and limitations in treating complex dermatologic conditions.

Financial Risk and Startup Costs—Launching any solo practice involves a considerable financial investment up front, including rent, medical equipment, electronic medical record systems, malpractice insurance, marketing, and staffing. In a direct care model, there is the added pressure of building a patient base without the referral stream of insurance contracts. In the first 6 to 12 months, income may be minimal, making this route challenging without savings, a financial cushion, or external funding.

Market Uncertainty—The success of direct care dermatology depends heavily on local market dynamics. In affluent or health-literate communities, patients may be more willing to pay out of pocket for expedited or personalized care; however, in other areas, patients may be unwilling or unable to do so—especially if they are accustomed to using insurance. Physicians may find that some of their patients will choose to see a different dermatologist for certain procedures because it is covered by their insurance.

Lack of Immediate Mentorship or Support—Transitioning from residency to independent practice (in any model) can be difficult. Residency provides a structured, team-based environment with colleagues and mentors at every turn. A solo or small-group direct care practice may feel isolating, especially in the early months. Without senior physicians to consult with on challenging cases or administrative decisions, the learning curve can be steep. Early-career dermatologists must be confident in their clinical acumen and be prepared to seek out alternative mentorship or continuing education opportunities.

Limitations in Complex Medical Dermatology—While direct care excels in most general dermatology visit types (from medical and cosmetic to minor surgical), this model may be less suited for patients requiring complex care coordination. Patients with high-cost conditions such as immunobullous diseases or those needing systemic immunosuppressives may still require referral to academic centers or insurance-covered specialists. Additionally, costlier procedures such as Mohs micrographic surgery may not fit well into a direct pay model, which may limit the scope of practice for direct care dermatologists in this subspecialty.

Considerations for Residents

Before committing to practicing via a direct care model, dermatology residents should reflect on the following:

• Risk tolerance: Are you comfortable navigating the business and financial risk?
• Location: Does your target community have patients willing and able to pay out of pocket?
• Scope of interest: Will a direct care practice align with your clinical passions?
• Support systems: Do you have access to mentors, legal and financial advisors, and operational support?
• Long-term goals: Are you building a lifestyle practice, a scalable business, or a stepping stone to a future opportunity?

Ultimately, the decision to pursue a direct care model requires careful reflection on personal values, financial preparedness, and the unique needs of the community one intends to serve.

Final Thoughts

The direct care dermatology model offers an appealing alternative to traditional practice, especially for those prioritizing autonomy, patient connection, and work-life balance; however, it demands an entrepreneurial spirit as well as careful planning and an acceptance of financial uncertainty—factors that may pose challenges for new graduates. For dermatology residents, the decision to pursue direct care should be grounded in personal values, practical considerations, and a clear understanding of both the opportunities and limitations of this evolving practice model.

As the health care landscape continues to shift, direct care (also known as direct pay) models have emerged as attractive alternatives to traditional insurance-based practice. For dermatology residents poised to enter the workforce, the direct care model offers potential advantages in autonomy, patient relationships, and work-life balance, but not without considerable risks and operational challenges. This article explores the key benefits and drawbacks of starting a direct care dermatology practice, providing a framework to help early-career dermatologists determine whether this path aligns with their personal and professional goals.

The transition from dermatology residency to clinical practice allows for a variety of paths, from large academic institutions to private practice to corporate entities (private equity–owned groups). In recent years, the direct care model has gained traction, particularly among physicians seeking greater autonomy and a more sustainable pace of practice.

Direct care dermatology practices operate outside the constraints of third-party payers, offering patients transparent pricing and direct access to care in exchange for fees paid out of pocket. By eliminating insurance companies as the middleman, it allows for less overhead, longer visits with patients, and increased access to care; however, though this model may seem appealing, direct care practices are not without their own set of challenges, especially amid rising concerns over physician burnout and administrative burden. 

This article explores the key benefits and drawbacks of starting a direct care dermatology practice, providing a framework to help early-career dermatologists determine whether this path aligns with their personal and professional goals.

The Case for Direct Care Dermatology

Autonomy and Control—Perhaps the most compelling advantage of the direct care model is clinical and operational autonomy. Without insurance contracts dictating codes, coverage limitations, and documentation demands, physicians regain full control over their practice—how much time they spend with each patient, what treatments they offer, and how they structure their schedules. This option is ideal for those who want to practice medicine the way they were trained—thoroughly, thoughtfully, and without rushing.

Improved Work-Life Balance—The direct care model allows for smaller patient panels, longer visits, and more flexible hours. In contrast to the high patient volumes required to maintain profitability in insurance-based models, direct care dermatologists often can sustain their practice with a smaller number of daily appointments. This results in reduced administrative overhead and the potential for substantial reduction in burnout, a concern that has been well documented among dermatologists in high-volume settings.^1-3 As a result, physicians are less likely to rush through patient visits or be consumed by concerns of falling behind, ultimately causing them to question their career choice.

