Impact of iodine concentration and iodine delivery rate on contrast enhancement in coronary CT angiography: a randomized multicenter trial (CT-CON).

OBJECTIVE: To 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). METHODS: One 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. RESULTS: Intracoronary 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). CONCLUSION: Intravascular 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.

Relative myocardial blood flow by dynamic computed tomographic perfusion imaging predicts hemodynamic significance of coronary stenosis better than absolute blood flow.

OBJECTIVES: Quantitative myocardial perfusion imaging by computed tomography (CT) was recently introduced to calculate myocardial blood flow (MBF). Because absolute MBF thresholds may be affected by technique, methodology, and the microvasculature, we investigated whether a relative measure of MBF improves accuracy to identify hemodynamically significant coronary stenosis. MATERIALS AND METHODS: In this prospective study, 42 patients (mean [SD] age, 62.3[8.7] years; 8 women) with suspected or known coronary disease underwent dynamic CT myocardial perfusion imaging using adenosine vasodilation, before invasive angiography (coronary angiography) with fractional flow reserve (FFR). Within each myocardial territory MBF, the MBF relative to remote myocardium (MBFratio) was calculated and compared with coronary angiography and FFR. RESULTS: Of the 91 vessels interrogated by FFR (median, 0.81; interquartile range, 0.73-0.94), 45 vessels (49%) had an FFR value lower than 0.8 and were considered hemodynamically significant. Hyperemic MBF was lower in ischemic territories: 75.6 ± 22.5 mL per 100 mL/min versus 98.3 ± 23.1 mL per 100 mL/min (P < 0.0001). The MBFratio correlated better with FFR (P = 0.76) than the absolute MBF did (P = 0.52). Receiver operating curve analysis showed better discrimination by MBFratio: area under the curve of 0.85 versus 0.75 (P = 0.02). The MBF of remote myocardium varied between 60.7 and 167.2 mL per 100 mL/min and was lower in patients without heart rate acceleration (P = 0.0035). CONCLUSIONS: The MBFratio seems to better identify hemodynamically significant coronary artery disease than does the absolute MBF determined by dynamic CT perfusion imaging. This may be caused by microvascular status or related to the methodology.

Quantitative computed tomographic coronary angiography: does it predict functionally significant coronary stenoses?

BACKGROUND: Coronary lesions with a diameter narrowing ≥50% on visual computed tomographic coronary angiography (CTCA) are generally considered for referral to invasive coronary angiography. However, similar to invasive coronary angiography, visual CTCA is often inaccurate in detecting functionally significant coronary lesions. We sought to compare the diagnostic performance of quantitative CTCA with visual CTCA for the detection of functionally significant coronary lesions using fractional flow reserve (FFR) as the reference standard. METHODS AND RESULTS: CTCA and FFR measurements were obtained in 99 symptomatic patients. In total, 144 coronary lesions detected on CTCA were visually graded for stenosis severity. Quantitative CTCA measurements included lesion length, minimal area diameter, % area stenosis, minimal lumen diameter, % diameter stenosis, and plaque burden [(vessel area-lumen area)/vessel area×100]. Optimal cutoff values of CTCA-derived parameters were determined, and their diagnostic accuracy for the detection of flow-limiting coronary lesions (FFR≤0.80) was compared with visual CTCA. FFR was ≤0.80 in 54 of 144 (38%) coronary lesions. Optimal cutoff values to predict flow-limiting coronary lesion were 10 mm for lesion length, 1.8 mm2 for minimal area diameter, 73% for % area stenosis, 1.5 mm for minimal lumen diameter, 48% for % diameter stenosis, and 76% for plaque burden. No significant difference in sensitivity was found between visual CTCA and quantitative CTCA parameters (P>0.05). The specificity of visual CTCA (42%; 95% confidence interval [CI], 31%-54%) was lower than that of minimal area diameter (68%; 95% CI, 57%-77%; P=0.001), % area stenosis (76%; 95% CI, 65%-84%; P<0.001), minimal lumen diameter (67%; 95% CI, 55%-76%; P=0.001), % diameter stenosis (72%; 95% CI, 62%-80%; P<0.001), and plaque burden (63%; 95% CI, 52%-73%; P=0.004). The specificity of lesion length was comparable with that of visual CTCA. CONCLUSIONS: Quantitative CTCA improves the prediction of functionally significant coronary lesions compared with visual CTCA assessment but remains insufficient. Functional assessment is still required in lesions of moderate stenosis to accurately detect impaired FFR.

