Identification of cortical lesions using DIR and FLAIR in early stages of multiple sclerosis

The use of non-routine MRI sequences such as DIR has highlighted the role of gray matter (GM) pathology in multiple sclerosis (MS). The aim of this study was to assess the detection and relevance of cortical lesions (CLs) using MRI in early (<5 years) MS patients. 3D DIR and 3D FLAIR images at 3T from 122 patients [93 relapsing–remitting MS (RRMS), 29 clinically isolated syndrome (CIS)] were scored for CLs by two blinded readers. Patients were divided into two groups depending on the presence or absence of CLs. For FLAIR, 51 CLs were identified, of which 13 were purely intracortical and 38 mixed CLs; for DIR, this was 60 in total and 16 and 44, respectively. In both groups, there was no difference in GM fraction. Neuropsychological testing was performed for a subgroup of 66 patients. In 22.1 % of patients CLs were identified. The number of CLs revealed an association with lower working memory scores and semantical word fluency. Overall, CLs imaged with 3D FLAIR and 3D DIR sequences are found more frequently in RRMS patients than CIS and may also be a correlate for mild neuropsychological pathology.