Abstract TP251: A novel imaging method using non-contrast CT for visualizing vessels distal to the occlusion in acute large vessel occlusion

Introduction: In patients with acute large vessel occlusion (LVO), CT angiography (CTA) or MR angiography (MRA) cannot visualize vessels distal to the occlusion (“stealth vessels”). A blind catheter procedure may increase a risk of serious complications during mechanical thrombectomy (MT). We developed a novel imaging method (counter-stealth technology: CST) to visualize stealth vessels. We aimed to evaluate whether counter-stealth vessels visualized by CST matched post-MT angiographic image. Methods: We included acute ischemic stroke patients with LVO between January 2019, and April 2024, who underwent MT and achieved successful reperfusion (TICI ≥2b). CST images were generated by manually tracing the relative high-density vessels distal to the hyperdense vessel sign on non-contrast CT images and reconstructed on the workstation. To assess anatomical consistency, we compared CST images with post-MT digital subtraction angiography (DSA). When CST images and post-MT DSA are consistent with all distal segments was visualized, it is classified as “visualized”; otherwise as “unvisualized”. The puncture to recanalization (P to R) time was compared between patients who underwent MT using with CST images generated in real time and those or without it. Results: Seventy-five patients were analyzed (56% male, a median age 81 years (IQR 71–87), a median baseline NIHSS score of 22 (IQR 13–26), with occlusion located in ICA; 22%, M1; 44%, M2; 20%, tandem lesion (ICA+M1); 5%, BA; 7%, P1; 1%). The mean CT value of stealth vessels was 39.1 (±9.5) HU. Compared with post-MT DSA, 84% of patients were classified as visualized. Based on the location of occluded vessels, the visualization rate of distal vessels were as follows: 71% (12/17) in ICA occlusion, 85% (28/33) in M1 occlusion, 83% (5/6) in M2 superior branch occlusion, 100% (9/9) in M2 inferior branch occlusion, 75% (3/4) in tandem lesion(ICA+M1), and 100% (5/5, 1/1) in both BA and P1 occlusions. P to R time showed no significant difference between CST and non-CST group in all patients, however, when limited to junior certified operators (n=43), it tended to have a shorter in CST group (n=25) than non-CST group (n=18) (41 min vs 48 min, p=0.91). Conclusions: CST enabled visualization of distal vessels in 84% of acute LVO cases. CST is useful tool for distal catheter navigation, especially for the junior operator.