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Computed tomography (CT) has become an important modality in the evaluation of coronary artery disease (CAD). The tremendous technological advances in CT in the last two decades has made it possible to obtain high quality images of coronary arteries with high spatial and temporal resolutions. Multiple trials have confirmed the accuracy of CT compared to invasive catheter angiography. CT is also able to evaluate beyond the lumen in characterizing and quantifying atherosclerotic plaques, including evaluation of high risk features. Although CTA has low specificity in identification of lesion-specific ischemia, functional techniques are now possible such as CT myocardial perfusion and CT-fractional flow reserve (FFR) which evaluate the hemodynamic significance of stenosis and help with revascularization strategies. Multi-energy CT provides additional information beyond what is possible with a conventional CT and is useful in variety of clinical applications, including myocardial perfusion imaging, lesion characterization and low contrast studies. Large trials have confirmed the ability of CT to predict major adverse cardiovascular events and recent trials have even demonstrated improved clinical outcomes by using CT for the evaluation of CAD. CT is also useful in structural heart disease and 3 D printing is now increasingly used for surgical/interventional planning. Machine learning is evolving rapidly and is likely to impact diagnosis and management.

There is an urgent need to develop new protocols to reduce radiation dose of coronary computed tomography angiography (CTA). The aim of this pilot study was to demonstrate the feasibility of an ultra-low dose CTA scanning., (Copyright © 2017. Published by Elsevier B.V.)

Aims: To determine the diagnostic accuracy of semi-automatic quantitative metrics compared to expert reading for interpretation of computed tomography perfusion (CTP) imaging., Methods: The CORE320 multicenter diagnostic accuracy clinical study enrolled patients between 45 and 85 years of age who were clinically referred for invasive coronary angiography (ICA). Computed tomography angiography (CTA), CTP, single photon emission computed tomography (SPECT), and ICA images were interpreted manually in blinded core laboratories by two experienced readers. Additionally, eight quantitative CTP metrics as continuous values were computed semi-automatically from myocardial and blood attenuation and were combined using logistic regression to derive a final quantitative CTP metric score. For the reference standard, hemodynamically significant coronary artery disease (CAD) was defined as a quantitative ICA stenosis of 50% or greater and a corresponding perfusion defect by SPECT. Diagnostic accuracy was determined by area under the receiver operating characteristic curve (AUC)., Results: Of the total 377 included patients, 66% were male, median age was 62 (IQR: 56, 68) years, and 27% had prior myocardial infarction. In patient based analysis, the AUC (95% CI) for combined CTA-CTP expert reading and combined CTA-CTP semi-automatic quantitative metrics was 0.87(0.84-0.91) and 0.86 (0.83-0.9), respectively. In vessel based analyses the AUC's were 0.85 (0.82-0.88) and 0.84 (0.81-0.87), respectively. No significant difference in AUC was found between combined CTA-CTP expert reading and CTA-CTP semi-automatic quantitative metrics in patient based or vessel based analyses(p > 0.05 for all)., Conclusion: Combined CTA-CTP semi-automatic quantitative metrics is as accurate as CTA-CTP expert reading to detect hemodynamically significant CAD., (Copyright © 2018 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.)

Objectives: Multi-detector-row computed tomography angiography (MDCTA) plays an important role in the assessment of patients with suspected coronary artery disease. However, MDCTA tends to overestimate stenosis in calcified coronary artery lesions. The aim of our study was to evaluate the diagnostic performance of calcification-suppressed material density (MD) images produced by using a single-detector single-source dual-energy computed tomography (ssDECT)., Methods: We enrolled 67 patients with suspected or known coronary artery disease who underwent ssDECT with rapid kilovolt-switching (80 and 140 kVp). Coronary artery stenosis was evaluated on the basis of MD images and virtual monochromatic (VM) images. The diagnostic performance of the two methods for detecting coronary artery disease was compared with that of invasive coronary angiography as a reference standard., Results: We evaluated 239 calcified segments. In all the segments, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy for detecting significant stenosis were respectively 88%, 88%, 75%, 95% and 88% for the MD images, 91%, 71%, 56%, 95% and 77% for the VM images. PPV was significantly higher on the MD images than on the VM images (P < 0.0001)., Conclusions: Calcification-suppressed MD images improved PPV and diagnostic performance for calcified coronary artery lesions., Key Points: • Computed tomography angiography tends to overestimate stenosis in calcified coronary artery. • Dual-energy CT enables us to suppress calcification of coronary artery lesions. • Calcification-suppressed material density imaging reduces false-positive diagnosis of calcified lesion.

We evaluated the performance of a new volume computed tomographic (CT) scanner with regards to image quality and signal homogeneity. Twenty-four subjects were prospectively enrolled. Subjects had prior imaging with rate control. Quantitative analyses performed placing regions of interest in myocardium, blood pool, and aorta. Image quality and diagnostic interpretability were assessed using Likert scales. Median heart rate was 60 and 57 bpm for volume and 64-slice coronary CT angiography (P=.02). Improvement in homogeneity was demonstrated within myocardium (30% improvement), blood pool (73%), and aorta (73%). Improvement in image quality observed at per-patient/per-segment level. Pilot study confirmed improvements in signal homogeneity and diagnostic interpretability, despite imaging at higher heart rates., (Copyright © 2015. Published by Elsevier Inc.)

