Diagnostic Performance of Coronary CT Angiography, Stress Dual-Energy CT Perfusion, and Stress Perfusion Single-Photon Emission Computed Tomography for Coronary Artery Disease: Comparison with Combined Invasive Coronary Angiography and Stress Perfusion Cardiac MRI

Comparative Analysis of the Feasibility of Myocardial Blood Flow Index Versus CT-FFR in the Diagnosis of Suspected Coronary Artery Disease

Background

Using fluid dynamic modeling, noninvasive fractional flow reserve (FFR) derived from coronary computed tomography angiography (CCTA) data provides better anatomic and functional information than CCTA, with a high diagnostic and discriminatory value for diagnosing hemodynamically significant lesions. Myocardial blood flow index (MBFI) based on CCTA is a physiological parameter that reflects myocardial ischemia. Thus, exploring the relationship between computed tomography derived fractional flow reserve (CT-FFR) and MBFI could be clinically significant. This study aimed to investigate the relationship between CT-FFR and MBFI and to analyze the feasibility of MBFI differing from CT-FFR in diagnosing suspected coronary artery disease (CAD).

Methods

Data from 61 patients (35 males, mean age: 59.2 ± 10.02 years) with suspected CAD were retrospectively analyzed, including the imaging data of CCTA, CT-FFR, and data of invasive coronary angiography performed within one week after hospitalization. CT-FFR and MBFI were calculated, and the correlation between MBFI or CT-FFR and invasive coronary angiography (ICA) was evaluated. Using ICA (value ≥ 0.70) as the gold standard and determining the optimal cutoff value via a diagnostic test, the diagnostic performance of MBFI or CT-FFR was evaluated.

Results

MBFI and CT-FFR were negatively correlated with ICA (r = -0.3670 and -0.4922, p = 0.0036 and 0.0001, respectively). Using ICA (value of ≥ 0.70) the gold standard, the optimal cutoff value was 0.115 for MBFI, and the area under the curve (AUC) was 0.833 (95% confidence interval [CI]: 0.716-0.916, Z = 5.357, p < 0.0001); using ICA (value of ≥ 0.70) the gold standard, the optimal cutoff value was 0.80 for CT-FFR, and the area under the curve (AUC) was 0.759 (95% CI: 0.632-0.859, Z = 3.665, p = 0.0002). No significant difference was observed between the AUCs of CT-FFR and MBFI (Z = 0.786, p = 0.4316).

Conclusions

MBFI based on CCTA can be used to evaluate myocardial ischemia similar to CT-FFR in suspected CAD; however, it should be noted that CT-FFR is a functional index based on the anatomical stenosis of the coronary artery, whereas MBFI is a physiological index reflecting myocardial mass remodeling.

Raw data consistent deep learning-based field of view extension for dual-source dual-energy CT

BACKGROUND

Due to technical constraints, dual-source dual-energy CT scans may lack spectral information in the periphery of the patient.

PURPOSE

Here, we propose a deep learning-based iterative reconstruction to recover the missing spectral information outside the field of measurement (FOM) of the second source-detector pair.

METHODS

In today's Siemens dual-source CT systems, one source-detector pair (referred to as A) typically has a FOM of about 50 cm, while the FOM of the other pair (referred to as B) is limited by technical constraints to a diameter of about 35 cm. As a result, dual-energy applications are currently only available within the small FOM, limiting their use for larger patients. To derive a reconstruction at B's energy for the entire patient cross-section, we propose a deep learning-based iterative reconstruction. Starting with A's reconstruction as initial estimate, it employs a neural network in each iteration to refine the current estimate according to a raw data fidelity measure. Here, the corresponding mapping is trained using simulated chest, abdomen, and pelvis scans based on a data set containing 70 full body CT scans. Finally, the proposed approach is tested on simulated and measured dual-source dual-energy scans and compared against existing reference approaches.

