Five-Year Outcomes of the Danish Cardiovascular Screening (DANCAVAS) Trial.

BACKGROUND: Limited data suggest a benefit of population-based screening for cardiovascular disease with respect to the risk of death. METHODS: We performed a population-based, parallel-group, randomized, controlled trial involving men 65 to 74 years of age living in 15 Danish municipalities. The participants were randomly assigned in a 1:2 ratio to undergo screening (the invited group) or not to undergo screening (the control group) for subclinical cardiovascular disease. Randomization was based on computer-generated random numbers and stratified according to municipality. Only the control group was unaware of the trial-group assignments. Screening included noncontrast electrocardiography-gated computed tomography to determine the coronary-artery calcium score and to detect aneurysms and atrial fibrillation, ankle-brachial blood-pressure measurements to detect peripheral artery disease and hypertension, and a blood sample to detect diabetes mellitus and hypercholesterolemia. The primary outcome was death from any cause. RESULTS: A total of 46,611 participants underwent randomization. After exclusion of 85 men who had died or emigrated before being invited to undergo screening, there were 16,736 men in the invited group and 29,790 men in the control group; 10,471 of the men in the invited group underwent screening (62.6%). In intention-to-treat analyses, after a median follow-up of 5.6 years, 2106 men (12.6%) in the invited group and 3915 men (13.1%) in the control group had died (hazard ratio, 0.95; 95% confidence interval [CI], 0.90 to 1.00; P = 0.06). The hazard ratio for stroke in the invited group, as compared with the control group, was 0.93 (95% CI, 0.86 to 0.99); for myocardial infarction, 0.91 (95% CI, 0.81 to 1.03); for aortic dissection, 0.95 (95% CI, 0.61 to 1.49); and for aortic rupture, 0.81 (95% CI, 0.49 to 1.35). There were no significant between-group differences in safety outcomes. CONCLUSIONS: After more than 5 years, the invitation to undergo comprehensive cardiovascular screening did not significantly reduce the incidence of death from any cause among men 65 to 74 years of age. (Funded by the Southern Region of Denmark and others; DANCAVAS ISRCTN Registry number, ISRCTN12157806.).

ECG-free cine MRI with data-driven clustering of cardiac motion for quantification of ventricular function.

BACKGROUND: Despite the widespread use of cine MRI for evaluation of cardiac function, existing real-time methods do not easily enable quantification of ventricular function. Moreover, segmented cine MRI assumes periodicity of cardiac motion. We aim to develop a self-gated, cine MRI acquisition scheme with data-driven cluster-based binning of cardiac motion. METHODS: A Cartesian golden-step balanced steady-state free precession sequence with sorted k-space ordering was designed. Image data were acquired with breath-holding. Principal component analysis and k-means clustering were used for binning of cardiac phases. Cluster compactness in the time dimension was assessed using temporal variability, and dispersion in the spatial dimension was assessed using the Calinski-Harabasz index. The proposed and the reference electrocardiogram (ECG)-gated cine methods were compared using a four-point image quality score, SNR and CNR values, and Bland-Altman analyses of ventricular function. RESULTS: A total of 10 subjects with sinus rhythm and 8 subjects with arrhythmias underwent cardiac MRI at 3.0 T. The temporal variability was 45.6 ms (cluster) versus 24.6 ms (ECG-based) (p < 0.001), and the Calinski-Harabasz index was 59.1 ± 9.1 (cluster) versus 22.0 ± 7.1 (ECG based) (p < 0.001). In subjects with sinus rhythm, 100% of the end-systolic and end-diastolic images from both the cluster and reference approach received the highest image quality score of 4. Relative to the reference cine images, the cluster-based multiphase (cine) image quality consistently received a one-point lower score (p < 0.05), whereas the SNR and CNR values were not significantly different (p = 0.20). In cases with arrhythmias, 97.9% of the end-systolic and end-diastolic images from the cluster approach received an image quality score of 3 or more. The mean bias values for biventricular ejection fraction and volumes derived from the cluster approach versus reference cine were negligible. CONCLUSION: ECG-free cine cardiac MRI with data-driven clustering for binning of cardiac motion is feasible and enables quantification of cardiac function.

Myocardial strain assessment in the human fetus by cardiac MRI using Doppler ultrasound gating and feature tracking.

