Flow evaluation software for four-dimensional flow MRI: a reliability and validation study

PURPOSE Four-dimensional time-resolved phase-contrast cardiovascular magnetic resonance imaging (4D flow MRI) enables blood flow quantification in multiple vessels, which is crucial for patients with congenital heart disease (CHD). We investigated net flow volumes in the ascending aorta and pulmonary arteries by four different postprocessing software packages for 4D flow MRI in comparison with 2D cine phase-contrast measurements (2D PC). MATERIAL AND METHODS 4D flow and 2D PC datasets of 47 patients with biventricular CHD (median age 16, range 0.6-52 years) were acquired at 1.5 T. Net flow volumes in the ascending aorta, the main, right, and left pulmonary arteries were measured using four different postprocessing software applications and compared to offset-corrected 2D PC data. Reliability of 4D flow postprocessing software was assessed by Bland-Altman analysis and intraclass correlation coefficient (ICC). Linear regression of internal flow controls was calculated. Interobserver reproducibility was evaluated in 25 patients. RESULTS Correlation and agreement of flow volumes were very good for all software compared to 2D PC (ICC ≥ 0.94; bias ≤ 5%). Internal controls were excellent for 2D PC (r ≥ 0.95, p < 0.001) and 4D flow (r ≥ 0.94, p < 0.001) without significant difference of correlation coefficients between methods. Interobserver reliability was good for all vendors (ICC ≥ 0.94, agreement bias < 8%). CONCLUSION Haemodynamic information from 4D flow in the large thoracic arteries assessed by four commercially available postprocessing applications matches routinely performed 2D PC values. Therefore, we consider 4D flow MRI-derived data ready for clinical use in patients with CHD

Right and Left Ventricular Strain Patterns After the Atrial Switch Operation for D-Transposition of the Great Arteries—A Magnetic Resonance Feature Tracking Study

Introduction: Adult survivors of the atrial switch operation for transposition of the great arteries present with a systemic morphologic right ventricle and a subpulmonary morphologic left ventricle. This physiology can be considered a model for the effects of long-term right ventricular pressure overload and of decreased left ventricular afterload. We aimed to determine the impact of these chronically altered loading conditions on myocardial deformation of the ventricles.Materials and methods: Two-dimensional steady state free precession cine images of 29 patients after atrial repair (age 29 ± 7 years) and 19 controls (24 ± 10 years; n.s.) were post-processed with feature tracking software (TomTec 2D CPA). Volumes, ejection fractions, global and free wall longitudinal and circumferential strains of both ventricles were compared between both groups.Results: Systemic right ventricular global longitudinal strain was decreased in patients compared to controls (−12.9 ± 3.3% vs. −18.9 ± 4.6%, p &lt; 0.001), while right ventricular circumferential strain was unchanged (−15.8 ± 3.4% vs. −15.1 ± 5%; n.s.). Left ventricular longitudinal strain was similar in both groups (−17 ± 5.6% vs. −17.5 ± 4.6%; n.s.), but global left ventricular circumferential strain was lower in patients (−20.7 ± 4.1% vs. −27.3 ± 4.5%, p &lt; 0.001). The systemic right ventricle, compared to the systemic left ventricle, showed decreased global longitudinal (p &lt; 0.001) and circumferential strain (p &lt; 0.001). The subpulmonary left ventricle, compared to the subpulmonary right ventricle, demonstrated similar longitudinal (p = 0.223) but higher circumferential strain (p &lt; 0.001).Conclusions: In patients after atrial switch repair for transposition of the great arteries, the systemic right ventricle shows poor longitudinal strain, but maintains normal right ventricular circumferential strain. The left ventricle shows higher circumferential strain than the right ventricle, in both systemic and subpulmonary positions

Feasibility of non-gated dynamic fetal cardiac MRI for identification of fetal cardiovascular anatomy

INTRODUCTION To evaluate the feasibility of identifying the fetal cardiac and thoracic vascular structures with non-gated dynamic balanced steady-state free precession (SSFP) MRI sequences. METHODS We retrospectively assessed the visibility of cardiovascular anatomy in 60 fetuses without suspicion of congenital heart defect. Non-gated dynamic balanced SSFP sequences were acquired in three anatomic planes of the fetal thorax. The images were analyzed following a segmental approach in consensus reading by an experienced pediatric cardiologist and radiologist. An imaging score was defined by giving one point to each visualized structure, yielding a maximum score of 21 points. Image quality was rated from 0 (poor) to 2 (excellent). The influence of gestational age (GA), field strength, placenta position, and maternal panniculus on image quality and imaging score were tested. RESULTS 30 scans were performed at 1.5T, 30 at 3T. Heart position, atria and ventricles could be seen in all 60 fetuses. Basic diagnosis (>12 points) was achieved in 54 cases. The mean imaging score was 16.8+/-3.8. Maternal panniculus (r=-0.3; p=0.015) and gestational age (r=0.6; p<0.001) correlated with imaging score. Field strength influenced image quality, with 1.5T being better than 3T images (p=0.012). Imaging score or quality were independent of placenta position. DISCUSSION/CONCLUSION Fetal cardiac MRI with non-gated SSFP sequences enables recognition of basic cardiovascular anatomy

Normal myocardial native T1_{1} values in children using single-point saturation recovery and modified look-locker inversion recovery (MOLLI)

BACKGROUND T$_{1}$ mapping is useful to quantify diffuse myocardial processes such as fibrosis, edema, storage disorders, or hemochromatosis. Normal pediatric myocardial T$_{1}$ values are scarce using modified Look-Locker inversion recovery (MOLLI) sequences and unavailable using Smart1Map, a single-point saturation recovery sequence that measures true T$_{1}$ . PURPOSE/HYPOTHESIS To establish normal pediatric myocardial T$_{1}$ values by Smart1Map and to compare them with T$_{1}$ by MOLLI. STUDY TYPE Prospective cohort study. SUBJECTS Thirty-four children and adolescents aged 8-18 years (14 males) without cardiovascular or inflammatory diseases. FIELD STRENGTH/SEQUENCES 1.5T, MOLLI, Smart1Map. ASSESSMENT Mean T$_{1}$ values of the left ventricular myocardium, the interventricular septum, and the blood pool were measured with MOLLI and Smart1Map in basal, mid-ventricular, and apical short axis slices. STATISTICAL TESTS T$_{1}$ values were compared between locations and methods by paired samples t-tests, Wilcoxon signed ranks test, repeated-measures analysis of variance (ANOVA), or Friedman's test. Pearson's correlation coefficient was calculated. For interobserver variability, intraclass correlation coefficients and coefficients of variation were calculated, and Bland-Altman analyses were performed. RESULTS T$_{1}$ values were longer by Smart1Map than by MOLLI in all measured locations (myocardium: 1191-1221 vs. 990-1042 msec; all P 0.05) by either method. Septal vs. total myocardial T$_{1}$ values in each slice did not differ by MOLLI (basal P = 0.371; mid-ventricular P = 0.08; apical P = 0.378) nor by Smart1Map (basal P = 0.056; mid-ventricular P = 0.918; apical P = 0. 392), after artifacts had been carefully excluded. DATA CONCLUSION We established pediatric normal native T$_{1}$ values using the Smart1Map sequence and compared the results with T$_{1}$ mapping with MOLLI. Septal T$_{1}$ values did not differ from total myocardial T$_{1}$ values in each of the myocardial slices. LEVEL OF EVIDENCE 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019