BackgroundCarotid artery stenting (CAS) is a common treatment for carotid artery stenosis, but it can lead to new ischemic brain lesions on diffusion-weighted images (DWI) during the perioperative period. Identifying these lesions early is crucial to preventing recurrent ischemic strokes. MethodsThis retrospective study included 47 patients who underwent CAS. Preoperative carotid PET/MR examinations and postoperative brain MRI were performed. Clinicians identified the responsible carotid artery based on symptoms and records. Vessel morphology, plaque characteristics, and inflammatory uptake were analyzed. The standardized uptake value and tissue-to-background ratio quantified 18F-fluorodeoxyglucose(18F-FDG) uptake. The symptomatic carotid atheroma inflammation lumen-stenosis(SCAIL) score assessed stenosis severity and inflammation. The primary outcome was the presence of new ischemic lesions on DWI. ResultsAmong the 47 patients (mean age, 65 +/- 7 years; 44 males), 30 (63.8%) exhibited new ischemic lesions. These patients had a higher prevalence of AHA type VI plaques (50.0% vs. 17.6%, p = 0.028), higher PET uptake (43.3% vs. 11.8%, p = 0.026), and higher SCAIL scores (63.3% vs. 23.5%, p = 0.009). The most common distribution pattern of new ischemic lesions was located in the mixed (in and beyond of the treated artery) territory (36.2%). Of the 30 participants with new ischemic lesions, 15 (50%) had lesions located in both peripheral brain areas and deep brain areas. In the adjusted model, high PET uptake and SCAIL scores were independently associated with new ischemic lesions (aOR = 7.26, 95% CI: 1.22, 73.59; p = 0.049 and aOR = 7.06 [95% CI: 1.50, 44.18]; p = 0.020). ConclusionCarotid PET/MR-related indicators can effectively predict the risk of new ischemic lesions on DWI during the perioperative period after carotid artery stenting, providing important references for early identification of high-risk patients for recurrent ischemic stroke. Further large-scale randomized controlled studies are necessary to validate the clinical application value of these indicators.