Single-Phase CTA Guided by the Time-Enhancement Curve Derived from CT Perfusion for Mechanical Thrombectomy.

Objective: Mechanical thrombectomy (MT) is currently the standard treatment for large vessel occlusion (LVO). However, advancing a microcatheter and microguidewire into non-visualized distal vessels carries a risk of vascular perforation, potentially resulting in serious hemorrhagic complications. This study aimed to evaluate the usefulness of a new imaging protocol using single-phase CTA guided by the time-enhancement curve (TEC) derived from CT perfusion (CTP) in patients with anterior circulation LVO undergoing MT, for improving distal vessel visualization compared with conventional CTA using a bolus-tracking (BT) method. Methods: Patients with anterior circulation LVO (intracranial internal carotid artery, M1 or proximal M2 segment of the middle cerebral artery) who underwent MT were retrospectively analyzed. The conventional BT-CTA protocol was used between October 2018 and June 2020, and a new CTP-derived TEC-guided CTA (TEC-CTA) protocol was used between July 2020 and August 2023. In the TEC-CTA protocol group, the scan timing of CTA was determined according to the TEC obtained from CTP to achieve optimal contrast filling of distal vessels. Visualization of vessels distal to the occlusion site was graded on a 4-point scale (0-3) and compared between the 2 protocols. Scores of 2 and 3 were considered useful for predicting the extent of thrombus and the vessel course. Additional outcomes included the puncture-to-recanalization time (PRT), thrombolysis in cerebral infarction (TICI) grade, complications, and modified Rankin Scale (mRS) score at 90 days. Results: Sixteen and 46 patients underwent MT using the BT-CTA and TEC-CTA protocols, respectively. The incidence of well-visualized vessels overall (score of 2 or 3) was significantly higher in the TEC-CTA protocol group than in the BT-CTA protocol group (80.4% vs. 37.5%; p = 0.0033). The PRT was significantly shorter in the TEC-CTA protocol group than in the BT-CTA protocol group (44 vs. 58 min; p = 0.0134). The proportion of patients with TICI ≥2b after revascularization appeared to be higher using the TEC-CTA protocol (82.6% vs. 75.0%), but this was not significant. No intraprocedural vascular perforation occurred in either protocol, and no significant difference was observed in the frequency of intracranial hemorrhage between the protocols. The proportion of patients whose mRS score was ≤3 at 90 days after stroke onset was significantly higher in the TEC-CTA protocol group than in the BT-CTA protocol group (56.5% vs. 25%; p = 0.0424). Conclusion: CTA performed with scan timing guided by CTP-derived TEC improves visualization of occluded vessels, contributing to safer and more effective MT.