Acute Heart Failure in Multisystem Inflammatory Syndrome in Children in the Context of Global SARS-CoV-2 Pandemic.

BACKGROUND: Cardiac injury and myocarditis have been described in adults with coronavirus disease 2019 (COVID-19). Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in children is typically minimally symptomatic. We report a series of febrile pediatric patients with acute heart failure potentially associated with SARS-CoV-2 infection and the multisystem inflammatory syndrome in children as defined by the US Centers for Disease Control and Prevention. METHODS: Over a 2-month period, contemporary with the SARS-CoV-2 pandemic in France and Switzerland, we retrospectively collected clinical, biological, therapeutic, and early outcomes data in children who were admitted to pediatric intensive care units in 14 centers for cardiogenic shock, left ventricular dysfunction, and severe inflammatory state. RESULTS: Thirty-five children were identified and included in the study. Median age at admission was 10 years (range, 2-16 years). Comorbidities were present in 28%, including asthma and overweight. Gastrointestinal symptoms were prominent. Left ventricular ejection fraction was <30% in one-third; 80% required inotropic support with 28% treated with extracorporeal membrane oxygenation. Inflammation markers were suggestive of cytokine storm (interleukin-6 median, 135 pg/mL) and macrophage activation (D-dimer median, 5284 ng/mL). Mean BNP (B-type natriuretic peptide) was elevated (5743 pg/mL). Thirty-one of 35 patients (88%) tested positive for SARS-CoV-2 infection by polymerase chain reaction of nasopharyngeal swab or serology. All patients received intravenous immunoglobulin, with adjunctive steroid therapy used in one-third. Left ventricular function was restored in the 25 of 35 of those discharged from the intensive care unit. No patient died, and all patients treated with extracorporeal membrane oxygenation were successfully weaned. CONCLUSIONS: Children may experience an acute cardiac decompensation caused by severe inflammatory state after SARS-CoV-2 infection (multisystem inflammatory syndrome in children). Treatment with immunoglobulin appears to be associated with recovery of left ventricular systolic function.

Myocardial involvement in children with post-COVID multisystem inflammatory syndrome: a cardiovascular magnetic resonance based multicenter international study-the CARDOVID registry.

BACKGROUND: Recent evidence shows an association between coronavirus disease 2019 (COVID-19) infection and a severe inflammatory syndrome in children. Cardiovascular magnetic resonance (CMR) data about myocardial injury in children are limited to small cohorts. The aim of this multicenter, international registry is to describe clinical and cardiac characteristics of multisystem inflammatory syndrome in children (MIS-C) associated with COVID-19 using CMR so as to better understand the real extent of myocardial damage in this vulnerable cohort. METHODS AND RESULTS: Hundred-eleven patients meeting the World Health Organization criteria for MIS-C associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), having clinical cardiac involvement and having received CMR imaging scan were included from 17 centers. Median age at disease onset was 10.0 years (IQR 7.0-13.8). The majority of children had COVID-19 serology positive (98%) with 27% of children still having both, positive serology and polymerase chain reaction (PCR). CMR was performed at a median of 28 days (19-47) after onset of symptoms. Twenty out of 111 (18%) patients had CMR criteria for acute myocarditis (as defined by the Lake Louise Criteria) with 18/20 showing subepicardial late gadolinium enhancement (LGE). CMR myocarditis was significantly associated with New York Heart Association class IV (p = 0.005, OR 6.56 (95%-CI 1.87-23.00)) and the need for mechanical support (p = 0.039, OR 4.98 (95%-CI 1.18-21.02)). At discharge, 11/111 (10%) patients still had left ventricular systolic dysfunction. CONCLUSION: No CMR evidence of myocardial damage was found in most of our MIS-C cohort. Nevertheless, acute myocarditis is a possible manifestation of MIS-C associated with SARS-CoV-2 with CMR evidence of myocardial necrosis in 18% of our cohort. CMR may be an important diagnostic tool to identify a subset of patients at risk for cardiac sequelae and more prone to myocardial damage. CLINICAL TRIAL REGISTRATION: The study has been registered on ClinicalTrials.gov, Identifier NCT04455347, registered on 01/07/2020, retrospectively registered.

Paediatric multisystem inflammatory syndrome associated with COVID-19: filling the gap between myocarditis and Kawasaki?

