Cardiac CT in emergency department patients with acute chest pain

Value of Machine Learning-based Coronary CT Fractional Flow Reserve Applied to Triple-Rule-Out CT Angiography in Acute Chest Pain

Purpose

To evaluate the additional value of noninvasive artificial intelligence (AI)-based CT-derived fractional flow reserve (CT FFR), derived from triple-rule-out coronary CT angiography for acute chest pain (ACP) in the emergency department (ED) setting.

Materials and Methods

AI-based CT FFR from triple-rule-out CT angiography data sets was retrospectively obtained in 159 of 271 eligible patients (102 men; mean age, 57.0 years ± 9.7 [standard deviation]) presenting to the ED with ACP. The agreement between CT FFR (≤ 0.80) and stenosis at triple-rule-out CT angiography (≥ 50%), as well as downstream cardiac diagnostic testing, was investigated. Furthermore, the predictive value of CT FFR for coronary revascularization and major adverse cardiac events (MACE) was assessed over a 1-year follow-up period.

Results

CT FFR and triple-rule-out CT angiography demonstrated agreement in severity of coronary artery disease (CAD) in 52% (82 of 159) of all cases. CT FFR of 0.80 and less served as a better predictor for coronary revascularization and MACE than stenosis of 50% and greater at triple-rule-out CT angiography (odds ratio, 3.4; 95% confidence interval: 1.4, 8.2 vs odds ratio, 2.2; 95% confidence interval: 0.9, 5.3) (P < .01). In the subgroup of patients with additional noninvasive cardiac testing (94 of 159), there was higher agreement as to the presence or absence of significant disease with CT FFR (55%) than with coronary triple-rule-out CT angiography (47%) (P = .23).

Conclusion

CT FFR derived from triple-rule-out CT angiography was a better predictor for coronary revascularization and MACE and showed better agreement with additional diagnostic testing than triple-rule-out CT angiography. Therefore, CT FFR may improve the specificity in identifying patients with ACP with significant CAD in the ED setting and reduce unnecessary downstream testing.© RSNA, 2020See also the commentary by Ihdayhid and Ben Zekry in this issue.

Low Iodine Contrast Injection for CT Acquisition Prior to Transcatheter Aortic Valve Replacement: Aorta Assessment and Screening for Coronary Artery Disease

RATIONALE AND OBJECTIVES

To assess both the complete aorta and coronary artery disease (CAD) using low iodine contrast computed-tomography angiography before transcatheter aortic valve replacement.

MATERIALS AND METHODS

84 patients underwent computed-tomography angiography before transcatheter aortic valve replacement: 42 with standard iodine injection protocol (P1:120 mL); 42 with a low dose iodine injection protocol (P2:60 mL). Mean attenuation and subjective image quality were rated at different levels of the aorta, iliac and coronary arteries. Sensitivity, specificity, negative and positive predictive values for depiction of CAD were calculated according to the coronary angiography.

RESULTS

Mean attenuation was significantly higher in P1 for the ascending aorta (p < 0.001). No significant difference was observed regarding image quality of the aortic valve (p = 0.876), the ascending aorta (p = 0.306), or the abdominal aorta (p = 1.0). Diagnostic image quality of coronary arteries was excellent for P1 and P2 (94.6% vs 96.5%, p = 0.08). Sensitivity, specificity, negative and positive predictive values, and accuracy for depiction of CAD were excellent for P1 and P2 (100% vs 100%; 79% vs 86%, 70% vs 87%, 100% vs 100% and 86% vs 93%) without significant differences (p = 0.93; p = 0.58; p = 0.90; p = 1.0; p = 0.74), respectively.

CONCLUSION

Despite a difference in aortic mean attenuation, a reduced iodine injection protocol showed similar image quality and detection of CAD in comparison with a standard injection protocol.

Coronary computed tomographic angiography in the emergency room: state of the art

Chest pain is a common complaint in the emergency department often necessitating testing to exclude underlying obstructive coronary artery disease. While the traditional evaluation of patients with suspected acute coronary syndrome often consists of serial electrocardiograms and cardiac biomarkers, followed by selective use of stress testing for further risk stratification, this approach is costly and inefficient. Recently, coronary computed tomographic angiography (CTA) has offered an alternative approach with a high sensitivity and negative predictive value to exclude obstructive coronary artery disease that can rapidly identify patients with low rates of downstream major adverse cardiac events. In this review, the authors provide an overview of available data on the use of CTA for evaluating acute chest pain, while emphasizing its advantages and disadvantages compared to existing strategies. In addition, we provide a suggested algorithm to identify how CTA can be incorporated into the evaluation of acute chest pain and discuss tips for successful implementation of CTA in the emergency department.

