Does high-field MR imaging improve cortical lesion detection in multiple sclerosis?

Area of Science:

• Neuroimaging
• Neuropathology
• Magnetic Resonance Imaging

Background:

• Cortical lesions in multiple sclerosis (MS) are challenging to detect using standard MRI.
• Higher magnetic field strengths may improve spatial resolution and lesion detection.
• This study investigates MRI sensitivity for post mortem MS cortical lesions.

Purpose of the Study:

• To compare the sensitivity of high-field (4.7 T) MRI versus standard-field (1.5 T) MRI for detecting post mortem cortical lesions in MS.
• To assess the impact of field strength on the detection of different cortical lesion subtypes.

Main Methods:

• Post mortem formalin-fixed MS and control brain hemispheres were imaged at 1.5 T and 4.7 T.
• MRI sequences included dual-echo T2-weighted spin-echo and 3D-FLAIR at 1.5 T, and PD-weighted at 4.7 T.
• Histological sections (PLP-stained) were used for comparison, with blinded and unblinded lesion scoring.

Main Results:

• Sensitivity for purely intracortical lesions (types II, III, IV) was below 10% at both 1.5 T and 4.7 T.
• Mixed gray/white matter lesions (type I) were detected in 4 out of 5 cases.
• Unblinded scoring increased lesion counts, but up to 80% of intracortical lesions remained undetected.

Conclusions:

• Post mortem MRI has low sensitivity for detecting MS cortical lesions, even at higher field strengths.
• Sensitivity varies significantly depending on the subtype of cortical lesion.
• Further advancements in MRI techniques are needed for improved detection of MS cortical pathology.