MPRAGE-derived quantitative T1 mapping to assess diffuse white matter alterations in multiple sclerosis.

BackgroundMultiple sclerosis (MS) is characterized by focal white matter (WM) lesions, but subtle damage also occurs in normal-appearing white matter (NAWM). We developed a method to generate quantitative T1 maps from MPRAGE (Magnetization Prepared Rapid Gradient Echo) images and evaluated its ability to detect NAWM abnormalities across different MS phenotypes. MethodsT1 maps were derived from MPRAGE using a theoretical signal model and compared with MP2RAGE (Magnetization Prepared 2 Rapid Gradient Echoes) T1 values in four healthy volunteers. The method was then applied to 87 MS patients, divided into clinically isolated syndrome (CIS), relapsing-remitting MS (RRMS), and primary progressive MS (PPMS), with age- and sex-matched healthy controls. T1 was measured in NAWM and lesions. Histogram analysis provided mean T1, full width at half maximum (FWHM), and skewness. ResultsIn healthy volunteers, T1 values matched MP2RAGE. In controls matched to the MS cohort, T1 increased with age (r = 0.35, p < 0.05). CIS patients showed no significant differences in any metric. RRMS and PPMS patients showed unchanged mean NAWM T1 but significantly different distributions, with higher FWHM (p<0.05) and skewness (p<0.001). An increase in T1 values was observed in MS lesions compared to NAWM in all groups. ConclusionThis study confirms the feasibility of deriving quantitative T1 maps from standard MPRAGE, offering reliable information to facilitate MS monitoring without additional acquisitions.