RESULTS

For all test cases, the proposed approach was able to provide artifact-free CT reconstructions of B for the entire patient cross-section. Considering simulated data, the remaining error of the reconstructions is between 10 and 17 HU on average, which is about half as low as the reference approaches. A similar performance with an average error of 8 HU could be achieved for real phantom measurements.

CONCLUSIONS

The proposed approach is able to recover missing dual-energy information for patients exceeding the small 35 cm FOM of dual-source CT systems. Therefore, it potentially allows to extend dual-energy applications to the entire-patient cross section.

Dual-Energy Computed Tomography in Cardiac Imaging

Dual-energy computed tomography (DECT) acquires images using two energy spectra and offers a variation of reconstruction techniques for improved cardiac imaging. Virtual monoenergetic images decrease artifacts improving coronary plaque and stent visualization. Further, contrast attenuation is increased allowing significant reduction of contrast dose. Virtual non-contrast reconstructions enable coronary artery calcium scoring from contrast-enhanced scans. DECT provides advanced plaque imaging with detailed analysis of plaque components, indicating plaque stability. Extracellular volume assessment using DECT offers noninvasive detection of myocardial fibrosis. This review aims to outline the current cardiac applications of DECT, summarize recent literature, and discuss their findings.

Cardiac Computed Tomography Perfusion: Contrast Agents, Challenges and Emerging Methodologies from Preclinical Research to the Clinics

Computed Tomography (CT) has long been regarded as a purely anatomical imaging modality. Recent advances on CT technology and Contrast Agents (CA) in both clinical and preclinical cardiac imaging offer opportunities for the use of CT in functional imaging. Combined with modern ECG-gating techniques, functional CT has now become a reality allowing a comprehensive evaluation of myocardial global and regional function, perfusion and coronary angiography. This article aims at reviewing the current status of cardiac CT perfusion and micro-CT perfusion with established and experimental scanners and contrast agents, from clinical practice to the experimental domain of investigations based on animal models of heart diseases.

The value of coronary computed tomography angiography in assessing the cardiac circulation of an outpatient-based population

To evaluate the perfusion of coronary circulation and its related factors and the difference in the peak filling times in aortic sinus and coronary sinus by coronary computed tomography angiography (CCTA).From January 1 to August 1, 2018, 61 outpatients with angina pectoris were recruited, completed a questionnaire about risk factors and underwent CCTA, which was also used to assess the stenosis of different coronary artery segments.The duration of circulation was 9.50 ± 2.43 seconds in patients with flat T wave, which was shorter than the duration in normal subjects (P = .021). However, other cardiovascular risk factors showed no effect on the duration of circulation. In addition, the duration of circulation was closely related to the peak filling time of coronary sinus [r(s) = 0.681]. We further divided the circulation time difference (delta) values into 3 levels (<6, 6-12, and ≥12 seconds).It showed that the circulation duration (Y) was associated with:Therefore, the cardiac circulation duration was negatively related to the degree of stenosis in the 1 diagonal and proximal LCA.It compensates for the inability of CCTA to assess circulation at rest simply by determining the peak filling time in the aortic sinus and the coronary sinus. Moderate cardiac microcirculation duration was related to a low incidence of clinical symptoms and electrocardiogram disorders, which was determined mainly by the diagonal and left circumflex branch 1 of LCA.

Dual-energy CT and coronary imaging

Dual-energy computed tomography has been proposed for enhancing the evaluation of coronary artery disease in many fronts. However, the clinical translation of such applications has followed a slower pace of clinical translation. This paper will review the evidence supporting the use of dual-energy computed tomography in coronary artery disease (CAD) and provide some practical illustrations, while underscoring the challenges and gaps in knowledge that have contributed to this phenomenon.

Myocardial Blood Flow Quantified by Low-Dose Dynamic CT Myocardial Perfusion Imaging Is Associated with Peak Troponin Level and Impaired Left Ventricle Function in Patients with ST-Elevated Myocardial Infarction

Objective

To investigate the association of myocardial blood flow (MBF) quantified by dynamic computed tomography (CT) myocardial perfusion imaging (MPI) with troponin level and left ventricle (LV) function in patients with ST-segment elevated myocardial infarction (STEMI).

