Summary cerebral small-vessel disease score mediates white-matter microstructural and perfusion changes in mild cognitive impairment: a diffusion kurtosis imaging and arterial spin labeling study.

PURPOSE: The summary cerebral small-vessel disease (CSVD) score reflects brain-damage severity, but its relationship with white-matter (WM) integrity and cerebral perfusion remains unclear. Here, we aimed to explore how this score links WM microstructure and cerebral blood flow (CBF).

METHODS

We included 31 patients with CSVD and mild cognitive impairment (CSVD-MCI) and 31 matched healthy controls. Diffusion kurtosis imaging (DKI) and three-dimensional arterial spin labeling were used with tract-based spatial statistics to assess group differences in axial kurtosis, mean kurtosis (MK), radial kurtosis (RK) and CBF. Pearson and Spearman correlation analyses and mediation effects analyses were performed.

RESULTS

CSVD-MCI patients showed widespread WM damage and reduced CBF. In the bilateral superior corona radiata (SCR), the summary CSVD score was negatively correlated with MK, RK, and CBF, whereas MK and RK were positively correlated with CBF. Mediation analysis revealed that the summary CSVD score statistically accounted for indirect effects of CBF on MK and RK in the SCR.

CONCLUSION

In CSVD-MCI, reduced CBF, higher cumulative lesion burden, and WM microstructural damage were linked in a tract-specific pattern. The summary CSVD score statistically accounted for part of the association between CBF and DKI-derived WM metrics in the SCR, supporting its role as an imaging marker that integrates vascular and structural injury.