Latorre Molins Álvaro T, Guala Andrea, Dux-Santoy Lydia, Teixidó-Turà Gisela, Rodríguez-Palomares José Fernando, Martínez Barca Miguel Ángel, Peña Baquedano Estefanía
Aragón Institute for Engineering Research (I3A), University of Zaragoza, Zaragoza, Spain.
Vall d'Hebron Institut de Recerca, Barcelona, Spain.
Biomech Model Mechanobiol. 2025 Feb;24(1):233-250. doi: 10.1007/s10237-024-01907-6. Epub 2024 Nov 26.
An ascending aortic aneurysm is an often asymptomatic localized dilatation of the aorta. Aortic rupture is a life-threatening event that occurs when the stress on the aortic wall exceeds its mechanical strength. Therefore, patient-specific finite element models could play an important role in estimating the risk of rupture. This requires not only the geometry of the aorta but also the nonlinear anisotropic properties of the tissue. In this study, we presented a methodology to estimate the mechanical properties of the aorta from magnetic resonance imaging (MRI). As a theoretical framework, we used finite element models to which we added noise to simulate clinical data from real patient geometry and different properties of healthy and aneurysmal aortic tissues collected from the literature. The proposed methodology considered the nonlinear properties, the zero pressure geometry, the heart motion, and the external tissue support. In addition, we analyzed the aorta as a homogeneous material and as a heterogeneous model with different properties for the ascending and descending parts. The methodology was also applied to pre-surgical,in vivo MRI data of a patient who underwent surgery during which an aortic wall sample was obtained. The results were compared with those obtained from ex vivo biaxial test of the patient's tissue sample. The methodology showed promising results after successfully recovering the nonlinear anisotropic material properties of all analyzed cases. This study demonstrates that the variable used during the optimization process can affect the result. In particular, variables such as principal strains were found to obtain more realistic materials than the displacement field.
升主动脉瘤是主动脉常见的无症状局部扩张。主动脉破裂是一种危及生命的事件，当主动脉壁上的应力超过其机械强度时就会发生。因此，针对患者的有限元模型在估计破裂风险方面可能发挥重要作用。这不仅需要主动脉的几何形状，还需要组织的非线性各向异性特性。在本研究中，我们提出了一种从磁共振成像（MRI）估计主动脉力学特性的方法。作为理论框架，我们使用有限元模型，并添加噪声以模拟来自真实患者几何形状的临床数据以及从文献中收集的健康和动脉瘤性主动脉组织的不同特性。所提出的方法考虑了非线性特性、零压力几何形状、心脏运动和外部组织支撑。此外，我们将主动脉分析为均质材料以及升部和降部具有不同特性的非均质模型。该方法还应用于一名接受手术的患者的术前体内MRI数据，手术期间获取了主动脉壁样本。将结果与患者组织样本的体外双轴试验结果进行比较。在成功恢复所有分析病例的非线性各向异性材料特性后，该方法显示出有前景的结果。本研究表明，优化过程中使用的变量会影响结果。特别是，发现诸如主应变等变量比位移场能获得更符合实际的材料。
