Objective: The role of hemodynamics in the growth of intracranial aneurysms is not completely clear. We present a hemodynamic study with two adjacent unruptured aneurysms arising from one parent artery but growing in different ways. This study aimed to investigate whether there were differences in hemodynamic characteristics between the two growing aneurysms. Methods: A 62-year-old female patient presented with six unruptured intracranial aneurysms. Catheter angiography at 6-month intervals revealed that two aneurysms located adjacently at the right posterior inferior cerebellar artery were growing over a 1-year period. Three-dimensional aneurysm geometries were acquired via rotational angiography. Computational fluid dynamic simulations were conducted on the 3D aneurysm geometries under patient-specific pulsatile flow conditions that were measured by magnetic resonance velocimetry. Results: The proximal multilobular aneurysm demonstrated high flow and physiological levels of wall shear stress (WSS) in the region of growth, whereas the distal rounded aneurysm had low flow and low WSS in the growing sac. Conclusion: Growing aneurysms can have heterogeneous hemodynamic and morphologic characteristics and different growing patterns. Growing regions of an aneurysm could be exposed to either high WSS at the inflow zone or low WSS and high oscillatory shear in the aneurysm sac.
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