Development and validation of a predictive screening tool for uninterpretable coronary CT angiography results

Virtual calcium removal in calcified coronary arteries with photon-counting detector CT-first in-vivo experience

Purpose

To evaluate the feasibility and accuracy of quantification of calcified coronary stenoses using virtual non-calcium (VNCa) images in coronary CT angiography (CCTA) with photon-counting detector (PCD) CT compared with quantitative coronary angiography (QCA).

Materials and methods

This retrospective, institutional-review board approved study included consecutive patients with calcified coronary artery plaques undergoing CCTA with PCD-CT and invasive coronary angiography between July and December 2022. Virtual monoenergetic images (VMI) and VNCa images were reconstructed. Diameter stenoses were quantified on VMI and VNCa images by two readers. 3D-QCA served as the standard of reference. Measurements were compared using Bland-Altman analyses, Wilcoxon tests, and intraclass correlation coefficients (ICC).

Results

Thirty patients [mean age, 64 years ± 8 (standard deviation); 26 men] with 81 coronary stenoses from calcified plaques were included. Ten of the 81 stenoses (12%) had to be excluded because of erroneous plaque subtraction on VNCa images. Median diameter stenosis determined on 3D-QCA was 22% (interquartile range, 11%-35%; total range, 4%-88%). As compared with 3D-QCA, VMI overestimated diameter stenoses (mean differences -10%, p < .001, ICC: .87 and -7%, p < .001, ICC: .84 for reader 1 and 2, respectively), whereas VNCa images showed similar diameter stenoses (mean differences 0%, p = .68, ICC: .94 and 1%, p = .07, ICC: .93 for reader 1 and 2, respectively).

Conclusion

First experience in mainly minimal to moderate stenoses suggests that virtual calcium removal in CCTA with PCD-CT, when feasible, has the potential to improve the quantification of calcified stenoses.

Cardiac imaging with photon counting CT

CT of the heart, in particular ECG-controlled coronary CT angiography (cCTA), has become clinical routine due to rapid technical progress with ever new generations of CT equipment. Recently, CT scanners with photon-counting detectors (PCD) have been introduced which have the potential to address some of the remaining challenges for cardiac CT, such as limited spatial resolution and lack of high-quality spectral data. In this review article, we briefly discuss the technical principles of photon-counting detector CT, and we give an overview on how the improved spatial resolution of photon-counting detector CT and the routine availability of spectral data can benefit cardiac applications. We focus on coronary artery calcium scoring, cCTA, and on the evaluation of the myocardium.

Pre-screening for non-diagnostic coronary computed tomography angiography

Aims

Indiscriminate coronary computed tomography angiography (CCTA) referrals for suspected coronary artery disease could result in a higher rate of equivocal and non-diagnostic studies, leading to inappropriate downstream resource utilization or delayed time to diagnosis. We sought to develop a simple clinical tool for predicting the likelihood of a non-diagnostic CCTA to help identify patients who might be better served with a different test.

Methods and results

We developed a clinical scoring system from a cohort of 21 492 consecutive patients who underwent CCTA between February 2006 and May 2021. Coronary computed tomography angiography study results were categorized as normal, abnormal, or non-diagnostic. Multivariable logistic regression analysis was conducted to produce a model that predicted the likelihood of a non-diagnostic test. Machine learning (ML) models were utilized to validate the predictor selection and prediction performance. Both logistic regression and ML models achieved fair discriminate ability with an area under the curve of 0.630 [95% confidence interval (CI) 0.618-0.641] and 0.634 (95% CI 0.612-0.656), respectively. The presence of a cardiac implant and weight >100 kg were among the most influential predictors of a non-diagnostic study.

Conclusion

We developed a model that could be implemented at the 'point-of-scheduling' to identify patients who would be best served by another non-invasive diagnostic test.

