Multiple sclerosis

40-50 years age
Relapsing-remitting type 85%
Primary-progressive type 15%
Characteristic abnormality – demyelinating plaques
Location of plaques – middle cerebellar peduncle, callososeptal interface, periventricular white matter, juxtacortical
Callososeptal interface involvement – pathognomonic

Plaque character
- Initial stages: acute, with surrounding edema
- Remyelination may occur: resulting in target lesions in pathology
- Eventually, chronic stage: axon loss, fluid accumulation, gliosis
Periventricular lesions
- White matter surrounding corpus callosum
- Perpendicular to ventricular margin due to clustering around deep matter veins
Juxtacortical lesions
- Adjacent to cortex with no intervening white matter
Infratentorial lesions
- Cerebellar white matter
- Cerebellar peduncles
- Brain stem white matter tracts
Spinal cord lesions
- Centrally or eccentrically within cord
- Eccentric lesions best picked in axial T2 imaging
Tumefactive lesions
- Large, swollen lesions
- Target appearance, bright central T2, with lighter surrounding T2 hyperintensity
- Multiple targets may be seen in one lesion – Balo’s concentric sclerosis
- Incomplete ring enhancement is highly suggestive
Contrast: identifies activity of lesions
Incomplete enhancement, mild perfusion elevation and mild diffusion restriction favor MS rather than a neoplasm
Imaging criteria:
- Dissemination in space: at least one lesion in two of the four typical locations
- Dissemination in time: mix of enhancing and non enhancing lesions in one scan or appearance of new lesion in follow up scan suggests dissemination in time