OBJECTIVES: Assessment of myocardial strain by feature tracking magnetic resonance imaging (FT-MRI) in human fetuses with and without congenital heart disease (CHD) using cardiac Doppler ultrasound (DUS) gating. METHODS: A total of 43 human fetuses (gestational age 28-41 weeks) underwent dynamic cardiac MRI at 3 T. Cine balanced steady-state free-precession imaging was performed using fetal cardiac DUS gating. FT-MRI was analyzed using dedicated post-processing software. Endo- and epicardial contours were manually delineated from fetal cardiac 4-chamber views, followed by automated propagation to calculate global longitudinal strain (GLS) of the left (LV) and right ventricle (RV), LV radial strain, and LV strain rate. RESULTS: Strain assessment was successful in 38/43 fetuses (88%); 23 of them had postnatally confirmed diagnosis of CHD (e.g., coarctation, transposition of great arteries) and 15 were heart healthy. Five fetuses were excluded due to reduced image quality. In fetuses with CHD compared to healthy controls, median LV GLS (- 13.2% vs. - 18.9%; p < 0.007), RV GLS (- 7.9% vs. - 16.2%; p < 0.006), and LV strain rate (1.4 s-1 vs. 1.6 s-1; p < 0.003) were significantly higher (i.e., less negative). LV radial strain was without a statistically significant difference (20.7% vs. 22.6%; p = 0.1). Bivariate discriminant analysis for LV GLS and RV GLS revealed a sensitivity of 67% and specificity of 93% to differentiate between fetuses with CHD and healthy fetuses. CONCLUSION: Myocardial strain was successfully assessed in the human fetus, performing dynamic fetal cardiac MRI with DUS gating. Our study indicates that strain parameters may allow for differentiation between fetuses with and without CHD. CLINICAL RELEVANCE STATEMENT: Myocardial strain analysis by cardiac MRI with Doppler ultrasound gating and feature tracking may provide a new diagnostic approach for evaluation of fetal cardiac function in congenital heart disease. KEY POINTS: • MRI myocardial strain analysis has not been performed in human fetuses so far. • Myocardial strain was assessed in human fetuses using cardiac MRI with Doppler ultrasound gating. • MRI myocardial strain may provide a new diagnostic approach to evaluate fetal cardiac function.

Reducing clustering of readouts in non-Cartesian cine magnetic resonance imaging.

BACKGROUND: Non-Cartesian magnetic resonance imaging trajectories at golden angle increments have the advantage of allowing motion correction and gating using intermediate real-time reconstructions. However, when the acquired data are cardiac binned for cine imaging, trajectories can cluster together at certain heart rates (HR) causing image artifacts. Here, we demonstrate an approach to reduce clustering by inserting additional angular increments within the trajectory, and optimizing them while still allowing for intermediate reconstructions. METHODS: Three acquisition models were simulated under constant and variable HR: golden angle (Mtrd), random additional angles (Mrnd), and optimized additional angles (Mopt). The standard deviations of trajectory angular differences (STAD) were compared through their interquartile ranges (IQR) and the Kolmogorov-Smirnov test (significance level: p = 0.05). Agreement between an image reconstructed with uniform sampling and images from Mtrd, Mrnd, and Mopt was analyzed using the structural similarity index measure (SSIM). Mtrd and Mopt were compared in three adults at high, low, and no HR variability. RESULTS: STADs from Mtrd were significantly different (p < 0.05) from Mopt and Mrnd. STAD (IQR × 10-2 rad) showed that Mopt (0.5) and Mrnd (0.5) reduced clustering relative to Mtrd (1.9) at constant HR. For variable HR, Mopt (0.5) and Mrnd (0.5) outperformed Mtrd (0.9). The SSIM (IQR) showed that Mopt (0.011) produced the best image quality, followed by Mrnd (0.014), and Mtrd (0.030). Mopt outperformed Mtrd at reduced HR variability in in-vivo studies. At high HR variability, both models performed well. CONCLUSION: This approach reduces clustering in k-space and improves image quality.

Three-dimensional aortic geometry mapping via registration of non-gated contrast-enhanced or gated and respiratory-navigated MR angiographies.

