Coronary Artery Bypass Graft CT Imaging and Interpretation

Cardiac CT angiography is an appropriate tool for the assessment of recurrent symptoms in patients who have undergone coronary artery bypass grafting. Multiple studies have shown high accuracy for determining whether arterial and venous grafts are occluded, and good accuracy in detecting stenosis without occlusion. Image acquisition is best obtained using a prospectively triggered scan protocol, and should span a long z-axis, from the lung apices to the diaphragm. Analysis should include evaluation of patency and presence of narrowing or obstruction of both grafts and native coronary arteries distal to the grafts. Three-dimensional representation and the generation of curved MPR images are of value in image analysis. Visualizing the site of anastomosis requires special attention. Occluded saphenous grafts usually display a residual “nubbin” that can easily be seen on axial images. Unusual grafts, and surgical errors or complications, may occasionally be observed.