Contrast-enhanced magnetic resonance angiography of mammary artery grafts after minimally invasive coronary bypass surgery

Background. The aim of the study was to investigate the application of the contrast-enhanced magnetic resonance angiography (CE-MRA) for the visualization of left internal mammary artery (LIMA) bypass. Methods. A total of 30 patients with LIMA bypass (22 men, 8 women, 35 to 77 years) received a CE-MRA 4 to 20 days after surgery. The non–ECG-triggered CE-MRA was performed during expiration using a body array coil at a 1.5 Tesla scanner (Magnetom-Vision). A three-dimensional gradient-echo sequence with slice interpolation technique was applied. For the three-dimensional visualization, single coronal slices were postprocessed with maximal intensity projection. Of 30 patients 22 agreed to a comparative coronary angiography. Results. Five bypasses were identified up to the end-to-side anastomosis. A total of 80% of the bypass course was detectable in 13 patients and 60% in 11 patients. In two LIMA bypasses only 30% of the proximal part could be viewed; one was found by conventional coronary angiography to be occluded. The other conventional coronary angiography showed the LIMA bypass to be patent. Conclusions. The complete course of the LIMA bypass to the left anterior descending coronary artery can be visualized by the MRA technique. The most reliable imaging of the distal anastomosis can be realized by reducing the negative influence of the beating heart.