Closer Patient Relationships—With fewer patients and longer visits, dermatologists often find the direct care model fosters a stronger therapeutic alliance that can improve treatment adherence, outcomes, and overall patient satisfaction. Additionally, patients often appreciate transparent pricing, the ability to reach their dermatologist more directly, and a sense of being truly seen and heard. This, in turn, can make dermatology more rewarding for the provider.

Entrepreneurial Opportunity—Direct care offers entrepreneurial individuals the chance to build a brand and shape a niche. It also provides the flexibility to explore complementary or alternative practice models.

The Challenges of Going Direct

Despite its appeal, starting a direct care practice is not without substantial risks and hurdles—particularly for residents just out of training. These challenges include financial risks and startup costs, market uncertainty, lack of mentorship or support, and limitations in treating complex dermatologic conditions.

Financial Risk and Startup Costs—Launching any solo practice involves a considerable financial investment up front, including rent, medical equipment, electronic medical record systems, malpractice insurance, marketing, and staffing. In a direct care model, there is the added pressure of building a patient base without the referral stream of insurance contracts. In the first 6 to 12 months, income may be minimal, making this route challenging without savings, a financial cushion, or external funding.

Market Uncertainty—The success of direct care dermatology depends heavily on local market dynamics. In affluent or health-literate communities, patients may be more willing to pay out of pocket for expedited or personalized care; however, in other areas, patients may be unwilling or unable to do so—especially if they are accustomed to using insurance. Physicians may find that some of their patients will choose to see a different dermatologist for certain procedures because it is covered by their insurance.

Lack of Immediate Mentorship or Support—Transitioning from residency to independent practice (in any model) can be difficult. Residency provides a structured, team-based environment with colleagues and mentors at every turn. A solo or small-group direct care practice may feel isolating, especially in the early months. Without senior physicians to consult with on challenging cases or administrative decisions, the learning curve can be steep. Early-career dermatologists must be confident in their clinical acumen and be prepared to seek out alternative mentorship or continuing education opportunities.

Limitations in Complex Medical Dermatology—While direct care excels in most general dermatology visit types (from medical and cosmetic to minor surgical), this model may be less suited for patients requiring complex care coordination. Patients with high-cost conditions such as immunobullous diseases or those needing systemic immunosuppressives may still require referral to academic centers or insurance-covered specialists. Additionally, costlier procedures such as Mohs micrographic surgery may not fit well into a direct pay model, which may limit the scope of practice for direct care dermatologists in this subspecialty.

Considerations for Residents

Before committing to practicing via a direct care model, dermatology residents should reflect on the following:

• Risk tolerance: Are you comfortable navigating the business and financial risk?
• Location: Does your target community have patients willing and able to pay out of pocket?
• Scope of interest: Will a direct care practice align with your clinical passions?
• Support systems: Do you have access to mentors, legal and financial advisors, and operational support?
• Long-term goals: Are you building a lifestyle practice, a scalable business, or a stepping stone to a future opportunity?

Ultimately, the decision to pursue a direct care model requires careful reflection on personal values, financial preparedness, and the unique needs of the community one intends to serve.

Final Thoughts

The direct care dermatology model offers an appealing alternative to traditional practice, especially for those prioritizing autonomy, patient connection, and work-life balance; however, it demands an entrepreneurial spirit as well as careful planning and an acceptance of financial uncertainty—factors that may pose challenges for new graduates. For dermatology residents, the decision to pursue direct care should be grounded in personal values, practical considerations, and a clear understanding of both the opportunities and limitations of this evolving practice model.

As the health care landscape continues to shift, direct care (also known as direct pay) models have emerged as attractive alternatives to traditional insurance-based practice. For dermatology residents poised to enter the workforce, the direct care model offers potential advantages in autonomy, patient relationships, and work-life balance, but not without considerable risks and operational challenges. This article explores the key benefits and drawbacks of starting a direct care dermatology practice, providing a framework to help early-career dermatologists determine whether this path aligns with their personal and professional goals.

The transition from dermatology residency to clinical practice allows for a variety of paths, from large academic institutions to private practice to corporate entities (private equity–owned groups). In recent years, the direct care model has gained traction, particularly among physicians seeking greater autonomy and a more sustainable pace of practice.

Direct care dermatology practices operate outside the constraints of third-party payers, offering patients transparent pricing and direct access to care in exchange for fees paid out of pocket. By eliminating insurance companies as the middleman, it allows for less overhead, longer visits with patients, and increased access to care; however, though this model may seem appealing, direct care practices are not without their own set of challenges, especially amid rising concerns over physician burnout and administrative burden. 

