Objective: To investigate hemodynamic characteristics of atherosclerotic lesions in intracranial aneurysms using computational fluid dynamics (CFD).
Methods: Intra-operative video recordings of thirty consecutive patients with an unruptured middle cerebral artery aneurysm were examined to identify atherosclerotic lesions on aneurysm wall. For CFD analyses, geometries of aneurysms and adjacent arteries were reconstructed from three-dimensional rotational angiography. Transient simulations were conducted under patient-specific pulsatile inlet conditions measured by phase-contrast magnetic resonance velocimetry. Three hemodynamic wall parameters were calculated: time-averaged wall shear stress (WSS), oscillatory shear index (OSI), and relative residence time (RRT). Statistical analyses were performed to discriminate the risk factors of atherosclerotic lesion formation.
Results: Among 30 aneurysms, seven atherosclerotic lesions with remarkable yellow lipid deposition were identified in five aneurysms. All seven atherosclerotic lesions were spatially agreed with the area with prolonged RRT. Univariate analysis revealed that male (P = 0.031), cigarette smoking (P = 0.047) and maximum RRT (P = 0.024) are significantly related to atherosclerotic lesion on the intracranial aneurysmal wall. Of those variables that influenced atherosclerotic lesion of the intracranial aneurysmal wall, the variable male (P = 0.0046) and maximum RRT (P = 0.0037) remained significant in the multivariate regression model.
Conclusion: The area with prolonged RRT co-localized with atherosclerotic change on the aneurysm wall. Male and maximum RRT were independent risk factors for atherogenesis in intracranial aneurysms.
From: Relative Residence Time Prolongation in Intracranial Aneurysms: A Possible Association with Atherosclerosis by Sugiyama et al.