Imaging cortical multiple sclerosis lesions with ultra-high field MRI

Area of Science:

• Neuroimaging
• Radiology
• Neurology

Background:

• Cortical lesions are a hallmark of multiple sclerosis (MS) but are challenging to detect in vivo.
• Ultra-high field (UHF) MRI, specifically at 7 Tesla (7T) and above, offers advanced capabilities for visualizing these lesions.

Purpose of the Study:

• To conduct a systematic review of the literature on UHF MRI for detecting cortical lesions in MS.
• To quantitatively compare lesion detection rates and sensitivity between different MRI strengths and sequences.

Main Methods:

• Systematic literature search for studies on UHF MRI of MS cortical lesions published before September 2020.
• Quantitative analysis of cortical lesion numbers at 3T vs. 7T MRI and comparison of 7T MRI sequences.
• Assessment of UHF MRI sensitivity against histopathological findings.

Main Results:

• 7T MRI detected 52% more cortical lesions than 3T MRI, particularly intracortical lesions (types II-IV).
• Mean lesion count was 17 per patient, with progressive MS showing four times more lesions than earlier stages.
• UHF MRI sensitivity for post-mortem lesions was modest (33% prospective, 71% retrospective), with highest sensitivity for type I and IV lesions.

Conclusions:

• UHF MRI substantially improves cortical lesion detection in MS compared to 3T MRI, aiding diagnosis and monitoring, especially in progressive MS.
• Despite limitations in sensitivity, UHF MRI visualizes cortical lesion pathology comprehensively.
• Standardization of UHF MRI acquisition and segmentation protocols is necessary for widespread clinical adoption.