Coronary Computed Tomographic Angiography in Clinical Practice

Artificial intelligence in cardiac radiology

Artificial intelligence (AI) is entering the clinical arena, and in the early stage, its implementation will be focused on the automatization tasks, improving diagnostic accuracy and reducing reading time. Many studies investigate the potential role of AI to support cardiac radiologist in their day-to-day tasks, assisting in segmentation, quantification, and reporting tasks. In addition, AI algorithms can be also utilized to optimize image reconstruction and image quality. Since these algorithms will play an important role in the field of cardiac radiology, it is increasingly important for radiologists to be familiar with the potential applications of AI. The main focus of this article is to provide an overview of cardiac-related AI applications for CT and MRI studies, as well as non-imaging-based applications for reporting and image optimization.

Functional cardiac CT-Going beyond Anatomical Evaluation of Coronary Artery Disease with Cine CT, CT-FFR, CT Perfusion and Machine Learning

The aim of this review is to provide an overview of different functional cardiac CT techniques which can be used to supplement assessment of the coronary arteries to establish the significance of coronary artery stenoses. We focus on cine-CT, CT-FFR, CT-myocardial perfusion and how developments in machine learning can supplement these techniques.

Cardiac CT: why, when, and how : Update 2019

PURPOSE

The aim of this study was to review established and emerging techniques of cardiac computed tomography (CT) and their clinical applications with a special emphasis on new techniques, recent trials, and guidelines.

TECHNOLOGICAL INNOVATIONS

Cardiac CT has made great strides in recent years to become an ever more robust and safe imaging technique. The improvements in spatial and temporal resolution are equally important as the substantial reduction in radiation exposure, which has been achieved through prospective ECG-triggering, low tube voltage scanning, tube current modulation, and iterative reconstruction techniques. CT-derived fractional flow reserve and CT myocardial perfusion imaging are novel, investigational techniques to assess the hemodynamic significance of coronary stenosis.

ESTABLISHED AND EMERGING INDICATIONS

In asymptomatic patients at risk for coronary artery disease, CT coronary artery calcium scoring is useful to assess cardiovascular risk and guide the intensity of risk factor modification. Coronary CT angiography is an excellent noninvasive test to rule out obstructive coronary artery disease in patients with stable chest pain. In acute chest pain with normal ECG and normal cardiac enzymes, cardiac CT can safely rule out acute coronary syndrome although its benefit and role in this indication remains controversial. Cardiac CT is the established standard for planning transcatheter aortic valve implantation and-increasingly-minimally invasive mitral valve procedures.

PRACTICAL RECOMMENDATIONS

Our review makes practical recommendations on when and how to perform cardiac CT and provides templates for structured reporting of cardiac CT examinations.

Echocardiographic diagnosis of anomalous origin of the left coronary artery from the pulmonary artery

The aim of this research is to investigate the application value of TTE in the diagnosis of the anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA).The echocardiographic findings of 11 patients with ALCAPA confirmed by surgery in our hospital from October 2007 to December 2018 were retrospectively analyzed and compared with the preoperative computed tomography angiography (CTA) diagnosis and intraoperative diagnosis.Surgery was performed in all of the patients to establish the dual coronary artery system. Four underwent the Takeuchi procedure and 7 had re-implantation of the anomalous left coronary artery. The CTA diagnoses of the 11 patients were consistent with the surgical diagnoses, and the diagnostic accuracy was 100% (11/11). Echocardiographic diagnosis showed consistent results in 10 cases, while one case was misdiagnosed as endocardial fibroelastosis; the diagnostic accuracy was 90.9% (10/11). The echocardiographic features of these patients with ALCAPA included: abnormal left coronary ostium arising from the pulmonary trunk with retrograde coronary artery flow in 10 patients; enlargement of the right coronary artery in 8 patients; abundant intercoronary septal collaterals in 6 patients; and moderate and significant mitral regurgitation in 7 patients. Echocardiography showed that the left ventricular end-diastolic diameter and left ventricular end-systolic diameter before surgery were significantly different from those after surgery (P < .05) and that the left ventricular ejection fraction and fractional shortening before surgery were not significantly different from those after surgery (P > .05).Transthoracic echocardiography can diagnose ALCAPA in a timely, accurate, and noninvasive manner, and it could be of great significance in guiding clinical operations and in predicting prognosis.

Liquid Biopsy of Extracellular Microvesicles Maps Coronary Calcification and Atherosclerotic Plaque in Asymptomatic Patients With Familial Hypercholesterolemia

Objective—

Heterozygous familial hypercholesterolemia (FH) is the most common genetic disorder associated with premature atherosclerotic cardiovascular disease. Circulating microvesicles (cMV) are released when cells are activated. We investigated whether cMV could provide information on coronary calcification and atherosclerosis in FH patients.

