The relationship between microvasculature in white matter hyperintensities and cognitive function

White matter hyperintensities (WMHs) are associated with cognitive decline, but less is known about pathophysiology of cognitive decline in patients with WMHs. We investigated microvasculature and microstructure in WMHs using intravoxel incoherent motion (IVIM) and their associations with cognitive function. Thirty-two subjects with WMHs were enrolled in our study. Fast diffusion coefficient (D*), perfusion fraction (f) and slow diffusion coefficient (D) from IVIM model were compared between regions of WMHs (periventricular WMHs, PWMHs and deep WMHs, DWMHs) and surrounding normal white matter. Multivariate linear model was used to determine the independent factors associated with cognitive function assessed by the Mini Mental State Examination (MMSE) and the standardized coefficient (beta) of factors was estimated. D* was significantly lower (4.95 x 10(-3) mm(2)/s versus 8.36 x 10(-3) mm(2)/s in PWMHs and 5.04 x 10(-3) mm(2)/s versus 8.67 x 10(-3) mm(2)/s in DWMHs, both P < 0.001), and f (14.64 % versus 12.01 % in PWMHs and 14.26 % versus 11.31 % in DWMHs, both P < 0.001) and D (1.02 x 10(-3) mm(2)/s versus 0.73 x 10(-3) mm(2)/s in PWMHs and 0.86 x 10(-3) mm(2)/s versus 0.70 x 10(-3) mm(2)/s in DWMHs, both P < 0.001) were significantly higher in WMHs. Only f in PWMHs was independently associated with MMSE (beta = 0.443, P = 0.016). The decreased D* and increased D in WMHs were similar to previous findings. The increased f in PWMHs relating with better cognition provides the pathophysiological basis in understanding cognitive decline in patients with WMHs.