Validation of the Reduced Unified Continuum Formulation Against In Vitro 4D-Flow MRI

TL;DR

This study validates a novel vascular fluid-structure interaction formulation against in vitro 4D-flow MRI data, demonstrating high accuracy in simulating complex patient-specific aortic dynamics at low computational cost.

Contribution

First validation of a cardiovascular FSI formulation against in vitro flow circuit data with complex patient-specific anatomy.

Findings

Close quantitative agreement in pressures and lumen area changes

Accurate simulation of pulse wave velocity and early systolic velocities

Qualitative match in late systolic flow structures

Abstract

In our recent work, we introduced the reduced unified continuum formulation for vascular fluid-structure interaction (FSI) and demonstrated enhanced solver accuracy, scalability, and performance compared to conventional approaches. We further verified the formulation against Womersley's deformable wall theory. In this study, we assessed its performance in a compliant patient-specific aortic model by leveraging 3D printing, 2D magnetic resonance imaging (MRI), and 4D-flow MRI to extract high-resolution anatomical and hemodynamic information from an in vitro flow circuit. To accurately reflect experimental conditions, we additionally enabled in-plane vascular motion at each inlet and outlet, and implemented viscoelastic external tissue support and vascular tissue prestressing. Validation of our formulation is achieved through close quantitative agreement in pressures, lumen area changes, pulse wave velocity, and early systolic velocities, as well as qualitative agreement in late systolic flow structures. Our validated suite of FSI techniques can be used to investigate vascular disease initiation, progression, and treatment at a computational cost on the same order as that of rigid-walled simulations. This study is the first to validate a cardiovascular FSI formulation against an in vitro flow circuit involving a compliant vascular phantom of complex patient-specific anatomy.