Approach and Results—

Eighty-two patients (mean of 44±9 years old) with molecular diagnosis of heterozygous FH and asymptomatic cardiovascular disease were investigated. Atherosclerotic plaque characterization was performed by computed tomography angiography, and Agatston coronary calcium score and plaque composition sum were calculated. cMV were quantified by flow cytometry using AV (annexin V) and cell surface-specific antibodies. Of the 82 FH patients, 48 presented atherosclerotic plaque. Patients with atherosclerosis were men and older in a higher percentage than patients without atherosclerotic plaque. FH patients with atherosclerotic plaque showed higher levels of total AV + cMV, cMV AV + from platelet origin, from granulocytes and neutrophils, and cMV AV +/− from endothelial cells than FH-patients without atherosclerotic plaque. Plaque composition sum correlated with platelet- and endothelial-derived cMV, and Agatston coronary calcium score correlated with granulocyte-, platelet-, and endothelial-derived cMV. Receiver operating characteristic curve analyses indicated that the cluster of platelet-, granulocyte-, neutrophil, and endothelial-derived cMV considered together, added significant predictive value to the specific SAFEHEART (Spanish Familial Hypercholesterolaemia Cohort Study) risk equation for plaque presence (area under the curve=0.866, 95% CI, 0.775–0.958; P <0.0001, P =0.030 for the increment of the area under the curve).

Conclusions—

Endothelial-, granulocyte-, neutrophil- and platelet-derived cMV discriminate and map coronary atherosclerotic plaque and calcification in asymptomatic patients with FH. Liquid biopsy of cMV may be a surrogate biomarker of coronary atherosclerotic plaque burden in FH patients.

Predictive value of coronary computed tomography angiography in asymptomatic individuals with diabetes mellitus: Systematic review and meta-analysis

BACKGROUND

Coronary CT angiography (CTA) is generally not established as a screening tool for asymptomatic individuals. However, it is controversial whether this test may have a role for screening asymptomatic individuals with diabetes mellitus (DM) due to the high prevalence of asymptomatic coronary artery disease (CAD) in this subgroup.

METHODS

We searched PubMed and EMBASE through May 2017 for studies that reported on the association between findings at coronary CTA and future cardiac events in asymptomatic individuals with DM. Summary hazard ratios for the presence of obstructive CAD (≥50% stenosis), presence of non-obstructive plaque (<50% stenosis), segment involvement score, and segment stenosis score were derived using a random effects regression model. I² was calculated to quantify between-study heterogeneity and causing factors were identified using meta-regression.

RESULTS

A total of 10 studies reporting on 5012 individuals with DM (median age: 62.3 years, median proportion of women: 40.5%) were included in the analysis. The presence of obstructive CAD on coronary CTA (vs. non-obstructive or no CAD) was associated with a significantly elevated risk for adverse events (summary HR: 4.07, 95% CI: 2.30 to 7.21). The estimated summary HR for non-obstructive plaque (vs. no CAD) was 2.17 (95% CI: 1.11 to 4.25). The pooled HRs per unit for segment stenosis score and segment involvement score were 1.44 (95% CI: 0.98 to 2.12), and 1.73 (95% CI: 1.07 to 2.80) respectively. On meta-regression analysis, we observed a trend towards a higher risk estimate in studies with a higher proportion of females (p = 0.1063).

CONCLUSION

The presence and extent of CAD on coronary CTA are strong, independent predictors of cardiovascular events in asymptomatic individuals with DM despite heterogeneity between studies in endpoints, study population and length of follow-up.

Impact of spatial characteristics in the left stenotic coronary artery on the hemodynamics and visualization of 3D replica models

Cardiovascular disease has been the major cause of death worldwide. Although the initiation and progression mechanism of the atherosclerosis are similar, the stenotic characteristics and the corresponding medical decisions are different between individuals. In the present study, we performed anatomic and hemodynamic analysis on 8 left coronary arterial trees with 10 identified stenoses. A novel boundary condition method had been implemented for fast computational fluid dynamics simulations and patient-specific three-dimensional printed models had been built for visualizations. Our results suggested that the multiple spatial characteristics (curvature of the culprit vessel multiplied by an angle of the culprit's vessel to the upstream parent branch) could be an index of hemodynamics significance (r = -0.673, P-value = 0.033). and reduction of the maximum velocity from stenosis to downstream was found correlated to the FFRCT (r = 0.480, p = 0.160). In addition, 3D printed models could provide accurate replicas of the patient-specific left coronary arterial trees compare to virtual 3D models (r = 0.987, P-value < 0.001). Therefore, the visualization of the 3D printed models could help understand the spatial distribution of the stenoses and the hand-held experience could potentially benefit the educating and preparing of medical strategies.