BACKGROUND: The measurement of aortic dimensions and their evolution are key in the management of patients with aortic diseases. Manual assessment, the current guideline-recommended method and clinical standard, is subjective, poorly reproducible, and time-consuming, limiting the capacity to track aortic growth in everyday practice. Aortic geometry mapping (AGM) via image registration of serial computed tomography angiograms outperforms manual assessment, providing accurate and reproducible 3D maps of aortic diameter and growth rate. This observational study aimed to evaluate the accuracy and reproducibility of AGM on non-gated contrast-enhanced (CE-) and cardiac- and respiratory-gated (GN-) magnetic resonance angiographies (MRA). METHODS: Patients with thoracic aortic disease followed with serial CE-MRA (n = 30) or GN-MRA (n = 15) acquired at least 1 year apart were retrospectively and consecutively identified. Two independent observers measured aortic diameters and growth rates (GR) manually at several thoracic aorta reference levels and with AGM. Agreement between manual and AGM measurements and their inter-observer reproducibility were compared. Reproducibility for aortic diameter and GR maps assessed with AGM was obtained. RESULTS: Mean follow-up was 3.8 ± 2.3 years for CE- and 2.7 ± 1.6 years for GN-MRA. AGM was feasible in the 93% of CE-MRA pairs and in the 100% of GN-MRA pairs. Manual and AGM diameters showed excellent agreement and inter-observer reproducibility (ICC>0.9) at all anatomical levels. Agreement between manual and AGM GR was more limited, both in the aortic root by GN-MRA (ICC=0.47) and in the thoracic aorta, where higher accuracy was obtained with GN- than with CE-MRA (ICC=0.55 vs 0.43). The inter-observer reproducibility of GR by AGM was superior compared to manual assessment, both with CE- (thoracic: ICC= 0.91 vs 0.51) and GN-MRA (root: ICC=0.84 vs 0.52; thoracic: ICC=0.93 vs 0.60). AGM-based 3D aortic size and growth maps were highly reproducible (median ICC >0.9 for diameters and >0.80 for GR). CONCLUSION: Mapping aortic diameter and growth on MRA via 3D image registration is feasible, accurate and outperforms the current manual clinical standard. This technique could broaden the possibilities of clinical and research evaluation of patients with aortic thoracic diseases.

Left ventricular shape index and eccentricity index with ECG-gated Nitrogen-13 ammonia PET/CT in patients with myocardial infarction, ischemia, and normal perfusion.

BACKGROUND: LV geometry with shape index (SI) and eccentricity index (EI) measured by myocardial perfusion positron emission tomography/computed tomography (PET/CT) may allow the evaluation of left ventricular (LV) adverse remodeling. This first study aims to explore the relationship of SI and EI values acquired by Nitrogen-13 ammonia PET/CT in patients with normal perfusion, ischemia, and myocardial infarction. And evaluate the correlations between the variables of LV geometry, and with the variables of LV function. METHODS AND RESULTS: One hundred and forty patients who underwent an electrocardiogram (ECG)-gated PET/CT were selected and classified into 4 groups according to ischemia or infarction burden (normal perfusion, mild ischemia, moderate-severe ischemia, and infarction). The variables were automatically retrieved using dedicated software (QPS/QGS; Cedars-Sinai, Los Angeles, CA, USA). On multicomparison analysis (one-way ANOVA and Dunnett's Test), subjects in the infarction group had significant higher values of SI end-diastolic rest (P < 0.001), and stress (P = 0.003), SI end-systolic rest (P = 0.002) and stress (P < 0.001) as well as statistically significant lower values of EI rest (P < 0.001) and stress (P < 0.001) when compared with all other groups. Regarding Pearson correlation, in the infarcted group all the variables of SI and EI were significantly correlated (P < 0.001) with strong correlation coefficients (>0.60). SI end-systolic correlated significantly with the variables of LV function independently of the group of patients (P < 0.05). CONCLUSIONS: Shape and eccentricity indices differ in patients with myocardial infarction as compared to patients with ischemia or normal perfusion. This encourage further research in their potential for detecting LV adverse remodeling.

Efficacy and safety of coronary computed tomography angiography in diagnosing coronary lesions in children.

INTRODUCTION: Identification of paediatric coronary artery abnormalities is challenging. We studied whether coronary artery CT angiography can be performed safely and reliably in children. MATERIALS: Retrospective analysis of consecutive coronary CT angiography scans was performed for image quality and estimated radiation dose. Both factors were assessed for correlation with electrocardiographic-gating technique that was protocoled on a case-by-case basis, radiation exposure parameters, image noise artefact parameters, heart rate, and heart rate variability. RESULTS: Sixty scans were evaluated, of which 96.5% were diagnostic for main left and right coronaries and 91.3% were considered diagnostic for complete coronary arteries. Subjective image quality correlated significantly with lower heart rate, increasing patient age, and higher signal-to-noise ratio. Estimated radiation dose only correlated significantly with choice of electrocardiographic-gating technique with median doses as follows: 2.42 mSv for electrocardiographic-gating triggered high-pitch spiral technique, 5.37 mSv for prospectively triggered axial sequential technique, 3.92 mSv for retrospectively gated technique, and 5.64 mSv for studies which required multiple runs. Two scans were excluded for injection failure and one for protocol outside the study scope. Five non-diagnostic cases were attributed to breathing motion, scanning prior to peak contrast enhancement, or scan acquisition during the incorrect portion of the R-R interval. CONCLUSIONS: Diagnostic-quality coronary CT angiography can be performed reliably with a low estimated radiation exposure by tailoring each scan protocol to the patient's body habitus and heart rate. We propose coronary CT angiography is a safe and effective diagnostic modality for coronary artery abnormalities in children.

