Abstract WMP41: The Value of Arterial Spin-Labeling Imaging in the Cerebral Collateral Circulation Evaluation of Carotid Occlusive Disease; Correlation Study With Acetazolamide-Stress Single Photon Emission Computed Tomography

Introduction: We investigated the relationship between the level of cerebral collateral circulation on arterial spin-labeling (ASL) magnetic resonance imaging (MRI) and cerebrovascular reserve (CVR) on acetazolamide (ACZ)-stress single photon emission computed tomography (SPECT) brain scans in internal carotid artery (ICA) stenosis. Methods: This study enrolled 129 patients with severe ICA stenosis (>70%). Collateral circulation was assessed in pulsed ASL images based on the presence of arterial transit artifact (ATA) that late-arriving flow appears as serpiginous high ASL signal within cortical vessels. CVR based on rest-SPECT and ACZ-stress SPECT with Tc-99m-ECD was calculated. The ASL CBF maps were independently assessed by two neuroradiologists blinded to clinical information. The two neuroradiologists graded on two slices of ASL images corresponding to Alberta Stroke Program Early Computed Tomography Score (ASPECTS) location using a 4-point scale for ASL intensity. Results: With ACZ-stress SPECT, the 88/129 (68%) patients showed normal CVR and 41/129 (32%) patients showed decreased CVR. In 73/88 (82%) of the normal CVR group patients, ASL showed ATA in ipsilateral to the stenosis. In 19/41 (46%) of the decreased CVR group patients, ASL showed no evidence of ATA in ipsilateral to the stenosis. Significant positive relationship was observed between the normal CVR group and the ATA showing group in ICA stenosis patients (p = 0.001, chi-square test). The ASL-based ASPECTS scores of brain in the ipsilateral side was lower than the scores in the contralateral side to the ICA stenosis (p < 0.0001, Wilcoxon signed rank test). The ASL-based ASPECTS scores of brain ipsilateral side to the ICA stenosis was lower in the reduced CVR group than normal CVR group (p = 0.005). Conclusion: This study demonstrated the statistically significant positive correlation between good collaterals on ASL MRI and intact CVR in patients with ICA stenosis.