First principles of magnetic resonance angiography.

For several years, magnetic resonance imaging (MRI) has shown promise as a noninvasive tool for the study of the vascular system. One interesting format, so-called MR angiography, produces results resembling conventional x-ray angiographic images. This article lays a solid, rigorous foundation for an intuitive understanding of these effects without the use of advanced mathematical concepts. The current state of the art in data acquisition and postprocessing is illustrated. Finally, relevant hemodynamic concepts are introduced, in order to characterize the physiology of complex blood flow at bifurcations. MR angiography is particularly sensitive to artifacts associated with complex flow. The article ends with a call to investigate these phenomena, because they will directly affect the success of MR angiography as a technique.