Background: Autopsy studies showed cortical and juxtacortical multiple sclerosis (MS) plaques. Fluid-attenuated inversion recovery (FLAIR) is an advanced magnetic resonance imaging sequence that reveals tissue T2 prolongation with cerebrospinal fluid suppression, allowing detection of superficial brain lesions.
Objectives: To assess FLAIR, T1-weighted, and T2-weighted images for detecting lesions in or near the cerebral cortex in patients with MS and to explore the relation between cortical lesions and cortical atrophy.
Design, setting, and patients: Cross-sectional study in a university MS clinic of 84 patients with MS and 66 age-matched healthy controls receiving 1.5-T fast FLAIR, T2-weighted, and T1-weighted images.
Main outcome measures: Regional cortical atrophy was rated vs controls. Cortical and juxtacortical lesions were ovoid hyperintensities involving the cortex and/or gray-white junction.
Results: A total of 810 cortical and juxtacortical lesions were seen by FLAIR in patients (mean, 9.6 per patient), most commonly in the superior frontal lobe. Cortical and juxtacortical lesions were identified in 72 patients and 6 controls. Fourteen percent of cortical and juxtacortical lesions were seen on T1-weighted images and 26% were seen on T2-weighted images. More cortical and juxtacortical lesions were present in secondary progressive disease than relapsing-remitting disease. The total number of cortical and juxtacortical lesions correlated significantly with disease duration and the regional number correlated with the degree of regional atrophy. After taking into account noncortical (white matter) lesions, only the cortical and juxtacortical lesion count predicted atrophy in that region.
Conclusions: FLAIR can detect many cortical and juxtacortical lesions in MS, which were appreciated previously in autopsy studies but usually missed by magnetic resonance imaging during life. Cortical and juxtacortical plaque formation may contribute to cortical atrophy in MS.