Is Contrast Stasis After Pipeline Embolization Device Deployment Associated with Higher Aneurysm Occlusion Rates? Kunal Vakharia 1,6 , Muhammad Waqas 1,6 , Stephan A. Munich 1,6 , Jaims Lim 1,6 , Andrew Gong 6,2 , Felix Chin 1,6 , Kenneth V. Snyder 1,6,3,4,7 , Adnan H. Siddiqui 1,6,4,5,7 , Elad I. Levy 1,6,4,5 - OBJECTIVE: To assess the association of degree of contrast stasis in intracranial aneurysms (IAs) immediately after Pipeline embolization device (PED; Medtronic, Dublin, Ireland) deployment with 6- and 12-month angiographic occlusion rates. - METHODS: This retrospective cohort study included consecutive patients undergoing PED deployment for saccular IA treatment at a large-volume cerebrovascular center over a 4-year 9-month period. Angiographic images obtained immediately after PED deployment were graded according to amount of intra-aneurysmal contrast flow during the late venous phase: 0 [ no stasis; 1 [ <50% contrast stasis; 2 [ 50%e75% stasis; and 3 [ >75%e99% stasis. Follow-up occlusion rates were determined by digital subtraction angiography, computed tomographic angiography, or magnetic resonance angiography. - RESULTS: The study included 119 patients in whom 182 PEDs were deployed to treat 141 aneurysms. A single PED was deployed in 105 (74.5%) aneurysms. The internal ca- rotid artery was the commonest aneurysm site (119 [85%]). Fifty-two (36.9%) aneurysms were grade 0; 33 (23.4%) were grade 1; 46 (32.6%) were grade 2; and 10 (7.1%) were grade 3 immediately post-treatment. A 6-month follow-up angio- gram available for 101 aneurysms showed complete oc- clusion (no flow into the aneurysm) in 74 (73.3%) aneurysms. A 12-month follow-up study available for 132 aneurysms showed complete occlusion in 79.5%. At last follow-up, occlusion rates were not significantly different for different contrast stasis grades (P [ 0.60). Mean angiographic follow up for all IAs was 23vv17.7 months. IA size, sex, age, and smoking were not significant pre- dictors of occlusion. - CONCLUSIONS: The degree of aneurysm contrast stasis immediately after PED deployment is not statistically associated with 6- and 12-month angiographic occlusion rates. INTRODUCTION T he goal of flow diversion with devices such as the Pipeline embolization device (PED; Medtronic, Dublin, Ireland) is to reduce pulsatile flow into the dome of the intracranial aneurysm (IA). 1 The long-term success of flow diversion relies on aneurysm occlusion caused by thrombus formation within the aneurysm dome and endothelial cell proliferation along the stent tines to divert flow away from the aneurysm. 1 PED deployment results in variable degrees of intra-aneurysmal contrast stasis. 2 The effect of the degree of IA contrast stasis immediately after PED deployment on the rate of IA occlusion has been a subject of interest. The association of contrast stasis with subsequent IA occlusion seems plausible. Several systems have been proposed to grade contrast stasis postdeployment, 3-6 yet few studies have explored its clinical relevance and effect on Key words - Aneurysm occlusion - Contrast stasis - Pipeline embolization device Abbreviations and Acronyms CTA: Computed tomography angiography DSA: Digital subtraction angiography IA: Intracranial aneurysm MRA: Magnetic resonance angiography OKM:O’Kelly-Marotta PED: Pipeline embolization device SMART : Simple Measurement of Aneurysm Residual Treatment From the 1 Department of Neurosurgery, Jacobs School of Medicine and Biomedical Sciences, 2 Jacobs School of Medicine and Biomedical Sciences, 3 Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, 4 Canon Stroke and Vascular Research Center, Jacobs School of Medicine and Biomedical Sciences, and 5 Department of Radiology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo; 6 Department of Neurosurgery, Gates Vascular Institute at Kaleida Health, Buffalo; and 7 Jacobs Institute, Buffalo, New York, USA To whom correspondence should be addressed: Elad I. Levy, M.D., M.B.A. [E-mail: elevy@ubns.com] Citation: World Neurosurg. (2019). https://doi.org/10.1016/j.wneu.2019.09.032 Journal homepage: www.journals.elsevier.com/world-neurosurgery Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2019 Elsevier Inc. All rights reserved. WORLD NEUROSURGERY -: e1-e9, - 2019 www.journals.elsevier.com/world-neurosurgery e1 Original Article