A pulsatile 3D flow relevant to thoracic hemodynamics: CFD - 4D MRI comparison

Application Area 7: Biomedical Flows

Application Challenge AC7-04

Abstract

3D time-resolved phase-contrast magnetic resonance (PC-MRI, also known as 4D Flow MRI) is a clinical modality of growing interest, which allows a non-invasive and non-ionizing access to blood velocity fields. The hemodynamics’ knowledge that it brings could help clinicians in the detection and follow-up of numerous cardiovascular diseases. However, 4D Flow MRI presents some limitations, such as poor spatio-temporal resolution, imaging artefacts or machine-specific variability. From another perspective, CFD simulations can also provide 3D velocity fields, while freeing oneself from some experimental constraints due to the MRI acquisition process. The objective of the current application challenge is to provide a well-controlled environment to be able to compare CFD and 4D MRI. To do so, an experimental set-up containing a non-deformable phantom has been developed. This phantom has been geometrically designed to contain some of the typical topology found in the cardiovascular system, and thus the associated flow patterns of interest. The in vitro 4D Flow measurements have been recorded under a pulsatile flow rate. The flow in the corresponding numerical phantom has been simulated by means of an in-house LES solver. Finally, some post-processing steps needed to be able to compare the two modalities will be presented. The methods described in the present Application Challenge are mainly based on T. Puiseux’s PhD work, which has been reported in Puiseux et al. (2019) and serves as the basis for on going research about in silico MRI (Puiseux et al. 2021).