Newly developed DWI hyperintensities and changes in cerebral blood flow after carotid stent placement for unilateral symptomatic carotid artery stenosis.

This study aimed to evaluate changes in cerebral blood flow and perioperative outcomes in patients with unilateral symptomatic carotid artery stenosis before and after carotid artery stenting (CAS), providing insights to guide surgical decision-making. Ninety-six patients with moderate to severe unilateral symptomatic carotid artery stenosis (>50%) admitted to the Neurology Department of the Second Affiliated Hospital of Zhejiang University from June 2023 to April 2024 were included. All patients underwent CAS and magnetic resonance imaging, including diffusion-weighted imaging (DWI) and 3D quasi-continuous arterial spin-labeled perfusion imaging, within 3 days preoperatively and on the third postoperative day. Patients were categorized into microembolic and non-embolic groups based on the presence of new diffusion-weighted imaging hyperintensities. Newly developed diffusion-weighted imaging hyperintensities were detected in 68 patients (70.8%), with a total of 704 lesions, though only 4 cases exhibited symptoms. Most lesions were localized to the frontal-parietal cortex and subcortical areas on the affected side (60.8%) and were <3 mm in size (92.6%). Postoperatively, cerebral blood flow in the frontal-parietal lobe was significantly higher than in the temporal lobe on both the affected (50.49 ± 8.02 vs 47.94 ± 9.08, t = 2.179, P < .05) and healthy sides (50.16 ± 5.79 vs 48.00 ± 5.98, t = 3.835, P < .05). Additionally, cerebral blood flow in the affected frontal and temporal lobes significantly increased after surgery (P < .05). Preoperative frontal-parietal cerebral blood flow was lower in the microembolic group compared to the non-embolic group (P < .05). Microemboli are common after CAS but are unlikely to result from immediate hemodynamic changes. Instead, they appear to be associated with chronic preoperative hypoperfusion, which impairs cerebral blood flow regulation.