ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

found that the age-adjusted annual incidence of aneurysmal subarachnoid hemorrage
differed among the countries, ranging from 2.0 to 22.5 cases per 100.000 population [1].
Aneurysm size is thought to be one of the main risk factors for rupture. Many studies
have compared size between ruptured and unruptured aneurysms [2-5], On the other
hand, many investigators have also evaluated other morphological aspects as a predictor
of rupture risk [2-4]. In this study, focus is redirected to hemodynamic behavior of
aneurysms after treatment. CFD analyses of various types of intracranial aneurysms
located on ICA were conducted. Results from CFD were compared against medical
outcomes, and level of treatment success was related to numerical outcomes that would
be easy and feasible to track during a stent deployment progress.
2. MATERIAL AND METHODS
2.1. Model Preparation
The aneurysm models were obtained form Cerrahpasa Medical School, Department of
NeuroRadiology, as real patient data viewed with Philips Integris Allura Biplane
Angiography (Philips Medical Systems Netherland B.V). The 3D reconstruction voxel
resolution of the device was 0.15mm, and the exported 3D data was in STL format
(Figure 1). STL data was then processed in Polyworks/IMEdit Software (Innovmetric
Inc., Canada), where the unnecessary portions of the exported model, the noise in the
point cloud data were cleaned, and curvature continuous point cloud model of the
aneurysm region was obtained (Figure 1).
Fig. 1 - Example Views of Original STL Data from CT and
Processed STL Data of the Aneurysm Region (Patient 3)
For efficiency purposes, it is necessary to develop a model to obtain the geometry of a
deployed stent without actually deploying it in computer environment (using FEA) to
estimate the deployed geometry. Thus, a method is developed using built-in capabilities
of Polyworks/IMEdit. The method presumes that, the deployed stent will have a similar
structure as if the aneurysm was not there; and the vessel wall was a curvaturecontinuous
extension of the remaining part. Thus, by manual editing, a model of the
arterial segment, without the aneurysm was reconstructed to draw a 3D stent model on.
All the STL models were converted to NURBS-surface models and the 3D solid model
of the lumen volume were prepared. A custom algorithm was developed to generate a
3D model of the silk stent. The woven structure of the stent was disregarded to prevent
CFD mesh distortions. The 3D model of the stent was then removed from the lumen to
obtain the stented aneurysm lumen model. For all models, real stent alignment was