Non-invasive coronary bypass graft imaging

Coronary artery bypass grafting (CABG) is the most commonly performed revascularization procedure for coronary multi-vessel disease. Clinical outcome depends mainly on bypass graft patency. The gold standard for the assessment of graft patency is angiography. This is invasive and has a significant X-ray exposure and there is a need for contrast. A minimally or non-invasive imaging method of evaluating early and late postoperative graft patency is desirable. Several new minimally invasive imaging techniques have potential value in demonstrating coronary graft patency. This review article will focus on three techniques: (spiral) computed tomography (SCT), electron beam computed tomography (EBCT), and magnetic resonance angiography (MRA). Both SCT and EBCT have comparable diagnostic power. EBCT offers the advantages of electrocardiographically triggered data acquisition and simultaneous quantitation of coronary calcification, as well as a myocardial perfusion modality. EBCT may have superior potential for visualizing graft stenoses. The rapid development of a subsecond SCT technique may provide similar advantages with a much higher spatial resolution. The main disadvantages of CT techniques remain exposure to ionizing radiation and contrast. The application of MRA for graft analysis, particularly using the recently developed fast contrast enhanced sequences, is another promising tool. Good accuracy is combined with no X-ray exposure. Moreover, MRA may be combined with MR perfusion imaging along with anatomical and functional MR imaging, thereby providing a comprehensive cardiac evaluation.{copy}