Intravascular Ultrasound Image-Based Finite Element Modeling Approach for Quantifying In Vivo Mechanical Properties of Human Coronary Artery

Summary

In vivo cine intravascular ultrasound images show the coronary cross-sectional movement corresponding to different pressure loading conditions. Based on a finite element model, an iterative scheme was employed to determine the patient-specific mechanical properties of coronary arteries in vivo by matching coronary motion from the computational model and medical images.

Abstract

Quantifying the mechanical properties of coronary arterial walls could provide meaningful information for the diagnosis, management, and treatment of coronary artery diseases. Since patient-specific coronary samples are not available for patients requiring continuous monitoring, direct experimental testing of vessel material properties becomes impossible. Current coronary models typically use material parameters from available literature, leading to significant mechanical stress/strain calculation errors. Here, we would introduce a finite element model-based updating approach (FEMBUA) to quantify patient-specific in vivo material properties of coronary arteries based on medical images. In vivo cine intravascular ultrasound (IVUS) and virtual histology (VH)-IVUS images of coronary arteries were acquired from a patient with coronary artery disease. Cine IVUS images showing the vascular movement over one cardiac cycle were segmented, and two IVUS frames with maximum and minimum lumen circumferences were selected to represent the coronary geometry under systolic and diastolic pressure conditions, respectively. VH-IVUS image was also segmented to obtain the vessel contours, and a layer thickness of 0.05 cm was added to the VH-IVUS contours to reconstruct the coronary geometry. A computational finite element model was created with an anisotropic Mooney-Rivlin material model used to describe the vessel's mechanical properties and pulsatile blood pressure conditions prescribed to the coronary luminal surface to make it contract and expand. Then, an iterative updating approach was employed to determine the material parameters of the anisotropic Mooney-Rivlin model by matching minimum and maximum lumen circumferences from the computational finite element model with those from cine IVUS images. This image-based finite element model-based updating approach could be successfully extended to determine the material properties of arterial walls in various vascular beds and holds the potential for risk assessment of cardiovascular diseases.

Introduction

Coronary artery disease (CAD) is one of the leading causes of mortality and morbidity, accounting for more than 9.14 million deaths in 2019 globally^1,2. The development of coronary artery diseases, such as atherosclerosis and stenosis, is often accompanied by alterations in mechanical forces and changes in vascular wall material properties³. The material properties of coronary arteries are not only the cornerstone to determine their mechanical response to the physiological loading but also the key elements to simulate the mechanical behavior of blood vessels, predict the development of ....

Protocol

De-identified clinical data, including in vivo IVUS images and blood pressure data, were acquired from a patient with CAD at Zhongda Hospital, Southeast University, with informed consent obtained. The sample patient was selected from the patient pool of a clinical study on intermediate coronary atherosclerotic lesions to demonstrate the method for quantifying the material properties of patient-specific coronary vessels¹⁴. The study was conducted following the protocol approved by the Clin.......

Discussion

Critical steps in the protocol
The most critical step in the finite element model-based updating approach lies in the iterative procedure. In the approach, the finite element model should accurately recover the coronary vessel motion on the vascular cross-section from in vivo cine IVUS images. To this purpose, minimizing the lumen circumference difference between the finite element model and in vivo images was adopted in this study to find the proper material properties. There wer.......

Materials

Name	Company	Catalog Number	Comments
Bee DICOM Viewer	SinoUnion Healthcare Inc.	Version 3.5.1	A DICOM image reader software
ADINA	Adina R & D	Version 9.0	Finite element solver
ImageJ	National Institutes of Health		Segmented IVUS contours
MATLAB	MathWorks	Version R2018a	Commercial programming platform
Volcano s5 imaging system	Volcano Company		Intravascular ultrasound imaging system