Richard R. Bayer

Diagnostic value of quantitative stenosis predictors with coronary CT angiography compared to invasive fractional flow reserve

OBJECTIVE To evaluate the diagnostic performance of CCTA-derived stenosis predictors including CT-FFR for the detection of ischemia-inducing stenosis compared to invasive FFR. MATERIALS AND METHODS Stenosis parameters were assessed using dual-source CT (DSCT). All patients underwent both CCTA and invasive FFR within 3 months and were retrospectively analyzed. Observers visually assessed all CCTA studies and performed multiple lesion measurements. Lesion length/minimal luminal diameter(4) (LL/MLD(4)), transluminal attenuation gradient (TAG), corrected coronary attenuation (CCO) and CT-FFR were calculated. RESULTS The cohort included 32 patients (58±12 years, 66%male). Among 32 coronary lesions, 8 (25%) were considered hemodynamically significant with an FFR <0.80. Compared to invasive FFR, the per-vessel sensitivity and specificity of CCTA, CT-FFR, LL/MLD(4), CCO and TAG for detecting hemodynamically significant lesions were 100% and 54%, 100% and 91%, 85% and 92%, 66% and 88%, 37% and 58%, respectively. Receiver operating characteristics analysis resulted in an area under the curve of 0.91 for CT-FFR (p=0.0005), 0.88 for LL/MLD(4) (p<0.0001), 0.85 for CCO (p<0.0001). TAG with an AUC of 0.67 (p=0.152) was unable to discriminate between vessels with or without hemodynamically significant lesions. CONCLUSION CT-FFR, LL/MLD(4) and CCO provide enhanced diagnostic performance over CCTA analysis alone for discrimination of hemodynamically significant coronary stenosis.

CT Myocardial Perfusion Imaging

OBJECTIVE. CT myocardial perfusion imaging is rapidly becoming an important adjunct to coronary CT angiography for the anatomic and functional assessment of coronary artery disease with a single modality. Existing techniques for CT myocardial perfusion imaging include static techniques, which provide a snapshot of the myocardial blood pool, and dynamic techniques. CONCLUSION. This review provides a systematic overview of the presently available approaches for the assessment of myocardial perfusion at CT, including diagnostic accuracy and limitations.

Dual-Source CT Imaging to Plan Transcatheter Aortic Valve Replacement: Accuracy for Diagnosis of Obstructive Coronary Artery Disease

PURPOSE To assess the accuracy of computed tomographic (CT) examinations performed for the purpose of transcatheter aortic valve replacement (TAVR) planning to diagnose obstructive coronary artery disease (CAD). MATERIALS AND METHODS With institutional review board approval, waivers of informed consent, and in compliance with HIPAA, 100 consecutive TAVR candidates (61 men, mean age 79.6 years ± 9.9) who underwent both TAVR planning CT (with a dual-source CT system) and coronary catheter (CC) angiographic imaging were retrospectively analyzed. At both modalities, the presence of stenosis in the native coronary arteries was assessed. Additionally, all coronary bypass grafts were rated as patent or occluded. With CC angiographic imaging as the reference standard, the accuracy of CT for lesion detection on a per-vessel and per-patient basis was calculated. The accuracy of CT for the assessment of graft patency was also analyzed. RESULTS For per-vessel and per-patient analysis for the detection of stenosis that was 50% or more in the native coronary arteries, CT imaging had, respectively, 94.4% and 98.6% sensitivity, 68.4% and 55.6% specificity, 94.7% and 93.8% negative predictive value (NPV), and 67.0% and 85.7% positive predictive value. Per-patient sensitivity of stenosis 50% or greater with CT for greater than 70% stenosis at CC angiographic imaging was 100%. All 12 vessels in which percutaneous coronary intervention was performed were correctly identified as demonstrating stenosis 50% or greater with CT. There was agreement between CT and CC angiographic imaging regarding graft patency in 114 of 115 grafts identified with CC angiographic imaging. CONCLUSION TAVR planning CT has high sensitivity and NPV in excluding obstructive CAD. An additional preprocedural CC angiographic examination may not be required in TAVR candidates with a CT examination that does not show obstructive CAD.

Coronary Computed Tomographic Angiography in Clinical Practice: State of the Art

In patients with stable chest pain, coronary CT angiography (CCTA) has demonstrated high accuracy in excluding coronary artery disease and CCTA findings carry prognostic significance for the occurrence of future cardiovascular events. Increasingly, CCTA has been adopted as a triage tool in patients with acute chest pain. In specific clinical scenarios, CCTA further represents a useful tool to exclude an ischemic etiology in patients with cardiac arrhythmias or newly diagnosed heart failure. Several novel techniques are currently being investigated which may extend the ability of CCTA to characterize and quantify coronary artery plaque and assess the hemodynamic significance of stenosis.

