Objective:To investigate the blood-brain barrier (BBB) permeability changes in the deep white matter (DWM) during hypoperfusion caused by asymptomatic cerebral artery stenosis.Methods:The CT perfusion weighted imaging (CTP) images of 36 patients with asymptomatic severe stenosis and unilateral internal carotid artery or middle cerebral artery, admitted to our hospital from January 2017 to April 2020, which revealed the prolongation of contrast medium delayed contrast medium max-time (Tmax), were analyzed. The regions of interest (ROIs) in the DWM of CTP images at the body of lateral ventricle and centrum semiovale, were drawn respectively: the anterior DWM (ROIa), middle DWM (ROIm), and posterior DWM (ROIp) in the stenotic side of maximum intensity projection maps; DWM with normal-appeared Tmax (ROI1), DWM with relatively delayed Tmax (ROI2), and DWM with obviously delayed Tmax (ROI3) in the stenotic side of Tmax maps; and their mirrored ROI on the healthy side. Statistical analysis was used to compare the value differences of Tmax, cerebral blood flow (CBF) and transfer constant (Ktrans) between/among the ROIs.Results:As compared with the mirrored ROI in the healthy side, respectively, the ROIa and ROIm in the stenotic side had significantly prolonged Tmax, significantly decreased CBF, and significantly increased Ktrans at the body of lateral ventricle ( P<0.05). As compared with the mirrored ROI in the healthy side, respectively, the ROIa and ROIp in the stenotic side had significantly prolonged Tmax, significantly decreased CBF, and significantly increased Ktrans at the centrum semiovale ( P<0.05). As compared with the mirrored ROI in the healthy side, respectively, the ROI2 and ROI3 in the stenotic side had significantly prolonged Tmax, significantly decreased CBF, and significantly increased Ktrans at the body of lateral ventricle and centrum semiovale ( P<0.05). In the stenotic side at the body of lateral ventricle, as compared with the mirrored ROIp, the ROIa and ROIm had significantly prolonged Tmax, significantly decreased CBF, and significantly increased Ktrans ( P<0.05). In the stenotic side at the body of lateral ventricle and centrum semiovale, as compared with the mirrored ROI1, the ROI2 and ROI3 had significantly prolonged Tmax, significantly decreased CBF, and significantly increased Ktrans ( P<0.05). Conclusion:The BBB permeability of DWM in the regions with delayed contrast medium Tmax is augmented when asymptomatic cerebral artery stenosis causes cerebral hypoperfusion.