In this study, we aimed to determine the frequency and clinical impact of new ischemic lesions detected with diffusion-weighted-imaging-MRI (DWI-MRI) as well as the clinical outcomes after carotid artery stenting (CAS) using the simple flow blockage technique (SFB). This is a retrospective study with data extraction from a monocentric prospective clinical registry (from 2017 to 2019) of consecutive patients admitted for symptomatic cervical ICA stenosis or web. Herein, patients benefited from DWI-MRI before and within 48 h of CAS for symptomatic ICA stenosis or web. The primary endpoint was the frequency of new DWI-MRI ischemic lesions and the secondary (composite) endpoint was the rate of mortality, symptomatic stroke or acute coronary syndrome within 30 days of the procedure. All of the 82 CAS procedures were successfully performed. Among the 33 patients (40.2%) with new DWI-MRI ischemic lesions, 30 patients were asymptomatic (90.9%). Irregular carotid plaque surface with (n = 13, 44.8%) or without ulceration (n = 12, 60.0%) was associated with higher rates of new DWI-MRI lesions by comparison to patients with a regular plaque (n = 7, 25%) (p = 0.048) using the univariate analysis. Less than half of this CAS cohort using the SFB technique had new ischemic lesions detected with DWI-MRI. Among these patients, more than 90% were asymptomatic. Irregularity of the plaque seems to increase the risk of peri-procedural DWI-MRI lesions.