Relationship between hsTnI and coronary stenosis in asymptomatic women with rheumatoid arthritis

Background

Rheumatoid arthritis (RA) is a condition associated with accelerated progression of atherosclerosis in affected individuals. Myocardial assessment using exercise testing in such patients, however, is often difficult to perform. Our objective was to determine the factors associated with severe coronary stenosis using computed tomography (CT) angiography of the coronary arteries in asymptomatic patients with RA.

Methods

Forty-four women with RA were examined using CT angiography to detect atherosclerotic involvement and significant coronary stenosis (>50 %). CT findings were correlated with the cardiovascular risk score, and with classical and most recent parameters of atherosclerosis.

Results

CT angiography of the coronary arteries revealed severe stenosis (>70 %) in 9 % of patients. High-sensitivity troponin I level was associated with severe coronary stenosis (odds ratio 6.37; 95 % confidence interval 1.53 − 26.48; P = 0.011). Adjustment for confounders did not alter this result (P = 0.039). In contrast, classical and modified Systemic Coronary Risk Evaluation scores had no value in predicting severe stenosis (P ≥ 0.49).

Conclusion

The present study showed the possible benefits of a coronary CT angiography in women with RA and asymptomatic ischemic coronary heart disease. Increased levels of high-sensitivity troponin I may be a potential indication for this type of examination. However, further studies are needed to confirm these results.

Radiation dose and diagnostic image quality associated with iterative reconstruction in coronary CT angiography: A systematic review

The aim of this systematic review is to evaluate the radiation dose reduction achieved using iterative reconstruction (IR) compared to filtered back projection (FBP) in coronary CT angiography (CCTA) and assess the impact on diagnostic image quality. A systematic search of seven electronic databases was performed to identify all studies using a developed keywords strategy. A total of 14 studies met the criteria and were included in a review analysis. The results showed that there was a significant reduction in radiation dose when using IR compared to FBP (P < 0.05). The mean and standard deviation (SD) difference of CTDIvol and dose-length-product (DLP) were 14.70 ± 6.87 mGy and 186 ± 120 mGy.cm respectively. The mean ± SD difference of effective dose (ED ) was 2.9 ± 1.7 mSv with the range from 1.0 to 5.0 mSv. The assessment of diagnostic image quality showed no significant difference (P > 0.05). The mean ± SD difference of image noise, signal-noise ratio (SNR) and contrast-noise ratio (CNR) were 1.05 ± 1.29 HU, 0.88 ± 0.56 and 0.63 ± 1.83 respectively. The mean ± SD percentages of overall image quality scores were 71.79 ± 12.29% (FBP) and 67.31 ± 22.96% (IR). The mean ± SD percentages of coronary segment analysis were 95.43 ± 2.57% (FBP) and 97.19 ± 2.62% (IR). In conclusion, this review analysis shows that CCTA with the use of IR leads to a significant reduction in radiation dose as compared to the use of FBP. Diagnostic image quality of IR at reduced dose (30-41%) is comparable to FBP at standard dose in the diagnosis of CAD.

Fractional flow reserve based on computed tomography: an overview

Computed tomography coronary angiography (CTCA) is a technique proved to provide high sensitivity and negative predictive value for the identification of anatomically significant coronary artery disease (CAD) when compared with invasive X-ray coronary angiography. While the CTCA limitation of a ionizing radiation dose delivered to patients is substantially overcome by recent technical innovations, a relevant limitation remains the only anatomical assessment of coronary stenoses in the absence of evaluation of their functional haemodynamic significance. This limitation is highly important for those stenosis graded as intermediate at the anatomical assessment. Recently, non-invasive methods based on computational fluid dynamics were developed to calculate vessel-specific fractional flow reserve (FFR) using data routinely acquired by CTCA [computed tomographic fractional flow reserve (CT-FFR)]. Here we summarize methods for CT-FFR and review the evidence available in the literature up to June 26, 2016, including 16 original articles and one meta-analysis. The perspective of CT-FFR may greatly impact on CAD diagnosis, prognostic evaluation, and treatment decision-making. The aim of this review is to describe technical characteristics and clinical applications of CT-FFR, also in comparison with catheter-based invasive FFR, in order to make a cost-benefit balance in terms of clinical management and patient's health.