Computed Tomography Imaging of Coronary Artery Plaque: Characterization and Prognosis

The exact definition and prognostication of vulnerable plaque remain elusive, and multiple imaging modalities aim to identify these plaques. As a noninvasive technique for the diagnosis of coronary artery disease, coronary computed tomography angiography has become increasingly utilized, primarily in patients with an elevated cardiovascular risk profile. Recent advances in technical methods have allowed for improved visualization of the vessel wall and surrounding tissue, allowing for improved characterization of vulnerable plaques by identifying features such as low-density plaques, positive remodeling, and spotty calcification. Quantification and qualification of these plaques may enhance the ability to predict future cardiovascular events.

Coronary CT Angiography–derived Fractional Flow Reserve

Invasive coronary angiography (ICA) with measurement of fractional flow reserve (FFR) by means of a pressure wire technique is the established reference standard for the functional assessment of coronary artery disease (CAD) ( 1 , 2 ). Coronary computed tomographic (CT) angiography has emerged as a noninvasive method for direct assessment of CAD and plaque characterization with high diagnostic accuracy compared with ICA ( 3 , 4 ). However, the solely anatomic assessment provided with both coronary CT angiography and ICA has poor discriminatory power for ischemia-inducing lesions. FFR derived from standard coronary CT angiography (FFRCT) data sets by using any of several advanced computational analytic approaches enables combined anatomic and hemodynamic assessment of a coronary lesion by a single noninvasive test. Current technical approaches to the calculation of FFRCT include algorithms based on full- and reduced-order computational fluid dynamic modeling, as well as artificial intelligence deep machine learning ( 5 , 6 ). A growing body of evidence has validated the diagnostic accuracy of FFRCT techniques compared with invasive FFR. Improved therapeutic guidance has been demonstrated, showing the potential of FFRCT to streamline and rationalize the care of patients suspected of having CAD and improve outcomes while reducing overall health care costs ( 7 , 8 ). The purpose of this review is to describe the scientific principles, clinical validation, and implementation of various FFRCT approaches, their precursors, and related imaging tests.

Low contrast medium-volume third-generation dual-source computed tomography angiography for transcatheter aortic valve replacement planning.

PurposeTo investigate feasibility, image quality and safety of low-tube-voltage, low-contrast-volume comprehensive cardiac and aortoiliac CT angiography (CTA) for planning transcatheter aortic valve replacement (TAVR).Materials and methodsForty consecutive TAVR candidates prospectively underwent combined CTA of the aortic root and vascular access route (270 mgI/ml iodixanol). Patients were assigned to group A (second-generation dual-source CT [DSCT], 100 kV, 60 ml contrast, 4.0 ml/s flow rate) or group B (third-generation DSCT, 70 kV, 40 ml contrast, 2.5 ml/s flow rate). Vascular attenuation, noise, signal-to-noise (SNR) and contrast-to-noise ratios (CNR) were compared. Subjective image quality was assessed by two observers. Estimated glomerular filtration (eGFR) at CTA and follow-up were measured.ResultsBesides a higher body-mass-index in group B (24.8±3.8 kg/m2 vs. 28.1±5.4 kg/m2, P=0.0339), patient characteristics between groups were similar (P≥0.0922). Aortoiliac SNR (P=0.0003) was higher in group B. Cardiac SNR (P=0.0003) and CNR (P=0.0181) were higher in group A. Subjective image quality was similar (P≥0.213) except for aortoiliac image noise (4.42 vs. 4.12, P=0.0374). TAVR-planning measurements were successfully obtained in all patients. There were no significant changes in eGFR among and between groups during follow-up (P≥0.302).ConclusionTAVR candidates can be safely and effectively evaluated by a comprehensive CTA protocol with low contrast volume using low-tube-voltage acquisition.Key Points• Third-generation dual-source CT facilitates low-tube-voltage acquisition.• TAVR planning can be performed with reduced contrast volume and radiation dose.• TAVR-planning CT did not result in changes in creatinine levels at follow-up.• TAVR candidates can be safely evaluated by comprehensive low-tube-voltage CT angiography.