[Radiologists in the emergency department: when and how to use multislice CT]

Chest pain is a challenging clinical problem in the emergency department. Despite advances in clinical diagnosis, many patients with atypical chest pain are needlessly hospitalized and others are mistakenly discharged. Faced with the specific clinical situation in which a patient has chest pain, an initially normal or inconclusive electrocardiogram, and normal cardiac biomarkers, multislice CT has proven useful for ruling out the conditions that involve the greatest morbidity and mortality and for establishing the cause of pain. This article reviews the current usefulness of multislice CT in the diagnostic workup of patients presenting at the emergency department with chest pain. We review the technique, define the most appropriate population, describe the acquisition protocols, and discuss the advantages and disadvantages of each study protocol.

Incremental value of myocardial perfusion over regional left ventricular function and coronary stenosis by cardiac CT for the detection of acute coronary syndromes in high-risk patients: a subgroup analysis of the ROMICAT trial

OBJECTIVES

To determine the incremental benefit of assessing myocardial perfusion defects (MPD) for acute coronary syndromes (ACS) over coronary and functional assessment by rest cardiac computed tomography (CT) in patients with acute chest pain.

BACKGROUND

Assessment of myocardial perfusion is feasible with cardiac CT; however, the diagnostic value of this assessment in patients at risk for ACS has not been demonstrated.

METHODS

The study included patients who presented to the emergency department with acute chest pain, nonischemic initial electrocardiogram (ECG), and negative cardiac biomarkers but had clinical suspicion for ACS and underwent invasive coronary angiography (ICA). Results were blinded to caregivers and patients. CT data sets were independently assessed for the presence of coronary plaque and stenosis, regional left ventricular function, and myocardial perfusion deficits by 2 blinded observers. Coronary angiography was assessed for the presence of stenosis, TIMI myocardial perfusion grade, and corrected TIMI frame count. The endpoint was ACS during index hospitalization.

RESULTS

We analyzed data from 35 subjects (69% male, mean age 58 ± 9 years) of whom 22 (63%) had ACS. The sensitivity and specificity of MPD for ACS were 86% (95% CI: 64%-96%) and 62% (95% CI: 32%-85%), respectively. Combined, MPD and RWMA assessment resulted in specificity and sensitivity of 86% (95% CI: 64%-96%) and 85% (95% CI: 54%-97%), respectively. Adding MPD and RWMA to the assessment for significant stenosis (>50%) resulted in a higher sensitivity of 91% (69-98%) and specificity of 85% (54-97%) and a significantly increased overall diagnostic accuracy when compared with assessment for stenosis (AUC: 0.88 vs 0.79; respectively, P = 0.02). Diagnostic accuracy of CT was not associated with impaired CTFC >40 or myocardial TIMI perfusion grade < 3.

CONCLUSIONS

Assessment of myocardial perfusion and regional wall motion abnormalities may enhance the ability of CT to detect ACS in patients with acute chest pain.

Congenital anomalies of coronary arteries: Diagnosis with 64 slice multidetector CT

OBJECTIVE

Congenital coronary artery anomalies are generally incidental, uncommon and asymptomatic. Some can cause severe potentially life threatening symptoms. The common mode of studying the coronary arteries is Conventional Coronary Angiogram. ECG-gated-multidetector CT is a non invasive modality. The objective of our study was to identify rare congenital coronary artery anomalies and discuss their clinical significance.

MATERIAL AND METHODS

A total number of 900 MDCT coronary angiograms were carried out at our institution between the period of April 2006 and October 2010. Patients with coronary artery anomaly constituted the subject of study.

RESULTS

The incidence of anomalous anatomical origin and course of the coronary arteries in our study was 1.55%. Hemodynamical significance was seen in five patients. 3 cases of single coronary artery originating from right coronary sinus were seen. 1 case of anomalous left coronary artery arising from main pulmonary artery was seen. 4 cases of anomalous RCA arising from left aortic cusp, 6 cases of absent LMCA with separate origin of LAD and LCX were seen.

CONCLUSION

Multidetector row CT is a noninvasive modality in cardiac imaging. It provides superior resolution of coronary tree and its variant. No projectional vascular overlap is seen. Various postprocessing techniques outclass catheter angiography imaging. Definition of ostia and proximal course of the coronary arteries by Multidetector CT is better than catheter angiography.

