4D Flow when and how?

4D Flow is an emerging MR technique enabling three-dimensional and cardiac phase-resolved flowmetry with ECG-gated phase-contrast MRI that increased the speed of data acquisitions, accuracy and robustness. The method is promoting researches in areas that have not been fully addressed before in the cardiovascular system, such as flowmetry of the bloodstream across the valves, within the heart chambers, complexed flow dynamics such as vortex, helical or retrograde. Wall shear stress and other potential biomarkers derived from 4D Flow are known to be related to vascular wall diseases such as atherosclerosis. In this review, fundamental concepts of 4D Flow technique and post-processing, benefits and limitations as well as its clinical applications are discussed, and the importance of quality control and validation of the method is emphasized. New ideas inspired by 4D Flow can help clinicians and MR scientists further understand the role of flow dynamics in health sciences, diseases and various aspects of cardiovascular physiology.