Aims The aim of our study was to investigate the accuracy of 64-slice computed tomography (CT) for assessing haemodynamically significant stenoses of coronary arteries. Methods and results CT angiography was performed in 67 patients (50 male, 17 female; mean age 60.1 + 10.5 years) with suspected coronary artery disease and compared with invasive coronary angiography. All vessels !1.5 mm were considered for the assessment of significant coronary artery stenosis (diameter reduction .50%). Forty-seven patients were identified as having significant coronary stenoses on invasive angiography with 18% (176/1005) affected segments. None of the coronary segments needed to be excluded from analysis. CT correctly identified all 20 patients having no significant stenosis on invasive angiography. Overall sensitivity for classifying stenoses was 94%, specificity was 97%, positive predictive value was 87%, and negative predictive value was 99%. Conclusion Sixty-four-slice CT provides a high diagnostic accuracy in assessing coronary artery stenoses.

The aim of this study was to assess the diagnostic accuracy of dualsource computed tomography (DSCT) for evaluation of coronary artery disease (CAD) in a population with extensive coronary calcifications without heart rate control. Thirty patients (24 male, 6 female, mean age 63.1±11.3 years) with a high pre-test probability of CAD underwent DSCT coronary angiography and invasive coronary angiography (ICA) within 14 ± 9 days. No beta-blockers were administered prior to the scan. Two readers independently assessed image quality of all coronary segments with a diameter ≥1.5 mm using a four-point score (1: excellent to 4: not assessable) and qualitatively assessed significant stenoses as narrowing of the luminal diameter >50%. Causes of false-positive (FP) and false-negative (FN) ratings were assigned to calcifications or motion artifacts. ICA was considered the standard of reference. Mean body mass index was 28.3 ± 3.9 kg/m 2 (range 22.4-36.3 kg/m 2 ), mean heart rate during CT was 70.3 ± 14.2 bpm (range 47-102 bpm), and mean Agatston score was 821 ± 904 (range 0-3,110). Image quality was diagnostic (scores 1-3) in 98.6% (414/420) of segments (mean image quality score 1.68 ± 0.75); six segments in three patients were considered not assessable (1.4%). DSCT correctly identified 54 of 56 significant coronary stenoses. Severe calcifications accounted for false ratings in nine segments (eight FP/one FN) and motion artifacts in two segments (one FP/one FN). Overall sensitivity, specificity, positive and negative predictive value for evaluating CAD were 96.4, 97.5, 85.7, and 99.4%, respectively. First experience indicates that DSCT coronary angiography provides high diagnostic accuracy for assessment of CAD in a high pre-test probability population with extensive coronary calcifications and without heart rate control.

Objective: To investigate the performance of low-dose, dual-source computed tomography (DSCT) coronary angiography in the step-and-shoot (SAS) mode for the diagnosis of significant coronary artery stenoses in comparison with conventional coronary angiography (CCA). Design, setting and patients: Prospective, singlecentre study conducted in a referral centre enrolling 120 patients (71 men, mean (SD) age 68 (9) years, mean (SD) body mass index 26.2 (3.2) kg/m 2 ). All study participants underwent DSCT in the SAS mode and CCA within 14 days. Twenty-seven patients were given intravenous b blockers for heart rate reduction before CT. Patients were excluded if a target heart rate (70 bpm could not be achieved by b blockers or when the patients were in nonsinus rhythm. Two blinded readers independently evaluated coronary artery segments for assessability and for the presence of significant (.50%) stenoses. Sensitivity, specificity, negative (NPV) and positive predictive values (PPV) were determined, with CCA being the standard of reference. Radiation dose values were calculated. Results: DSCT coronary angiography in the SAS mode was successfully performed in all 120 patients. Mean (SD) heart rate during scanning was 59 (6) bpm (range 44-69). 1773/1803 coronary segments (98%) were depicted with a diagnostic image quality in 109/120 patients (91%). The overall patient-based sensitivity, specificity, PPV and NPV for the diagnosis of significant stenoses were 100%, 93%, 94% and 100%, respectively. The mean (SD) effective dose of the CT protocol was 2.5 (0.8) mSv (range 1.2-4.4). Conclusions: DSCT coronary angiography in the SAS mode allows, in selected patients with a regular heart rate, the accurate diagnosis of significant coronary stenoses at a low radiation dose.Computed tomography coronary angiography is an accurate method for the non-invasive diagnosis of coronary artery disease (CAD).1-8 Because of the high robustness, performance and clinical implications of the technique, cardiac CT is increasingly performed in more and more centres world wide. The recent advances in the spatial and temporal resolution of cardiac CT, however, were obtained at the cost of an increased radiation dose. This was mainly caused by the thin detector widths and the low helical pitch values, the latter being required for data acquisition in the retrospective ECGgating mode. Recently, serious concerns about the increasing use of CT and the associated increase in the collective radiation dose to the general population have abounded. 10Several techniques for reduction of the radiation exposure of cardiac CT examinations to a degree that is as low as reasonably achievable have been developed. These include the ECG-based tube current modulation algorithm, 11 a reduction of tube voltage 12 and the implementation of attenuation-based tube current modulation. 13 Another algorithm that is associated with a low radiation exposure is prospective ECG triggering, or stepand-shoot (SAS) mode. With this technique, radiation is only applied at a p...

Coronary angiography with 64-section CT provides diagnostic image quality within a wide range of heart rates. Reducing average heart rate and heart rate variability is beneficial for reducing artifacts.

Dual-source SAS-mode CT coronary angiography yielded diagnostic image quality for 97.9% of coronary segments at a low radiation dose.