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.
翻译:直径和直径增长率的几何测量结果,建议进行有选择的外科手术,以防止在AAA的直径和直径增长率的基础上,对AAA直径进行分解。这些用于预测AAA破裂风险的几何参数的可靠性受到质疑,并提议进行生物机械评估,以区分高和低破裂风险的病人。在这种评估中,心血管壁的压力是感兴趣的主要变数。大多数研究使用有限的元素来计算AAAA压力。这需要将特定病人的几何测量(肾脏墙和光性内胸膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内膜内压力, 过程需要时间消耗精度的节度,以确保内膜内衬内的内膜内膜内衣, 需要较低的内质的内膜内质的内膜内膜内膜内衬, 的内衬内衬内衬内衬内衬内衬内衣, 要求要求要求要求更低质的内衬内衬内衬内衬内衬内衬内部的内部的内部的内衣, ;此外的内衬内衬内衬内衬内衣,,,,,要求为这种内衬内衬内衬内衬内衬内衬内衬内体内衣的内衣的内衬内衣,这种内衣的内衣, 的内衣, 的内衣的内衣,,,,,, 的内衬内衣,作为这个解的内衬内衬内衬内衬内衬内衣的内衣的内体内衣,作为的内衣的内部的内部的内衣,作为的内衣, 的内衣, 的内衣,作为的体, 的体, 的内衣, 的体, 的体, 的体,供作, 的内的内的内的内的内体, 的内衣的内衣的内衣, 的内衣, 的