Diagnostic Value of Transthoracic Echocardiography in Patients With Anomalous Origin of the Left Coronary Artery From the Pulmonary Artery

Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital coronary abnormality associated with early infant mortality and sudden death in adults. Transthoracic echocardiography (TTE) plays an important role in early detection and diagnosis of ALCAPA as a noninvasive modality. However, its diagnostic value is not well studied. The purpose of this study is to determine the performance of TTE in the diagnostic assessment of ALCAPA as compared with coronary CT and invasive coronary angiography. A total of 22 patients (13 women and 9 men, mean age, 12.9 ± 19.5 years) with ALCAPA who underwent echocardiographic examination for clinical diagnosis were retrospectively reviewed and analyzed. Transthoracic echocardiographic features of ALCAPA were analyzed and its diagnostic value was compared with invasive coronary angiography and coronary CT angiography (CTA) with surgical findings serving as the gold standard. Surgery was performed in all of the patients to establish the dual coronary artery system. Five underwent the Takeuchi procedure and 17 had re-implantation of the anomalous left coronary artery. Of 20 patients, echocardiographic diagnoses were in good agreement with findings at surgery, resulting in the diagnostic accuracy of 90.9%. Two cases were misdiagnosed-one as the right coronary artery to pulmonary artery fistula and the other as rheumatic heart disease. The echocardiographic features of these patients with ALCAPA included: abnormal left coronary ostium arising from the pulmonary trunk with retrograde coronary artery flow in 20 patients; enlargement of the right coronary artery in 17 patients; abundant intercoronary septal collaterals in 17 patients; and moderate and significant mitral regurgitation in 14 patients. The diagnostic accuracy of invasive coronary angiography (in 17 patients) and coronary CTA (in 9 patients) was 100%. This study shows that TTE is an accurate, noninvasive imaging modality for displaying the origin of coronary arteries and demonstrating the coronary courses as well as other associated abnormalities in patients with ALCAPA.

Coronary CT angiography derived morphological and functional quantitative plaque markers correlated with invasive fractional flow reserve for detecting hemodynamically significant stenosis

OBJECTIVE

Compare morphological and functional coronary plaque markers derived from coronary CT angiography (CCTA) for their ability to detect lesion-specific ischemia.

MATERIALS AND METHODS

Data of patients who had undergone both dual-source CCTA and invasive fractional flow reserve (FFR) measurement within 3 months were retrospectively analyzed. Various quantitative stenosis markers were derived from CCTA: Corrected coronary opacification (CCO), transluminal attenuation gradient (TAG), remodeling index (RI), computational FFR (cFFR), lesion length (LL), vessel volume (VV), total plaque volume (TPV), and calcified and non-calcified plaque volume (CPV and NCPV). Discriminatory power of these markers for flow-limiting versus non-significant coronary stenosis was assessed against invasive FFR as the reference standard.

RESULTS

The cohort included 37 patients (61 ± 12 years, 68% male). Among 37 lesions, 11 were hemodynamically significant by FFR. On a per-lesion level, sensitivity and specificity of TPV, CPV, and NCPV for hemodynamically significant stenosis detection were 88% and 74%, 67% and 53%, and 92% and 81%, respectively. For CCO, TAG, RI, and cFFR these were 64% and 86%, 35% and 56%, 82% and 54%, and 100% and 90%, respectively. At ROC analysis, only TPV (0.78, p = 0.013), NCPV (0.79, p = 0.009), cFFR (0.85, p = 0.003), and CCO (0.82, p = 0.0003) showed discriminatory power for detecting hemodynamically significant stenosis.

CONCLUSION

TPV, NCPV, CCO, and cFFR derived from CCTA can aid detecting hemodynamically significant coronary lesions with cFFR showing the greatest discriminatory ability.

Current utilization of cardiac computed tomography in mainland China: A national survey

BACKGROUND

Surveys that describe the utilization of cardiac CT are available for the United States, Germany, and Taiwan, but not mainland China.

OBJECTIVES

To analyze the clinical utilization of cardiac CT in mainland China.

METHODS

A 25-item questionnaire was created and 240 tertiary hospitals were randomly selected to participate. Survey data were collected and confirmed by email as well as phone interviews.

RESULTS

In total, 237 (99%) hospitals consented to this survey, but 85 were excluded because of lack of cardiac CT patient volume or advanced technology. Finally, 152 (64%) questionnaires were available for analysis. Median patient volume was 1,037 patients (range: 150-8,072) annually. The most common clinical indications for coronary CT angiography were exclusion of coronary artery disease in patients with low to intermediate pretest likelihood, asymptomatic individuals with cardiovascular risk factors, and follow-up after coronary bypass grafting. The median heart rate threshold for beta blocker administration was >70 beats/min; most centers (86%) used sublingual nitroglycerin. Prospectively ECG triggered acquisition was the predominant technique in 44% of hospitals. Most (59%) providers adjusted the tube current to the body mass, but few (16%) adjusted the contrast injection rate. Per case, the mean examination duration was 14.2 min; post-processing time 13.6 min; and reporting time 18.0 min.

CONCLUSIONS

Cardiac CT is widely established in clinical practice in mainland China but there is a need for more uniform standards regarding performance and clinical utilization.