Materials and Methods

Thirty-five STEMI patients who successfully had undergone reperfusion treatment within 1 week of their infarction were consecutively enrolled. All patients were referred for dynamic CT-MPI. Serial high-sensitivity troponin T (hs-TnT) levels and left ventricular ejection fraction (LVEF) measured by echocardiography were recorded. Twenty-six patients with 427 segments were included for analysis. Various quantitative parameters derived from dynamic CT-MPI were analyzed to determine if there was a correlation between hs-TnT levels and LVEF on admission and again at the 6-month mark.

Results

The mean radiation dose for dynamic CT-MPI was 3.2 ± 1.1 mSv. Infarcted territories had significantly lower MBF (30.5 ± 7.4 mL/min/100 mL versus 73.4 ± 8.1 mL/min/100 mL, p < 0.001) and myocardial blood volume (MBV) (2.8 ± 0.9 mL/100 mL versus 4.2 ± 1.1 mL/100 mL, p = 0.044) compared with those of reference territories. MBF showed the best correlation with the level of peak hs-TnT (r = −0.682, p < 0.001), and MBV showed a moderate correlation with the level of peak hs-TnT (r = −0.437, p = 0.026); however, the other parameters did not show any significant correlation with hs-TnT levels. As for the association with LV function, only MBF was significantly correlated with LVEF at the time of admission (r = 0.469, p = 0.016) and at 6 months (r = 0.585, p = 0.001).

Conclusion

MBF quantified by dynamic CT-MPI is significantly inversely correlated with the level of peak hs-TnT. In addition, patients with lower MBF tended to have impaired LV function at the time of their admission and at 6 months.

Age of Data in Contemporary Research Articles Published in Representative General Radiology Journals

Objective

To analyze and compare the age of data in contemporary research articles published in representative general radiology journals.

Materials and Methods

We searched for articles reporting original research studies analyzing patient data that were published in the print issues of the Korean Journal of Radiology (KJR), European Radiology (ER), and Radiology in 2017. Eligible articles were reviewed to extract data collection period (time from first patient recruitment to last patient follow-up) and age of data (time between data collection end and publication). The journals were compared in terms of the proportion of articles reporting the data collection period to the level of calendar month and regarding the age of data.

Results

There were 50, 492, and 254 eligible articles in KJR, ER, and Radiology, respectively. Of these, 44 (88%; 95% confidence interval [CI]: 75.8-94.8%), 359 (73%; 95% CI: 68.9-76.7%), and 211 (83.1%; 95% CI: 78-87.2%) articles, respectively, provided enough details of data collection period, revealing a significant difference between ER and Radiology (p = 0.002). The age of data was significantly greater in KJR (median age: 826 days; range: 299-2843 days) than in ER (median age: 570 days; range: 56-4742 days; p < 0.001) and Radiology (median age: 618; range: 75-4271 days; p < 0.001).

Conclusion

Korean Journal of Radiology did not fall behind ER or Radiology in reporting of data collection period, but showed a significantly greater age of data than ER and Radiology, suggesting that KJR should take measures to improve the timeliness of its data.

Comparison of the Diagnostic Accuracies of 1.5T and 3T Stress Myocardial Perfusion Cardiovascular Magnetic Resonance for Detecting Significant Coronary Artery Disease

Objective

To compare the diagnostic performance of cardiovascular magnetic resonance (CMR) myocardial perfusion at 1.5- and 3-tesla (T) for detecting significant coronary artery disease (CAD), with invasive coronary angiography (ICA) as the reference method.

Materials and Methods

We prospectively enrolled 281 patients (age 62.4 ± 8.3 years, 193 men) with suspected or known CAD who had undergone 1.5T or 3T CMR and ICA. Two independent radiologists interpreted perfusion defects. With ICA as the reference standard, the diagnostic performance of 1.5T and 3T CMR for identifying significant CAD (≥ 50% diameter reduction of the left main and ≥ 70% diameter reduction of other epicardial arteries) was determined.

