Assessment of Coronary Artery Bypass Graft (CABG) Patency and Graft Disease Using Multidetector Computed Tomography (MDCT)

Abstract

Coronary artery bypass graft (CABG) surgery is the standard care in the treatment of advanced coronary artery disease. Notwithstanding the clear benefits of bypass grafting, recurrent chest pain after myocardial revascularization surgery is a common postoperative presentation and the long-term clinical outcome after myocardial revascularization surgery is largely dependent on graft patency and the progression of coronary artery disease. Therefore, assessment of the status of the grafts and graft disease after CABG surgery is an important issue in cardiology. Although conventional coronary angiography is still standard method for assessment of the status of naive and recipient vessels after CABG surgery, it is an invasive and costly procedure that is not risk-free. Recently, multidetector row computed tomography (MDCT) with retrospective electrocardiographic (ECG) gating has gained rapid acceptance as a diagnostic cardiac imaging modality, allowing assessment of coronary bypass graft patency with high spatial resolution. Initial assessment of bypass grafts was done with single-slice scanners and electron-beam CT. Subsequently, the addition of electrocardiographic ECG gating and the improved capabilities available with 4or 16-slice MDCT scanners for rapid scanning of the area of interest led to promising results in the imaging of bypass grafts (Marano et al., 2005; Ueyama et al., 1999). Recently, the introduction of 64-slice MDCT permitted improved temporal resolution (94 to 200 msec) and spatial resolution (upto submillimeter) and reduction of both cardiac and respiratory motion, leading to improved assessment of graft stenosis and occlusion (Frazier et al., 2005; Lee et al., 2010). Moreover, 3-dimensional (3D) image processing and advanced volumetric visualization techniques now allow radiologists and cardiologists to evaluate coronary grafts in multiple planes using various projections. With the capability of acquiring 3D data volumes along with its tomographic nature, it shares many of the advantages of intravascular ultrasound and thus has the potential to enhance the practice of percutaneous