Quantifying Patient-Specific in vivo Coronary Plaque Material Properties for Accurate Stress/Strain Calculations: An IVUS-Based Multi-Patient Study.

Liang Wang,Xiaoya Guo,Lijuan Chen,Genshan Ma,Rui Lv,Gary S Mintz,Jian Zhu,Kristen L Billiar,Yangyang Qu,Akiko Maehara,Xiaoguo Zhang,Dalin Tang

doi:10.3389/fphys.2021.721195

Abstract

Introduction: Mechanical forces are closely associated with plaque progression and rupture. Precise quantifications of biomechanical conditions using in vivo image-based computational models depend heavily on the accurate estimation of patient-specific plaque mechanical properties. Currently, mechanical experiments are commonly performed on ex vivo cardiovascular tissues to determine plaque material properties. Patient-specific in vivo coronary material properties are scarce in the existing literature.Methods: In vivo Cine intravascular ultrasound and virtual histology intravascular ultrasound (IVUS) slices were acquired at 20 plaque sites from 13 patients. A three-dimensional thin-slice structure-only model was constructed for each slice to obtain patient-specific in vivo material parameter values following an iterative scheme. Effective Young's modulus (YM) was calculated to indicate plaque stiffness for easy comparison purposes. IVUS-based 3D thin-slice models using in vivo and ex vivo material properties were constructed to investigate their impacts on plaque wall stress/strain (PWS/PWSn) calculations.Results: The average YM values in the axial and circumferential directions for the 20 plaque slices were 599.5 and 1,042.8 kPa, respectively, 36.1% lower than those from published ex vivo data. The YM values in the circumferential direction of the softest and stiffest plaques were 103.4 and 2,317.3 kPa, respectively. The relative difference of mean PWSn on lumen using the in vivo and ex vivo material properties could be as high as 431%, while the relative difference of mean PWS was much lower, about 3.07% on average.Conclusion: There is a large inter-patient and intra-patient variability in the in vivo plaque material properties. In vivo material properties have a great impact on plaque stress/strain calculations. In vivo plaque material properties have a greater impact on strain calculations. Large-scale-patient studies are needed to further verify our findings.

Highlights

Mechanical forces are closely associated with plaque progression and rupture
Even though considerable experimental data have accumulated based on ex vivo tissues, it is still desirable to use patient-specific in vivo material properties in computational modeling for better accuracies in disease management
Grayscale intravascular ultrasound (IVUS) images were obtained by scanning crosssections of coronary plaques using a 20-MHz, 2.9-French catheter (Eagle Eye Platinum; Volcano Corp., Rancho Cordova, CA, United States)

Summary

Introduction

Precise quantifications of biomechanical conditions using in vivo image-based computational models depend heavily on the accurate estimation of patient-specific plaque mechanical properties. Patient-specific in vivo coronary material properties are scarce in the existing literature Cardiovascular diseases, such as heart attack and stroke, are the number 1 cause of death globally, and killed more than 17.7 million people in 2017 (GBD 2017 Causes of Death Collaborators, 2018). Precise quantifications of biomechanical conditions depend heavily on accurate material properties of patient-specific plaque tissues (Akyildiz et al, 2014). Even though considerable experimental data have accumulated based on ex vivo tissues, it is still desirable to use patient-specific in vivo material properties in computational modeling for better accuracies in disease management

Methods

Results

Conclusion