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ObjectiveTo compare the effect of contrast medium iodine concentration on contrast enhancement, heart rate, and injection pressure when injected at a constant iodine delivery rate in coronary CT angiography (CTA).MethodsOne thousand twenty-four patients scheduled for coronary CTA were prospectively randomized to receive one of four contrast media: iopromide 300 mg I/ml, iohexol 350 mg I/ml, iopromide 370 mg I/ml, or iomeprol 400 mg I/ml. Contrast media were delivered at an equivalent iodine delivery rate of 2.0 g I/s. Intracoronary attenuation was measured and compared (per vessel and per segment). Heart rate before and after contrast media injection was documented. Injection pressure was recorded (n = 403) during contrast medium injection and compared between groups.ResultsIntracoronary attenuation values were similar for the different contrast groups. The mean attenuation over all segments ranged between 384 HU for 350 mg I/ml and 395 HU for 400 mg I/ml (p = 0.079). Dose-length product (p = 0.8424), signal-to-noise ratio (all p > 0.05), time to peak (p = 0.324), and changes in heart rate (p = 0.974) were comparable between groups. The peak pressures differed: 197.4 psi for 300 mg I/ml (viscosity 4.6 mPa s), 229.8 psi for 350 mg I/ml (10.4 mPa s), 216.1 psi for 370 mg I/ml (9.5 mPa s), and 243.7 psi for 400 mg I/ml (12.6 mPa s) (p < 0.0001).ConclusionIntravascular attenuation and changes in heart rate are independent of iodine concentration when contrast media are injected at the same iodine delivery rate. Differences in injection pressures are associated with the viscosity of the contrast media.Key Points• The contrast enhancement in coronary CT angiography is independent of the iodine concentration when contrast media are injected at body temperature (37 °C) with the same iodine delivery rate.• Iodine concentration does not influence the change in heart rate when contrast media are injected at identical iodine delivery rates.• For a fixed iodine delivery rate and contrast temperature, the viscosity of the contrast medium affects the injection pressure.

Objectives We evaluated the influence of sinogram-affirmed iterative reconstruction (SAFIRE) on the coronary artery calcium (CAC) score by computed tomography (CT). Materials and methods Seventy patients underwent CAC imaging by 128-slice dual-source CT. CAC volume, mass and Agatston score were calculated from images reconstructed by filtered back projection (FBP) without and with incremental degrees of the SAFIRE algorithm (10-50 %). We used the repeated measuring test and the Steel-Dwass test for multiple comparisons of values and the difference ratio among different SAFIRE groups using the FBP as reference. Results The median Agatston score (range) decreased with incremental SAFIRE degrees: 163 (0.1 − 3,393.3), 158.4 (0.3 − 3,079.3), 137.7 (0.1 − 2,978.0), 120.6 (0 − 2,783.6), 102.6 (0 − 2,468.4) and 84.1 (0 − 2,186.9) for 0 % (FBP), 10 %, 20 %, 30 %, 40 % and 50 % SAFIRE, respectively ( P  < 0.05). In comparison with FBP, CAC volume (from 8.1 % to 47.7 %), CAC mass (from 5.3 % to 44.7 %) and CAC Agatston score (from 7.3 % to 48.4 %) all decreased with increasing SAFIRE from 10 % to 50 %, respectively ( P  < 0.05). High-grade SAFIRE resulted in the disappearance of detectable calcium in three cases with low calcium burden. Conclusion SAFIRE noise reduction techniques significantly affected the CAC, which potentially alters perceived cardiovascular risk. Key points • Iterative reconstruction reduces the amount of coronary calcium detected. • Iterative reconstruction potentially changes the calcium-based cardiovascular risk estimation. • Incidentally, calcium is no longer detectable using iterative reconstruction.

Patients with familial hypercholesterolemia (FH) are at markedly increased risk of developing premature coronary artery disease. The objective of the present study was to evaluate the role of carotid ultrasonography as a measure of subclinical coronary artery disease in patients with FH. The present prospective study compared the presence of subclinical carotid and coronary artery disease in 67 patients with FH (mean age 55 ± 8 years, 52% men) to that in 30 controls with nonanginal chest pain (mean age 56 ± 9 years, 57% men). The carotid intima–media thickness and carotid plaque burden were assessed using B-mode ultrasonography, according to the Mannheim consensus. Coronary artery disease was assessed using computed tomographic coronary angiography. A lumen reduction >50% was considered indicative of obstructive coronary artery disease. The patients with FH and the controls had a comparable carotid intima-media thickness (0.64 vs 0.66 mm, p = 0.490), prevalence of carotid plaque (93% vs 83%, p = 0.361), and median carotid plaque score (3 vs 2, p = 0.216). Patients with FH had a significantly greater median coronary calcium score than did the controls (62 vs 5, p = 0.015). However, the prevalence of obstructive coronary artery disease was comparable (27% vs 31%, p = 0.677). No association was found between the carotid intima-media thickness and coronary artery disease. An association was found between the presence of carotid plaque and coronary artery disease in the patients with FH and the controls. The absence of carotid plaque, observed in 5 patients (7%) with FH, excluded the presence of obstructive coronary artery disease. In conclusion, the patients with FH had a high prevalence of carotid plaque and a significantly greater median coronary calcium score than did the controls. A correlation was found between carotid plaque and coronary artery disease in patients with FH; however, the presence of carotid plaque and carotid plaque burden are not reliable indicators of obstructive coronary artery disease.

