Regional Values of Diffusional Kurtosis Estimates in the Healthy Brain during Normal Aging

To provide estimates of the diffusional kurtosis in different anatomical regions of a healthy brain and to assess age dependency of diffusion kurtosis imaging (DKI) and diffusion tensor imaging (DTI) derived parametric values in these regions. Eighty healthy volunteers underwent DKI of the brain with 3.0 T magnetic resonance imaging. The DKI was obtained by using three b values of 0, 1000, 2000 s/mm(2), and with 50 diffusion directions. The regions of interest-based measurements were calculated to obtain several DKI estimates of 21 different locations of brain, and then, the age dependency for DKI- and DTI-derived parameters in these regions were assessed by using linear and nonlinear regressions. The mean kurtosis varied from 0.73 +/- 0.01 (head of caudate nucleus) to 1.07 +/- 0.08 (splenium of corpus callosum (CC)). The radial kurtosis varied from 0.84 +/- 0.06 (head of caudate nucleus) to 1.05 +/- 0.07 (splenium of CC), and axial kurtosis from 0.41 +/- 0.02 (genu of CC) to 0.78 +/- 0.02 (pallidum). DTI-derived parametric values also varied across the region. Age dependence was found for DKI-derived parameters in almost all measured regions except for corona radiata and centrum semiovale. On the contrary, DTI failed to show age dependency in many regions including gray matter structure. In conclusion, the knowledge of range of diffusion kurtosis parameters in each anatomical region in different age group is important before its clinical application to diagnose the pathology.