Development of a simple method to construct finite element models of aortas from MRI images and its application to thoracic aortic aneurysm

We have developed a method to construct finite element models of the whole thoracic aortas from T1-weighted MRI images. Intraluminal shape of the aorta perpendicular to its axis was assumed to be circular. We constructed a normal aortic model from a healthy male. Aneurysm models were made by adding a fusiform bulge to the ascending, arch, or descending regions of the normal model. In the analysis, aortic walls were assumed to be linearly elastic and the inner surface were pressurized at the pulse pressure of the subject. In all models, high stress appeared in the inner and lateral regions of the arch where aneurysm is prone to form. Peak stress in the wall was highest in the model with aneurysm at aortic arch. Eccentricity increased the peak stress: Aneurysms at the arch or with eccentricity have higher risk of rupture. Stress analysis may provide important information on aneurysm treatment.