Hemodynamic significance of intracranial atherosclerotic disease and ipsilateral imaging markers of cerebral small vessel disease

Introduction: Cerebral small vessel disease (CSVD) commonly exists in patients with symptomatic intracranial atherosclerotic disease (sICAD). We aimed to investigate the associations of hemodynamic features of sICAD lesions with imaging markers and overall burden of CSVD.Patients and methods: Patients with anterior-circulation sICAD (50%-99% stenosis) were analyzed in this cross-sectional study. Hemodynamic features of a sICAD lesion were quantified by translesional pressure ratio (PR = Pressure(post-stenotic)/Pressure(pre-stenotic)) and wall shear stress ratio (WSSR = WSSstenotic-throat/WSSpre-stenotic) via CT angiography-based computational fluid dynamics modeling. PR <= median was defined as low ("abnormal") PR, and WSSR >= fourth quartile as high ("abnormal") WSSR. For primary analyses, white matter hyperintensities (WMHs), lacunes, and cortical microinfarcts (CMIs) were assessed in MRI and summed up as overall CSVD burden, respectively in ipsilateral and contralateral hemispheres to sICAD. Enlarged perivascular spaces (EPVSs) and cerebral microbleeds (CMBs) were assessed for secondary analyses.Results: Among 112 sICAD patients, there were more severe WMHs, more lacunes and CMIs, and more severe overall CSVD burden ipsilaterally than contralaterally (all p < 0.05). Abnormal PR and WSSR (vs normal PR and WSSR) was significantly associated with moderate-to-severe WMHs (adjusted odds ratio = 10.12, p = 0.018), CMI presence (5.25, p = 0.003), and moderate-to-severe CSVD burden (12.55; p = 0.033), ipsilaterally, respectively independent of contralateral WMHs, CMI(s), and CSVD burden. EPVSs and CMBs were comparable between the two hemispheres, with no association found with the hemodynamic metrics.Discussion and conclusion: There are more severe WMHs and CMI(s) in the hemisphere ipsilateral than contralateral to sICAD. The hemodynamic significance of sICAD lesions was independently associated with severities of WMHs and CMI(s) ipsilaterally.