Modern Techniques and MRI Markers in Multiple Sclerosis Imaging or How to Increase Specificity and Sensitivity of Examinations
MRI is a key component in the diagnosis of multiple sclerosis (MS). However, despite significant progress in imaging methods, specificity is still not optimal. The current trend is to refine and clearly define MRI criteria for diagnosing multiple sclerosis and distinguishing it from MS-mimicking white matter lesions.
Limitations of Imaging Methods in MS Diagnosis
The diagnosis of multiple sclerosis (MS) is primarily based on detecting hyperintense lesions in the CNS on T2-weighted sequences (T2W) and FLAIR imaging (fluid attenuated inversion recovery). However, it appears that conventional MRI techniques exhibit suboptimal specificity. In clinical practice, we often encounter ambiguous and poorly grasped cases where available techniques cannot clearly distinguish whether it is MS or another demyelinating process. This limitation is also evidenced by the discrepancy between MRI findings and histopathological examination.
CVS as a New Diagnostic Marker
The presence of a central vein (CVS − central vein sign) in the white matter on T2-weighted images has long been considered a biomarker of demyelination. Suh et al., in their 2019 work, provide a systematic review focused on evaluating CVS in T2W images in patients with MS. They also addressed the use of this radiological criterion to distinguish other white matter lesions, such as neuromyelitis optica, inflammatory vasculopathies, migraines, or small vessel disease (CSVD − cerebral small vessel disease).
The study results clearly emphasize the significance of this new MRI criterion in the diagnosis of MS. In 74% of patients, the presence of a central vein was demonstrated in T2-weighted images. The results also indicate that CVS serves as a suitable diagnostic tool for distinguishing multiple sclerosis from other demyelinating diseases, with a specificity of 97% and sensitivity of 98%.
These findings are also supported by a multicenter study published a year earlier by Maggi et al., which focused on the differential diagnosis of multiple sclerosis and CNS inflammatory vasculopathies. The presence of CVS alone, or in combination with other available MRI criteria, significantly improves specificity on both 3T and 1.5T MRI devices.
Conclusion
In conclusion, the evaluation of CVS is a useful tool in diagnosing multiple sclerosis and is a highly specific technique for distinguishing other inflammatory or demyelinating processes in the central nervous system that may clinically mimic MS. Some recently published studies have shown that merely using conventional MRI imaging methods achieves very low specificity (around 29%). The development of new techniques and diagnostic biomarkers, including CVS, allows for a more comprehensive view of CNS structural damage, increases the specificity of examinations, and thus reduces the number of false-positive cases.
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Sources:
1. Suh C. H., Kim S. J., Jung S. C. et al. The "central vein sign" on T2*-weighted images as a diagnostic tool in multiple sclerosis: a systematic review and meta-analysis using individual patient data. Sci Rep 2019 Dec 3; 9: 18188, doi: 10.1038/s41598-019-54583-3.
2. Maggi P., Absinta M., Grammatico M. et al. Central vein sign differentiates Multiple Sclerosis from central nervous system inflammatory vasculopathies. Ann Neurol 2018; 83 (2): 283−294, doi: 10.1002/ana.25146.
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