Additional diagnostic value of integrated analysis of cardiac CTA and SPECT MPI using the SMARTVis system in patients with suspected coronary artery disease.

UNLABELLED: CT angiography (CTA) and SPECT myocardial perfusion imaging (MPI) are complementary imaging techniques to assess coronary artery disease (CAD). Spatial integration and combined visualization of SPECT MPI and CTA data may facilitate correlation of myocardial perfusion defects and subtending coronary arteries and thus offer additional diagnostic value over either stand-alone or side-by-side interpretation of the respective datasets from the 2 modalities. In this study, we investigated the additional diagnostic value of a software-based CTA/SPECT MPI image fusion system over conventional side-by-side analysis in patients with suspected CAD. METHODS: Seventeen symptomatic patients who underwent both CTA and SPECT MPI within a 90-d period were included in our study; 7 of them also underwent invasive coronary angiography (ICA). The potential benefits of the synchronized multimodal heart visualization (SMARTVis) system in assessing CAD were investigated through a case study involving 4 experts from 2 medical centers, in which we performed, first, a side-by-side analysis using structured CTA and SPECT reports and, second, an integrated analysis using the SMARTVis system in addition to the reports. RESULTS: The fused interpretation led to a more accurate diagnosis, reflected in an increase in the individual observers' sensitivity and specificity to correctly refer for invasive angiography eventually followed by revascularization. For the first, second, third, and fourth observers, the respective sensitivities improved from 50%, 60%, 80%, and 80% to 70%, 80%, 100%, and 90% and the respective specificities from 100%, 94%, 83%, and 83% to 100%, 100%, 94%, and 83%. Additionally, the interobserver diagnosis agreement increased from 74% to 84%. The improvement was primarily found in patients presenting with CAD in more vessels than the number of reported perfusion defects. CONCLUSION: Integrated analysis of cardiac CTA and SPECT MPI using the SMARTVis system results in an improved diagnostic performance.

Effect of body mass index on the image quality of rotational angiography without rapid pacing for planning of transcatheter aortic valve implantation: a comparison with multislice computed tomography.

AIMS: To evaluate the feasibility of procedural planning for transcatheter aortic valve implantation (TAVI) using rotational angiography (R-angio) by comparison with multislice computed tomography (MSCT) and to investigate determinants of the image quality of R-angio. METHODS AND RESULTS: Patients who underwent R-angio of the left ventricle and cardiac MSCT were eligible. R-angio acquisition was performed during contrast injection through a 6F pigtail catheter positioned in the left ventricle. On 3D R-angio and MSCT data sets, diameter measurements were made on short-axis images at the level of the aortic annulus (D(perimeter), D(area)), ascending aorta, sino-tubular junction (ST-junction), and the sinus of Valsalva. At the level of the aortic annulus, diagnostic image quality was obtained in 49 of 56 patients. In all patients with a body mass index (BMI) < 29 kg/m(2), image quality was acceptable whether or not rapid pacing was used. In patients with BMI ≥ 29 kg/m(2), the image quality was poor in 1 of 9 (11%) who were rapidly paced compared with 6 of 12 (50%) who were not. The correlation between R-angio and MSCT measurements was high for aortic annulus D(perimeter), D(area), ST-junction, Valsalva sinus, and ascending aorta (respectively, R = 0.90, 0.90, 0.91, 0.92, and 0.89). The correlations improved further when the analysis was limited to patients with a BMI < 29 kg/m(2) (respectively, 0.92, 0.92, 0.92, 0.92, and 0.93). CONCLUSION: R-angio of the left ventricle allows precise measurement of the aortic root and annulus and was feasible for sizing at the time of TAVI. Diagnostic image quality was obtained without rapid pacing in all patients with a BMI < 29 kg/m(2).

Diagnostic performance of hyperaemic myocardial blood flow index obtained by dynamic computed tomography: does it predict functionally significant coronary lesions?