Fully automatic coronary calcium scoring in non-ECG-gated low-dose chest CT: comparison with ECG-gated cardiac CT.

OBJECTIVES: To validate an artificial intelligence (AI)-based fully automatic coronary artery calcium (CAC) scoring system on non-electrocardiogram (ECG)-gated low-dose chest computed tomography (LDCT) using multi-institutional datasets with manual CAC scoring as the reference standard. METHODS: This retrospective study included 452 subjects from three academic institutions, who underwent both ECG-gated calcium scoring computed tomography (CSCT) and LDCT scans. For all CSCT and LDCT scans, automatic CAC scoring (CAC_auto) was performed using AI-based software, and manual CAC scoring (CAC_man) was set as the reference standard. The reliability and agreement of CAC_auto was evaluated and compared with that of CAC_man using intraclass correlation coefficients (ICCs) and Bland-Altman plots. The reliability between CAC_auto and CAC_man for CAC severity categories was analyzed using weighted kappa (κ) statistics. RESULTS: CAC_auto on CSCT and LDCT yielded a high ICC (0.998, 95% confidence interval (CI) 0.998-0.999 and 0.989, 95% CI 0.987-0.991, respectively) and a mean difference with 95% limits of agreement of 1.3 ± 37.1 and 0.8 ± 75.7, respectively. CAC_auto achieved excellent reliability for CAC severity (κ = 0.918-0.972) on CSCT and good to excellent but heterogenous reliability among datasets (κ = 0.748-0.924) on LDCT. CONCLUSIONS: The application of an AI-based automatic CAC scoring software to LDCT shows good to excellent reliability in CAC score and CAC severity categorization in multi-institutional datasets; however, the reliability varies among institutions. KEY POINTS: • AI-based automatic CAC scoring on LDCT shows excellent reliability with manual CAC scoring in multi-institutional datasets. • The reliability for CAC score-based severity categorization varies among datasets. • Automatic scoring for LDCT shows a higher false-positive rate than automatic scoring for CSCT, and most common causes of a false-positive are image noise and artifacts for both CSCT and LDCT.

Diagnostic accuracy of lower-dose cardiac CT in evaluating young infants with non-coronary complex congenital heart disease on a 64-slice multidetector CT scanner.

BACKGROUND: Redoable precise and non-invasive diagnostic imaging modality with the least radiation dose is essential for infants with congenital heart disease (CHD) . PURPOSE: To investigate the accuracy and estimate the radiation dose of our cardiac computed tomography (CCT) protocol. MATERIAL AND METHODS: A total of 82 infants with CHD underwent non-ECG-gated CCT without contrast timing scanning techniques and were retrospectively studied. The image quality and radiation dose were estimated. The radiation dose was compared statistically to virtual retrospective ECG-gated and prospective ECG-triggering scanning modes. The diagnostic accuracy was assessed assuming the surgical results as the diagnostic gold standard. RESULTS: Most exams showed a high quality with low radiation doses compared to previous studies. The mean effective dose (ED) was 0.39 ± 1.2, significantly lower than that of the virtual retrospective ECG-gated and prospective ECG-triggering scanning and lower than in previous studies. Our CCT protocol has achieved a diagnostic accuracy of 99.52% with a sensitivity of 94.83% and specificity of 99.91%. CONCLUSION: Non-ECG-gated CCT without contrast timing techniques can detect the non-coronary cardiovascular defects of CHD in infants with an ultralow radiation dose and a high diagnostic accuracy.

Late gadolinium enhancement-MRI determines definite lesion formation most accurately at 3 months post ablation compared to later time points.

