Microstructural and microvascular alterations in small vessel diseases using multi-shell DTI inside and outside white matter hyperintensities

The pathophysiology underlying white matter hyperintensities (WMHs) and changes in perilesional white matter are not fully understood in cerebral small vessel disease (SVD). Using multi-shell diffusion tensor imaging (DTI), we studied the mean (parenchymal) diffusivity (MD) and microvascular perfusion (f) inside and outside WMHs in sporadic and monogenetic (CADASIL) SVDs. The microstructure (expressed by MD) was most damaged inside WMHs and extended beyond the WMHs. Furthermore, f was highest at the WMH border, decreased towards the WMH center, and decreased outside WMHs, possibly reflecting multiple SVD-related alterations in the microvasculature, such as dilated microvessels, capillary rarefaction, and reduced microvascular integrity.