Assessment of coronary artery bypass grafts: Value of different breath-hold MR imaging techniques

OBJECTIVE, Our aim was to evaluate the patency of coronary artery bypass gr afts and to detect graft stenosis using different breath-hold MR imaging te chniques. SUBJECTS AND METHODS. Twenty-two patients with 59 grafts (14 internal mamma ry artery grafts and 45 saphenous vein grafts) and 76 distal anastomoses (s ingular and sequential grafts) were studied using a 1.5-T scanner. A two-di mensional T2-weighbd breath-hold half-Fourier acquisition single-shot turbo spin echo (HASTE) sequence and a three-dimensional breath-hold contrast-en hanced MR angiography sequence (fast imaging with steady-state free precess ion) were performed. For MR angiography, a bolus of 20 ml of gadopentetate dimeglumine was used. Time delay for contrast injection was calculated by a test bolus. The gold standard was coronary angiography performed within 14 days of MR imaging. All images were evaluated independently by two radiolo gists. RESULTS. With the HASTE sequence, 95% of the patent grafts were recognized (42/44); specificity was 93% (14/15). MR angiography had both a sensitivity (41/44) and specificity (14/15) of 93%. Interobserver agreement for both s equences was good (Cohen's kappa = 87%; McNemar test, p = 56%). Forty-nine (83%) of 59 patent distal graft anastomoses were revealed with the HASTE se quence; 38 (64%) of 59 were seen on contrast-enhanced angiography, With HAS TE imaging, only two of eight hemodynamically significant graft stenoses we re detected. MR angiography revealed only four of eight significant graft s tenoses, CONCLUSION. The HASTE sequence and three-dimensional MR angiography proved to be useful MR techniques when evaluating the patency of coronary artery b ypass grafts. However, reliable detection of graft stenosis does not yet se em possible with these imaging techniques.