Reproducibility of the quantitative assessment of atherosclerosis by computed tomography coronary angiography (CTCA) is paramount for the design of longitudinal studies. The purpose of this study was to assess the inter- and intra-observer reproducibility using semiautomated CT plaque analysis software in symptomatic individuals. CTCA was performed in 10 symptomatic patients after percutaneous treatment of the culprit lesions and was repeated after 3 years. The plaque quantitative analysis was performed in untreated vessels with mild-to-moderate atherosclerosis and included geometrical and compositional characteristics using semiautomated CT plaque analysis software. A total of 945 matched cross-sections from 21 segments were analyzed independently by a second reviewer to assess inter-observer variability; the first observer repeated all the analyses after 3 months to assess intra-observer variability. The observer variability was also compared to the absolute plaque changes detected over time. Agreement was evaluated by Bland–Altman analysis and concordance correlation coefficient. Inter-observer relative differences for lumen, vessel, plaque area and plaque burden were 1.2, 0.6, 2.2, 1.6 % respectively. Intra-observer relative differences for lumen, vessel, plaque area and plaque burden were 1.0, 0.4, 0.2, 0.4 % respectively. For the average plaque attenuation values the inter- and intra-observer variability was 5 and 2 % respectively. For the % low-attenuation-plaque the inter- and intra-observer variability was 16 and 6 % respectively. The absolute intra-observer variability for the plaque burden was 1.30 ± 1.09 %, while the temporal plaque burden difference was 3.55 ± 3.02 % ( p  = 0.001). The present study shows that the geometrical assessment of coronary atherosclerosis by CTCA is highly reproducible within and between observers using semiautomated quantification software and that serial plaque changes can be detected beyond observer variability. The compositional measurements are more variable between observers than geometrical measurements.

Objectives To determine the diagnostic performance of CT coronary angiography (CTCA) in detecting and excluding left main (LM) and/or three-vessel CAD (“high-risk” CAD) in symptomatic patients and to compare its discriminatory value with the Duke risk score and calcium score. Materials and methods Between 2004 and 2011, a total of 1,159 symptomatic patients (61 ± 11 years, 31 % women) with stable angina, without prior revascularisation underwent both invasive coronary angiography (ICA) and CTCA. All patients gave written informed consent for the additional CTCA. High-risk CAD was defined as LM and/or three-vessel obstructive CAD (≥50 % diameter stenosis). Results A total of 197 (17 %) patients had high-risk CAD as determined by ICA. The sensitivity, specificity, positive predictive value, negative predictive value, positive and negative likelihood ratios of CTCA were 95 % (95 % CI 91–97 %), 83 % (80–85 %), 53 % (48–58 %), 99 % (98–99 %), 5.47 and 0.06, respectively. CTCA provided incremental value (AUC 0.90, P  < 0.001) in the discrimination of high-risk CAD compared with the Duke risk score and calcium score. Conclusions CTCA accurately excludes high-risk CAD in symptomatic patients. The detection of high-risk CAD is suboptimal owing to the high percentage (47 %) of overestimation of high-risk CAD. CTCA provides incremental value in the discrimination of high-risk CAD compared with the Duke risk score and calcium score. Key Points • Computed tomography coronary angiography ( CTCA ) accurately excludes high - risk coronary artery disease . • CTCA overestimates high - risk coronary artery disease in 47  %. • CTCA discriminates high - risk CAD better than clinical evaluation and coronary calcification .

