Regarding MRI characteristics of multiple sclerosis plaques, which finding is MOST specific for active demyelinating lesions?

• A Gadolinium-enhancing lesion indicating active blood-brain barrier breakdown ✓
• B T2/FLAIR hyperintense lesion perpendicular to the corpus callosum (Dawson's fingers)
• C T1 hypointense 'black holes' representing irreversible axonal loss
• D Cortical/juxtacortical lesion distribution

Explanation

Gadolinium enhancement in MS lesions indicates active inflammation with blood-brain barrier breakdown, and is the most specific marker of an active demyelinating plaque (typically persisting 4-8 weeks). Dawson's fingers (periventricular T2-hyperintense lesions perpendicular to the ventricles along medullary veins) are a classic diagnostic finding but do not distinguish active from chronic lesions. T1 black holes represent chronic irreversible axonal loss. Cortical lesions are better seen on 3D FLAIR/DIR sequences and reflect disease burden but not activity specifically.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.