Morphologic and Hemodynamic Analysis in the Patients with Multiple Intracranial Aneurysms: Ruptured versus Unruptured

Abstract

Background and purpose: The authors evaluated the impact of morphologic and hemodynamic factors on multiple intracranial aneurysms and aimed to identify which parameters can be reliable indexes as one aneurysm ruptured, and the others did not.

Methods: Between June 2011 and May 2014, 69 patients harboring multiple intracranial aneurysms (69 ruptured and 86 unruptured) were analyzed from 3D-digital subtraction angiography (DSA) images and computational fluid dynamics (CFD). Morphologic and hemodynamic parameters were evaluated for significance with respect to rupture. Receiver operating characteristic (ROC) analysis identified area under the curve (AUC) and optimal thresholds separating ruptured from unruptured intracranial aneurysms for each parameter. Significant parameters were examined by binary logistic regression analysis to identify independent discriminators.

Results: Nine morphologic (size, neck width, surface area, volume, diameter of parent arteries, aspect ratio, size ratio, lateral/bifurcation type and regular/irregular type) and 6 hemodynamic (WSSmean, WSSmin, OSI, LSA, flow stability and flow complexity) parameters achieved statistical significance (p<0.05). Six morphologic (size, surface area, volume, aspect ratio, size ratio and regular/irregular type) and five hemodynamic (WSSmean, WSSmin, LSA, flow stability and flow complexity) parameters had high AUC values (AUC>0.7). By binary logistic regression analysis, large aspect ratio and low WSSmean were the independently significant rupture factors (AUC, 0.924; 95% CI, 0.883-0.965).

Conclusions: Large aspect ratio and low WSSmean were independently associated with the rupture status of multiple intracranial aneurysms.

Fig 1. Morphological-hemodynamic characteristics of multiple intracranial aneurysms in the ipsilateral anterior circulation.

A 60-year-old female presented with severe headache. CT scan showed subarachnoid hemorrhage (A). The angiograms of left internal carotid artery showed a ruptured aneurysm (B, large arrow) and an unruptured aneurysm (B, small arrow). The distribution of normalized wall shear stress (WSS) magnitude on the aneurysms sac showing the ruptured aneurysm had a lower WSS than the unruptured one (C). The Streamlines showing the flow pattern of the ruptured aneurysm was complex at peak systole (D). Streamlines are rendered with colors according to the velocity magnitude.

Fig 2. Morphological-hemodynamic characteristics of intracranial mirror aneurysms.

A 42-year-old male presented with severe headache. The angiograms of internal carotid artery showed an unruptured aneurysm (A) and a ruptured aneurysm (B). The distribution of normalized WSS magnitude on the aneurysms sac showing the ruptured aneurysm had a lower WSS than the unruptured one (C and D). The Streamlines showing the flow pattern of the ruptured aneurysm was complex at peak systole (E and F). Streamlines are rendered with colors according to the velocity magnitude.

Fig 3. Receiver operating characteristic (ROC) curves for key parameters.