  Abdominal Aortic Aneurysm (AAA) is an enlargement in the lower part of the
main artery Aorta by 1.5 times its normal diameter. AAA can cause death if
rupture occurs. Elective surgeries are recommended to prevent rupture based on
geometrical measurements of AAA diameter and diameter growth rate. Reliability
of these geometric parameters to predict the AAA rupture risk has been
questioned, and biomechanical assessment has been proposed to distinguish
between patients with high and low risk of rupture. Stress in aneurysm wall is
the main variable of interest in such assessment. Most studies use finite
element method to compute AAA stress. This requires discretising
patient-specific geometry (aneurysm wall and intraluminal thrombus ILT) into
finite elements/meshes. Tetrahedral elements are most commonly used as they can
be generated in seemingly automated and effortless way. In practice, however,
due to complex aneurysm geometry, the process tends to require time consuming
mesh optimisation to ensure sufficiently high quality of tetrahedral elements.
Furthermore, ensuring solution convergence requires large number of tetrahedral
elements, which leads to long computation times. In this study, we focus on
generation of hexahedral meshes as they are known to provide converged solution
for smaller number of elements than tetrahedral meshes. Generation of
hexahedral meshes for continua with complex/irregular geometry, such as
aneurysms, requires analyst interaction. We propose a procedure for generating
high quality patient-specific hexahedral discretisation of aneurysm wall using
the algorithms available in commercial software package for mesh generation.
For aneurysm cases, we demonstrate that the procedure facilitates
patient-specific mesh generation within timeframe consistent with clinical
workflow constraints while requiring only limited input from the analyst.
