Three-dimensional contrast-enhanced MR angiography.

Three-dimensional contrast-enhanced magnetic resonance (MR) angiography is a relatively new technique that uses the transient shortening in blood T1 following the intravenous injection of gadolinium chelates to image blood vessels irrespective of flow. For many applications, 3D contrast-enhanced MR angiography is developing into a safe, fast, and cost-effective alternative to conventional diagnostic angiography. One of its biggest advantages over other MR angiography techniques (and CT angiography) is the ability to image in a plane parallel to the vessel of interest. This feature, combined with the inherent properties of a 3D gradient refocused sequence, make 3D contrast-enhanced MR angiography intrinsically fast, high resolution and free from saturation and turbulence-related artifacts. This article is designed to familiarize the reader with the theory of 3D contrast-enhanced MR angiography and the application of the technique to different vascular territories. Contrast agents, relaxation effects, contrast bolus effects, pulse sequences, artifacts, and post-processing, as well as the present state of thinking with regard to optimal contrast injection timing/detection and Fourier space mapping are discussed. Patient preparation and techniques and imaging parameters for body applications of gadolinium-enhanced MR angiography, including aorta, renal arteries, mesenteric arteries, portal venous system, pelvis and legs, pulmonary arteries, and carotid arteries are included.