DCE-MRI reveals spatial pattern in heterogeneous blood-brain barrier leakage within white matter in cerebral small vessel disease

Cerebral small vessel disease (cSVD) is associated with vascular cognitive impairment, dementia, and stroke. Blood-brain barrier (BBB) dysfunction is central to its pathophysiology and is involved in the formation of tissue lesions. The spatial heterogeneity of BBB leakage remains largely unclear. This cross-sectional study assessed BBB leakage rate (K_i), fractional volume of leaking tissue (v_l), and blood plasma volume (v_p) in various tissue regions, including gray matter (GM), normal appearing white matter (NAWM), and white matter hyperintensities (WMH) of 59 patients with cSVD and 32 controls using a high spatial resolution dynamic-contrast enhanced MRI protocol. Using regionally averaged measures, patients with cSVD had higher v_l (p = 0.020) and lower v_p (p < 0.001) within WMH compared to controls, K_i did not differ in any region. To evaluate the spatial heterogeneity of leakage in the NAWM, we analyzed 2-mm-wide shells extending outward from WMH edges. This revealed stronger BBB leakage in perilesional NAWM (p = 0.032) of cSVD patients compared to controls, with a striking dip close to the WMH. K_i, v_l, and v_p increased with distance from WMH edges (all p < 0.001). This pattern of lower BBB leakage in the perilesional NAWM could be caused by local reductions in microvascular blood flow or vessel surface area.