TSPO-Detectable Chronic Active Lesions Predict Disease Progression in Multiple Sclerosis

Area of Science:

• Neuroimmunology
• Radiology
• Neurology

Background:

• Chronic active lesions in multiple sclerosis (MS) brain are detectable via MRI and PET imaging.
• Innate immune cell activation within these lesions is a key pathological feature.

Purpose of the Study:

• To investigate the association between TSPO-PET-detectable chronic active lesions and MS disease progression.
• To determine if lesion characteristics predict disability measured by the Expanded Disability Status Scale (EDSS) over a 5-year follow-up.

Main Methods:

• 82 MS patients underwent TSPO-PET imaging to assess chronic lesion activity.
• Lesions were classified as rim-active, inactive, or overall active based on immune cell patterns.
• Logistic regression analysis identified predictors of disease progression.

Main Results:

• Patients with disability progression showed a higher proportion of rim-active lesions and fewer inactive lesions.
• A specific lesion pattern ( >10% rim-active and ≤50% inactive lesions) strongly predicted progression (OR = 26.8).
• These findings held true even in patients without relapses during follow-up.

Conclusions:

• In vivo phenotyping of MS chronic lesions using TSPO-PET is a robust predictor of disease progression.
• The study highlights the critical role of chronic active lesions in MS disability accumulation.