Regional ADC measurements during normal brain aging in the clinical range of b values: a DWI study.

The aim of our work was to evaluate the apparent diffusion coefficient (ADC) values of normal brain over a wide age range and in different cerebral structures, including the white and grey matter. A population of 89 subjects (39 male, 50 female, age range: 3-69 years) was divided into age groups designated as 1-7 as follows: 3-9; 10-19; 20-29; 30-39; 40-49; 50-59; 60-69 years old. All subjects underwent a head MRI using a 1,5 T GE system with diffusion-weighted imaging using spin echo echo planar imaging (EPI) for b=0, 500, 1000, and 1200 s/mm(2). The ADC values of the following 10 regions of interest were analysed: head of the caudate nucleus (L=left and R=right side), thalamus (L and R side), centrum semiovale (L and R side), pons, respectively, as well as in cerebellum (L and R side) and vermis of the cerebellum. The ADC values of the studied brain structures showed a polynomial dependence on age indicating a logarithmic decline in children, some stabilisation during adulthood and a small trend of increasing diffusivity for subjects over the age of 50 years old. Significant interhemispheric differences in the ADC values were mainly found for thalamus, especially in older age groups. Moreover, the best differentiation of the examined structures was found in the mature brain. The knowledge of age-dependent diffusion changes in the human brain can be helpful in the proper interpretation of diffusion-weighted images in clinical practice.