Vascular imaging with magnetic resonance and computed tomography.

Cross-sectional imaging of the cardiovascular system is successfully achieved with computed tomography (CT) and, more recently, magnetic resonance imaging (MRI). Limits of spatial resolution confine the routine application of either device to assessment of larger vessels, such as the aorta, vena cava, and renal veins. The decision to use one modality versus the other is frequently influenced by the clinical status of the patient, as well as the indication for diagnostic imaging. Some of the more common vascular abnormalities are depicted in this article, as imaged by these relatively new and expensive technologies. An explanation of the complex appearance of blood flow on MR is dependent on an understanding of some basic physical principles, such as flow-related enhancement and even-echo rephasing. MRI is presently more suitable than CT for the evaluation of medium-size vessels since the development of effective techniques for magnetic resonance angiography (MRA). Some of the important concepts, along with the terminology of this still-evolving field are presented. The quantification of blood flow by MRI is similarly an area of active research, and may ultimately supplant the existing methods.