Assessment of the distal anastomosis of coronary artery bypass grafts with a 2D T2-weighted turbo spin echo sequence and correlation to conventional coronary angiography.

OBJECTIVE: The aim of the study was to evaluate the patency of the distal anastomoses of coronary artery bypass grafts and to detect graft stenoses and occlusions with a magnetic resonance (MR) spin echo sequence. PATIENTS AND METHODS: One hundred and eighty-five patients with 481 distal anastomoses were examined with a 1.5 T MR scanner and coronary angiography. A 2-dimensional T2-weighted breath-hold half-Fourier acquisition single-shot turbo spin echo sequence (Haste) was performed. All images were evaluated independently by a radiologist and cardiologist and compared to the conventional coronary angiography. The observers were blinded to the coronary angiography findings, but informed in regard to the surgical graft anastomosis. RESULTS: With the Haste sequence, 76% of the distal anastomoses were recognized (368/481). Forty-five of 52 (87%) stenoses and all occlusions were identified. The sensitivity and specificity for the evaluation of the distal anastomosis with the spin echo sequence was 87% and 96%. Twenty-four percent of the distal anastomoses were not identified due to a poor image quality or motion artefacts. CONCLUSION: Using the Haste sequence, a reliable assessment of graft patency of the distal anastomosis is possible. Further improvements of the spatial resolution and the image quality are necessary to recommend this MR technique for routine clinical use.

Non-invasive magnetic resonance imaging of coronary bypass grafts. comparison of the haste- and navigator techniques with conventional coronary angiography.

OBJECTIVE: The aim was the study was to evaluate the patency of coronary artery bypass grafts with the 3D Navigator and the Haste magnetic resonance imaging techniques. MATERIAL AND METHODS: Thirty-four patients with 82 grafts (18 internal mammarian artery and 64 saphenous venous grafts) were examined at 1.5 T using a phased arrray body coil. A 2D T-2 weighted turbo spin echo sequence (Haste) and a 3D-angiography sequence in navigator technique were used. Reference method was the conventional coronary angiography that was performed within 7 days. RESULTS: With the HASTE sequence 54 of 56 patent and 12 of the 16 occluded grafts were recognized, the sensitivity and specificity was 96 and 75%. The distal anastomosis could be assessed in 28 of 76 cases. With the Haste sequence 54 of the 56 patent and 12 of the 14 occluded grafts were detected correctly. Eight patent and two occluded grafts were judged as not assessable. The sensitivity and specificity was 96 and 85%. Sixty-six percent (50/76) of the distal anastomosis were identified correctly. With both sequences none of the bypass stenosis could be detected. CONCLUSIONS: The patency of coronary bypass grafts can be evaluated noninvasively with a sensitivity of 96% and a specificity of 76%. No inference can be made with respect to the nature of bypass graft stenosis. Better results can be expected with the development of a blood pool contrast medium, an improvement of the spatial resolution and in the combination of flow measurements.