Background Complex 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.
Methods One 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.
Results The 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).
Conclusion High 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.
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Contributors All authors gave final approval of the published version and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. ST, FI, TK, MT, KT, SS collected the data and performed simulations. MT, NK, TS and HS helped to analyze the data. ST, FI and HS wrote the manuscript.
Funding This work was supported by Scientific Research from Japan Society for the Promotion of Science grant number 17K10825 and 18K16556.
Competing interests None declared.
Patient consent Not required.
Provenance and peer review Not commissioned; externally peer reviewed.