Spectral detector CT for cardiovascular applications

Spectral detector computed tomography (SDCT) is a novel technology that uses two layers of detectors to simultaneously collect low and high energy data. Spectral data is used to generate conventional polyenergetic images as well as dedicated spectral images including virtual mo-noenergetic and material composition (iodine-only, virtual unenhanced, effective atomic number) images. This paper provides an overview of SDCT technology and a description of some spectral image types. The potential utility of SDCT for cardiovascular imaging and the impact of this new technology on radiation and contrast dose are discussed through presentation of initial patient studies performed on a SDCT scanner. The value of SDCT for salvaging suboptimal studies including those with poor contrast-enhancement or beam hardening artifacts through retrospective reconstruction of spectral data is discussed. Additionally, examples of specific benefits for the evaluation of aortic disease, imaging before transcatheter aortic valve implantation, evaluation of pulmonary veins pre- and post-pulmonary radiofrequency ablation, evaluation of coronary artery lumen, assessment of myocardial perfusion, detection of pulmonary embolism, and characterization of incidental findings are presented

Imaging features of leadless cardiovascular devices

Cardiovascular devices and hemodynamic monitoring systems continue to evolve with the goal of allowing for rapid clinical intervention and management. Cardiovascular devices including the CardioMicroelectromechanical (CardioMEMS) device, implantable loop recorder, and right ventricular (RV) leadless pacemaker are now widely used for treatment and monitoring of advanced cardiac conditions, as many of these devices have been shown to significantly improve patient outcomes. Additionally, hemodynamic monitoring devices have shown utility in monitoring patients with aortic aneurysms after endovascular aortic repair (EVAR) for early detection of Type I and Type II endoleaks. There is limited published data regarding the imaging features of these devices. As these devices become more widely used, it is important for radiologists to become familiar with the normal imaging features and potential complications. The goal of this review is to summarize the data regarding the use of leadless cardiovascular devices including the CardioMEMS device, implantable loop recorder, and RV leadless pacemaker, and to present cases demonstrating their utility and normal imaging features

Ultra-low dose contrast CT pulmonary angiography in oncology patients using a high-pitch helical dual-source technology

PURPOSEWe aimed to determine if the image quality and vascular enhancement are preserved in computed tomography pulmonary angiography (CTPA) studies performed with ultra-low contrast and optimized radiation dose using high-pitch helical mode of a second generation dual source scanner.METHODSWe retrospectively evaluated oncology patients who had CTPA on a 128-slice dual-source scanner, with a high-pitch helical mode (3.0), following injection of 30 mL of Ioversal at 4 mL/s with body mass index (BMI) dependent tube potential (80–120 kVp) and current (130–150 mAs). Attenuation, noise, and signal-to-noise ratio (SNR) were measured in multiple pulmonary arteries. Three independent readers graded the images on a 5-point Likert scale for central vascular enhancement (CVE), peripheral vascular enhancement (PVE), and overall quality.RESULTSThere were 50 males and 101 females in our study. BMI ranged from 13 to 38 kg/m2 (22.8±4.4 kg/m2). Pulmonary embolism was present in 29 patients (18.9%). Contrast enhancement and SNR were excellent in all the pulmonary arteries (395.3±131.1 and 18.3±5.7, respectively). Image quality was considered excellent by all the readers, with average reader scores near the highest possible score of 5.0 (CVE, 4.83±0.48; PVE, 4.68±0.65; noise/quality, 4.78±0.47). The average radiation dose length product (DLP) was 161±60 mGy.cm.CONCLUSIONUsing a helical high-pitch acquisition technique, CTPA images of excellent diagnostic quality, including visualization of peripheral segmental/sub-segmental branches can be obtained using an ultra-low dose of iodinated contrast and low radiation dose

Evaluation of left ventricular ejection fraction using through-time radial GRAPPA