To study the feasibility of evaluation of collateral channel (CC) classification in patients with coronary chronic total occlusion (CTO) by coronary computed tomography angiography (CTA) with reference to invasive coronary angiography (ICA) validation. We retrospectively included CTO-confirmed patients who underwent both coronary CTA and ICA within 1 month. Collaterals were classified by coronary CTA into three types: CC0, no continuous connection between donor and recipient vessel; CC1, continuous thread-like connection; CC2, continuous, small sidebranch-like connection. With comparison to ICA results, the diagnostic performance of CTA-based CC classification was further assessed. 118 patients with 132 ICA-confirmed CTO lesions were included. Compared to ICA-based evaluation, good overall diagnostic accuracy of CT-based CC classification was observed (78%, 103/132, κ = 0.674, p < 0.001). Coronary CTA was also revealed to be accurate in terms of assessment of collateral tortuosity (76.2%, 77/101) and identification of principal donor vessel (70.3%, 71/101). Impaired diagnostic performance was observed in sub-group of septal collaterals as the accuracy for evaluation of the above parameters was 60.6% (20/33), 72.7% (24/33) and 45.5% (15/33) respectively. Non-invasive evaluation of CC classification by coronary CTA correlates well with ICA findings. In addition, the septal collaterals are much less visible at coronary CTA than epicardial collaterals.

Computed tomography coronary angiography (CTA) and cardiac magnetic resonance myocardial perfusion imaging (CMR-MPI) are state-of-the-art tools for noninvasive assessment of coronary artery disease (CAD). We aimed to compare the diagnostic accuracy of CTA and CMR-MPI for the detection of functionally relevant CAD, using invasive coronary angiography (XA) with fractional flow reserve (FFR) as a reference standard, and to evaluate the best protocol integrating these techniques for assessment of patients with suspected CAD. 95 patients (68 % men; 62 ± 8.1 years) with intermediate pre-test probability (PTP) of CAD underwent a sequential protocol of CTA, CMR-MPI and XA. Significant CAD was defined as >90 % coronary stenosis, 40-90 % stenosis with FFR ≤ 0.80 or left main stenosis ≥50 %. Prevalence of significant CAD was 43 %. CTA was more sensitive (100 %) but less specific (59 %) than CMR-MPI (88 and 89 %, respectively) for detection of significant CAD, with a strong trend for higher global diagnostic accuracy of CMR-MPI (88 vs. 77 %, p = 0.05). An integrated approach based on an initial CTA and subsequent referral to CMR-MPI of positive/inconclusive results had the best diagnostic performance (AUC 0.91). The direct referral to XA of patients with positive/inconclusive CTA performed worse than a selective approach based on CMR-MPI results (AUC 0.80 vs. 0.91, p = 0.005). In this intermediate PTP population, CMR-MPI showed a strong trend toward better performance compared to CTA for the assessment of functionally significant CAD. A combined protocol integrating coronary anatomy and function seems to be a very effective approach in the accurate diagnosis of CAD.

Coronary computed tomography angiography (CCTA) contrast opacification gradients, or transluminal attenuation gradients (TAG) offer incremental value to predict functionally significant lesions. This study introduces and evaluates an automated gradients software package that can potentially supplant current, labor-intensive manual TAG calculation methods. All 60 major coronary arteries in 20 patients who underwent a clinically indicated single heart beat 320 × 0.5 mm detector row CCTA were retrospectively evaluated by two readers using a previously validated manual measurement approach and two additional readers who used the new automated gradient software. Accuracy of the automated method against the manual measurements, considered the reference standard, was assessed via linear regression and Bland-Altman analyses. Inter- and intra-observer reproducibility and factors that can affect accuracy or reproducibility of both manual and automated TAG measurements, including CAD severity and iterative reconstruction, were also assessed. Analysis time was reduced by 68% when compared to manual TAG measurement. There was excellent correlation between automated TAG and the reference standard manual TAG. Bland-Altman analyses indicated low mean differences (1 HU/cm) and narrower inter- and intra-observer limits of agreement for automated compared to manual measurements (25 and 36% reduction with automated software, respectively). Among patient and technical factors assessed, none affected agreement of manual and automated TAG measurement. Automated 320 × 0.5 mm detector row gradient software reduces computation time by 68% with high accuracy and reproducibility.