Guidance of percutaneous coronary interventions by multidetector row computed tomography coronary angiography

Guidance of percutaneous coronary interventions (PCI) by intravascular ultrasound (IVUS) provides more precise information in terms of quantitative measurement and qualitative assessment of coronary artery disease (CAD) than does conventional angiography. Several studies have tested the efficacy of IVUS to guide stent implantation. However, the conflicting results have left behind a continued debate as to whether IVUS-guided PCI has an impact on clinical outcome and angiographic restenosis. IVUS and computed tomography coronary angiography (CTCA) share the ability to evaluate the lumen along with the vessel wall, enabling characterisation of proximal and distal reference segments. Nevertheless, IVUS imaging is expensive and usually precluded in severe stenoses. In the present article, we discuss the potential application of CTCA for the guidance of PCI, particularly of complex lesions such as chronic total occlusions (CTO) and bifurcations.

Accuracy of low-dose prospectively gated axial coronary CT angiography for the assessment of coronary artery stenosis in patients with stable heart rate

BACKGROUND

Desirable methods for cardiac CT angiography would both reduce radiation exposure from cardiac CT angiography and preserve accuracy.

OBJECTIVES

We assessed image quality, radiation dose, and diagnostic accuracy of a low-dose, prospectively gated axial cardiac CT angiography protocol for the evaluation of patients with suspected coronary artery disease (CAD).

METHODS

Fifty consecutive patients referred for diagnostic invasive coronary angiography (ICA) and with a stable heart rate < 60 beats/min after beta-blocker administration were prospectively enrolled in a single center study. Subjects underwent CT angiography with a 64-row multidetector CT scanner with a prospectively gated axial imaging protocol. If the examination was determined to be nondiagnostic, then a retrospectively gated helical scan was performed. Two reviewers independently assessed image quality and the presence of significant coronary artery stenosis (>50%).

RESULTS

Prospectively gated CT angiography was successfully performed in 46 of 50 patients. Of 794 coronary segments, 777 were determined to be of diagnostic image quality. The overall patient-based sensitivity (95% CI), specificity, positive predictive value, negative predictive value, and accuracy for the diagnosis of significant coronary stenosis were 100% (87%-100%), 75% (53%-90%), 81% (64%-93%), 100% (81%-100%), and 88% (81%-95%), respectively. The mean effective radiation dose for CT angiography and ICA were 3.4 +/- 0.4 mSv and 6.9 +/- 0.8 mSv, respectively.

CONCLUSIONS

Cardiac CT angiography performed in a prospectively gated axial mode with 64-row multidetector CT provides an accurate, low-dose alternative for the detection of CAD.

Triphasic contrast bolus for whole-chest ECG-gated 64-MDCT of patients with nonspecific chest pain: evaluation of arterial enhancement and streak artifact

OBJECTIVE

The purpose of this study was to evaluate the use of a triphasic contrast bolus for ECG-gated CT in the assessment of chest pain by measuring vascular luminal attenuation and determining the degree of contrast-related streak artifact.

MATERIALS AND METHODS

We reviewed the images from 44 ECG-gated CT examinations performed with a coronary contrast bolus modified for imaging of the entire chest. Luminal attenuation achieved with the resulting triphasic bolus was measured at specified vascular locations in the right side of the heart, pulmonary arteries, coronary arteries, and thoracic aorta. The occurrence of contrast-related streak artifact was recorded, and artifact severity was scored on a subjective 4-point scale.

RESULTS

The mean attenuation values in the pulmonary arteries (345.3 +/- 136.7 HU), coronary arteries (340.8 +/- 82.5 HU), and thoracic aorta (386.4 +/- 67.2 HU) were above a diagnostic threshold of 200 HU. Although there was no significant difference between the mean arterial values, the right-heart attenuation (281.6 +/- 121.8 HU) was significantly lower than the attenuation in the other two locations. On a location basis, 92.2% of the 1,972 arterial measurements were above the 200-HU threshold. Streak artifacts were found in 21 examinations (47.7%), and none was scored as severe. Statistical analysis revealed that the occurrence of streak artifact increased with higher right-heart attenuation.

CONCLUSION

In this series, a triphasic contrast bolus for ECG-gated whole-chest CT consistently achieved arterial attenuation above a diagnostic threshold in the pulmonary arteries, coronary arteries, and aorta. Right-heart attenuation was simultaneously reduced, which is important for decreasing the prevalence and severity of streak artifacts.

The "post-64" era of coronary CT angiography: understanding new technology from physical principles

Multidetector CT now provides noninvasive coronary imaging, and patients with a low or intermediate probability of coronary artery disease can be imaged with radiation levels comparable to catheterization. Cardiac imaging drives rapid progress in CT hardware. To best apply evolving technology, imagers and referring clinicians need a solid understanding of spatial resolution, temporal resolution, volume coverage, and radiation dose. This article defines and discusses interactions between these parameters for state-of-the-art CT.

