Cardiovascular function and flow by 4-dimensional magnetic resonance imaging techniques: new applications.

Acquisition techniques related to 4-dimensional (4D) flow magnetic resonance imaging (MRI) improved rapidly over the last 3 decades. Most importantly, a major improvement was the acceleration of the acquisition, which resulted in a clinically feasible scan duration and led to more comprehensive use of 4D flow MRI in clinical research. This resulted in several new applications of 4D flow MRI for the evaluation of various physiological and pathologic cardiovascular flow patterns. Visualization tools aim at displaying the direction and magnitude of blood flow velocity from 4D flow data, by using for instance a vector glyph or streamline representation or by constructing pathlines from particle tracing. Such tools are applied to provide insight in the temporal distribution of the 3D flow velocity and enable the quantification of hemodynamic markers. These hemodynamic markers play an important role in the quantitation of abnormalities in cardiovascular blood flow patterns and the characterization of vascular and myocardial remodelling, which can possibly be used to predict pathology such as heart failure, aortic dissection, or aneurysm or thrombus formation. This review focuses on the clinical use of 4D flow MRI and presents an overview of new applications of visualization and quantification tools to describe physiological and pathologic cardiovascular blood flow.