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%, respective, 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.