Objectives To investigate the diagnostic accuracy of CT coronary angiography (CTCA) in women at low to intermediate pre-test probability of coronary artery disease (CAD) compared with men. Methods In this retrospective study we included symptomatic patients with low to intermediate risk who underwent both invasive coronary angiography and CTCA. Exclusion criteria were previous revascularisation or myocardial infarction. The pre-test probability of CAD was estimated using the Duke risk score. Thresholds of less than 30 % and 30–90 % were used for determining low and intermediate risk, respectively. The diagnostic accuracy of CTCA in detecting obstructive CAD (≥50 % lumen diameter narrowing) was calculated on patient level. P  < 0.05 was considered significant. Results A total of 570 patients (46 % women [262/570]) were included and stratified as low (women 73 % [80/109]) and intermediate risk (women 39 % [182/461]). Sensitivity, specificity, PPV and NPV were not significantly different in and between women and men at low and intermediate risk. For women vs. men at low risk they were 97 % vs. 100 %, 79 % vs. 90 %, 80 % vs. 80 % and 97 % vs. 100 %, respectively. For intermediate risk they were 99 % vs. 99 %, 72 % vs. 83 %, 88 % vs. 93 % and 98 % vs. 99 %, respectively. Conclusion CTCA has similar diagnostic accuracy in women and men at low and intermediate risk. Key Points • Coronary artery disease (CAD) is increasingly investigated by computed tomography angiography (CTCA) . • CAD detection or exclusion by CTCA is not different between sexes . • CTCA diagnostic accuracy was similar between low and intermediate risk sex-specific-groups . • CTCA rarely misses obstructive CAD in low–intermediate risk women and men . • CAD yield by invasive coronary angiography after positive CTCA is similar between sex-risk-specific groups .

Objectives To compare the diagnostic performance and radiation exposure of 128-slice dual-source CT coronary angiography (CTCA) protocols to detect coronary stenosis with more than 50 % lumen obstruction. Methods We prospectively included 459 symptomatic patients referred for CTCA. Patients were randomized between high-pitch spiral vs. narrow-window sequential CTCA protocols (heart rate below 65 bpm, group A), or between wide-window sequential vs. retrospective spiral protocols (heart rate above 65 bpm, group B). Diagnostic performance of CTCA was compared with quantitative coronary angiography in 267 patients. Results In group A (231 patients, 146 men, mean heart rate 58 ± 7 bpm), high-pitch spiral CTCA yielded a lower per-segment sensitivity compared to sequential CTCA (89 % vs. 97 %, P  = 0.01). Specificity, PPV and NPV were comparable (95 %, 62 %, 99 % vs. 96 %, 73 %, 100 %, P  > 0.05) but radiation dose was lower (1.16 ± 0.60 vs. 3.82 ± 1.65 mSv, P  < 0.001). In group B (228 patients, 132 men, mean heart rate 75 ± 11 bpm), per-segment sensitivity, specificity, PPV and NPV were comparable (94 %, 95 %, 67 %, 99 % vs. 92 %, 95 %, 66 %, 99 %, P  > 0.05). Radiation dose of sequential CTCA was lower compared to retrospective CTCA (6.12 ± 2.58 vs. 8.13 ± 4.52 mSv, P  < 0.001). Diagnostic performance was comparable in both groups. Conclusion Sequential CTCA should be used in patients with regular heart rates using 128-slice dual-source CT, providing optimal diagnostic accuracy with as low as reasonably achievable (ALARA) radiation dose. Key Points • 128-slice dual-source CT coronary angiography offers several different acquisition protocols. • Randomized comparison of protocols reveals an optimal protocol selection strategy. • Appropriate CTCA protocol selection lowers radiation dose, while maintaining high quality. • CTCA protocol selection should be based on individual patient characteristics. • A prospective sequential protocol is preferred for CTCA.

Objective To investigate the value of the calcium score (CaSc) plus clinical evaluation to restrict referral for CT coronary angiography (CTCA) by reducing the number of patients with an intermediate probability of coronary artery disease (CAD). Methods We retrospectively included 1,975 symptomatic stable patients who underwent clinical evaluation and CaSc calculation and CTCA or invasive coronary coronary angiography (ICA). The outcome was obstructive CAD (≥50 % diameter narrowing) assessed by ICA or CTCA in the absence of ICA. We investigated two models: (1) clinical evaluation consisting of chest pain typicality, gender, age, risk factors and ECG and (2) clinical evaluation with CaSc. Discrimination of the two models was compared. The stepwise reclassification of patients with an intermediate probability of CAD (10–90 %) after clinical evaluation followed by clinical evaluation with CaSc was assessed by clinical net reclassification improvement (NRI). Results Discrimination of CAD was significantly improved by adding CaSc to the clinical evaluation (AUC: 0.80 vs. 0.89, P  < 0.001). CaSc and CTCA could be avoided in 9 % using model 1 and an additional 29 % of CTCAs could be avoided using model 2. Clinical NRI was 57 %. Conclusion CaSc plus clinical evaluation may be useful in restricting further referral for CTCA by 38 % in symptomatic stable patients with suspected CAD. Key Points • CT calcium scores ( CaSc ) could proiritise referrals for CT coronary angiography ( CTCA ) • CaSc provides an incremental discriminatory value of CAD compared with clinical evaluation • Risk stratification is better when clinical evaluation is combined with CaSc • Appropriate use of clinical evaluation and CaSc helps avoid unnecessary CTCA referrals