MRI of coronary arteries.

Magnetic Resonance Angiography (MRA) of the coronary arteries has recently become possible due to the development of a new group of ultrafast imaging sequences. Although the role of coronary MR angiography in screening for coronary artery lesions has not yet been established, coronary MR angiography has been very successful in the detection of coronary artery variants, and the imaging of coronary stents and bypass grafts. Variants of these new MRI techniques can also quantitate velocity in native coronary arteries. Coronary MR angiographic techniques can be subdivided in breath-hold (single or repeated breath-hold) and non-breath-hold techniques. Most of the clinical experience so far has been with a single breath-hold technique, and was limited to cooperative patients. The recent introduction of navigator pulses for real-time respiratory gating or triggering allows non-breath-hold or repeated breath-hold 3-D coronary MR angiography, and will allow a more widespread use of this technique. Notwithstanding the progress being made and the excitement created by the prospect of a noninvasive coronary artery screening tool, several key technical problems remain unresolved and are now being addressed by the scientific and clinical community. This paper reviews ongoing research in coronary MR angiography.