On MRI of a patient with multiple sclerosis, Dawson's fingers are best seen on which sequence and orientation?

• A Axial T2-weighted imaging through the corpus callosum
• B Sagittal FLAIR imaging along the callosal-septal interface ✓
• C Coronal T1 post-gadolinium imaging
• D Axial DWI showing restricted diffusion in periventricular lesions

Explanation

Dawson's fingers are periventricular demyelinating plaques oriented perpendicular to the lateral ventricles along medullary veins. They are BEST demonstrated on sagittal FLAIR (fluid-attenuated inversion recovery) imaging where the CSF signal is nulled, allowing the bright T2 lesions radiating from the callosal-septal surface to be clearly seen as finger-like projections. Axial T2 can show periventricular lesions but the characteristic finger orientation is not well appreciated. Post-gadolinium T1 shows active plaques with enhancement. DWI is typically unremarkable in chronic MS plaques.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.