Tract integrity in amyotrophic lateral sclerosis: 6–month evaluation using MR diffusion tensor imaging

BACKGROUND: This study was performed to assess changes in diffusion tensor imaging (DTI) over time in patients with amyotrophic lateral sclerosis (ALS). METHODS: We performed DTI in 23 ALS patients who had two magnetic resonance imaging (MRI) scans at 6 month intervals and to correlate results with clinical features. The revised ALS functional rating scale (ALSFRS–R) was administered at each clinical visit. Data analysis included voxel–based white matter tract–based spatial statistics (TBSS) and atlas–based region–of–interest (ROI) analysis of fractional anisotropy (FA) and mean diffusivity (MD). RESULTS: With TBSS, there were no significant changes between the two scans. The average change in FA and MD in the ROIs over 6 months was small and not significant after allowing for multiple comparisons. After allowing for multiple comparisons, there was no significant correlation of FA or MD with ALSFRS–R. CONCLUSION: This study shows that there is little evidence of progressive changes in DTI over time in ALS. This could be because white matter is already substantially damaged by the time of onset of symptoms of ALS.