BACKGROUND: The determination of left ventricular ejection fraction using cardiovascular magnetic resonance (CMR) requires a steady cardiac rhythm for electrocardiogram (ECG) gating and multiple breathholds to minimize respiratory motion artifacts, which often leads to scan times of several minutes. The need for gating and breathholding can be eliminated by employing real-time CMR methods such as through-time radial GRAPPA. The aim of this study is to compare left ventricular cardiac functional parameters obtained using current gold-standard breathhold ECG-gated functional scans with non-gated free-breathing real-time imaging using radial GRAPPA, and to determine whether scan time or the occurrence of artifacts are reduced when using this real-time approach. METHODS: 63 patients were scanned on a 1.5T CMR scanner using both the standard cardiac functional examination with gating and breathholding and the real-time method. Total scan durations were noted. Through-time radial GRAPPA was employed to reconstruct images from the highly accelerated real-time data. The blood volume in the left ventricle was assessed to determine the end systolic volume (ESV), end diastolic volume (EDV), and ejection fraction (EF) for both methods, and images were rated for the presence of artifacts and quality of specific image features by two cardiac readers. Linear regression analysis, Bland-Altman plots and two-sided t-tests were performed to compare the quantitative parameters. A two-sample t-test was performed to compare the scan durations, and a two-sample test of proportion was used to analyze the presence of artifacts. For the reviewers´ ratings the Wilcoxon test for the equality of the scores’ distributions was employed. RESULTS: The differences in EF, EDV, and ESV between the gold-standard and real-time methods were not statistically significant (p-values of 0.77, 0.82, and 0.97, respectively). Additionally, the scan time was significantly shorter for the real-time data collection (p<0.001) and fewer artifacts were reported in the real-time images (p<0.01). In the qualitative image analysis, reviewers marginally preferred the standard images although some features including cardiac motion were equivalently rated. CONCLUSION: Real-time functional CMR with through-time radial GRAPPA performed without ECG-gating under free-breathing can be considered as an alternative to gold-standard breathhold cine imaging for the evaluation of ejection fraction in patients

Predicting postoperative systolic dysfunction in mitral regurgitation: CT vs. echocardiography

IntroductionVolume overload from mitral regurgitation can result in left ventricular systolic dysfunction. To prevent this, it is essential to operate before irreversible dysfunction occurs, but the optimal timing of intervention remains unclear. Current echocardiographic guidelines are based on 2D linear measurement thresholds only. We compared volumetric CT-based and 2D echocardiographic indices of LV size and function as predictors of post-operative systolic dysfunction following mitral repair.MethodsWe retrospectively identified patients with primary mitral valve regurgitation who underwent repair between 2005 and 2021. Several indices of LV size and function measured on preoperative cardiac CT were compared with 2D echocardiography in predicting post-operative LV systolic dysfunction (LVEFecho &lt;50%). Area under the curve (AUC) was the primary metric of predictive performance.ResultsA total of 243 patients were included (mean age 57 ± 12 years; 65 females). The most effective CT-based predictors of post-operative LV systolic dysfunction were ejection fraction [LVEFCT; AUC 0.84 (95% CI: 0.77–0.92)] and LV end systolic volume indexed to body surface area [LVESViCT; AUC 0.88 (0.82–0.95)]. The best echocardiographic predictors were LVEFecho [AUC 0.70 (0.58–0.82)] and LVESDecho [AUC 0.79 (0.70–0.89)]. LVEFCT was a significantly better predictor of post-operative LV systolic dysfunction than LVEFecho (p = 0.02) and LVESViCT was a significantly better predictor than LVESDecho (p = 0.03). Ejection fraction measured by CT demonstrated significantly greater reproducibility than echocardiography.DiscussionCT-based volumetric measurements may be superior to established 2D echocardiographic parameters for predicting LV systolic dysfunction following mitral valve repair. Validation with prospective study is warranted

Pictorial essay: Non-coronary applications of cardiac CT

Recent advances in scanner technology have enabled computed tomography (CT) scan to evolve into a valuable tool in the noninvasive evaluation of coronary artery disease. Due to its high negative predictive value, CT can act as a gatekeeper, determining which patients require cardiac catheterization. Although mainly used for the evaluation of coronary artery disease, cardiac CT is also useful in the evaluation of various non-coronary cardiac conditions involving the pericardium, pulmonary veins, and the coronary veins and valves, as well as in the assessment of cardiomyopathies, masses, and ventricular and valvular function. This review discusses and illustrates the various non-coronary applications of cardiac CT