New insights in the Fontan circulation: 4-dimensional respiratory- and ECG-triggered phase contrast magnetic resonance imaging

Abstract

Background Evaluation of blood flow characteristics in total cavo-pulmonary connection (TCPC) with CMR remains difficult due to its strong modulation by respiration, and is not yet entirely understood. New approaches using 4D phase contrast magnetic resonance imaging (4D PC MRI) are promising and can contribute to the understanding of hemodynamics in the Fontan Circulation. Our objective was to compare flow, velocities, wall shear stress (WSS) and circulation in the TCPC using respiratory- and ECG triggered 4D PC MRI. Methods 10 children with hypoplastic left heart syndrome were evaluated after surgical completion of the Fontan circulation (TCPC with lateral intra-atrial tunnel) in a single center. In all patients one respiratory- (80 -100 phases) and one ECG-triggered (30 phases) 4D PC MRI covering the whole thorax, voxel size ranging from isotropic 1.5 to 2.0 mm were acquired during a single CMR examination with a custom-made electronic respiratory triggering compatible with our scanner. Dedicated commercial and custom software was used for further analysis of flow, velocity, WSS and circulation. Results