Abstract
Four-dimensional (4D) flow cardiac magnetic resonance (CMR) is an advanced imaging modality that enables comprehensive qualitative and quantitative assessment of blood flow in the three spatial dimensions plus time. This technique is more accurate, reproducible, and easier to interpret visually than conventional two-dimensional phase-contrast techniques. In this narrative review, we synthesize our clinical experience-including practical insights from representative cases from routine practice-with published research to describe the technical foundations, clinical applications, advantages, and limitations of this technique. We discuss the technical aspects, including spatial and temporal resolution, velocity encoding, contrast administration, workflow requirements, and post-processing software, and their influence on diagnostic performance. Thus, 4D-flow CMR imaging can accurately assess cardiac shunts through advanced visualization of pathlines and streamlines, providing direct quantification of pulmonary flow: systemic flow ratios, blood flow volumes, and complex hemodynamic patterns in congenital heart disease (CHD). Moreover, 4D-flow CMR imaging provides robust characterization of valvular and aortic disease through dynamic flow analysis and quantitative hemodynamic metrics. Overall, 4D flow CMR imaging is a powerful, noninvasive diagnostic tool that can greatly enhance clinical decision-making. The growing body of evidence supports the use of 4D-flow CMR imaging in routine clinical practice, particularly for evaluating CHD and valvular and aortic disorders.