Changes in preoperative and postoperative blood flow parameters are closely associated with in-stent stenosis after flow diverter treatment in unruptured intracranial aneurysms: a retrospective cohort study.

Flow diverters (FDs) have emerged as a promising therapeutic option for unruptured intracranial aneurysms (UIAs), demonstrating favorable clinical outcomes. Nevertheless, the association between hemodynamic alterations and in-stent stenosis (ISS) following FD implantation remains poorly understood. This study sought to elucidate the independent relationship between perioperative blood flow velocity changes and ISS development in patients undergoing FD treatment for UIAs. A retrospective cohort analysis was conducted on 127 consecutive patients treated with FDs at our institution between July 2023 to September 2024. Hemodynamic parameters, including peak systolic velocity (PSV), end-diastolic velocity (EDV), and mean velocity (MV), were meticulously assessed using transcranial color-coded duplex (TCCD) sonography at both preoperative and postoperative time points. Of the 74 patients who completed follow-up, 8 (10.81%) developed significant ISS, defined as stenosis exceeding 25% of the luminal diameter. Multivariate logistic regression analysis revealed a statistically significant inverse correlation between PSV changes and ISS risk (OR = 0.96, 95% CI: 0.92-0.99, P = 0.026). Stratification of PSV changes into tertiles demonstrated a dose-dependent protective effect, with the highest tertile exhibiting the most pronounced risk reduction. Furthermore, MV changes were independently associated with a 6% reduction in ISS risk per unit increase (OR = 0.94, 95% CI: 0.89-1.00, P = 0.048). A lower variation in preoperative and postoperative peak systolic velocity and MV was associated with an increased risk of ISS. If significant PSV and MV changes are observed between preoperative and postoperative measurements of the parent artery, it may suggest an increased risk of ISS, indicating the need for clinicians to provide additional interventions.