Aneurysm of an autologous aorta to right coronary artery reverse saphenous vein graft presenting as a mediastinal mass: a case report

Aneurysmal dilation of saphenous vein grafts is a relatively rare complication of the now common surgical procedure of coronary artery bypass graft (CABG) surgery. The true prevalence of this condition is not clear, however, literature review by Jorgensen et. al. between 1975 and 2002 revealed only 76 published cases. [1] Recent review of literature, utilizing OVID (search terms: saphenous vein, aneurysm, graft, pseudoaneurysm, coronary bypass) suggests a significantly higher prevalence with 14 such cases published in a variety of multinational journals during the period of 2006 to April 2007. The causes of this dramatic increase is likely multifactorial, however, in the author's opinion, likely reflects the increased sophistication and utilization of cross sectional imaging modalities. Regardless of the true prevalence of the condition, there is little debate that the potential for serious morbidity and mortality in this patient population is significant, and that increased detection and discussion of viable therapeutic options is critical. [1] Therefore, we present a case report and discussion of a patient with symptomatic cardiac ischemia, found to have a large saphenous vein graft aneurysm (SVGA) on coronary CTA.

Prospectively gated axial CT coronary angiography: preliminary experiences with a novel low-dose technique

To assess image quality and radiation exposure with prospectively gated axial CT coronary angiography (PGA) compared to retrospectively gated helical techniques (RGH). Forty patients with suspected coronary artery disease (CAD) and a stable heart rate below 65 bpm underwent CT coronary angiography (CTCA) using a 64-channel CT system. The patient cohort consisted of 20 consecutive patients examined using a PGA technique and 20 patients examined using a standard RGH technique. Both groups were matched demographically according to age, gender, body mass index, and heart rate. For both groups, two independent observers assessed image quality for all coronary segments on an ordinal scale from 1 (nonassessable) to 5 (excellent quality). Image quality and radiation exposure were compared between patient groups. There were no significant differences in vessel-based image quality between the two groups (P > 0.05). Mean (+/- SD) effective radiation exposure in the PGA group was 3.7 +/- 0.8 mSv compared to 18.9 +/- 3.8 mSv in the RGH group without ECG-based tube current modulation (P < 0.001). Preliminary experience shows PGA technique to be a promising approach for CTCA resulting in a substantial reduction in radiation exposure with image quality comparable to that of standard RGH technique.

The triple work-up for emergency department patients with acute chest pain: how often does it occur?

OBJECTIVES

To measure the degree of overlap and diagnostic yield for evaluations of acute coronary syndrome (ACS), pulmonary embolism (PE), and aortic dissection (AD) among Emergency Department (ED) patients.

METHODS

We conducted a cross-sectional descriptive study of consecutive adult patients seen in the ED of a 78,000-annual-visit urban academic medical center. Patients who had received at least one of eight of the tests used in our ED to diagnose these three diseases were identified through three methods, and a final study population list was created. Overlap of evaluations and diagnostic yields were calculated by simple descriptive statistics.

RESULTS

Over a 2-week period, 626 patient encounters among 622 unique patients were identified. Among these 626 visits, 139 (22%) included diagnostic tests for more than one of the three diagnoses of interest. The majority of these multiple tests were for ACS plus PE (n = 121, 87% of all multiple tests), whereas a minority of patients received tests for ACS plus AD (n = 14, 10% of all multiple tests) or for the "triple work-up" of ACS plus PE plus AD (n = 4, 2.9% of all multiple tests).

CONCLUSION

Although the "triple work-up" evaluation for ACS, PE, and AD is relatively uncommon, a significant number of ED patients who are evaluated for at least one of these three major chest pain syndromes receive simultaneous testing for one of the others.

Anatomy of the heart at multidetector CT: what the radiologist needs to know

Continued improvements in multidetector computed tomographic (CT) scanners have made cardiac CT an important clinical tool that is revolutionizing cardiac imaging. Multidetector CT with submillimeter collimation and gantry rotation times under 0.5 seconds allows the acquisition of studies with high temporal resolution and isotropic voxels. The volumetric data set that is generated can be analyzed with a depth previously not possible, requiring a solid understanding of the cardiac anatomy and its appearance on CT scans and postprocessed images.

Role of cardiac computed tomography and magnetic resonance imaging in the evaluation of acute chest pain in the emergency department

Evaluation of patients presenting with chest pain to the emergency department remains a challenging task because of a variety of etiologies that range from benign to potentially fatal. Although majority of patients do not have myocardial ischemia as the cause of their presentation, the clinical work up can be time consuming, costly and inconclusive. Recent technical advances in cardiac computed tomography and magnetic resonance imaging have led to better diagnostic accuracy in evaluating patients with chest pain. In this paper, we review the role of cardiac computed tomography and magnetic resonance imaging in evaluating patients with chest pain in the emergency department.