CT coronary calcium scoring with tin filtration using iterative beam-hardening calcium correction reconstruction

OBJECTIVES To investigate the diagnostic accuracy of CT coronary artery calcium scoring (CACS) with tin pre-filtration (Sn100kVp) using iterative beam-hardening correction (IBHC) calcium material reconstruction compared to the standard 120kVp acquisition. BACKGROUND Third generation dual-source CT (DSCT) CACS with Sn100kVp acquisition allows significant dose reduction. However, the Sn100kVp spectrum is harder with lower contrast compared to 120kVp, resulting in lower calcium score values. Sn100kVp spectral correction using IBHC-based calcium material reconstruction may restore comparable calcium values. METHODS Image data of 62 patients (56% male, age 63.9±9.2years) who underwent a clinically-indicated CACS acquisition using the standard 120kVp protocol and an additional Sn100kVp CACS scan as part of a research study were retrospectively analyzed. Datasets of the Sn100kVp scans were reconstructed using a dedicated spectral IBHC CACS reconstruction to restore the spectral response of 120kVp spectra. Agatston scores were derived from 120kVp and IBHC reconstructed Sn100kVp studies. Pearsons correlation coefficient was assessed and Agatston score categories and percentile-based risk categorization were compared. RESULTS Median Agatston scores derived from IBHC Sn100kVp scans and 120kVp acquisition were 31.7 and 34.1, respectively (p=0.057). Pearsons correlation coefficient showed excellent correlation between the acquisitions (r=0.99, p<0.0001). Agatston score categories and percentile-based cardiac risk categories showed excellent agreement (ĸ=1.00 and ĸ=0.99), resulting in a low cardiac risk reclassification of 1.6% with the use of IBHC CACS reconstruction. Image noise was 24.9±3.6HU in IBHC Sn100kVp and 17.1±3.9HU in 120kVp scans (p<0.0001). The dose-length-product was 13.2±3.4mGycm with IBHC Sn100kVp and 59.1±22.9mGycm with 120kVp scans (p<0.0001), resulting in a significantly lower effective radiation dose (0.19±0.07mSv vs. 0.83±0.33mSv, p<0.0001) for IBHC Sn100kVp scans. CONCLUSION Low voltage CACS with tin filtration using a dedicated IBHC CACS material reconstruction algorithm shows excellent correlation and agreement with the standard 120kVp acquisition regarding Agatston score and cardiac risk categorization, while radiation dose is significantly reduced by 75% to the level of a chest x-ray.

Giant Left Ventricular Pseudoaneurysm as a Complication After Mitral Valve Replacement Surgery

57-year-oldwomanpresentedwith seizure, exertional Ashortness of breath (New York Heart Association Class III) and angina-like chest pain. Her cardiac history revealed successful bioprostheticmitral valve replacement for endocarditis 1 year prior. Chest radiography detected a 9-cm mass overlying the left hilum with an incomplete right border (Fig 1A, arrows). On transthoracic echocardiography, there was a communication from the posterior mitral valve annulus with an apparent left ventricular (LV) pseudoaneurysm (PSA) measuring approximately 51 52 mm (Fig 1B). Visualized valves showed thickening of the mitral valve leaflets with adjacent high-density

Coronary Computed Tomographic Angiography-Derived Fractional Flow Reserve Based on Machine Learning for Risk Stratification of Non-Culprit Coronary Narrowings in Patients with Acute Coronary Syndrome

This study investigated the prognostic value of coronary computed tomography angiography (cCTA)-derived fractional flow reserve (CT-FFR) in patients with acute coronary syndrome (ACS) and multivessel disease to gauge significance and guide management of non-culprit lesions. We retrospectively analyzed data of 48 patients (56 ± 10 years, 60% men) who were admitted for symptoms suggestive of ACS and underwent dual-source cCTA followed by invasive coronary angiography with culprit lesion intervention. Culprit lesions were retrospectively identified on cCTA using images obtained during invasive coronary angiography. Non-culprit lesions with ≥25% luminal stenosis and deferred intervention were evaluated using a machine learning CT-FFR algorithm to determine lesion-specific ischemia (CT-FFR ≤0.80). Follow-up was performed. CT-FFR identified lesion-specific ischemia in 23 of 81 non-culprit lesions. After a median follow-up of 19.5 months, 14 patients (29%) had major adverse cardiac events (MACE). Univariate Cox regression analysis revealed that CT-FFR ≤0.80 (hazard ratio [HR] 3.77 [95% confidence interval 1.16 to 12.29], p = 0.027), Framingham risk score (FRS) (HR 2.96 [1.01 to 7.63], p = 0.038), and a CAD-RADS classification ≥3 (HR 3.12 [1.03 to 10.17], p = 0.051) were predictors of MACE. In a risk-adjusted model controlling for FRS and CAD-RADS ≥3, CT-FFR ≤0.80 remained a predictor of MACE (1.56 [1.01 to 2.83], p = 0.048). Receiver operating characteristics analysis including FRS, CAD-RADS ≥ 3, and CT-FFR ≤0.80 (area under the curve 0.78) showed incremental discriminatory power over FRS alone (area under the curve 0.66, p = 0.032). CT-FFR of non-culprit lesions in patients with ACS and multivessel disease adds prognostic value to identify risk of future MACE.