Introduction 1 8 9 10 11 12 1 8 2 10 13 2 6 8 11 14 15 16 17 18 19 20 The purpose of our study was to determine the performance of DSCT coronary angiography in diagnosing significant stenoses in comparison to invasive coronary angiography (ICA) in a high pre-test probability patient population without heart rate control. Materials and methods Patients 1 21 Table 1 Synopsis of cardiovascular risk factors and symptoms  Frequency (%) Risk factors Family history 16 (53%) Obesity 23 (77%) Dyslipidemia 18 (60%) Diabetes 19 (63%) Smoking 25 (83%) Hypertension 23 (77%) Symptoms Angina pectoris 21 (70%) Probable angina pectoris 7 (23%) Atypical chest pain 2 (7%) Dual-source CT scan protocol All CT examinations were performed on a DSCT scanner (Somatom Definition, Siemens Medical Solutions, Forchheim, Germany). The patients were centrally placed in the scanner to ensure that the entire heart was covered with the smaller field-of-view of the second tube detector array. Irrespective of the individual heart rate and the heart rate variability, no beta-blockers were given prior to the scan. Three patients took oral beta-blockers as part of their baseline medication. Nonenhanced DSCT for calcium scoring was performed from 1 cm below the level of the tracheal bifurcation to the diaphragm in a cranio-caudal direction using the following scanning parameters: detector collimation 32×0.6 mm, slice acquisition 64×0.6 mm by means of a z-flying focal spot, gantry rotation time 330 ms, pitch of 0.2–0.39 adapted to the heart rate, tube current 80 mAs per rotation, and tube potential 120 kV. 22 Dual-source CT image reconstruction 18 Dual-source CT data analysis The mean Agatston score was calculated for each patient from the non-enhanced DSCT data with a detection threshold of 130 HU by using semi-automated software (Syngo Calcium Scoring, Siemens Medical Solutions). 23 1 In addition, both readers assessed all coronary artery segments for the presence of hemodynamically significant stenoses. Significant stenosis was defined as narrowing of the coronary luminal diameter exceeding 50%. The vessel diameters were measured on reconstructions perpendicularly oriented to the vessel course. For any disagreement in data analysis, consensus agreement was achieved. Invasive coronary angiography 23 Statistical analysis 24 Results DSCT and ICA were successfully performed in all patients without complications. The DSCT protocol was well tolerated by all patients, and all were able to hold their breath during data acquisition. The average HR during scanning was 70.3±14.2 bpm (range 47–102 bpm). Seventeen patients (56.7%) had a heart rate below 70 bpm (mean 59.7±5.9 bpm, range 47–66 bpm), while 13 patients (43.3%) had a heart rate of ≥70 bpm (mean 84.2±8.4 bpm, range 72–102 bpm). Prevalance of coronary artery stenosis and calcium score A total of 56 coronary artery stenoses with a luminal narrowing of more than 50% in diameter were identified in 15 patients (50.0%) using ICA. Single-vessel disease was present in 13.3% (4/30), two-vessel disease in 10.0% (3/30), and three-vessel disease in 26.7% (8/30). Significant coronary artery stenoses could be excluded in 15 patients (50.0%). Calcified vessel wall deposits were present in 24 patients (80%). Fourteen of these patients (58.3%) had significant coronary artery stenoses, while 10 patients (41.7%) had calcifications without significant stenoses. The mean Agatston score was 821±904 (range 0–3,110). Agatston score was <400 in 15 patients (50%, mean score 85±118) and ≥400 in the other 15 patients (50%, mean score 1,483±893). Image quality and image reconstruction intervals with DSCT A total of 420 coronary