Cardiac magnetic resonance has become common in the management of congenital heart disease because of its ability to visualize structures that remain obscure by echocardiography without ionizing radiation. The 4D flow is an MRI method that simultaneously processes the quantification of blood flow, the quantification of ventricular volumes and function, the visualization of intracardiac and extracardiac structures and blood flow.

The objectives of this study are to assess the feasibility of 4D flow routinely in children and young adults, to compare 4D flow with 2D phase-contrast MRI for quantification of aortic and pulmonary flow and to evaluate the advantage of 4D flow-based volumetric flow analysis compared to 2D phase contrast MRI.

Two-dimensional phase-contrast MRI of the aortic root, main pulmonary artery, right and left ventricles and atrias and 4D flow with volumetric coverage of the aorta and pulmonary arteries were performed in 14 patients, 2 (12 and 14 years old) and 12 adults (mean age: 24.1±7.3years). This CMR concerned various diseases: repaired tetralogy of Fallot (n=10), aortic coarctation (n=1), single ventricle heart defect (n=1) and ventricular communicating shunt (2). Four-dimensional volumetric assessments of ventricles, pulmonary flow and aortic flow were performed and compared to 2D phase-contrast. Four dimensional flow analyses included calculation of net flow and regurgitant fraction with 4D flow analysis.

Excellent correlations were found between 2D phase-contrast MRI and 4D flow for stroke volumes, aortic and pulmonary flows. Four-dimensional flow provided both anatomic visualization and comprehensive functional analysis showing stenosis, aneurysm and complex turbulent flows.

In each of these circumstances, CMR has been achieved and has been found to be contributory for complete visualization and adequate evaluation.