One hundred and six saccular MCA aneurysms (43, ruptured; 63, unruptured) diagnosed with 3-dimensional rotational angiography were analyzed. The patient-specific geometries were reconstructed from 3-dimensional rotational angiography images. Computational fluid dynamics simulations were performed under pulsatile flow conditions driven from typical blood-flow waveforms of the common carotid artery in normal humans, 3 and the following hemodynamic parameters were calculated: wall shear stress (WSS), normalized WSS (NWSS), 2 oscillatory shear index (OSI), 4 WSS gradient (WSSG), 5 gradient oscillatory number, 6 and aneurysm-formation indicator (AFI). 7Morphological (aneurysm size and aspect ratio) and hemodynamic parameters were compared between ruptured and unruptured aneurysms (see expanded methods in the online only data supplement). Results Univariate AnalysisAs not all morphological and hemodynamic parameters were normally distributed, they were analyzed with the Wilcoxon rank-sum test (Table 1). The median of the size of the aneurysmal dome and the aspect ratio were 5.36 mm and 1.43, respectively, for ruptured aneurysms, and 5.30 mm and 1.33, respectively, for unruptured aneurysms. There was no significant difference in the size of the aneurysmal dome (P=0.122), whereas the aspect ratio was significantly different (P=0.0298).Distributions of WSS, OSI, WSSG, gradient oscillatory number, and AFI for ruptured and unruptured aneurysms are shown in Figure. Ruptured aneurysms had significantly lower WSS, lower NWSS, higher OSI, lower WSSG, and lower AFI than unruptured aneurysms (7.19 Pa versus 9.55 Pa, P=0.00010; 0.490 versus 0.618, P=0.0129; 0.0165 versus 0.0125, P=0.00891; 7.15 Pa/mm versus 10.40 Pa/mm, P=0.00020; and 0.971 versus 0.978, P=0.00631, respectively).Background and Purpose-We determined which hemodynamic parameter independently characterizes the rupture status of middle cerebral artery (MCA) aneurysms using computational fluid dynamics analysis.Methods-In 106 patient-specific geometries of MCA aneurysms (43 ruptured, 63 unruptured), morphological and hemodynamic parameters were compared between the ruptured and unruptured groups. Multivariate logistic regression analysis was performed to determine parameters that independently characterized the rupture status of MCA aneurysms.Results-Univariate analyses showed that the aspect ratio, wall shear stress (WSS), normalized WSS, oscillatory shear index, WSS gradient, and aneurysm-formation index were significant parameters. The size of the aneurysmal dome and the gradient oscillatory number were not significantly different between the 2 groups. With multivariate analyses, only lower WSS was significantly associated with the rupture status of MCA aneurysms. Conclusions-WSS Intercorrelations Among ParametersIntercorrelations between significant parameters with univariate analyses were examined using Multivariate AnalysesBecause WSS had the lowest P value in the Wilcoxon ranksum test among WSS, NWSS, and WSSG, which were significantly correlated, only...

Wide variability exists in the prediction of intracranial aneurysm WSS. While segmentation and CFD solver techniques may be difficult to standardize across groups, our findings suggest that some of the variability in image-based CFD could be reduced by establishing guidelines for model extents, inflow rates, and blood properties, and by encouraging the reporting of normalized hemodynamic parameters.

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ObjectiveThis study aimed to predict recurrence after coil embolization of unruptured cerebral aneurysms with computational fluid dynamics (CFD) using porous media modeling (porous media CFD).MethodA total of 37 unruptured cerebral aneurysms treated with coiling were analyzed using follow-up angiograms, simulated CFD prior to coiling (control CFD), and porous media CFD. Coiled aneurysms were classified into stable or recurrence groups according to follow-up angiogram findings. Morphological parameters, coil packing density, and hemodynamic variables were evaluated for their correlations with aneurysmal recurrence. We also calculated residual flow volumes (RFVs), a novel hemodynamic parameter used to quantify the residual aneurysm volume after simulated coiling, which has a mean fluid domain > 1.0 cm/s.ResultFollow-up angiograms showed 24 aneurysms in the stable group and 13 in the recurrence group. Mann-Whitney U test demonstrated that maximum size, dome volume, neck width, neck area, and coil packing density were significantly different between the two groups (P < 0.05). Among the hemodynamic parameters, aneurysms in the recurrence group had significantly larger inflow and outflow areas in the control CFD and larger RFVs in the porous media CFD. Multivariate logistic regression analyses demonstrated that RFV was the only independently significant factor (odds ratio, 1.06; 95% confidence interval, 1.01–1.11; P = 0.016).ConclusionThe study findings suggest that RFV collected under porous media modeling predicts the recurrence of coiled aneurysms.

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We investigated particularly the proactive nature of the visual-motor system by steady and transient experiments of a hand-tracking task, and confirmed that the hand motion precedes on the average the target motion in steady runs within a finite frequency range of the sinusoidal target motion. The question why and how much the hand motion should precede was answered by frequency-jump experiments. The results implied that the positive phase shift of the hand motion represents the proactive nature of the visual-motor control system which is adaptationally developed for each person to minimize the transient error of the hand motion when the target motion changes unexpectedly.

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Background & purposeHyperplastic remodeling (HR) lesions are sometimes found on cerebral aneurysm walls. Atherosclerosis is the results of HR, which may cause an adverse effect on surgical treatment for cerebral aneurysms. Previous studies have demonstrated that atherosclerotic changes had a correlation with certain hemodynamic characteristics. Therefore, we investigated local hemodynamic characteristics of HR lesions of cerebral aneurysms using computational fluid dynamics (CFD).MethodsTwenty-four cerebral aneurysms were investigated using CFD and intraoperative video recordings. HR lesions and red walls were confirmed on the intraoperative images, and the qualification points were determined on the center of the HR lesions and the red walls. The qualification points were set on the virtual operative images for evaluation of wall shear stress (WSS), normalized WSS (NWSS), oscillatory shear index (OSI), relative residence time (RRT), and aneurysm formation indicator (AFI). These hemodynamic parameters at the qualification points were compared between HR lesions and red walls.ResultsHR lesions had lower NWSS, lower AFI, higher OSI and prolonged RRT compared with red walls. From analysis of the receiver-operating characteristic curve for hemodynamic parameters, OSI was the most optimal hemodynamic parameter to predict HR lesions (area under the curve, 0.745; 95% confidence interval, 0.603–0.887; cutoff value, 0.00917; sensitivity, 0.643; specificity, 0.893; P<0.01). With multivariate logistic regression analyses using stepwise method, NWSS was significantly associated with the HR lesions.ConclusionsAlthough low NWSS was independently associated with HR lesions, OSI is the most valuable hemodynamic parameter to distinguish HR lesions from red walls.