Safety, accuracy, and prediction of prognosis in patients with end-stage chronic kidney disease undergoing dobutamine stress cardiac magnetic resonance imaging

Introduction

Advanced chronic kidney disease (CKD) is an independent risk factor for coronary artery disease (CAD). Due to its unique uremia-derived pathophysiology of atherosclerosis and the limitations of using potentially harmful contrast agents, the best non-invasive approach to assess CAD in these patients remains unclear. We sought to investigate the accuracy, safety, and prognosis of patients with severe CKD undergoing dobutamine stress cardiac magnetic resonance imaging (CMR).

Materials and methods

In this retrospective, single-center study, patients on dialysis or with a glomerular filtration rate of <15 ml/min/1.73 m2 who underwent dobutamine stress CMR were included. A rest and stress wall motion analysis was performed using dobutamine/atropine as stressor. The target heart rate was 85% of the maximum heart rate. Periprocedural adverse events and 1-year follow-up data were obtained.

Results

A total of 176 patients (127 men, 49 women) with a mean age of 60.9 ± 14.7 years were included, of which 156 patients were on permanent dialysis. Short-term symptoms such as angina or shortness of breath during stress CMR were frequent (22.1%), but major complications were rare (one patient with myocardial infarction, 0.6%). The 1-year event rate was high (16.4%) with a significant independent correlation to reduced ejection fraction at rest (p = 0.037) and failure to achieve the target heart rate (p = 0.029). The overall accuracy for predicting significant CAD was good (sensitivity of 71.4%, specificity of 98.4%) and excellent if the target heart rate was achieved (83.3%, 97.9%). A negative stress CMR was highly predictive for the absence of major adverse cardiac event or any coronary revascularization during the 1-year follow-up (negative predictive value of 95.0%).

Discussion

Dobutamine stress CMR is a safe and accurate diagnostic imaging technique in patients at advanced stages of chronic kidney disease. A reduced ejection fraction and the inability to reach the target heart rate are independent predictors of a poor outcome.

Technical Basics and Clinical Benefits of Photon-Counting CT

ABSTRACT

Novel photon-counting detector CT (PCD-CT) has the potential to address the limitations of previous CT systems, such as insufficient spatial resolution, limited accuracy in detecting small low-contrast structures, or missing routine availability of spectral information. In this review article, we explain the basic principles and potential clinical benefits of PCD-CT, with a focus on recent literature that has grown rapidly since the commercial introduction of a clinically approved PCD-CT.

Coronary Computed Tomography vs. Cardiac Magnetic Resonance Imaging in the Evaluation of Coronary Artery Disease

Coronary artery disease (CAD) represents a widespread burden to both individual and public health, steadily rising across the globe. The current guidelines recommend non-invasive anatomical or functional testing prior to invasive procedures. Both coronary computed tomography angiography (cCTA) and stress cardiac magnetic resonance imaging (CMR) are appropriate imaging modalities, which are increasingly used in these patients. Both exhibit excellent safety profiles and high diagnostic accuracy. In the last decade, cCTA image quality has improved, radiation exposure has decreased and functional information such as CT-derived fractional flow reserve or perfusion can complement anatomic evaluation. CMR has become more robust and faster, and advances have been made in functional assessment and tissue characterization allowing for earlier and better risk stratification. This review compares both imaging modalities regarding their strengths and weaknesses in the assessment of CAD and aims to give physicians rationales to select the most appropriate modality for individual patients.

Coronary computed tomography in heart transplant patients: detection of significant stenosis and cardiac allograft vasculopathy, image quality, and radiation dose

