To compare four-dimensional flow MRI with automated valve tracking to manual valve tracking in patients with acquired or congenital heart disease and healthy volunteers. Materials and Methods: In this retrospective study, data were collected from 114 patients and 46 volunteers who underwent fourdimensional flow MRI at 1.5 T or 3.0 T from 2006 through 2017. Among the 114 patients, 33 had acquired and 81 had congenital heart disease (median age, 17 years; interquartile range [IQR], 13-49 years), 51 (45%) were women, and 63 (55%) were men. Among the 46 volunteers (median age, 28 years; IQR, 22-36 years), there were 19 (41%) women and 27 (59%) men. Two orthogonal cine views of each valve were used for valve tracking. Wilcoxon signed-rank test was used to compare analysis times, net forward volumes (NFVs), and regurgitant fractions. Intra-and interobserver variability was tested by using intraclass correlation coefficients (ICCs). Results: Analysis time was shorter for automated versus manual tracking (all patients, 14 minutes [IQR, 12-15 minutes] vs 25 minutes [IQR, 20-25 minutes]; P , .001). Although overall differences in NFV and regurgitant fraction were comparable between both methods, NFV variation over four valves was smaller for automated versus manual tracking (all patients, 4.9% [IQR, 3.3%-6.7%] vs 9.8% [IQR, 5.1%-14.7%], respectively; P , .001). Regurgitation severity was discordant for seven pulmonary valves, 22 mitral valves, and 21 tricuspid valves. Intra-and interobserver agreement for automated tracking was excellent for NFV assessment (intra-and interobserver, ICC  0.99) and strong to excellent for regurgitant fraction assessment (intraobserver, ICC  0.94; interobserver, ICC  0.89). Conclusion: Automated valve tracking reduces analysis time and improves reliability of valvular flow quantification with fourdimensional flow MRI in patients with acquired or congenital heart disease and in healthy volunteers.

PurposeTo evaluate the in‐scan and scan–rescan consistency of left ventricular (LV) in‐ and outflow assessment from 1) 2D planimetry; 2) 4D flow magnetic resonance imaging (MRI) with retrospective valve tracking, and 3) 4D flow MRI with particle tracing.Materials and MethodsTen healthy volunteers (age 27 ± 3 years) underwent multislice cine short‐axis planimetry and whole‐heart 4D flow MRI on a 3T MRI scanner twice with repositioning between the scans. LV in‐ and outflow was compared from 1) 2D planimetry; 2) 4D flow MRI with retrospective valve tracking over the mitral valve (MV) and aortic valve (AV), and 3) 4D flow MRI with particle tracing through forward and backward integration of velocity data.ResultsIn‐scan consistency between MV and AV flow volumes is excellent for both 4D flow MRI methods with r ≥ 0.95 (P ≤ 0.001). In‐scan AV and MV flow by retrospective valve tracking shows good to excellent correlations versus AV and MV flow by particle tracing (r ≥ 0.81, P ≤ 0.004). Scan–rescan SV assessment by 2D planimetry shows excellent reproducibility (intraclass correlation [ICC] = 0.98, P < 0.001, coefficient of variation [CV] = 7%). Scan–rescan MV and AV flow volume assessment by retrospective valve tracking shows strong reproducibility (ICCs ≥ 0.89, P ≤ 0.05, CVs = 12%), as well as by forward and backward particle tracing (ICCs ≥ 0.90, P ≤ 0.001, CVs ≤ 11%). Multicomponent particle tracing shows good scan–rescan reproducibility (ICCs ≥ 0.81, P ≤ 0.007, CVs ≤ 16%).ConclusionLV in‐ and outflow assessment by 2D planimetry and 4D flow MRI with retrospective valve tracking and particle tracing show good in‐scan consistency and strong scan–rescan reproducibility, which indicates that both 4D flow MRI methods are reliable and can be used clinically. Level of Evidence: 2 Technical Efficacy Stage: 2J. Magn. Reson. Imaging 2018;47:511–522.

