Evidence for a white matter lesion size threshold to support the diagnosis of relapsing remitting multiple sclerosis

• Published in: Multiple sclerosis and related disorders Vol. 29; pp. 124 - 129
• Main Authors: Grahl, S., Pongratz, V., Schmidt, P., Engl, C., Bussas, M., Radetz, A., Gonzalez-Escamilla, G., Groppa, S., Zipp, F., Lukas, C., Kirschke, J., Zimmer, C., Hoshi, M., Berthele, A., Hemmer, B., Mühlau, M.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.04.2019
• Subjects: Relapsing-remitting multiple sclerosis; Structural MRI; White matter lesion; White matter lesion size threshold; CS1; TIV; CS2; D; MS1; MS2; White matter lesion; LOESS; sWML; WM; CSF; T2w; OR; GM; MS; ROC; Structural MRI; CIS; CS; TE; White matter lesion size threshold; TI; WML; Relapsing-remitting multiple sclerosis; T1w; TR
• ISSN: 2211-0348; 2211-0356
• DOI: 10.1016/j.msard.2019.01.042

•White matter lesions smaller than 3 mm are more frequent in patients with multiple sclerosis than in control subjects.•White matter lesion size threshold of 3 mm distinguishes best between MS patients and control subjects.•Consistent findings across two 3 T scanners from different vendors. The number of white matter lesions (WML) in brain MRI is the most established paraclinical tool to support the diagnosis of multiple sclerosis (MS) and to monitor its course. Diagnostic criteria have stipulated a minimum detectable diameter of 3 mm per WML, although this threshold is not evidence-based. We aimed to provide a rationale for a WML size threshold for three-dimensional MRI sequences at 3 T by comparing patients with relapsing-remitting MS (RRMS) to control subjects (CS). We analyzed MR images from two cohorts, obtained at scanners from two different vendors, each comprising patients with RRMS and CS. Both cohorts were examined with FLAIR and T1w sequences. In total, 232 patients with RRMS (Expanded Disability Status Scale: mean = 1.6 ± 1.2; age: mean = 36 ± 10) as well as 116 age- and sex-matched CS were studied. We calculated odds ratios across WML volumes. The WML size threshold, which discriminated best between patients and CS, was estimated with receiver operating characteristic curve analysis. In both cohorts, odds ratios increased continuously with increasing WML volumes, and discriminative power was highest at a WML size threshold corresponding to a diameter of about 3 mm. The stipulated WML size threshold of 3 mm in diameter for the diagnostic criteria of MS seems a reasonable choice for three-dimensional MRI sequences at 3 T.