Altered gray and white matter microstructure in Cushing's disease: A diffusional kurtosis imaging study

Exposure to chronic hypercortisolism has multiple adverse effects on brain biology in humans. Cushing's disease (CD) represents a unique and natural human model for examining the effects of hypercortisolism on the brain. This cross-sectional study used Diffusional Kurtosis Imaging (DKI) to investigate the microstructure alterations in both white matter (WM) and gray matter (GM) of CD patients and to determine the relationship of these changes with clinical characteristics. DKI images were obtained from 15 active CD patients. DKI parametric maps were estimated through voxel-based analyses (VBA) and compared with 15 healthy controls matched for age, sex and education. In addition, correlations were analyzed between the altered DKI parameters and clinical characteristics. Compared with healthy controls, CD patients mainly exhibited significantly altered diffuse parameters in the GM and WM of the left medial temporal lobe (MTL). The mean values of increased radial diffusivity (RD) of CD patients in GM of the left hippocampus/parahippocampal gyrus correlated positively with the clinical severity of CD. Additionally, we also found altered kurtosis parameters in the cerebellum and frontal lobe. DKI imaging of CD patients could represent complementary information in both white matter and gray matter. The impairment of the left MTL might explain some part of the memory and cognition impairments in CD patients.