Quality and Quantity of Diffuse and Focal White Matter Disease and Cognitive Disability of Patients with Multiple Sclerosis

BACKGROUND AND PURPOSE Using high-field magnetic resonance imaging (MRI), we investigated the relationships between white matter (WM) lesion volume (LV), normal-appearing WM (NAWM) normalized volume, WM-lesion and NAWM magnetization transfer ratios (MTRs), brain parenchyma fraction (BPF), and cognitive impairment (CI) in multiple sclerosis (MS). METHODS Twenty-four patients and 24 healthy volunteers (age, sex, and years of education-matched) underwent a 3.0 Tesla (3T) scan and evaluation of depression, fatigue, and CI using the Minimal Assessment of Cognitive Function in MS (MACFIMS) battery. RESULTS In this clinically relatively well-preserved cohort of patients (median score on the Expanded Disability Status Scale = 1.5), CI was detected on Symbol Digit Modalities Test (SDMT), California Verbal Learning Test-II (CVLT-II), and Controlled Oral Word Association Test. MT data were available in 19 pairs on whom correlation analyses were performed. Associations were seen between SDMT and normalized NAWM volume (P = .034, r = .502), CVLT-II long delay and normalized NAWM volume (P = .012, r = .563), WM-LV (P = .024, r = .514), and BPF (P = .002, r = .666). CONCLUSIONS The use of 3T MRI in a sample of clinically stable MS patients shows the importance of WM disease in hampering processing speed and word retrieval.