Normal-Appearing Brain T1 Relaxation Time Predicts Disability in Early Primary Progressive Multiple Sclerosis

Abstract

To investigate whether patients with early primary progressive multiple sclerosis show changes in T1 relaxation time (T1-RT) in normal-appearing white matter (NAWM) and normal-appearing gray matter (NAGM) during 2 years and whether T1-RT at baseline predicts disability. Twenty-one patients and 12 control subjects were studied at baseline and after 2 years. Expanded Disability Status Scale (EDSS) and Multiple Sclerosis Functional Composite (MSFC) scores were assessed. T1 relaxation time histograms of NAWM and NAGM were obtained in all subjects, and mean, peak height, and peak location of the histograms were measured. Paired t tests were used to compare baseline and 2-year histogram values in patients and control subjects. To investigate whether T1-RT predicted clinical changes, multiple linear regression analysis was used. Patients showed increases in NAWM and NAGM T1-RT mean and peak location during follow-up, and significant decreases in NAWM and NAGM peak height. Baseline NAWM T1-RT mean values and peak height predicted disability at 2 years, as measured with the Multiple Sclerosis Functional Composite score. T1 relaxometry is a good marker of disease progression and has prognostic potential in primary progressive multiple sclerosis.