MS lesions demonstrate distinct patterns of expansion based on their location within the brain, particularly in relation to the cerebrospinal fluid (CSF).

Periventricular Gradient

Lesion expansion follows a clear gradient pattern related to CSF proximity:

• Expansion rates are highest near ventricles
• Each millimeter away from ventricles reduces expansion rate by 1.5%
• 91% of expanding lesion volume occurs within first 10mm of ventricles

Tissue Damage Patterns

The severity of tissue damage also follows this gradient:

• Higher mean diffusivity (MD) in lesions closer to CSF
• More pronounced T1 hypointensity near ventricles
• Progressive tissue damage accumulates faster in periventricular regions

Clinical Significance

This spatial pattern has important implications:

• Helps explain heterogeneity in lesion expansion between patients
• Suggests CSF-mediated factors influence disease progression
• May guide development of targeted therapies
• Provides new biomarkers for monitoring disease progression

Research Applications

Understanding these spatial patterns enables:

• Better prediction of lesion evolution
• More accurate assessment of treatment efficacy
• Improved patient stratification for clinical trials
• Development of location-specific therapeutic approaches