SURVIVAL IMPROVEMENT in patients with congenital heart disease (CHD) has led to a growing number of adults living with CHD.
4D flow magnetic resonance imaging (MRI)1-5 has been used for the evaluation of various challenging CHD types. Quantitative measures of flow perturbations using 4D flow can aid in surveillance and treatment decision-making, and have been shown to be similar to standard clinical 2D phase-contrast (PC) MRI with acceptable test–retest repeatability.6-8 Using 4D flow, it is possible to assess flow volume in large thoracic vessels, comprising the pulmonary-systemic shunt ratio (Qp/Qs), shunt flow, peak flow, valvular regurgitant flow, and collateral flow volumes. Intracardiac flow patterns, including flow connectivity and distribution, pressure gradients, vortex/helical flow patterns, directionality, and turbulent and laminar energy losses can also be assessed.
The aim of these recommendations from the ISMRM Flow & Motion Study Group is to standardize 4D flow in CHD with recommended acquisition, reconstruction, and postprocessing. This document focuses on CHD assessment with 4D flow, which requires, for example, coverage of a large volume in the thorax, and a wide range of velocities. Details on aortic 4D flow acquisitions can be found in the 2015 4D flow consensus statement.