Background and purpose: The age effect on the diffusion pattern in the basal ganglia differs from that in the white matter. The main purpose of our study was to provide further insight into the change of water diffusion in the basal ganglia during human brain aging by using the eigenvalues of DTI.
Materials and methods: We examined 71 healthy subjects (mean age, 41.8 +/- 14.5 years; age range, 20-79 years). The values of MD, FA, and the eigenvalues lambda(1) and lambda(23) (lambda(23) = [lambda(2) + lambda(3)]/2) were determined in regions of the head of the caudate nucleus, putamen, globus pallidus, and in some regions of white matter. The age-dependence of these measurements was tested for statistical significance by using the Pearson correlation analysis.
Results: A significant reduction of MD with aging was found in the head of caudate nucleus (r = -0.319, P = .007) and putamen (r = -0.410, P < .001), and an increase in FA with aging was found in the putamen (r = 0.535, P < .001). Eigenvalue lambda(23) showed a significant age-related decrease in the putamen (r = -0.451, P < .001) and the head of the caudate nucleus (r = -0.312, P = .008), but no significant changes of lambda(23) were found in the globus pallidus. The results for eigenvalue lambda(1) in the head of caudate nucleus (r = -0.299, P = .011) were close to statistical significance.
Conclusions: The eigenvalues provide more insights into the different diffusion patterns in the basal ganglia during human brain aging.