Diffusion Tensor Imaging (DTI) and its clinical correlates in drug naïve Wilson’s disease

Abstract

The purpose is to evaluate white matter (WM) abnormalities in Wilson's disease (WD) using the technique of diffusion tensor imaging (DTI). The prospective case-control study comprised of 15 drug-naïve patients with WD and 15 controls. The phenotype of subjects was evaluated. The DTI/conventional MRI was acquired (3T MRI): Fractional anisotropy (FA) and mean diffusivity (MD) values were extracted from regions of interest placed in pons, midbrain, bilateral frontal and occipital cerebral white matter, bilateral internal capsules (IC), middle cerebellar peduncles (MCP) and corpus callosum (CC). Six patients showed lobar WM signal changes on T(2)-Weighted (T2W)/Fluid attenuation inversion recovery (FLAIR) images while remaining had normal appearing WM. MD was significantly increased in the lobar WM, bilateral IC and midbrain of WD patients. FA was decreased in the frontal and occipital WM, bilateral IC, midbrain and pons. Normal-appearing white matter on FLAIR images showed significantly increased MD and decreased FA values in both frontal and occipital lobar WM and IC compared with those in controls. Correlation of clinical scores and DTI metrics revealed positive correlation between neurological symptom score (NSS) and MD of anterior limb of right internal capsule, Chu stage and MD of frontal and occipital WM. Negative correlation was observed between the Modified Schwab and England Activities of Daily Living (MSEADL) score and MD of bilateral frontal and occipital WM and IC. This is the probably the first study to reveal widespread alterations in WM by DTI metrics in drug naïve WD. DTI analysis revealed lobar WM abnormalities which is less frequently noted on conventional MRI and suggests widespread WM abnormalities in WD. It may be valuable in assessing the true extent of involvement and therefore the severity of the illness.