AIMS: The severity of coronary artery narrowing is a poor predictor of functional significance, in particular in intermediate coronary lesions (30-70% diameter narrowing). The aim of this work was to compare the performance of a quantitative hyperaemic myocardial blood flow (MBF) index derived from adenosine dynamic computed tomography perfusion (CTP) imaging with that of visual CT coronary angiography (CTCA) and semi-automatic quantitative CT (QCT) in the detection of functionally significant coronary lesions in patients with stable chest pain. METHODS AND RESULTS: CTCA and CTP were performed in 80 patients (210 analysable coronary vessels) referred to invasive coronary angiography (ICA). The MBF index (mL/100 mL/min) was computed using a model-based parametric deconvolution method. The diagnostic performance of the MBF index in detecting functionally significant coronary lesions was compared with visual CTCA and QCT. Coronary lesions with invasive fractional flow reserve of ≤0.75 were defined as functionally significant. The optimal cut-off value of the MBF index to detect functionally significant coronary lesions was 78 mL/100 mL/min. On a vessel-territory level, the MBF index had a larger area under the curve (0.95; 95% confidence interval [95% CI]: 0.92-0.98) compared with visual CTCA (0.85; 95% CI: 0.79-0.91) and QCT (0.89; 95% CI: 0.84-0.93) (both P-values <0.001). In the analysis restricted to intermediate coronary lesions, the specificity of visual CTCA (69%) and QCT (77%) could be improved by the subsequent use of the MBF index (89%). CONCLUSION: In this proof-of-principle study, the MBF index performed better than visual CTCA and QCT in the identification of functionally significant coronary lesions. The MBF index had additional value beyond CTCA anatomy in intermediate coronary lesions. This may have a potential to support patient management.

Impact of iterative reconstruction on CT coronary calcium quantification.

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.

Diagnostic performance of computed tomography coronary angiography to detect and exclude left main and/or three-vessel coronary artery disease.

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.

Restriction of the referral of patients with stable angina for CT coronary angiography by clinical evaluation and calcium score: impact on clinical decision making.

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.

Carotid plaque burden as a measure of subclinical coronary artery disease in patients with heterozygous familial hypercholesterolemia.

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.

Diagnostic accuracy of 128-slice dual-source CT coronary angiography: a randomized comparison of different acquisition protocols.

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.

Quantification of myocardial blood flow by adenosine-stress CT perfusion imaging in pigs during various degrees of stenosis correlates well with coronary artery blood flow and fractional flow reserve.

AIMS: Only few preliminary experimental studies demonstrated the feasibility of adenosine stress CT myocardial perfusion imaging to calculate the absolute myocardial blood flow (MBF), thereby providing information whether a coronary stenosis is flow limiting. Therefore, the aim of our study was to determine whether adenosine stress myocardial perfusion imaging by Dual Source CT (DSCT) enables non-invasive quantification of regional MBF in an animal model with various degrees of coronary flow reduction. METHODS AND RESULTS: In seven pigs, a coronary flow probe and an adjustable hydraulic occluder were placed around the left anterior descending coronary artery to monitor the distal coronary artery blood flow (CBF) while several degrees of coronary flow reduction were induced. CT perfusion (CT-MBF) was acquired during adenosine stress with no CBF reduction, an intermediate (15-39%) and a severe (40-95%) CBF reduction. Reference standards were CBF and fractional flow reserve measurements (FFR). FFR was simultaneously derived from distal coronary artery pressure and aortic pressure measurements. CT-MBF decreased progressively with increasing CBF reduction severity from 2.68 (2.31-2.81)mL/g/min (normal CBF) to 1.96 (1.83-2.33) mL/g/min (intermediate CBF-reduction) and to 1.55 (1.14-2.06)mL/g/min (severe CBF-reduction) (both P < 0.001). We observed very good correlations between CT-MBF and CBF (r = 0.85, P < 0.001) and CT-MBF and FFR (r = 0.85, P < 0.001). CONCLUSION: Adenosine stress DSCT myocardial perfusion imaging allows quantification of regional MBF under various degrees of CBF reduction.

Coronary CT angiography outperforms calcium imaging in the triage of acute coronary syndrome.

BACKGROUND: In this prospective study we determine the diagnostic value of coronary CT angiography (CTA) and calcium imaging in low to intermediate risk acute chest pain patients. METHODS: One hundred and eleven consecutive patients (57 ± 11 years, 71 males) presenting to the emergency department with chest pain suggestive of acute coronary syndrome (ACS), but without indication for immediate catheter angiography, underwent both coronary CTA and calcium imaging without disclosure of the findings to the treating physicians. RESULTS: ACS was diagnosed in 19 patients (17%). Coronary calcium was present in 71 patients (64%). Coronary CTA identified 74 (67%) patients with coronary plaque and 36 (32%) patients with obstructive (≥ 50%) plaque. The sensitivity and specificity of the calcium scan were: 89% and 41%. The sensitivity and specificity of coronary CTA were: 100% and 40% based on the presence of any plaque and 89% and 79% based on the presence of >50% stenosis. C-statistics of the GRACE risk score (0.77 [95% CI 0.66-0.89]) improved after addition of coronary CTA (0.93 [0.88-0.98], p<0.01), though not after addition of calcium scores (0.81 [0.71-0.91], p=0.52). Follow-up at 3 months revealed four late revascularizations (no deaths or myocardial infarctions), all of whom had obstructive CAD with calcium on CT at presentation. CONCLUSIONS: Coronary CTA outperforms calcium imaging in the triage of patients suspected of developing ACS. Absence of plaque on coronary CTA allows safe discharge. Coronary CTA has incremental value to clinical risk scores and has the potential to reduce unnecessary hospital admissions.