Background Cardiac allograft vasculopathy (CAV) is an accelerated form of atherosclerosis unique to heart transplant (HTX) patients. Purpose To investigate the detection of significant coronary artery stenosis and CAV, determinants of image quality, and the radiation dose in coronary computed tomography angiography (CCTA) of HTX patients with 64-slice multidetector CT (64-MDCT). Material and Methods Fifty-two HTX recipients scheduled for invasive coronary angiography (ICA) were prospectively enrolled and underwent CCTA before ICA with intravascular ultrasound (IVUS). Results Interpretable CCTA images were acquired in 570 (95%) coronary artery segments ≥2 mm in diameter. Sensitivity, specificity, and positive and negative predictive values of CCTA for the detection of segments with significant stenosis (lumen reduction ≥50%) on ICA were 100%, 98%, 7.7%, and 100%, respectively. Twelve significant stenoses were located in segments with uninterpretable image quality or vessel diameter <2 mm; only one was eligible for intervention. IVUS detected CAV (maximal intimal thickness ≥0.5 mm) in 33/41 (81%) patients; CCTA and ICA identified CAV (any wall or luminal irregularity) in 18 (44%) and 14 (34%) of these 33 patients, respectively. The mean estimated radiation dose was 19.0 ± 3.4 mSv for CCTA and 5.7 ± 3.3 mSv for ICA ( P < 0.001). Conclusion CCTA with interpretable image quality had a high negative predictive value for ruling out significant stenoses suitable for intervention. The modest detection of CAV by CCTA implied a limited value in identifying subtle CAV. The high estimated radiation dose for 64-MDCT is of concern considering the need for repetitive examinations in the HTX population.

Non-diagnostic coronary artery calcification and stenosis: a correlation of coronary computed tomography angiography and invasive coronary angiography

Background Heavy coronary artery calcification (CAC) impairs diagnostic accuracy of coronary computed tomography angiography (cCTA) and is considered to be a major limitation. Purpose To investigate the effect of non-evaluable CAC seen on cCTA on clinical decision-making by determining the degree of subsequent invasive testing and to assess the relationship between non-evaluable segments containing CAC and significant stenosis as seen in invasive coronary angiography (ICA). Material and Methods The study comprised of 356 patients who underwent cCTA and subsequent ICA within 2 months between 2005 and 2009. Clinical reports were reviewed to identify the indications for referral to ICA. In a subset of 68 patients where non-diagnostic CAC on cCTA and significant stenosis on ICA were present in the same segment, we correlated and analyzed the underlying stenosis severity of the lesion on ICA to the cCTA. Lesions with CAC were analyzed in a standardized fashion by application of reading rules. Results Non-diagnostic CAC on cCTA prompted ICA in 5.6% of patients. CAC occurred at the site of maximum stenosis in segments with stenosis <50% (95.9% [47/49]), 50-69% (82.4% [28/34]), 70-99% (64.5% [31/48]), and 100% (33.3% [1/3]). At the point of maximum calcium deposit, non-obstructive disease was present in 61.2%. Application of reading rules resulted in a 44% reduction in non-diagnostic cCTA reads. Conclusion Severe CAC may prompt further investigation with ICA. There is less CAC with increasing lesion severity at the point of maximum stenosis. Additional application of reading rules improved non-diagnostic cCTA reads.

Difference of coronary stenosis severity between systolic and diastolic phases in quantitative CT angiography

BACKGROUND

To compare the difference of coronary diameter stenosis by quantitative analysis of CT angiography (QCT) in the systolic (QCT-S) and diastolic phase (QCT-D) of the cardiac cycle, with invasive catheter angiography (QCA) as reference standard.

METHODS

A total of 109 patients (57.5 ± 10.6 years, 78.9% male) with suspected coronary artery disease (CAD) who underwent both CT angiography and invasive catheter angiography were retrospectively included in this study. Coronary diameter stenoses in systolic and diastolic coronary CTA reconstructions were compared with QCA.

RESULTS

Mean time interval between CT angiography and invasive angiography was 17.4 ± 4.4 days. QCT-D overestimated coronary diameter stenosis by 5.7%-8.5% while QCT-S overestimated coronary diameter stenosis by 9.4%-11.9% (p < 0.05). In calcified lesions, QCT-D overestimated coronary diameter stenosis by 13.2 ± 4.3%, while QCT-S overestimated by stenosis by 16.6 ± 4.3% (p < 0.05).

CONCLUSIONS

Coronary diameter stenosis was overestimated by QCT-D as well as QCT-S, respectively, when compared with QCA. Overestimation was more pronounced in calcified lesions.

