• Satoru Tanioka, Fujimaro Ishida, Tomoyuki Kishimoto, Masanori Tsuji, Katsuhiro Tanaka, Shinichi Shimosaka, Mitsuru Toyoda, Nobuhisa Kashiwagi, Takanori Sano, and Hidenori Suzuki.
• Department of Neurosurgery, Mie Chuo Medical Center, Tsu, Japan.
• J Neurointerv Surg. 2019 Jun 1; 11 (6): 614-617.

BackgroundComplex and unstable flow patterns are reported to be associated with the rupture status of cerebral aneurysms, while their evaluation depends on qualitative analysis of streamlines of bloodflow. Oscillatory velocity index (OVI) is a hemodynamic parameter to quantify flow patterns. The aim of this study is to elucidate the associations between OVI and the rupture status of cerebral aneurysms.MethodsOne hundred and twenty-nine ruptured and unruptured cerebral aneurysms were analyzed with computational fluid dynamics under pulsatile flow conditions. With the use of median value of OVI, all aneurysms were divided into high and low OVI groups. Statistical analysis was performed to compare rupture status, and morphological and hemodynamic parameters between the two groups.ResultsThe median value of OVI was 0.006. High OVI was more likely observed in ruptured aneurysms (P=0.028) and associated with irregular shape, complex flow patterns, and unstable flow patterns (P<0.001, respectively). In morphological parameters, maximum size, aspect, projection, size, and volume-to-ostium area ratios were significantly higher in the high OVI group (P<0.001, respectively). In hemodynamic parameters, wall shear stress and wall shear stress gradient were significantly lower, and oscillatory shear index and gradient oscillatory number were significantly higher in the high OVI group (P<0.001, respectively).ConclusionHigh OVI was associated with rupture status, and morphological and hemodynamic characteristics of ruptured aneurysms. These results indicate that OVI may serve as a valuable hemodynamic parameter for diagnosing rupture status and risks of aneurysms.© Author(s) (or their employer(s)) 2019. No commercial re-use. See rights and permissions. Published by BMJ.

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