Reproducibility of computed tomography angiography data analysis using semiautomated plaque quantification software: implications for the design of longitudinal studies.

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.

Computed tomography coronary angiography accuracy in women and men at low to intermediate risk of coronary artery disease.

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.

Assessment of atherosclerotic plaques at coronary bifurcations with multidetector computed tomography angiography and intravascular ultrasound-virtual histology.

AIMS: We evaluated the distribution and composition of atherosclerotic plaques at bifurcations with intravascular ultrasound-virtual histology (IVUS-VH) and multidetector computed tomography (MDCT) in relation to the bifurcation angle (BA). METHODS AND RESULTS: In 33 patients (age 63±11 years, 79% male) imaged with IVUS-VH and MDCT, 33 bifurcations were matched and studied. The analysed main vessel was divided into a 5 mm proximal segment, the in-bifurcation segment, and a 5 mm distal segment. Plaque contours were manually traced on MDCT and IVUS-VH. Plaques with >10% confluent necrotic core and <10% dense calcium on IVUS-VH were considered high risk, whereas plaque composition by MDCT was graded as non-calcified, calcified, or mixed. The maximum BA between the main vessel and the side branch was measured on diastolic MDCT data sets. Overall the mean plaque area decreased from the proximal to the distal segment [8.5±2.8 vs. 6.0±3.0 mm2 (P<0.001) by IVUS-VH and 9.0±2.6 vs. 6.5±2.5 mm2 (P<0.001) by MDCT]. Similarly, the necrotic core area was higher in the proximal compared with the distal segment (1.12±0.7 vs. 0.71±0.7 mm2, P=0.001). The proximal segment had the higher percentage of high-risk plaques (13/25, 52%), followed by the in-bifurcation (6/25, 24%), and the distal segment (6/25, 24%); these plaques were characterized by MDCT as non-calcified (72%) or mixed (28%). The presence of high-risk and non-calcified plaques in the proximal segment was associated with higher BA values (71±19° vs. 55±19°, P=0.028 and 74±20° vs. 50±14°, P=0.001, respectively). CONCLUSION: The proximal segment of bifurcations is more likely to contain high-risk plaques, especially when the branching angle is wide.

Natural history of coronary atherosclerosis by multislice computed tomography.

OBJECTIVES: This study sought to analyze the natural history of coronary atherosclerosis by multislice computed tomography (MSCT) and assess the serial changes in coronary plaque burden, lumen dimensions, and arterial remodeling. BACKGROUND: MSCT can comprehensively assess coronary atherosclerosis by combining lumen and plaque size parameters. METHODS: Thirty-two patients with acute coronary syndromes underwent 64-slice computed tomography angiography after percutaneous coronary intervention at baseline and after a median of 39 months. All patients received contemporary medical treatment. All available coronary segments in every subject were analyzed. The progression of atherosclerosis per segment and per patient was assessed by means of change in percent atheroma volume (PAV), change in normalized total atheroma volume (TAVnorm), and percent change in TAV (% change in TAV). Serial coronary remodeling was also assessed. Measures of lumen stenosis included percent diameter stenosis (%DS), minimum lumen diameter (MLD), percent area stenosis (%AS), and minimum lumen area (MLA). For each patient, the mean of all matched segments was calculated at the 2 time points. Clinical events at follow-up were documented. RESULTS: The PAV did not change significantly (-0.15 ± 3.64%, p = 0.72). The mean change in TAVnorm was 47.36 ± 143.24 mm(3) (p = 0.071), and the % change in TAV was 6.7% (p = 0.029). The MLD and MLA increased by 0.15 mm (-0.09 to 0.24, p = 0.039) and 0.52 mm(2) (-0.38 to 1.04, p = 0.034) respectively, which was accompanied by vessel enlargement, with 53% of the patients showing expansive positive remodeling. Patients with clinical events had a larger TAVnorm at baseline (969.72 mm(3) vs. 810.77 mm(3), p = 0.010). CONCLUSIONS: MSCT can assess the progression of coronary atherosclerosis and may be used for noninvasive monitoring of pharmacological interventions in coronary artery disease. ( PROSPECT: An Imaging Study in Patients With Unstable Atherosclerotic Lesions; NCT00180466).

