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MRI represents the most established liver iron content (LIC) evaluation approach by estimation of liver T2* value, but it is dependent on the choice of the measurement region and the software used for image analysis.To develop a deep-learning method for unsupervised classification of LIC from magnitude T2* multiecho MR images.Retrospective.A total of 1069 thalassemia major patients enrolled in the core laboratory of the Myocardial Iron Overload in Thalassemia (MIOT) network, which were included in the training (80%) and test (20%) sets. Twenty patients from different MRI vendors included in the external test set.A5 T, T2* multiecho magnitude images.Four deep-learning convolutional neural networks (HippoNet-2D, HippoNet-3D, HippoNet-LSTM, and an ensemble network HippoNet-Ensemble) were used to achieve unsupervised staging of LIC using five classes (normal, borderline, middle, moderate, severe). The training set was employed to construct the deep-learning model. The performance of the LIC staging model was evaluated in the test set and in the external test set. The model's performances were assessed by evaluating the accuracy, sensitivity, and specificity with respect to the ground truth labels obtained by T2* measurements and by comparison with operator-induced variability originating from different region of interest (ROI) placements.The network's performances were evaluated by single-class accuracy, specificity, and sensitivity and compared by one-way repeated measures analysis of variance (ANOVA) and one-way ANOVA.HippoNet-Ensemble reached an accuracy significantly higher than the other networks, and a sensitivity and specificity higher than HippoNet-LSTM. Accuracy, sensitivity, and specificity values for the LIC stages were: normal: 0.96/0.93/0.97, borderline: 0.95/0.85/0.98, mild: 0.96/0.88/0.98, moderate: 0.95/0.89/0.97, severe: 0.97/0.95/0.98. Correctly staging of cases was in the range of 85%-95%, depending on the LIC class. Multiclass accuracy was 0.90 against 0.92 for the interobserver variability.The proposed HippoNet-Ensemble network can perform unsupervised LIC staging and achieves good prognostic performance.4 TECHNICAL EFFICACY: Stage 2.

Purpose To define reference values of cardiac volumes, dimensions, and new morpho-functional parameters normalized for age, gender, and body surface area by cine-bSSFP (balanced steady-state free-precession) magnetic resonance (MR). Materials and Methods We enrolled 308 healthy subjects subdivided by gender and by six age classes: class I, >15–20 years; class II, >20–30 years; class III, >30–40 years; class IV, >40–50 years; class V, >50–60 years; and class VI >60 years. Dimensional, volumetric and morpho-functional parameters of the left (LV) and right (RV) ventricles were measured using cine-bSSFP MRI at 1.5T. Results The LV and RV end-diastolic volume indexes (EDVi) were inversely related to age (P < 0.0001 r = –0.34 and P < 0.0001 r = –0.37, respectively). In addition, the LV mass index decreased with age (P = 0.0004, r = –0.21). The LV longitudinal shortening was not significantly different among groups: ≥15% in all populations (95% confidence interval [CI]: 16–31). The sphericity index measured in end-diastole was higher in females than in males (P < 0.03): the upper limit was 40% for males and 42% for females. The normality cutoff of LV global function index was ≥33% in males and ≥35% in females. The end-diastolic volume (EDV) of RV and LV was balanced (RV/LV ratio 0.85–1.15) without differences in the population. The LV EDV/mass was 1.0–1.8 in males and 1.0–2.1 in females. Conclusion This study provides potential age- and gender-specific reference. Evidence level 2 J. Magn. Reson. Imaging 2016.

Purpose To evaluate the efficiency of a novel transit time (Δt) estimation method from cardiovascular magnetic resonance flow curves. Materials and Methods Flow curves were estimated from phase contrast images of 30 patients. Our method (TT-GD: transit time group delay) operates in the frequency domain and models the ascending aortic waveform as an input passing through a discrete-component “filter,” producing the observed descending aortic waveform. The GD of the filter represents the average time delay (Δt) across individual frequency bands of the input. This method was compared with two previously described time-domain methods: TT-point using the half-maximum of the curves and TT-wave using cross-correlation. High temporal resolution flow images were studied at multiple downsampling rates to study the impact of differences in temporal resolution. Results Mean Δts obtained with the three methods were comparable. The TT-GD method was the most robust to reduced temporal resolution. While the TT-GD and the TT-wave produced comparable results for velocity and flow waveforms, the TT-point resulted in significant shorter Δts when calculated from velocity waveforms (difference: 1.8 ± 2.7 msec; coefficient of variability: 8.7%). The TT-GD method was the most reproducible, with an intraobserver variability of 3.4% and an interobserver variability of 3.7%. Conclusion Compared to the traditional TT-point and TT-wave methods, the TT-GD approach was more robust to the choice of temporal resolution, waveform type, and observer. J. Magn. Reson. Imaging 2014;39:550–558. © 2013 Wiley Periodicals, Inc.

