The 2024 update to the McDonald criteria formally integrated the central vein sign (CVS) and paramagnetic rim lesions (PRL) as optional diagnostic markers for multiple sclerosis (MS). These markers offer high specificity, helping to differentiate MS from mimics, à la small-vessel ischemic disease.
Pro Tip: While many protocols suggest adding a T2-FLAIR or specialized SWI sequence, as Joshua P. Nickerson, MD, tipped us off during ARRS 2026, you can often visualize the CVS using existing 3D data and your PACS vendor’s MPR tool.
- Process—Load a 3D SWI image in the MPR tool, then right-click and drag a 3D FLAIR image on top of it to create a composite map.
- Benefit—Using a slider bar to blend the two images allows you to confirm if a vessel is centrally located within a T2 hyperintensity…without adding length to your clinical protocol.
More From McDonald ‘24:
- Optic Nerve: Now recognized as a fifth topographic site for assessing dissemination in space (DIS).
- Rule of 6: Identifying 6 or more CVS-positive lesions can substitute for dissemination in time (DIT) criteria.
- CSF Markers: Kappa free light chains are an approved substitute for DIT, providing a quantitative alternative to traditional oligoclonal bands.
- Stricter Thresholds: For patients over 50 (or those with vascular risk factors), a diagnosis now strongly recommends the presence of a spinal cord lesion, CSF positivity, or at least 6 CVS-positive lesions.
RadFYI: Imagers should transition to structured reporting that includes the count of CVS-positive lesions, as well as PRLs. Whereas 3T is preferred for detecting these subtle markers, creative use of PACS post-processing may help you satisfy the latest standards.
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