AIMS: Neither the long-term development of ablation lesions nor the capability of late gadolinium enhancement (LGE)-MRI to detect ablation-induced fibrosis at late stages of scar formation have been defined. We sought to assess the development of atrial ablation lesions over time using LGE-MRI and invasive electroanatomical mapping (EAM). METHODS AND RESULTS: Ablation lesions and total atrial fibrosis were assessed in serial LGE-MRI scans 3 months and >12 months post pulmonary vein (PV) isolation. High-density EAM performed in subsequent repeat ablation procedures served as a reference. Serial LGE-MRI of 22 patients were analyzed retrospectively. The PV encircling ablation lines displayed an average LGE, indicative of ablation-induced fibrosis, of 91.7% ± 7.0% of the circumference at 3 months, but only 62.8% ± 25.0% at a median of 28 months post ablation (p < 0.0001). EAM performed in 18 patients undergoing a subsequent repeat procedure revealed that the consistent decrease in LGE over time was owed to a reduced detectability of ablation-induced fibrosis by LGE-MRI at time-points > 12 months post ablation. Accordingly, the agreement with EAM regarding detection of ablation-induced fibrosis and functional gaps was good for the LGE-MRI at 3 months (κ .74; p < .0001), but only weak for the LGE-MRI at 28 months post-ablation (κ .29; p < .0001). CONCLUSION: While non-invasive lesion assessment with LGE-MRI 3 months post ablation provides accurate guidance for future redo-procedures, detectability of atrial ablation lesions appears to decrease over time. Thus, it should be considered to perform LGE-MRI 3 months post-ablation rather than at later time-points > 12 months post ablation, like for example, prior to a planned redo-ablation procedure.

Additional value of deep learning computed tomographic angiography-based fractional flow reserve in detecting coronary stenosis and predicting outcomes.

BACKGROUND: Deep learning (DL) has achieved great success in medical imaging and could be utilized for the non-invasive calculation of fractional flow reserve (FFR) from coronary computed tomographic angiography (CCTA) (CT-FFR). PURPOSE: To examine the ability of a DL-based CT-FFR in detecting hemodynamic changes of stenosis. MATERIAL AND METHODS: This study included 73 patients (85 vessels) who were suspected of coronary artery disease (CAD) and received CCTA followed by invasive FFR measurements within 90 days. The diagnostic accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the receiver operating characteristics curve (AUC) were compared between CT-FFR and CCTA. Thirty-nine patients who received drug therapy instead of revascularization were followed for up to 31 months. Major adverse cardiac events (MACE), unstable angina, and rehospitalization were evaluated and compared between the study groups. RESULTS: At the patient level, CT-FFR achieved 90.4%, 93.6%, 88.1%, 85.3%, and 94.9% in accuracy, sensitivity, specificity, PPV, and NPV, respectively. At the vessel level, CT-FFR achieved 91.8%, 93.9%, 90.4%, 86.1%, and 95.9%, respectively. CT-FFR exceeded CCTA in these measurements at both levels. The vessel-level AUC for CT-FFR also outperformed that for CCTA (0.957 vs. 0.599, P < 0.0001). Patients with CT-FFR ≤0.8 had higher rates of rehospitalization (hazard ratio [HR] 4.51, 95% confidence interval [CI] 1.08-18.9) and MACE (HR 7.26, 95% CI 0.88-59.8), as well as a lower rate of unstable angina (HR 0.46, 95% CI 0.07-2.91). CONCLUSION: CT-FFR is superior to conventional CCTA in differentiating functional myocardial ischemia. In addition, it has the potential to differentiate prognoses of patients with CAD.

[Three-dimensional volume rendering for dynamic characteristics of secundum atrial septal defect during various phases of the cardiac cycle and the impact on occluder selection].

Objective: To investigate the dynamic change of the secundum atrial septal defect (ASD) throughout the cardiac cycle, and assess its impact on occluder selection. Methods: This study retrospectively analyzed 35 patients with ASD who received electrocardiogram-gated coronary CT angiography (CCTA) throughout the cardiac cycle as well as interventional closure therapy in Fuwai Hospital from December 2016 to December 2019. The raw data were reconstructed into 20 phasic images of RR intervals (RRI) ranging from 0 to 95% in an increment of 5% and transmitted to a workstation for postprocessing. For each phase image, CT virtual endoscopy reconstruction technique (CTVE) was used to provide views of ASD. Axial sequence assisted CT volumetric measurement (CTAS) was used to calculate the maximum dimensions in axial planes (Da) and in superior-inferior direction (Db). Using a formula for converting circumference to diameter, the equivalent circle dimensions were calculated (De, De=minor axis+2 (major axis-minor axis)/3). Taking the data of 75% RRI phase, the patients were divided into Da75%RRI≥Db75%RRI group and Da75%RRIDa. Db is basically constant while Da changes significantly during cardiac cycle (10%-90% RRI). Nonetheless, both values peak and maintain the maximum status at end-systolic phase (35%-45% RRI). For patients with huge ASD, occluder selection should be based on the De at 35% RRI phase, which is helpful for the successful intervention.

Magnetic resonance elastography for estimating in vivo stiffness of the abdominal aorta using cardiac-gated spin-echo echo-planar imaging: a feasibility study.