Results

No differences were observed in baseline characteristics or prevalence of CAD and old myocardial infarction (MI) using 1.5T (n = 135) or 3T (n = 146) systems. Sensitivity, specificity, positive and negative predictive values, and area under the receiver operating characteristic curve (AUC) for detecting significant CAD were similar between the 1.5T (84%, 64%, 74%, 76%, and 0.75 per patient and 68%, 83%, 66%, 84%, and 0.76 per vessel) and 3T (80%, 71%, 71%, 80%, and 0.76 per patient and 75%, 86%, 64%, 91%, and 0.81 per vessel) systems. In patients with multi-vessel CAD without old MI, the sensitivity, specificity, and AUC with 3T were greater than those with 1.5T on a per-vessel basis (71% vs. 36%, 92% vs. 69%, and 0.82 vs. 0.53, respectively).

Conclusion

3T CMR has similar diagnostic performance to 1.5T CMR in detecting significant CAD, except for higher diagnostic performance in patients with multi-vessel CAD without old MI.

Evaluation of dual energy computed tomography iodine mapping within the myocardial blood pool for detection of acute myocardial infarction: correlation with histopathological findings in a porcine model

OBJECTIVE

We assessed the diagnostic value of "one-step" dual energy CT (DECT) in combination with coronary CT angiography and iodine mapping within the myocardial blood pool in detecting acute myocardial infarction (AMI).

METHODS

Five minipigs were subjected to transcatheter embolization of coronary artery with a gelatin sponge to induce AMI. Arterial-phase myocardial DECT imaging was carried out 1 h before and 24 h after embolism of the coronary. Color-coded iodine maps were used to evaluate myocardial blood pool deficits in the 17-segment model. Myocardial DECT imaging 24 h after MI induction was used for final comparison with post-mortem histology.

RESULTS

We found a sensitivity of 95.55% and a specificity of 95%, respectively, for AMI detection by DECT-based iodine mapping within the myocardial blood pool. The dose-length product values were 219.4 ± 60.9 mGy.cm (172-321 mGy.cm) and the effective radiation dose was 5.7 ± 1.5 mSv (4.4-8.3 mSv).

CONCLUSION

This experimental study demonstrated that DECT-based iodine mapping shows a high value for the detection of myocardial perfusion defects in the first-pass myocardial perfusion. Hybrid heart images obtained by coronary CT angiography and DECT-based iodine mapping may yield valuable data and help clinicians accurately identify cases requiring further treatment after AMI. Advances in knowledge: This study demonstrated that DECT-based iodine mapping is a promising new technique for the detection of myocardial perfusion defects in the first-pass myocardial perfusion.

Congenital absence of the right coronary artery: A case report and literature review

RATIONALE

Congenital absence of the right coronary artery (RCA) is a rare congenital malformation of the cardiovascular system which may have fatal consequences.

PATIENT CONCERNS

A 63-year-old man with a 5-year history of chest pain after exertion which had aggravated for >1 month was advised for admission and computed tomography angiography (CTA) examination of the coronary artery to screen for coronary artery disease (CAD).

DIAGNOSES

The coronary artery CTA showed absence of RCA arising form the aortic root after which a selective coronary angiography (SCA) examination was done that confirmed the diagnosis of congenital absence of RCA.

INTERVENTIONS

As the patient refused to receive a coronary artery stent implantation citing his financial condition, only symptomatic treatment was given.

OUTCOMES

The patient requested to be discharged from the hospital against the advice of his doctors 1 week later. A query made by the telephone suggested that the patient's symptoms were under control by use of prescribed medications only.

LESSONS

Although being a rare condition, a coronary artery CTA examination can be utilized to screen for congenital absence of RCA and other varieties of cardiovascular malformation whereas SCA can be performed to confirm the diagnosis.