Abstract Body: Background: Hyperperfusion phenomenon (HPP) constitutes a significant risk factor for adverse outcomes following carotid artery stenting (CAS). Currently, the sole method for evaluating the risk of HPP post-CAS is the invasive acetazolamide (ACZ) challenge test. This study aimed to identify the most effective parameters of computed tomography perfusion imaging (CTP) for detecting patients at risk for HPP after CAS, as a non-invasive alternative to the ACZ challenge test.

Methods: Consecutive patients with internal carotid artery stenosis who underwent ¹²³I-IMP-SPECT at rest and CTP prior to CAS, and subsequently underwent ¹²³I-IMP-SPECT at rest the day following CAS, were included in this study between April 2019 and March 2024. The asymmetry index (AI) was calculated as the ratio of ipsilateral to contralateral cerebral blood flow (CBF) within the middle cerebral artery (MCA) territories, as measured by postoperative ¹²³I-IMP-SPECT at rest. HPP was defined as AI ≥1.1, and patients were categorized into two groups based on the presence or absence of HPP post-CAS. Additionally, we calculated the ratio of CBF, cerebral blood volume (CBV), mean transit time (MTT), and time-to-peak (TTP) within the affected MCA territories relative to the unaffected side, as determined by preoperative CTP using the Bayesian method, and compared these ratios between the HPP and non-HPP groups. Receiver operating characteristic (ROC) curve analysis was conducted to identify the most accurate CTP parameter for predicting HPP.

Results: Forty-six patients were enrolled; four patients exhibited HPP after CAS, and one patient experienced a cerebral hemorrhage. Significant differences were observed in the CBV ratio (p=0.001), MTT ratio (p=0.003), and TTP ratio (p=0.011) between the HPP and non-HPP groups. ROC curve analysis demonstrated that the CBV ratio had the highest area under the receiver operating characteristic curve (AUC-ROC) for predicting HPP, with an AUC of 0.946 (95% CI, 0.86-1.0).

Conclusion: Preoperative CTP could effectively identify patients at risk for HPP after CAS. The CBV ratio may serve as a reliable parameter, potentially obviating the need for the invasive ACZ challenge test.