Material parameter identification of the proximal and distal segments of the porcine thoracic aorta based on ECG-gated CT angiography

Abstract

Vessel wall material parameters are important in biomechanical research. The purpose of this study was to identify the material parameters of two porcine thoracic aortic segments and verify the accuracy of the identification results with uniaxial tensile testing. Principal component analysis (PCA) was used to reduce the dimensionality of the stress matrix. Data points in PCA space were initially screened by K-means cluster analysis, and connection networks of two levels were constructed based on the distance between the data points. The material parameters corresponding to the data points were substituted, and pressure was applied to convert the diastolic models to systolic models to match those reconstructed from electrocardiographic (ECG) gated computed tomography angiography (CTA), and determine the optimal material parameters. The proximal and distal segments of the thoracic aorta were selected for uniaxial tensile testing, and the stress-strain curves obtained from numerical simulations and experiments were compared. The average distances between the simulated systolic proximal and distal segments and their corresponding systolic models reconstructed from the ECG-gated-CTA were 0.388 mm and 0.257 mm, respectively. The fit goodness of the stress-strain data obtained by two methods was 0.9953 and 0.9750, respectively, with equivalent elastic moduli differences of 1.08% and 0.36%. Thus, a material parameter screening method for different aortic segments was proposed and its accuracy was verified experimentally with good consistency. This method is expected to provide a theoretical basis for biomechanical studies of aortic diseases.

Keywords: ECG-gated-CTA; Experimental verification; Material identification; Principal component analysis (PCA); Uniaxial tensile testing.