Florian VIXEGE : Study of 4-D intraventricular flow by Doppler echocardiography

Clinical context: During filling of the left ventricle (diastole), a vortex is formed. It facilitates the transition to ejection in healthy subjects. When filling is impaired (diastolic dysfunction), a change in blood flow can be observed, with a significant impact on this vortex. Intracardiac vortex imaging may lead to early diag- nosis of diastolic dysfunction. This intracardiac blood flow can be quantified non-invasively by cardiac magnetic resonance, which is not used clinically because of its cost-effectiveness. Damien Garcia and his colleagues thus developed iVFM ("intraventricular Vector Flow Mapping") by Doppler echocardiog- raphy1. This technique is based on cardiac ultrasound imaging. iVFM has the advantage of being fast and 100% compatible with the clinic standards, since it uses conventional clinical echocardiography.

Objective: The current version of iVFM uses echocardiographic heart cross-sectional planes. The recon- structed intracardiac flow is therefore two-dimensional. The objective of the thesis is to reconstruct 4-D intraventricular flow (3-D + time), and to validate this technique in silico and in vivo.

Methods: The numerical approach will stem from the optimization problem previously described by Assi et al.2, which will have to be adapted for 3-D and for triplane echocardiographic measurements. 4-D iVFM will be validated using realistic heart simulations3, as well as in healthy patients and volunteers, based on magnetic resonance imaging4. An in-depth study will be carried out on the analysis of vortices and their dynamics.