INTRODUCTION: Magnetic resonance elastography (MRE)-derived aortic stiffness is a potential biomarker for multiple cardiovascular diseases. Currently, gradient-recalled echo (GRE) MRE is a widely accepted technique to estimate aortic stiffness. However, multi-slice GRE MRE requires multiple breath-holds (BHs), which can be challenging for patients who cannot consistently hold their breath. The aim of this study was to investigate the feasibility of a multi-slice spin-echo echo-planar imaging (SE-EPI) MRE sequence for quantifying in vivo aortic stiffness using a free-breathing (FB) protocol and a single-BH protocol. METHOD: On Scanner 1, 25 healthy subjects participated in the validation of FB SE-EPI against FB GRE. On Scanner 2, another 15 healthy subjects were recruited to compare FB SE-EPI with single-BH SE-EPI. Among all volunteers, five participants were studied on both scanners to investigate the inter-scanner reproducibility of FB SE-EPI aortic MRE. Bland-Altman analysis, Lin's concordance correlation coefficient (LCCC) and coefficient of variation (COV) were evaluated. The phase-difference signal-to-noise ratios (PD SNR) were compared. RESULTS: Aortic MRE using FB SE-EPI and FB GRE yielded similar stiffnesses (paired t-test, P = 0.19), with LCCC = 0.97. The FB SE-EPI measurements were reproducible (intra-scanner LCCC = 0.96) and highly repeatable (LCCC = 0.99). The FB SE-EPI MRE was also reproducible across different scanners (inter-scanner LCCC = 0.96). Single-BH SE-EPI scans yielded similar stiffness to FB SE-EPI scans (LCCC = 0.99) and demonstrated a low COV of 2.67% across five repeated measurements. CONCLUSION: Multi-slice SE-EPI aortic MRE using an FB protocol or a single-BH protocol is reproducible and repeatable with advantage over multi-slice FB GRE in reducing acquisition time. Additionally, FB SE-EPI MRE provides a potential alternative to BH scans for patients who have challenges in holding their breath.

Motion compensated whole-heart coronary cardiovascular magnetic resonance angiography using focused navigation (fNAV).

BACKGROUND: Radial self-navigated (RSN) whole-heart coronary cardiovascular magnetic resonance angiography (CCMRA) is a free-breathing technique that estimates and corrects for respiratory motion. However, RSN has been limited to a 1D rigid correction which is often insufficient for patients with complex respiratory patterns. The goal of this work is therefore to improve the robustness and quality of 3D radial CCMRA by incorporating both 3D motion information and nonrigid intra-acquisition correction of the data into a framework called focused navigation (fNAV). METHODS: We applied fNAV to 500 data sets from a numerical simulation, 22 healthy subjects, and 549 cardiac patients. In each of these cohorts we compared fNAV to RSN and respiratory resolved extradimensional golden-angle radial sparse parallel (XD-GRASP) reconstructions of the same data. Reconstruction times for each method were recorded. Motion estimate accuracy was measured as the correlation between fNAV and ground truth for simulations, and fNAV and image registration for in vivo data. Percent vessel sharpness was measured in all simulated data sets and healthy subjects, and a subset of patients. Finally, subjective image quality analysis was performed by a blinded expert reviewer who chose the best image for each in vivo data set and scored on a Likert scale 0-4 in a subset of patients by two reviewers in consensus. RESULTS: The reconstruction time for fNAV images was significantly higher than RSN (6.1 ± 2.1 min vs 1.4 ± 0.3, min, p < 0.025) but significantly lower than XD-GRASP (25.6 ± 7.1, min, p < 0.025). Overall, there is high correlation between the fNAV and reference displacement estimates across all data sets (0.73 ± 0.29). For simulated data, healthy subjects, and patients, fNAV lead to significantly sharper coronary arteries than all other reconstruction methods (p < 0.01). Finally, in a blinded evaluation by an expert reviewer fNAV was chosen as the best image in 444 out of 571 data sets (78%; p < 0.001) and consensus grades of fNAV images (2.6 ± 0.6) were significantly higher (p < 0.05) than uncorrected (1.7 ± 0.7), RSN (1.9 ± 0.6), and XD-GRASP (1.8 ± 0.8). CONCLUSION: fNAV is a promising technique for improving the quality of RSN free-breathing 3D whole-heart CCMRA. This novel approach to respiratory self-navigation can derive 3D nonrigid motion estimations from an acquired 1D signal yielding statistically significant improvement in image sharpness relative to 1D translational correction as well as XD-GRASP reconstructions. Further study of the diagnostic impact of this technique is therefore warranted to evaluate its full clinical utility.

