No abstract

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...

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

The purpose of this study was to investigate the effect of low kilovoltage dual-source computed tomography coronary angiography (CTCA) on qualitative and quantitative image quality parameters and radiation dose. Dual-source CTCA with retrospective ECG gating was performed in 80 consecutive patients of normal weight. Forty were examined with a standard protocol (120 kV/330mAs), 20 were examined at 100 kV/330mAs, and 20 at 100 kV/220mAs. Two blinded observers independently assessed image quality of each coronary segment and measured the image parameters noise, attenuation, and contrast-to-noise ratio (CNR). The effective radiation dose was calculated using CT dose volume index and the dose-length product. Diagnostic image quality was obtained in 99% of all coronary segments (1,127/1,140) without significant differences among the protocols. Image noise, attenuation, and CNR were significantly higher for 100 kV/330mAs (26±3 HU, 549± 62 HU, 25.5±3.2; each P<0.01) and 100 kV/220mAs (27±2 HU, 560± 43 HU, 25.0±2.2; each P<0.01) when compared to the 120-kV protocol (21±2 HU, 317±28 HU, 20.6±1.7). There was no significant difference between the two 100-kV protocols. Estimated effective radiation dose of the 120-kV protocol (8.9±1.2 mSv) was significantly higher than the 100 kV/330mAs (6.7±0.8 mSv, P<0.01) or 100 kV/220mAs (4.4± 0.6 mSv, P<0.001) protocols. Dualsource CTCA with 100 kV is feasible in patients of normal weight, results in a diagnostic image quality with a higher CNR, and at the same time significantly reduces the radiation dose.

Myocardial perfusion imaging with SPECT (SPECT-MPI) and 64-slice CT angiography (CTA) are both established techniques for the noninvasive evaluation of coronary artery disease (CAD). Three-dimensional (3D) SPECT/CT image fusion may offer an incremental diagnostic value by integrating both sets of information. We report our first clinical experiences with fused 3D SPECT/CT in CAD patients. Methods: Thirty-eight consecutive patients with at least 1 perfusion defect on SPECT-MPI (1-d adenosine stress/rest SPECT with 99m Tc-tetrofosmin) and 64-slice CTA were included. 3D volume-rendered fused SPECT/ CT images were generated and compared with the findings from the side-by-side analysis with regard to coronary lesion interpretation by assigning the perfusion defects to their corresponding coronary lesion. Results: The fused SPECT/CT images added information on pathophysiologic lesion severity in 27 coronary stenoses (22%) of 12 patients (29%) (P , 0.001). Among 40 equivocal lesions on side-by-side analysis, the fused interpretation confirmed hemodynamic significance in 14 lesions and excluded functional relevance in 10 lesions. In 3 lesions, assignment of perfusion defect and coronary lesion appeared to be reliable on side-by-side analysis but proved to be inaccurate on fused interpretation. Added diagnostic information by SPECT/CT was more commonly found in patients with stenoses of small vessels (P 5 0.004) and involvement of diagonal branches (P 5 0.01). Conclusion: In addition to being intuitively convincing, 3D SPECT/CT fusion images in CAD may provide added diagnostic information on the functional relevance of coronary artery lesions. A precise, noninvasive technique for the diagnosis of coronary artery disease (CAD) should provide complementary information on coronary artery anatomy and pathophysiologic lesion severity (1-4). Although this can be achieved by mental integration of the information from coronary angiography (CA) and SPECT myocardial perfusion imaging (SPECT-MPI), standard myocardial distribution territories correspond in only 50%-60% with the real anatomic coronary tree (5). Several pioneering attempts of software-based image fusion from conventional CA and SPECT-MPI have been paving the way but were not implemented into clinical practice because its invasiveness precluded its use for noninvasive preinterventional decision making (5-8).Recently, 64-slice CT angiography (CTA) has emerged as a truthful alternative to conventional CA, with excellent diagnostic accuracy, in selected patients (9,10). Combined with the advancements in fast-processing software for 3-dimensional (3D) reconstructions (11), this has allowed initial promising attempts of purely noninvasive SPECT/ CT, directly relating individual myocardial wall territories to the subtending coronary artery (12-14).The increasing interest in cardiac fusion imaging is currently raising the question of its clinical feasibility and usefulness. An evaluation seems all the more pertinent, as the integration of SPECT or PET scanners and high-end CT...

DSCT coronary angiography provides best image quality for various HRs at 70%. The ECG-pulsing window can be adapted according to the HR while maintaining diagnostic image quality.

Functionally relevant coronary artery disease: comparison of 64-section CT angiography with myocardial perfusion SPECT Gaemperli, O; Schepis, T; Valenta, I; Koepfli, P; Husmann, L; Scheffel, H; Leschka, S; Eberli, F R; Luscher, T F; Alkadhi, H; Kaufmann, P A Gaemperli, O; Schepis, T; Valenta, I; Koepfli, P; Husmann, L; Scheffel, H; Leschka, S; Eberli, F R; Luscher, T F; Alkadhi, H; Kaufmann, P A (2008 Functionally relevant coronary artery disease: comparison of 64-section CT angiography with myocardial perfusion SPECT Abstract PURPOSE: To prospectively determine the accuracy of 64-section computed tomographic (CT) angiography for the depiction of coronary artery disease (CAD) that induces perfusion defects at myocardial perfusion imaging with single photon emission computed tomography (SPECT), by using myocardial perfusion imaging as the reference standard. MATERIALS AND METHODS: All patients gave written informed consent after the study details, including radiation exposure, were explained. The study protocol was approved by the local institutional review board. In patients referred for elective conventional coronary angiography, an additional 64-section CT angiography study and a myocardial perfusion imaging study (1-day adenosine stress-rest protocol) with technetium 99m-tetrofosmin SPECT were performed before conventional angiography. Coronary artery diameter narrowing of 50% or greater at CT angiography was defined as stenosis and was compared with the myocardial perfusion imaging findings. Quantitative coronary angiography served as a reference standard for CT angiography. RESULTS: A total of 1093 coronary segments in 310 coronary arteries in 78 patients (mean age, 65 years +/-9 [standard deviation]; 35 women) were analyzed. CT angiography revealed stenoses in 137 segments (13%) corresponding to 91 arteries (29%) in 46 patients (59%). SPECT revealed 14 reversible, 13 fixed, and six partially reversible defects in 31 patients (40%). Sensitivity, specificity, and negative and positive predictive values, respectively, of CT angiography in the detection of reversible myocardial perfusion imaging defects were 95%, 53%, 94%, and 58% on a per-patient basis and 95%, 75%, 96%, and 72% on a per-artery basis. Agreement between CT and conventional angiography was very good (96% and kappa = 0.92 for patient-based analysis, 93% and kappa = 0.84 for vessel-based analysis). CONCLUSION: Sixty-four-section CT angiography can help rule out hemodynamically relevant CAD in patients with intermediate to high pretest likelihood, although an abnormal CT angiography study is a poor predictor of ischemia. Purpose:To prospectively determine the accuracy of 64-section computed tomographic (CT) angiography for the depiction of coronary artery disease (CAD) that induces perfusion defects at myocardial perfusion imaging with single photon emission computed tomography (SPECT), by using myocardial perfusion imaging as the reference standard. Materials and Methods:All patients gave written informed consent after the study details, includi...