Influence of surface model extraction parameter on computational fluid dynamics modeling of cerebral aneurysms

Threshold image intensity for reconstructing patient-specific vascular models is generally determined subjectively. We assessed the effects of threshold image intensity differences on computational fluid dynamics (CFD) using a simple method of threshold determination. This study included 11 consecutive patients with internal carotid artery aneurysms collected retrospectively between April 2009 and March 2010. In 3-dimensional rotational angiography image data, we set a line probe across the coronal cross-section of the parent internal carotid artery, and calculated a profile curve of the image intensity along this line. We employed the threshold coefficient (C_thre) value in this profile curve, in order to determine the threshold image intensity objectively. We assessed the effects of C_thre value differences on vascular model configuration and the wall shear stress (WSS) distribution of the aneurysm. The threshold image intensity increased as the C_thre value increased. The frequency of manual editing increased as the C_thre value decreased, while disconnection of the posterior communicating artery occurred more frequently as the C_thre value increased. The volume of the vascular model decreased and WSS increased according to the C_thre value increase. The pattern of WSS distribution changed remarkably in one case. Threshold image intensity differences can produce profound effects on CFD. Our results suggest the uniform setting of C_thre value is important for objective CFD.