Toward modeling the effects of regional material properties on the wall stress distribution of abdominal aortic aneurysms

Abstract

The overall geometry and different biomechanical parameters of an abdominal aortic aneurysm (AAA), contribute to its severity and risk of rupture, therefore they could be used to track its progression. Previous and ongoing research efforts have resorted to using uniform material properties to model the behavior of AAA. However, it has been recently illustrated that different regions of the AAA wall exhibit different behavior due to the effect of the biological activities in the metalloproteinase matrix that makes up the wall at the aneurysm site. In this work, we introduce a non-invasive patient-specific regional material property model to help us better understand and investigate the AAA wall stress distribution, peak wall stress (PWS) severity, and potential rupture risk. Our results indicate that the PWS and the overall wall stress distribution predicted using the proposed regional material property model, are higher than those predicted using the traditional homogeneous, hyper-elastic model (p <1.43E-07). Our results also show that to investigate AAA, the overall geometry, presence of intra-luminal thrombus (ILT), and loading condition in a patient specific manner may be critical for capturing the biomechanical complexity of AAAs.

A machine leaning approach for abdominal aortic aneurysm severity assessment using geometric, biomechanical, and patient-specific historical clinical features

“…Contrast enhanced computed tomography angiography (CTA) images of 66 patients were retrospectively obtained from the Division of Vascular Surgery at the University of Rochester following approval by the Human Subject Review Board. The images were used to calculate 26 geometrical indices and 4 biomechanical parameters, details of which are available in [11,20,21]. Moreover, 15 patient-specific clinical factors, consisting of patient demographics, habitual information such as risk factors, and other clinical pre-existing conditions, were also extracted from the clinical dataset.…”

“…Moreover, it has been shown that in addition to geometric indices such as D max , a variety of biomechanical parameters and material properties affect AAA morphology and behavior [3,[7][8][9]. Wall stress distribution and mainly the peak wall stress -which is directly related to the failure site on the AAA surface -computed using finite element analysis (FEA) have been helpful to comprehensively consider the effects of all mentioned parameters [10][11][12]. Additionally, it has been illustrated that patient-specific historical data, such as the presence of clinical pre-existing conditions or risk factors, such as smoking, hypertension, or chronic kidney disease (CKD) may increase AAA severity and risk of rupture [6,13].…”