Preliminary study of multiple diffusion MRI in defining brain microstructural changes in hypertensive individuals

to use multiple diffusion models to characterize the microstructural changes in the brains of patients with hypertension.

This study included 35 healthy controls (HC), 21 patients with untreated hypertension, and 25 patients with medically treated hypertension. All subjects underwent both routine MRI and diffusion spectrum imaging (DSI). DSI were reconstructed to obtain diffusion MRI models, including diffusion tensor imaging (DTI), neurite orientation dispersion and density imaging (NODDI) and mean apparent propagator-MRI (MAP-MRI). Tract-based spatial statistics (TBSS) were used to analyze the parameters among the three groups. Depending on the type of data, the proper statistical tests were used.

No statistically significant differences were observed between the HC group and the treated group. The untreated group showed considerably lower fractional anisotropy (FA) values than the HC group in almost all white matter areas. Significantly higher mean diffusivity (MD) and radial diffusivity (RD) values were seen in the untreated group. The untreated group exhibited considerably greater extracellular volume fraction (ECVF) values of the white matter. Compared to the differences found between the HC and untreated groups, the differences in multiple derived-parameters of NODDI and MAP-MRI were comparatively less between the treated and untreated groups. Strong positive associations were seen between the systolic pressure and the ECVF values of multiple brain regions.

NODDI and MAP-MRI derived-parameters are more sensitive to brain white matter injury in hypertension. The ECVF readings of the NODDI may more accurately represent white matter damage linked to hypertension.