artery segments with a diameter ≥1.5 mm were evaluated (11 segments were missing because of anatomical variants, 26 segments had a diameter less than 1.5 mm at their origin, and 9 segments were distal to an occluding stenosis). An intermedial artery was present in 16 patients (53.3%). Inter-observer agreement for image quality rating using clustered data was moderate (kappa=0.68). The initially used reconstruction time-points of 60 and 70% provided excellent image quality (score 1) in 21.9% (92/420) and 60.2% (253/420), respectively, while additional reconstructions were necessary in 17.9% (75/420) to improve image quality. Whereas in the subgroup of patients with heart rates ≥70 bpm additional reconstructions at 30 to 50% were considered necessary in 27.4% (48/175), in patients with heart rates <70 bpm, the 60 and 70% interval provided excellent image quality (score 1) in 90.2% of the segments [30.2% (74/245) and 60.0% (147/245), respectively]. n n n n n n n Diagnostic accuracy of DSCT in comparison to ICA 1 2 3 Fig. 1a, b a RCA LAD LCX b insert  Fig. 2a, b a arrow arrowheads b arrow arrowheads  Fig. 3a, b a b  2 Table 2 Demographic data, overall image quality, and diagnostic accuracy     Mean heart rate Agatston score   Total <70 bpm ≥70 bpm <400 ≥400 No. of patients 30 17 13 15 15 Age (years) 63.1±11.3 63.2±10.1 62.9±13.3 62.8±13.7 63.4±8.9 Male/female 24/6 15/2 9/4 10/5 14/1 2 28.3±3.9 28.9±4.3 27.6±3.5 28.1±3.5 28.5±4.4 Mean heart rate (bpm) 70.3±14.2 59.7±5.9 84.2±8.4 70.6±13.7 70.0±15.1 Agatston score 821±904 901±991 674±780 85±118 1,483±893 a 1.68±0.75 1.60±0.73 1.81±0.77 1.59±0.75 1.79±0.75  Score 1 47.4% (199/420) 51.8% (131/245) 38.9% (68/175) 54.2% (116/214) 40.3% (83/206)  Score 2 37.9% (159/420) 32.4% (82/245) 44.0% (77/175) 35.5% (76/214) 40.3% (83/206)  Score 3 13.3% (56/420) 11.9% (30/245) 14.9% (26/175) 7.5% (16/214) 19.4% (40/206)  Score 4 1.4% (6/420) 0.8% (2/245) 2.2% (4/175) 2.8% (6/214) – Sensitivity 96.4% (54/56) 97.2% (35/36) 95.0% (19/20) 100% (5/5) 96.1% (49/51)   95% CI 87.7–99.6 85.5–99.9 75.1–99.9 47.8–100 86.5–99.5 Specificity 97.5% (355/364) 97.1% (203/209) 98.0% (152/155) 99.5% (208/209) 94.8% (147/155)  95% CI 95.4–98.9 94.2–98.8 94.5–99.6 97.4–100 90.1–97.8 PPV 85.7% (54/63) 85.4% (35/41) 86.4% (19/22) 83.3% (5/6) 86.0% (49/57)  95% CI 74.6–93.3 70.8–94.4 65.1–97.1 35.9–99.6 74.2–93.7 NPV 99.4% (355/357) 99.5% (203/204) 98.8% (152/153) 100% (208/208) 98.7% (147/149)  95% CI 98.0–99.9 97.3–100 96.4–100 98.2–100 95.2–99.8 a  1  2  3  4 BMI  CI  PPV  NPV On a per-patient analysis, sensitivity was 93.3% (14/15; 95% CI: 68.1–99.8), specificity was 100% (15/15; 95% CI: 78.2–100), positive predictive value was 100% (14/14; 95% CI: 76.8–100), and negative predictive value was 93.8% (15/16; 95% CI: 69.8–99.8). 2 Discussion Four main conclusions can be drawn from this study. First, DSCT coronary angiography provides a high diagnostic accuracy for the evaluation of CAD. Second, this high diagnostic performance of DSCT could be achieved in a patient population with extensive calcifications and in whom no heart rate control using beta blocker medication prior to CT was performed. Third, taking into account these circumstances, only six (1.4%) segments had to be excluded from data analysis, all in the distal part of the coronary artery tree with small vessel diameters. Fourth, false ratings were primarily due to severe vessel wall calcifications rather than motion artifacts. 18 19 20 9 25 26 27 2 28 17 29 30 Conclusion 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. Further studies are needed to confirm our results in appropriate clinical settings with larger patient populations.