Abnormal diffusion tensor in nonsymptomatic familial amyotrophic lateral sclerosis with a causative superoxide dismutase 1 mutation

Abstract Purpose To determine whether diffusion abnormalities can be observed in nonsymptomatic family members with a known causative Cu/Zn superoxide dismutase mutation (asymptomatic familial amyotrophic lateral sclerosis; AFALS +SOD1 ) in a family with autosomal dominant familial amyotrophic lateral sclerosis (ALS) using diffusion tensor imaging (DTI). Materials and Methods A total of eight AFALS +SOD1 subjects (aged 17–43 years) were age‐matched with 13 healthy controls (aged 19–45 years) without SOD1 mutations. DTI was carried out on a 1.5T scanner. The diffusion index maps derived were then normalized spatially for voxel‐based analysis. region of interest (ROI)‐based analysis was also carried out. Results Our voxel‐based and ROI‐based analysis showed that AFALS +SOD1 subjects have decreased fractional anisotropy (FA) (0.5401 vs. 0.5168, P < 0.05) and increased tensor trace (TT) (2.5854 × 10 −3 mm 2 /second vs. 2.6226 × 10 −3 mm 2 /second, P < 0.04) at the posterior limb of the internal capsule compared to the control subjects. Increased radial diffusivity (E (2,3)/2 ) was detected on both sides (right = 0.5710 × 10 –3 mm 2 /second vs. 0.5943 × 10 –3 mm 2 /second, P < 0.05; left = 0.5666 × 10 –3 mm 2 /second vs. 0.5872 × 10 –3 mm 2 /second, P < 0.05). No significant change in axial diffusivity (E 1 ) was detected. Conclusion Abnormal diffusivity was found at the posterior limb of the internal capsule in AFALS +SOD1 subjects, hitherto unreported. Our results suggest that DTI may detect diffusion abnormalities in AFALS +SOD1 subjects before symptoms develop. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.