Diagnostic accuracy of 16- versus 64-slice multidetector computed tomography angiography in the evaluation of coronary artery bypass grafts: a comparative study

OBJECTIVES Multidetector computed tomography (MDCT) angiography, which is used for native coronary vessels and bypass graft (CABG) imaging is a non-invasive test. Here, we aimed to compare the diagnostic accuracy of 16- and 64-slice MDCT for graft patency and stenosis. METHODS A total of 129 consecutive patients with CABG who underwent both MDCT (58 patients with 16-slice, 71 patients with 64-slice) and invasive angiography were included. Median time interval between the two procedures was 12 days (range 3-28 days). Bypass grafts were evaluated concerning patency and presence of stenosis ≥50%. Both 16- and 64-slice MDCT results were compared with invasive angiography. RESULTS Overall diagnostic accuracy for the detection of graft patency was 95% for 64-slice vs 92% for 16-slice MDCT. By analyzing the 173 grafts by 64-slice vs 153 grafts by 16-slice MDCT that could be evaluated, sensitivity, specificity, positive predictive values (PPV) and negative predictive values (NPV) of the MDCT for visualization of graft patency were 90, 98, 90 and 98% vs 87, 97, 94 and 93%, respectively. The accuracy of MDCT for the detection of significant graft stenosis was relatively low (sensitivity, specificity, PPV and NPV were 67, 98.6, 50 and 98.6% with 16-slice vs 80, 98.1, 72.7 and 98.7% with 64-slice). CONCLUSIONS This study showed that the 16-slice has a diagnostic accuracy comparable with the 64-slice system for graft patency and can still be used for this purpose if newer systems with improved performance are not available on-site. On the other hand, by the virtue of better image quality, the 64-slice MDCT demonstrates significant graft lesions with higher sensitivity.