Electrocardiogram-less, free-breathing myocardial extracellular volume fraction mapping in small animals at high heart rates using motion-resolved cardiovascular magnetic reesonance multitasking: a feasibility study in a heart failure with preserved ejection fraction rat model.

BACKGROUND: Extracellular volume fraction (ECV) quantification with cardiovascular magnetic resonance (CMR) T1 mapping is a powerful tool for the characterization of focal or diffuse myocardial fibrosis. However, it is technically challenging to acquire high-quality T1 and ECV maps in small animals for preclinical research because of high heart rates and high respiration rates. In this work, we developed an electrocardiogram (ECG)-less, free-breathing ECV mapping method using motion-resolved CMR Multitasking on a 9.4 T small animal CMR system. The feasibility of characterizing diffuse myocardial fibrosis was tested in a rat heart failure model with preserved ejection fraction (HFpEF). METHODS: High-salt fed rats diagnosed with HFpEF (n = 9) and control rats (n = 9) were imaged with the proposed ECV Multitasking technique. A 25-min exam, including two 4-min T1 Multitasking scans before and after gadolinium injection, were performed on each rat. It allows a cardiac temporal resolution of 20 ms for a heart rate of ~ 300 bpm. Myocardial ECV was calculated from the hematocrit (HCT) and fitted T1 values of the myocardium and the blood pool. Masson's trichrome stain was used to measure the extent of fibrosis. Welch's t-test was performed between control and HFpEF groups. RESULTS: ECV was significantly higher in the HFpEF group (22.4% ± 2.5% vs. 18.0% ± 2.1%, P = 0.0010). A moderate correlation between the ECV and the extent of fibrosis was found (R = 0.59, P = 0.0098). CONCLUSIONS: Motion-resolved ECV Multitasking CMR can quantify ECV in the rat myocardium at high heart rates without ECG triggering or respiratory gating. Elevated ECV found in the HFpEF group is consistent with previous human studies and well correlated with histological data. This technique has the potential to be a viable imaging tool for myocardial tissue characterization in small animal models.

The prognostic value of myocardial perfusion imaging in patients with type 2 myocardial infarction.

OBJECTIVES: The aim of this retrospective study is to evaluate the prognostic role of myocardial perfusion imaging (MPI) in patients with type 2 myocardial infarction (T2MI). BACKGROUND: T2MI is an increasingly common diagnosis in clinical practice. The management of this condition is controversial and the prognostic value of MPI has not been established in this setting. METHODS: We retrospectively studied T2MI patients who underwent vasodilator gated MPI within 90 days of T2MI at a single tertiary care institution in 2013. Abnormal myocardial perfusion was defined as the perfusion defect involving ≥ 5% of left ventricular (LV) myocardium. Abnormal LV ejection fraction (EF) was defined as < 50% by gated images. The primary outcome was a composite of death, myocardial infarction (other than index event) or coronary revascularization (CR). RESULTS: There were 234 patients (62 ± 14 years, 57% men) with T2MI (peak troponin 0.2 ng/ml, interquartile 0.1-1.4), of whom 136 (58%) had an abnormal MPI. During a median follow-up of 20 months, 155 patients (66%) had the primary outcome (39% death, 42% MI, 5% CR). An abnormal MPI was associated with an increased risk of the primary outcome with a hazard ratio of 1.56, 95%CI (1.12-2.18, P = .008) that remained statistically significant after multivariate adjustment (1.45, 95%CI (1.02-2.06, P = .04))). CONCLUSIONS: Patients with T2MI are at high risk for death or cardiac events in the intermediate term. More than one-half of patients with T2MI have an abnormal MPI and this is associated with the increased risk of cardiac events during follow-up. Risk stratification with MPI after T2MI may identify patients who would benefit from aggressive risk reduction.

Incremental value of myocardial wall motion and thickening to perfusion alone by gated SPECT myocardial perfusion imaging for viability assessment in patients with ischemic heart failure.

