Use of time resolved 3D ultrasound data for the determination of the anisotropic elastic properties of the human aorta

Abstract

Purpose: Over last two decades computational methods for the analysis of the biomechanics of the vascular system have been developed, aiming at a better understanding of its physiology and pathophysiology and at clinical use as a tool for diagnosis and risk prediction of vascular diseases such as aortic aneurysms or plaque rupture. However, the benefit of such studies is currently limited by the lack of information on the patient specific material properties. In this work we employ blood pressure measurements and 3D ultrasound speckle tracking imaging to acquire the time resolved 3D displacement field of the abdominal aortic wall during blood pressure induced deformation in healthy volunteers. An inverse Finite Element Updating Method is applied to these data to determine the anisotropic hyperelastic mechanical properties of the abdominal aorta in vivo. Material and methods: Time resolved 3D ultrasound image data of abdominal aortic segments were acquired by use of a customized commercial real time 3D-echocardiography system (Artida, Toshiba). 3D speckle tracking of the full 4D data sets was performed using the algorithm implemented in the ACP-software. The spatially and temporally resolved strain fields resulting from the measurements or from a simulation of systolic pressure loading are compared to identify the parameters of a material model for arterial walls. Results: Spatially and temporally resolved strain fields of the abdominal aorta of healthy volunteers were calculated from 3D ultrasound data. These data were successfully used to identify the material properties of arterial walls in vivo. Conclusion: Recently, several approaches of constitutive parameter identification based on full-field measurements of displacement and strain fields have been presented. In this paper we present the application of such a method to in vivo full field displacement data of human aortas. This can be used to develop new tools for the diagnosis of vascular pathologies.