New-onset DWI high signal and cerebral blood flow changes after CAS for unilateral symptomatic carotid artery stenosis

ObjectiveTo compare the relationship between the dynamic changes of cerebral blood flow(CBF) before and after carotid artery stent （CAS） placement and perioperative events in patients with unilateral symptomatic carotid artery stenosis, providing reference for patients to choose surgical methods. Methods A total of 24 patients with moderate to severe （＞50%） symptomatic unilateral carotid artery stenosis admitted in Dongfang Hospital, Beijing University of Chinese Medicine from January 2018 to June 2020 were included, all of whom underwent CAS. All patients underwent magnetic resonance imaging （including DWI and 3D quasi continuous arterial spin labeled perfusion imaging） within 3 days before and 3 days after surgery. Changes in CBF and perioperative events were measured. According to whether there were new DWI high signals, they were divided into micro-embolic group and non-embolic group. ResultsWhile the incidence of new DWI lesions was high （17/24, 70.8%） and 176 lesions were observed among the 17 cases, there was only one subject showing the symptoms. The majority of the lesions were located at the cortex/subcortex of the ipsilateral frontal and parietal lobes （60.8%）, and 92.6% of the lesions size being less than 3mm. The CBF in the frontoparietal lobe were higher than that in the temporal lobe after surgery (lesion side 50.49±8.02vs47.94±9.08, t=2.179, P＜0.05; contralateral side 50.16±5.79 vs 48.00±5.98, t=3.835, P＜0.05); the CBF of the lesion side of the frontoparietal and temporal lobes increased significantly after surgery compared to before surgery （P＜0.05）. The preoperative relative CBF in the frontal parietal lobe of the micro-embolization group was lower than that of the non-embolization group （P＜0.05）. Conclusion The high incidence rate of micro-embolism in patients receiving CAS may not be the result of direct changes of hemodynamics in the brain but rather the loss of CBF regulation due to long-term hypoperfusion prior to the stenting.