Intraoperative aneurysm flow analysis predicts intracranial large and giant aneurysm occlusion after flow diversion

Objectives: Incompletely occluded flow-diverter (FD)-treated aneurysms are at risk of rupture and thromboembolic complications; however, intraoperative prediction of FD treatment outcomes has not yet been established. In this study, we investigated the association between intraoperative aneurysm flow analysis, using optical flow imaging, and FD treatment outcomes. Materials and methods: This retrospective study included patients with large unruptured internal carotid artery aneurysms (>= 10 mm) who underwent FD treatment. During the procedure, a flow analysis method using optical flow digital subtraction angiography (DSA) was used to measure the flow within the aneurysm sac by calculating the mean aneurysm flow amplitude (MAFA) before and after stent deployment. Occlusion was assessed using the O'Kelly-Marotta (OKM) grading scale on DSA 12 months after FD. The patients were divided into a nearly complete occlusion group (OKM grades C and D) and an incomplete occlusion group (OKM grades A and B). Results: Eleven patients with 11 aneurysms (mean age, 67.5 [standard deviation, 8.3] years; 10 women, 88.9 %) were treated with FD. Nearly complete occlusion was observed in 6/11 (54.5 %) patients at 12-month follow-up imaging. The nearly complete occlusion group had significantly lower pre-MAFA and post-MAFA values than the incomplete occlusion group (P = 0.023 and P = 0.008, respectively). There was no difference in the MAFA ratio between the two groups (P = 0.315) Conclusions: Aneurysm flow analysis before and after FD deployment is a simple and beneficial approach to predict treatment outcomes, which would indicate the need for intraoperative strategy changes, such as adding FD layers or intrasaccular coils.