Recent developments in the use of computed tomography scanners in coronary artery imaging

INTRODUCTION

Within the past decade, substantial evolution of Coronary CT Angiography (CCTA) has affected evaluation and management of coronary artery disease. In particular, technical advancement of hardware technology and image reconstruction of CT scanners have played an important role in this context making it possible to acquire abundant data with excellent temporal and spatial resolution within a shorter scan time. In addition, a concern related to the high radiation exposure in the initial noninvasive coronary artery imaging has triggered improvement in dose reduction techniques.

AREAS COVERED

In this review article, we have focused on recent technological developments in CT scanners and the impact of these developments on CCTA parameters. Expert Commentary: CCTA plays an important role in coronary artery disease management, and technical development of the CT scanners can be expected to address and remedy technical limitations.

Prognostic value of coronary CTA vs. exercise treadmill testing: results from the Partners registry

AIMS

We sought to compare the complementary prognostic value of exercise treadmill testing (ETT) and coronary computed tomographic angiography (CTA) among patients referred for both exams.

METHODS AND RESULTS

We studied 582 patients without known coronary artery disease (CAD) who were clinically referred for ETT and CTA within 6 months. Patients were followed for cardiovascular (CV) death, non-fatal myocardial infarction (MI), or late revascularization (>90 days), stratified by Duke Treadmill Score (DTS) and CAD severity (≥50% stenosis). Mean age was 54 ± 13 years (63% male). In median follow-up of 40 months, there were 3 CV deaths, 7 non-fatal MIs, and 26 late revascularizations. ETT was inconclusive in 23%, positive in 31%, and negative in 46%. CTA demonstrated no CAD in 37%, non-obstructive CAD in 28%, and obstructive CAD in 35%. Among low-risk ETT patients (n = 326), there were 3 MI, 10 late revascularizations, and the frequent presence of non-obstructive (32%, n = 105) and obstructive CAD (27%, n = 88). When present, ETT features (i.e., angina, DTS, ischaemic electrocardiogram changes, and exercise capacity) individually failed to predict CV death/MI after adjustment for Morise score. Conversely, both obstructive CAD [HR 4.9 (1.0-23.3), P = 0.048] and CAD extent by segment involvement score >4 [HR 3.9 (1.0-15.2), P = 0.049] predicted increased risk for CV death or MI.

CONCLUSION

Patients with a low-risk ETT have an excellent prognosis at 40 months, despite the frequent presence of non-obstructive (32%) and obstructive (27%) CAD. In patients with an intermediate- to high-risk ETT (DTS <5), CTA can provide incremental risk stratification for future CV events.

Diagnostic accuracy of computed tomography angiography for the detection of coronary artery disease in patients referred for transcatheter aortic valve implantation

OBJECTIVES

We aimed to investigate the diagnostic accuracy of a standardized computed tomography angiography (CTA) for the identification of significant coronary artery disease (CAD) in patients evaluated for transcatheter aortic valve implantation (TAVI).

BACKGROUND

The diagnostic performance of CTA for the detection of CAD in patients with aortic stenosis referred for TAVI has thus far not been validated.

METHODS

A consecutive series of 475 patients (194 male, mean age: 82 ± 6 years) with CTA data sets obtained during the routine diagnostic work-up before TAVI were included. A total of 6,603 coronary segments in 1,899 coronary arteries ≥ 1.5 mm in diameter and 271 grafts were evaluated for the presence of significant CAD defined as ≥ 50% luminal narrowing. Results were compared with invasive coronary angiography as the standard of reference.

RESULTS

Prevalence of significant CAD was 57% (270/475), and 5,925 coronary segments (90%) and 257 bypass grafts (95%) were evaluable by CTA. In the per-patient analysis, sensitivity (Se), specificity, and positive and negative predictive values (NPV) were 98, 37, 67 and 94%, respectively. CTA showed satisfactory ability to exclude significant CAD in the following subgroups: (1) patients (221/475) without prior known CAD (Se: 97%, NPV: 97%), (2) patients (13/475) without prior known CAD and absent coronary calcification (NPV: 100%) and (3) bypass grafts (Se: 97%, NPV: 99%).

CONCLUSIONS

Comprehensive evaluation of a pre-TAVI CTA could prove to be a useful rule-out test for significant CAD in selected subgroups of patients.