Objective: To evaluate the relationship between gantry rotation time, heart rate and image quality during multislice spiral CT coronary angiography (MSCTCA)., Patients and Methods: Data of 83 patients who underwent MSCTCA were reviewed. Based on the ratio between cardiac cycle and gantry rotation time, the patients were divided into two groups. Patients whose heart rates fell in the resonance frequency (the cardiac cycle / gantry rotational time ratio of 1.5, 2 or 2.5) ± 2 bpm were classified as synchronous (25 cases), while the remaining 58 patients (included a subgroup of 34 cases in whom heart rates were the same as in synchronous group but who had a different gantry rotation time). comprised the asynchronous group. Image qualities were compared between both groups., Results: In the synchronous group, most (199/287; 69.33%) images were poor. When gantry rotation time was changed in the subgroup of the asynchronous group, the majority (423/442 or 95.70%) of images improved. There was a significant difference (p < 0.001) in the image quality among these patients. In 58 patients from asynchronous group, 757 segments of coronary arteries were evaluated, and 716 segments were of best quality (716/757; 94.58%)., Conclusions: When heart rate and gantry rotation time correlate and synchronous, the so-called frequency harmonics, coronary artery image quality is poor. However, by changing gantry rotation time to avoid the harmonic helps to improve the image quality on MSCTCA. Based on the patient's heart rate, appropriate gantry rotation time can be selected in order to avoid resonance and obtain high quality images.

Background: The aim of this study was to compare the diagnostic accuracy of 64-slice multidetector computed tomography (MDCT) with conventional coronary angiography to detect graft patency and stenosis., Methods: In this retrospective analysis, we included a total of 284 subjects (210 men, 73.9%; mean ± SD age, 62.6 ± 9.9) and evaluated 684 bypass grafts using a dual-source 64-slice MDCT scanner The mean ± SD time interval between coronary artery bypass grafting operation and MDCT was 30.8 ± 6.2 months. The mean ± SD interval between MDCT angiography and conventional coronary angiography was 14.2 ± 3.6 days. Significant stenosis was defined as lesions causing 50% or greater luminal narrowing. All atherosclerotic lesion components were assessed on per-segment basis., Results: All of the 684 grafts (420 venous and 264 arterial grafts) were evaluable and included in the analysis. For the detection of 50% or greater graft stenosis, the sensitivity, specificity, positive predictive value and negative predictive value of MDCT was 98.3%, 99.3%, 98.3%, and 99.3% for venous grafts and 100%, 99.5%, 98.0%, and 100% for arterial grafts. In detection of graft patency, the sensitivity, specificity, positive predictive value, and negative predictive value of MDCT was 99.6%, 97.2%, 99.0%, and 99.0% for venous grafts and 99.5%, 97.5%, 99.5%, and 97.5% for arterial grafts. Diagnostic accuracy for the detection of graft patency was 99% (416/420) and 99.2% (262/264) for venous and arterial grafts, respectively., Conclusion: The diagnostic accuracy of dual-source 64-slice MDCT angiography for evaluating coronary artery bypass grafts patency and stenosis was high. Dual-source 64-slice MDCT can be used for the evaluation of patients after coronary artery bypass grafting.

A negative (zero) Agatston coronary calcium score (CCS) by current methods confers a very low risk for hard coronary events during the next years. However, controversy remains on how to use a negative score since some hard events still occur. We report on a new method with improved detection sensitivity for very small calcifications with the potential to more confidently rule out early atherosclerotic disease. Seventy-eight (78) patients with negative Agatston scores by conventional methods with 2.5 mm slices were selected from routine GE 64 MDCT scans. Each scan was reconstructed a second time from the same data to create 0.625 mm isotropic voxels. The 2.5 mm images were manually scored by the usual Agatston method using the GE SmartScore™ software. Both the 2.5 and 0.625 mm image sets were scored with a new automated and calibrated method (N-vivo™, Image Analysis). The software automatically computes dual scoring thresholds that are statistically defined and specific for each patient, scanner, and scan. The images were hybrid calibrated by simultaneous scanned phantoms in combination with in vivo blood/muscle references. The output reported the calibrated mass scores along with the number of plaques using 18 pt, 3-D connectivity criteria. A CCS Test phantom with known CaHA microspheres was used to validate the method. Twenty-three percent (18 of 78) of the patients with negative Agatston scores by the conventional method scored positive for coronary calcifications by the N-vivo method. The number of small plaques scored per patient varied from 1 to 4. One patient with a single small calcification suffered a hard coronary event during the CT scan. All of the detected plaques were located in the proximal heart. The conventional CCS method misclassified 23% of these patients as having negative coronary calcium scores. The N-vivo automated scoring method with small voxel CT images increased the detection sensitivity of small calcifications with no increase in radiation dose. Detection of small coronary calcified plaques occult to conventional scoring methods may increase the negative predictive power of calcium scoring and may improve plaque composition analysis.

Comprehensive examination was made in women (mean age 49.6 +/- 7.4 years) with rheumatoid arthritis diagnosed abnormalities of brachiocephalic and coronary arteries in 86% of cases. Duplex scanning of brachiocephalic arteries revealed changes in 82% of the women. 64-section spiral computed tomography established coronary artery abnormalities in 33% of cases. There were isolated changes in the brachiocephalic arteries in 50% of the patients, a concomitant lesion of the brachiocephalic and coronary arteries in 32%, and isolated changes in the coronary arteries in 4%. A direct correlation was found between the index of coronary artery calcification and the intima-media thickness of brachiocephalic arteries.