Backround Huntington's disease (HD) is an inherited autosomal dominant neurodegenerative disorder with progressive impairment of motor and cognitive functions and behavioural abnormalities. The clinical features of HD are closely related to the degeneration of the basal ganglia, predominantly the striatum. The main striatal output structure, the globus pallidus, strongly accumulates ferritin-bound iron, which is believed to change the diffusion tensor in a systematic way.
Aim, subject and methods To test the hypothesis that this same effect exists in the iron-rich basal ganglia of HD patients, we examined changes in the globus pallidus using a DTI WIP sequence and a T2 relaxometry CPMG sequence. Quantitative MR, clinical data and genetic data (the number of CAG repeats) were obtained from 14 HD patients. Coregistered MR parameters such as the T2 relaxation rate (RR), fractional anisotrophy (FA) and mean diffusivity (MD) were analysed by two independent readers in FSL and further processed in GraphPad. Bonferroni's correction was used for multiple statistical comparisons.
Results Significant correlations between RR and FA (R2=0.84), between RR and MD (R2=0.66), between FA and MD (R2=0.85) and between CAG and RR (R2=0.59) were found. A trend towards a significant correlation between CAG and FA (R2=0.44) was noted. No significant correlation between CAG and MD or between MR and clinical parameters was found. We also found that there were no significant hemispheric differences in the MR parameters and no significant difference between HD patients and age-matched healthy controls.
Conclusion These results indicate that FA in the globus pallidus may have the potential to be used as a biomarker of iron accumulation in future studies of HD patients.
- Huntington's disease
- T2 relaxation time
- fractional anisotropy
- mean diffusivity
- globus pallidus