Assessment of coronary artery disease using coronary computed tomography angiography in patients with aortic valve stenosis referred for surgical aortic valve replacement

BACKGROUND

In patients referred for aortic valve replacement (AVR) a pre-surgical assessment of coronary artery disease is mandatory to determine the possible need for additional coronary artery bypass grafting. The diagnostic accuracy of coronary computed tomography angiography (coronary CTA) was evaluated in patients with aortic valve stenosis referred for surgical AVR.

METHODS

Between March 2008 and March 2010 a total of 181 consecutive patients were included. All patients underwent pre-surgical coronary CTA (64- or 320-detector CT scanner) and invasive coronary angiography (ICA). The analyses were performed blinded to each other.

RESULTS

The mean ± SD age of the included patients was 71 ± 9 years and 59% were male. The prevalence of significant coronary artery stenosis >70% by ICA was 36%. Average heart rate during coronary CTA was 65 ± 16 b pm. In a patient based analysis 94% of the patients (171/181) were considered fully evaluable. Coronary CTA had a sensitivity of 68%, a specificity of 91%, a positive predictive value of 81%, and a negative predictive value of 83%. Advanced age, obstructive lung disease, NYHA function class III/IV, and high Agatston score were found to be significantly associated with disagreement between ICA and coronary CTA in univariate analysis.

CONCLUSION

In patients with aortic valve stenosis referred for surgical AVR the diagnostic accuracy of coronary CTA to identify significant coronary artery disease is moderate. Coronary CTA may be used successfully in a subset of patients with low age, no chronic obstructive lung disease, NYHA function class<III and low coronary Agatston score.

Circulation: Cardiovascular Imaging Editors’ Picks

The following articles are being highlighted as part of Circulation: Cardiovascular Imaging Topic Review. This series summarizes the most important articles, as selected by the editors, that have been published in the Circulation portfolio. The studies included in this article represent the most significant research in advances in the use of imaging biomarkers for risk prediction.

Diagnostic accuracy of 320-row computed tomography as compared with invasive coronary angiography in unselected, consecutive patients with suspected coronary artery disease

Noninvasive coronary angiography with multislice computed tomography (CT) scanners is feasible with high sensitivity and negative predictive value. The radiation exposure associated with this technique, however, is high and concerns in the widespread use of CT have arisen. We evaluated the diagnostic accuracy of coronary angiography using 320-row CT, which avoids exposure-intensive overscanning and overranging. We prospectively studied 118 unselected consecutive patients with suspected coronary artery disease (CAD) referred for invasive coronary angiography (ICA). All patients had 320-row CT within 1 week of ICA, which, together with quantitative analysis, served as the reference standard. Of the 65 out of 118 patients who were diagnosed as having CAD by ICA, 64 (98 %) were correctly identified at 320-row CT. Noteworthy, 320-row CT correctly detected CAD in 3 patients with atrial fibrillation and ruled out the disease in the other 8 patients. From 151 significant coronary stenoses detected on ICA, 137 (91 %) were correctly identified with 320-row CT. In the per-patient analysis, sensitivity and specificity of 320-row CT were 98 and 91 %, respectively. In the per-vessel analysis, sensitivity and specificity of 320-row CT were 93 and 95 %, respectively. In the per segment analysis, sensitivity and specificity of 320-row CT were 91 and 99 %, respectively. Diameter stenosis determined with the use of CT showed good correlation with ICA (P < 0.001, R = 0.81) without significant underestimation or overestimation (-3.1 ± 24.4 %; P = 0.08). Comparison of CT with ICA revealed a significantly smaller effective radiation dose (3.1 ± 2.3 vs. 6.5 ± 4.2 mSv; P < 0.05) and amount of contrast agent required (99 ± 51 vs. 65 ± 42 ml, P < 0.05) for 320 row CT. The present study in an unselected population including patients with atrial fibrillation demonstrates that 320-row CT may significantly reduce the radiation dose and amount of contrast agent required compared with ICA while maintaining a very high diagnostic accuracy.