Estimate the risks of intracranial aneurysm rupture by using wall shear stress divergence

![CDATA[Purpose Although wall shear stress (WSS) has long been considered as a critical indicator of intracranial aneurysm rupture, there is still no definite conclusion. The reason may be that the effect of WSS direction was not fully considered. The objectives of this study are to investigate WSS with its divergence on the aneurysm surface and test the significance of both in aneurysm rupture. Methods Wall shear stress divergence (WSSD) takes into account both the magnitude and direction of WSS and can be used to identify “tensile” and “compressing” regions on the aneurysm surface. Patient-specific computational fluid dynamics (CFD) were used to simulate WSS and WSSD l for 32 aneurysms (16 ruptured and 16 un-ruptured). The risk factors were defined the ratio of between WSS and WSSD. Results The results indicated that the WSS direction alternation significantly influence to the results. The risk factor of ruptured aneurysms reached 6.0±2.3, about 2 times higher than that of un-ruptured aneurysms (3.21± 1.0). Our results revealed that if high WSS is pulling aneurysm wall and the pulling region is concentrated, the aneurysm is under a high risk of rupture. As considering both direction and magnitude of WSS, WSSD may be a better indicator for the risk estimation of aneurysm rupture. Conclusion A new concept of WSSD was proposed, which considers both WSS magnitude and effective directions in the prediction of aneurysm rupture. Based on the WSSD calculation, it seems that considering both direction and magnitude of WSS, WSSD may be a better indicator for the risk estimation.]]