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Background Patients who have undergone the Fontan procedure are at high risk of circulatory failure. In an exploratory analysis we aimed to determine the prognostic value of blood biomarkers in a young cohort who have undergone the Fontan procedure. Methods and Results In multicenter prospective studies patients who have undergone the Fontan procedure underwent blood sampling, cardiopulmonary exercise testing, and stress cardiac magnetic resonance imaging. Several biomarkers including NT‐proBNP (N‐terminal pro‐B‐type natriuretic peptide), GDF‐15 (growth differentiation factor 15), Gal‐3 (galectin‐3), ST2 (suppression of tumorigenicity 2), DLK‐1 (protein delta homolog 1), FABP‐4 (fatty acid‐binding protein 4), IGFBP‐1 (insulin‐like growth factor‐binding protein 1), IGFBP‐7, MMP‐2 (matrix metalloproteinase 2), and vWF (von Willebrand factor) were assessed in blood at 9.6 (7.1–12.1) years after Fontan completion. After this baseline study measurement, follow‐up information was collected on the incidence of adverse cardiac events, including cardiac death, out of hospital cardiac arrest, heart transplantation (listing), cardiac reintervention (severe events), hospitalization, and cardioversion/ablation for arrhythmias was collected and the relation with blood biomarkers was assessed by Cox proportional hazard analyses. The correlation between biomarkers and other clinical parameters was evaluated. We included 133 patients who have undergone the Fontan procedure, median age 13.2 (25th, 75th percentile 10.4–15.9) years, median age at Fontan 3.2 (2.5–3.9) years. After a median follow‐up of 6.2 (4.9–6.9) years, 36 (27.1%) patients experienced an event of whom 13 (9.8%) had a severe event. NT‐proBNP was associated with (all) events during follow‐up and remained predictive after correction for age, sex, and dominant ventricle (hazard ratio, 1.89; CI, 1.32–2.68). The severe event‐free survival was better in patients with low levels of GDF‐15 ( P =0.005) and vWF ( P =0.008) and high levels of DLK‐1 ( P =0.041). There was a positive correlation (β=0.33, P =0.003) between DLK‐1 and stress cardiac magnetic resonance imaging functional reserve. Conclusions NT‐proBNP, GDF‐15, vWF, DLK‐1, ST‐2 FABP‐4, and IGFBP‐7 levels relate to long‐term outcome in young patients who have undergone the Fontan procedure.

Knowledge of normal and abnormal flow patterns in the human cardiovascular system increases our understanding of normal physiology and may help unravel the complex pathophysiological mechanisms leading to cardiovascular disease. Four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) has emerged as a suitable technique that enables visualization of in vivo blood flow patterns and quantification of parameters that could potentially be of prognostic value in the disease process. In this review, current image processing tools that are used for comprehensive visualization and quantification of blood flow and energy distribution in the heart and great vessels will be discussed. Also, imaging biomarkers extracted from 4D flow CMR will be reviewed that have been shown to distinguish between normal and abnormal flow patterns. Furthermore, current applications of 4D flow CMR in the heart and great vessels will be discussed, showing its potential as an additional diagnostic modality which could aid in disease management and timing of surgical intervention.

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The aim of the current study was to assess the scan-rescan reproducibility of left ventricular (LV) kinetic energy (KE), viscous energy loss (EL) and vorticity during diastole from four-dimensional flow magnetic resonance imaging (4D flow MRI) in healthy subjects. Twelve volunteers (age 27 ± 3 years) underwent whole-heart 4D flow MRI twice in one session. In-scan consistency was evaluated by correlation between KE and EL. EL index was computed to measure the amount of EL relative to KE over diastole. Scan-rescan analysis was performed to test reproducibility of volumetric measurements of KE, EL, EL index and vorticity in the LV over early (E) and late (A) diastolic filling. In-scan consistency between KE and EL was strong-excellent (E-filling scan1: r = 0.92, P < 0.001; scan2: ρ = 0.96, P < 0.001 and A-filling scan1: ρ = 0.87, P < 0.001; scan2: r = 0.99, P < 0.001). For the majority of subjects (10 out of 12), KE and EL measures showed good to strong reproducibility. However, with a wide range of agreement [intraclass correlation (ICC): 0.64-0.95] and coefficients of variation (CV) ≤ 25%. EL index showed strong reproducibility for all 12 subjects with a strong ICC (0.94, P < 0.001) and a CV of 9%. Scan-rescan reproducibility of volumetric vorticity showed good-excellent ICCs (0.83-0.95) with CVs ≤ 11%. In conclusion, the current study shows strong-excellent in-scan consistency and overall good agreement between scans for 4D flow MRI assessment of left ventricular kinetic energy, energy loss and vorticity over diastole. However, substantial differences between the scans were also found in some parameters in two out of twelve subjects. Strong reproducibility was found in the dimensionless EL index , which measures the amount of viscous energy loss relative to the average kinetic energy over diastole.

Fontan patients show disproportionate intraventricular EL relative to KE. Intraventricular EL is elevated in these patients compared to healthy controls, and highest EL is found in patients with discordant inflow-to-outflow.