Project Description
The project aims to investigate the central hypothesis, that within the context of dynamical assessment of aneurysm mechanics, the
primary biomechanical determinant of AAA rupture potential is the non-uniform arterial wall thickness. The overall goal of this project is to address this
hypothesis by predicting AAA risk of rupture on a patient-specific basis for subjects that will undergo elective repair as well as retrospectively examine
patient-specific ruptured aneurysms. The biomechanical environment of the patient specific AAAs will be reproduced by segmenting and modeling the AAA with
non uniform wall thickness, and applying patient specific boundary conditions (non-invasively evaluating blood flow from PC MR Images and applying it over
the cardiac cycle as inlet boundary condition ). The dynamic indicators of AAA risk of rupture to be evaluated include peak wall stress, peak intra-aneurysmal
sac pressure, and spatial and temporal changes in aneurysmal wall thickness. Retrospectively evaluating these indicators for ruptured aneurysms will provide a
threshold for which future diagnosed AAAs can be measured against to assess their potential for mechanical failure in a clinical setting. These biomechanical
and clinical endpoints will be assessed using standard computational and imaging techniques i.e. cine, phase-contrast and spin echo magnetic resonance imaging,
computed tomography imaging, segmentation and reconstruction algorithms, particle image velocimetry, soft tissue mechanics frameworks , computational solid and
fluid mechanics and fluid-structure interaction modeling.
In addition, we propose
A novel constitutive material model for the mechanical properties of the AAA wall based on a strain energy function for soft
tissues that accounts for anisotropy and arrangement of a collagen fiber network;
A new method for generating the unloaded configuration of the abdominal aorta based on the pressurized geometry reconstructed from
medical images;
A custom-based code for calculation of impedance-derived outflow boundary conditions from in vivo phase-contrast MRI data.
This project represents a pilot study for the development of a methodology to specifically evaluate the biomechanics of AAAs dynamically within
the context of assessing their rupture potential. The innovative nature of the proposed research is based not only on the non-invasive methodology, but also on the
unprecedented validation of the numerical techniques used herein, and the application of patient-specific intraluminal flow conditions and arterial wall thickness
measured at the time of patient examination. This advanced computational framework will allow surgical management of AAA patients to be planned in a timely and
cost-effective manner and provide better care while improving the quality of life of the patients.
FSI modeling of a patient-specific AAA model.
Back |