Image quality and radiation exposure using different low-dose scan protocols in dual-source CT coronary angiography: randomized study.

PURPOSE: To compare image quality, radiation dose, and their relationship with heart rate of computed tomographic (CT) coronary angiographic scan protocols by using a 128-section dual-source CT scanner. MATERIALS AND METHODS: Institutional review board approved the study; all patients gave informed consent. Two hundred seventy-two patients (175 men, 97 women; mean ages, 58 and 59 years, respectively) referred for CT coronary angiography were categorized according to heart rate: less than 65 beats per minute (group A) and 65 beats per minute or greater (group B). Patients were randomized to undergo prospective high-pitch spiral scanning and narrow-window prospective sequential scanning in group A (n = 160) or wide-window prospective sequential scanning and retrospective spiral scanning in group B (n = 112). Image quality was graded (1 = nondiagnostic; 2 = artifacts present, diagnostic; 3 = no artifacts) and compared (Mann-Whitney and Student t tests). RESULTS: In group A, mean image quality grade was significantly lower with high-pitch spiral versus sequential scanning (2.67 ± 0.38 [standard deviation] vs 2.86 ± 0.21; P < .001). In a subpopulation (heart rate, <55 beats per minute), mean image quality grade was similar (2.81 ± 0.30 vs 2.94 ± 0.08; P = .35). In group B, image quality grade was comparable between sequential and retrospective spiral scanning (2.81 ± 0.28 vs 2.80 ± 0.38; P = .54). Mean estimated radiation dose was significantly lower (high-pitch spiral vs sequential scanning) in group A (for 100 kV, 0.81 mSv ± 0.30 vs 2.74 mSv ± 1.14 [P < .001]; for 120 kV, 1.65 mSv ± 0.69 vs 4.21 mSv ± 1.20 [P < .001]) and in group B (sequential vs retrospective spiral scanning) (for 100 kV, 4.07 mSv ± 1.07 vs 5.54 mSv ± 1.76 [P = .02]; for 120 kV, 7.50 mSv ± 1.79 vs 9.83 mSv ± 3.49 [P = .1]). CONCLUSION: A high-pitch spiral CT coronary angiographic protocol should be applied in patients with regular and low (<55 beats per minute) heart rates; a sequential protocol is preferred in all others.

Detection and quantification of coronary atherosclerotic plaque by 64-slice multidetector CT: a systematic head-to-head comparison with intravascular ultrasound.

OBJECTIVE: We evaluated the ability of 64-slice multidetector computed tomography (MDCT)-derived plaque parameters to detect and quantify coronary atherosclerosis, using intravascular ultrasound (IVUS) as the reference standard. METHODS: In 32 patients, IVUS and 64-MDCT was performed. The MDCT and IVUS datasets of 44 coronary arteries were co-registered using a newly developed fusion technique and quantitative parameters were derived from both imaging modalities. The threshold of >0.5 mm of maximum wall thickness was used to establish plaque presence on MDCT and IVUS. RESULTS: We analyzed 1364 coregistered 1-mm coronary cross-sections and 255 segments of 5-mm length. Compared with IVUS, 64-MDCT enabled correct detection in 957 of 1109 cross-sections containing plaque (sensitivity 86%). In 180 of 255 cross-sections atherosclerosis was correctly excluded (specificity 71%). On the segmental level, MDCT detected 213 of 220 segments with any atherosclerotic plaque (sensitivity 96%), whereas the presence of any plaque was correctly ruled out in 28 of 32 segments (specificity 88%). Interobserver agreement for the detection of atherosclerotic cross-sections was moderate (Cohen's kappa coefficient K=0.51), but excellent for the atherosclerotic segments (K=1.0). Pearson's correlation coefficient for vessel plaque volumes measured by MDCT and IVUS was r=0.91 (p<0.001). Bland-Altman analysis showed a slight non-significant underestimation of any plaque volume by MDCT (p=0.5), with a trend to underestimate noncalcified and overestimate mixed/calcified plaque volumes (p=0.22 and p=0.87 respectively). CONCLUSION: MDCT is able to detect and quantify atherosclerotic plaque. Further improvement in CT resolution is necessary for more reliable assessment of very small and distal coronary plaques.