Diagnostic performance of 64-versus 256-slice computed tomography coronary angiography compared with conventional coronary angiography in patients with suspected coronary artery disease

Purpose: The newer 256-slice computed tomography coronary angiography (CTCA) has the capability of improving diagnostic performance in the detection of obstructive coronary artery disease (CAD) compared to 64-slice CTCA. The aim of this study was to compare the diagnostic performance of 64- versus 256-slice CTCA in two similar populations. Methods: Our study included 120 consecutive patients who were referred for CTCA and subsequently underwent conventional coronary angiography (CCA). Sixty patients were studied by 64-slice CTCA, with the other 60 by 256-slice CTCA. We compared the technical characteristics and diagnostic performance of 64- and 256-slice CTCA for the detection of ≥ 50% stenosis of the coronary arteries on CCA. Results: The 256-slice CTCA had a shorter scanning time (4.4 ± 0.6 sec vs. 5.0 ± 0.7 sec, p <0.001) compared to 64-slice CTCA. The diagnostic accuracy rates of 256-slice CTCA based on patient analysis (97% vs. 83%, p <0.05), vessel analysis (95% vs. 85%, p <0.05), and segment analysis (94% vs. 88%, p <0.05) were significantly superior to those of 64-slice CTCA. The diagnostic accuracy rates of 64- and 256-slice CTCA were affected by the presence of stent (65% vs. 75%, respectively, p > 0.05) and severe calcifications (75% vs. 82%, respectively, p > 0.05). Conclusions: In two similar populations, 256-slice CTCA displayed superior diagnostic performance than 64-slice CTCA. However, the performance of 256-slide CTCA is affected in those segments that are severely calcified and/or stented.