Hemodynamic characteristics of hyperplastic remodeling lesions in cerebral aneurysms

<div><p>Background & purpose</p><p>Hyperplastic 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).</p><p>Methods</p><p>Twenty-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.</p><p>Results</p><p>HR 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.</p><p>Conclusions</p><p>Although low NWSS was independently associated with HR lesions, OSI is the most valuable hemodynamic parameter to distinguish HR lesions from red walls.</p></div

Summary of hemodynamic parameters in hyperplastic remodeling (HR) lesions and red walls.

<p>Summary of hemodynamic parameters in hyperplastic remodeling (HR) lesions and red walls.</p

Logistic regression analysis of independent parameters associated with hyperplastic remodeling lesions of aneurysms, with stepwise regression using P values to drop variables.

<p>Logistic regression analysis of independent parameters associated with hyperplastic remodeling lesions of aneurysms, with stepwise regression using P values to drop variables.</p

Clinical characteristics of cerebral aneurysms.

<p>Clinical characteristics of cerebral aneurysms.</p

Comparison of intraoperative image (a) and virtual operative image of the same angle as the intraoperative image (b).

<p>The qualification points are set on both images as white or pink dots. White dots are set on the hyperplastic remodeling lesion, and pink dots on the red walls.</p

Virtual operative images of normalized wall shear stress (a), oscillatory shear index (b), relative residence time (c), and aneurysm formation indicator (d), with the qualification points.

<p>Virtual operative images of normalized wall shear stress (a), oscillatory shear index (b), relative residence time (c), and aneurysm formation indicator (d), with the qualification points.</p

Comparison of intraoperative image and visualized hemodynamic parameters in 2 cases: middle cerebral artery aneurysm (a) and internal carotid artery-posterior communicating artery bifurcation aneurysm (b).

<p>The shape of aneurysm in the intraoperative image is partly different from that in geometry model because of the atherosclerotic hyperplastic remodeling of the wall (red circle). The qualification points are set on images as white (indicating hyperplastic remodeling lesion) or pink (indicating red wall) dots. Low normalized wall shear stress (NWSS), high oscillatory shear index (OSI), low aneurysm formation indicator (AFI), and prolonged relative residence time (RRT) are observed at or near most of hyperplastic remodeling lesions, but one hyperplastic remodeling lesion is located on the area with high NWSS, low OSI, high AFI, and shortened RRT (yellow arrow).</p