This article explores the key benefits and drawbacks of starting a direct care dermatology practice, providing a framework to help early-career dermatologists determine whether this path aligns with their personal and professional goals.

The Case for Direct Care Dermatology

Autonomy and Control—Perhaps the most compelling advantage of the direct care model is clinical and operational autonomy. Without insurance contracts dictating codes, coverage limitations, and documentation demands, physicians regain full control over their practice—how much time they spend with each patient, what treatments they offer, and how they structure their schedules. This option is ideal for those who want to practice medicine the way they were trained—thoroughly, thoughtfully, and without rushing.

Improved Work-Life Balance—The direct care model allows for smaller patient panels, longer visits, and more flexible hours. In contrast to the high patient volumes required to maintain profitability in insurance-based models, direct care dermatologists often can sustain their practice with a smaller number of daily appointments. This results in reduced administrative overhead and the potential for substantial reduction in burnout, a concern that has been well documented among dermatologists in high-volume settings.^1-3 As a result, physicians are less likely to rush through patient visits or be consumed by concerns of falling behind, ultimately causing them to question their career choice.

Closer Patient Relationships—With fewer patients and longer visits, dermatologists often find the direct care model fosters a stronger therapeutic alliance that can improve treatment adherence, outcomes, and overall patient satisfaction. Additionally, patients often appreciate transparent pricing, the ability to reach their dermatologist more directly, and a sense of being truly seen and heard. This, in turn, can make dermatology more rewarding for the provider.

Entrepreneurial Opportunity—Direct care offers entrepreneurial individuals the chance to build a brand and shape a niche. It also provides the flexibility to explore complementary or alternative practice models.

The Challenges of Going Direct

Despite its appeal, starting a direct care practice is not without substantial risks and hurdles—particularly for residents just out of training. These challenges include financial risks and startup costs, market uncertainty, lack of mentorship or support, and limitations in treating complex dermatologic conditions.

Financial Risk and Startup Costs—Launching any solo practice involves a considerable financial investment up front, including rent, medical equipment, electronic medical record systems, malpractice insurance, marketing, and staffing. In a direct care model, there is the added pressure of building a patient base without the referral stream of insurance contracts. In the first 6 to 12 months, income may be minimal, making this route challenging without savings, a financial cushion, or external funding.

Market Uncertainty—The success of direct care dermatology depends heavily on local market dynamics. In affluent or health-literate communities, patients may be more willing to pay out of pocket for expedited or personalized care; however, in other areas, patients may be unwilling or unable to do so—especially if they are accustomed to using insurance. Physicians may find that some of their patients will choose to see a different dermatologist for certain procedures because it is covered by their insurance.

Lack of Immediate Mentorship or Support—Transitioning from residency to independent practice (in any model) can be difficult. Residency provides a structured, team-based environment with colleagues and mentors at every turn. A solo or small-group direct care practice may feel isolating, especially in the early months. Without senior physicians to consult with on challenging cases or administrative decisions, the learning curve can be steep. Early-career dermatologists must be confident in their clinical acumen and be prepared to seek out alternative mentorship or continuing education opportunities.

Limitations in Complex Medical Dermatology—While direct care excels in most general dermatology visit types (from medical and cosmetic to minor surgical), this model may be less suited for patients requiring complex care coordination. Patients with high-cost conditions such as immunobullous diseases or those needing systemic immunosuppressives may still require referral to academic centers or insurance-covered specialists. Additionally, costlier procedures such as Mohs micrographic surgery may not fit well into a direct pay model, which may limit the scope of practice for direct care dermatologists in this subspecialty.

Considerations for Residents

Before committing to practicing via a direct care model, dermatology residents should reflect on the following:

• Risk tolerance: Are you comfortable navigating the business and financial risk?
• Location: Does your target community have patients willing and able to pay out of pocket?
• Scope of interest: Will a direct care practice align with your clinical passions?
• Support systems: Do you have access to mentors, legal and financial advisors, and operational support?
• Long-term goals: Are you building a lifestyle practice, a scalable business, or a stepping stone to a future opportunity?

Ultimately, the decision to pursue a direct care model requires careful reflection on personal values, financial preparedness, and the unique needs of the community one intends to serve.

Final Thoughts

The direct care dermatology model offers an appealing alternative to traditional practice, especially for those prioritizing autonomy, patient connection, and work-life balance; however, it demands an entrepreneurial spirit as well as careful planning and an acceptance of financial uncertainty—factors that may pose challenges for new graduates. For dermatology residents, the decision to pursue direct care should be grounded in personal values, practical considerations, and a clear understanding of both the opportunities and limitations of this evolving practice model.