PURPOSE: The objective of this study was to assess the incremental value of myocardial wall motion and thickening compared with perfusion alone obtained from gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) in diagnosing myocardial viability in patients with ischemic heart failure. METHODS: Eighty-three consecutive patients with ischemic heart failure who underwent both 99mTc-MIBI gated SPECT MPI and 18F-FDG positron emission tomography (PET) myocardial metabolic imaging were retrospectively enrolled. SPECT/PET myocardial viability was defined as the reference standard. Segmental myocardial perfusion, wall motion, and thickening were measured by an automated algorithm from gated SPECT MPI. Univariate and stepwise multivariate analysis were conducted to establish an optimal multivariate model for predicting hibernating myocardium and scar. RESULTS: Among the 1411 segments evaluated, 774 segments had normal perfusion and 637 segments had decreased perfusion. The latter were classified by 18F-FDG PET into 338 hibernating segments and 299 scarred segments. The multivariate regression analysis showed that the model that combined myocardial perfusion uptake with wall motion and thickening scores had the optimal predictive efficiency to distinguish hibernating myocardium from scar in the segments with decreased perfusion. The model had the largest C-statistic (0.753 vs 0.666, P < 0.0001), and the global chi-square was increased from 53.281 to 111.234 when compared with perfusion alone (P < 0.001). CONCLUSIONS: Assessment of myocardial wall motion and thickening in addition to conventional perfusion uptake in the segments with decreased perfusion enables better differentiation of hibernating myocardium from scar in patients with ischemic heart failure. Considering wide availability and high cost-effectiveness, regional myocardial function integrated with perfusion on gated SPECT MPI has great promise to become a clinical tool in the assessment of myocardial viability.

Imaging diagnosis of aortic stenosis.

Aortic valve stenosis (AS) is the commonest primary valve disorder with increasing prevalence with age. Trans-thoracic echocardiogram is the main imaging technique used to diagnose AS, but discrepancy in diagnosis has been described in almost one third of cases. Other imaging methods, particularly electrocardiogram (ECG)-gated computed tomography, have now emerged to further clarify the diagnosis of AS by both demonstrating the degree of calcification in the valve as well as aortic valve area. Cardiac magnetic resonance imaging allows accurate quantification of ventricular function and evaluation of the myocardium. This paper provides a comprehensive review of the diagnosis of AS for the radiologist.

Pulmonary Artery Size Measurements: A Comparison Study Between Electrocardiogram-Gated and Nonelectrocardiogram-Gated Computed Tomography.

OBJECTIVES: The aim of this study was to determine the difference and correlation in pulmonary artery (PA) size when measured from the electrocardiogram (ECG)-gated computed tomography (CT) and non-ECG-gated CT. METHODS: In the retrospective study, 279 patients who underwent both ECG-gated CT and non-ECG-gated CT were enrolled. Maximum and minimum diameters of main pulmonary artery (MPA), right pulmonary artery (RPA), and ascending aorta (AAO) were measured, whereas mean diameters of MPA and RPA were obtained. The same PA size parameters were also measured on non-ECG-gated CT. RESULTS: There was a significant difference in maximum and minimum PA diameters between ECG-gated CT and non-ECG-gated CT, whereas mean PA diameters showed no statistically difference. The PA parameters showed a strong positive correlation between these 2 examinations. CONCLUSIONS: The PA size was different between ECG-gated CT and non-ECG-gated CT, whereas the PA size parameters on non-ECG-gated CT could be used to predict those with ECG-gated CT, which allow for confident prediction of pulmonary hypertension and guide further surgical intervention.

Right and left ventricular function and flow quantification in pediatric patients with repaired tetralogy of Fallot using four-dimensional flow magnetic resonance imaging.

BACKGROUND: To assess the accuracy and reproducibility of right ventricular (RV) and left ventricular (LV) function and flow measurements in children with repaired tetralogy of Fallot (rTOF) using four-dimensional (4D) flow, compared with conventional two-dimensional (2D) magnetic resonance imaging (MRI) sequences. METHODS: Thirty pediatric patients with rTOF were retrospectively enrolled to undergo 2D balanced steady-state free precession cine (2D b-SSFP cine), 2D phase contrast (PC), and 4D flow cardiac MRI. LV and RV volumes and flow in the ascending aorta (AAO) and main pulmonary artery (MPA) were quantified. Pearson's or Spearman's correlation tests, paired t-tests, the Wilcoxon signed-rank test, Bland-Altman analysis, and intraclass correlation coefficients (ICC) were performed. RESULTS: The 4D flow scan time was shorter compared with 2D sequences (P < 0.001). The biventricular volumes between 4D flow and 2D b-SSFP cine had no significant differences (P > 0.05), and showed strong correlations (r > 0.90, P < 0.001) and good consistency. The flow measurements of the AAO and MPA between 4D flow and 2D PC showed moderate to good correlations (r > 0.60, P < 0.001). There was good internal consistency in cardiac output. There was good intraobserver and interobserver biventricular function agreement (ICC > 0.85). CONCLUSIONS: RV and LV function and flow quantification in pediatric patients with rTOF using 4D flow MRI can be measured accurately and reproducibly compared to those with conventional 2D sequences.