Purpose To assess the transferability of the magnetic resonance imaging (MRI) multislice multiecho T2* technique for global and segmental measurement of iron overload in thalassemia patients. Materials and Methods Multiecho T2* sequences were installed on six MRI scanners. Five healthy subjects (n = 30) were scanned at each site; five thalassemia major (TM) patients were scanned at the reference site and were rescanned locally (n = 25) within 1 month. T2* images were analyzed using previously validated software. Results T2* values of healthy subjects showed intersite homogeneity. On TM patients, for global heart T2* values the correlation coefficient was 0.97, coefficients of variation (CoVs) ranged from 0.04–0.12, and intraclass coefficients (ICCs) ranged from 0.94–0.99. The mean CoV and ICC for segmental T2* distribution were 0.198 and 88, respectively. Conclusion The multislice multiecho T2* technique is transferable among scanners with good reproducibility. J. Magn. Reson. Imaging 2009;30:62–68. © 2009 Wiley-Liss, Inc.

Purpose To determine whether T2* measurements quantifying myocardial iron overload in thalassemia patients are influenced by myocardial fibrosis and blood oxygenation. Materials and Methods Multislice multiecho T2* was performed in 94 thalassemia patients in order to quantify myocardial iron overload. The left ventricle was automatically segmented into a 16-segment standardized heart model, and the T2* value on each segment as well as the global T2* were calculated. Delayed enhanced cardiovascular magnetic resonance (DE-CMR) images were obtained to detect myocardial fibrosis. The blood oxygenation was assessed by the noninvasive measurement of partial pressure of oxygen (pO2). Results Myocardial fibrosis was detected in 31 patients (33%). The global T2* value in patients with fibrosis was comparable with that of patients without fibrosis (P = 0.88) and T2* values in segments with fibrosis were comparable with those in segments without fibrosis (P = 0.83). The global T2* value was not correlated with the pO2 (Spearman's coefficient of correlation = 0.99). Conclusion Myocardial fibrosis and blood oxygenation did not significantly affect the T2* values. These data further support the use of heart T2* as equivalent of heart iron in the clinical arena. J. Magn. Reson. Imaging 2009;29:832–837. © 2009 Wiley-Liss, Inc.

Purpose To evaluate the feasibility of assessing coronary vasodilation following exogenous nitrates, using magnetic resonance angiography (MRA). The assessment of coronary response to exogenous nitrovasodilators may have a diagnostic and prognostic impact in patients with coronary artery disease. To date, stress imaging of coronary artery vasomotion has been confined to the catheterization laboratory. MRA is emerging as a noninvasive tool for coronary artery imaging. Materials and Methods Coronary MRA was performed in 20 healthy volunteers (12 males, age = 33 ± 8). We used spiral spoiled gradient echo (SSGE) sequences for imaging of coronary artery lumen. After the baseline short-axis view of the coronary artery was obtained, sublingual nitroglycerin (NTG) (0.3 mg) was administered. In all subjects, short-axis views of the coronary artery were acquired repetitively (8–10 times) from 1 up to 10 minutes after NTG administration. Measurements were obtained by two independent investigators. Results Interpretable short-axis view of left anterior descending artery (LAD) was obtained in 15 subjects (75%); in the remaining five subjects the right coronary artery (RCA) was examined. The interobserver variability was 15%, and the intraobserver variability 4%. The NTG-induced maximal vasodilation was 43 ± 22%. The vasodilator response over time after NTG was maximal on average at 279 ± 112 seconds, but with substantial heterogeneity. Conclusion Entity and time course of nitrate-induced coronary vasodilation in the left anterior descending and/or RCA can be assessed using MRA with high feasibility and reproducibility. Coronary MRA has potential for dynamic imaging of coronary vasomotion. J. Magn. Reson. Imaging 2004;20:390–394. © 2004 Wiley-Liss, Inc.