Myocarditis and Kawasaki disease are common but usually distinct diseases in children. During the coronavirus pandemic (COVID-19), reports of a new form of myocarditis with clinical features of Kawasaki appeared. We investigated the place of this new disease in the spectrum encompassing Kawasaki disease and myocarditis.Thirty two consecutive children referred to our centre for a suspicion of Kawasaki or a diagnosis of myocarditis were included and eventually divided into four groups: 11 Kawasaki diseases, 6 Kawasaki syndromes (children with another diagnosis), 7 myocarditis without Kawasaki clinical feature and 7 myocarditis with incomplete Kawasaki clinical features. All were treated with immunoglobulins except those of the myocarditis group. The survival rate was 91%. The 7 children with myocarditis and clinical features of incomplete Kawasaki were all positive for SARS-CoV-2. They had a transient myocardial failure with a favourable course and none had coronary artery disease.Conclusion: Every COVID-19 child within our population had a mild to severe myocarditis and presented with fever plus two or three Kawasaki clinical features. Short-term evolution was good for these children. This new disease seems to fill the gap between isolated myocarditis and Kawasaki disease. What is Known: • A new paediatric disease close to Kawasaki disease appeared during the COVID-19 pandemic What is New: • In our population, children presented with fever, vivid Kawasaki clinical features (although the Kawasaki syndrome was always incomplete) and a myocarditis without coronary abnormalities. • The new disease fills the gap between paediatric myocarditis and Kawasaki disease but its prognosis is much better.

Noninvasive fetal electrocardiography for the detection of fetal arrhythmias.

OBJECTIVE: To assess whether noninvasive fetal electrocardiography (NI-FECG) enables the diagnosis of fetal arrhythmias. METHODS: A total of 500 echocardiography and NI-FECG recordings were collected from pregnant women during a routine medical visit in this multicenter study. All the cases with fetal arrhythmias (n = 12) and a matching number of control (n = 14) were used. Two perinatal cardiologists analyzed the extracted NI-FECG while blinded to the echocardiography. The NI-FECG-based diagnosis was compared with the reference fetal echocardiography diagnosis. RESULTS: NI-FECG and fetal echocardiography agreed on all cases (Ac = 100%) on the presence of an arrhythmia or not. However, in one case, the type of arrhythmia identified by the NI-FECG was incorrect because of the low resolution of the extracted fetal P-wave, which prevented resolving the mechanism (2:1 atrioventricular conduction) of the atrial tachycardia. CONCLUSION: It is possible to diagnose fetal arrhythmias using the NI-FECG technique. However, this study identifies that improvement in algorithms for reconstructing the P-wave is critical to systematically resolve the mechanisms underlying the arrhythmias. The elaboration of a NI-FECG Holter device will offer new opportunities for fetal diagnosis and remote monitoring of problematic pregnancies because of its low-cost, noninvasiveness, portability, and minimal setup requirements.

Myocardial volume change during cardiac cycle derived from three orthogonal systolic strains: towards a quality assessment of strains.

BACKGROUND: The relative modification of the myocardial volume between end-systole and end-diastole ( Vs/d=Vend-systole/Vend-diastole ) has already been assessed with different methods and falls in a range of 0.9-0.97 (mean value = 0.93). PURPOSE: To estimate Vs/d from the three longitudinal ( ɛl) , circumferential ( ɛc ), and radial ( ɛr ) strains of the left ventricle using the formula: Vs/d=(1+ɛc)(1+ɛr)(1+ɛl) and to test whether this estimate of Vs/d can be used as a marker of the echocardiography quality. MATERIAL AND METHODS: Two hundred manuscripts, including a total of 34,690 patients or healthy volunteers, were identified in the Medline database containing values of ɛl , ɛc , and ɛr measured from echocardiography. RESULTS: The median value of was 0.93, in accordance with the literature, with no significant difference between patients or healthy volunteers ( P = 0.38). The proportion of studies with Vs/d=0.93±0.1 was 79%. When only considering groups of healthy volunteers, the studies failing this test had higher standard deviations for the three individual strains: 0.038 vs. 0.029 ( P = 0.02) for ɛl ; 0.060 vs. 0.034 ( P < 10-6) for ɛc , and 0.243 vs. 0.101 ( P < 10-14) for ɛr . CONCLUSION: The median ratio of the left ventricular myocardial volumes between end-systole and end-diastole in the investigated studies was Vs/d=0.93 . The formula (1+ɛc)(1+ɛr)(1+ɛl)∉[0.83;1.03] could be used to detect studies with inaccurate strain measurements.

Isotropic 3D cardiac cine MRI allows efficient sparse segmentation strategies based on 3D surface reconstruction.

PURPOSE: Segmentation of cardiac cine MRI data is routinely used for the volumetric analysis of cardiac function. Conventionally, 2D contours are drawn on short-axis (SAX) image stacks with relatively thick slices (typically 8 mm). Here, an acquisition/reconstruction strategy is used for obtaining isotropic 3D cine datasets; reformatted slices are then used to optimize the manual segmentation workflow. METHODS: Isotropic 3D cine datasets were obtained from multiple 2D cine stacks (acquired during free-breathing in SAX and long-axis (LAX) orientations) using nonrigid motion correction (cine-GRICS method) and super-resolution. Several manual segmentation strategies were then compared, including conventional SAX segmentation, LAX segmentation in three views only, and combinations of SAX and LAX slices. An implicit B-spline surface reconstruction algorithm is proposed to reconstruct the left ventricular cavity surface from the sparse set of 2D contours. RESULTS: All tested sparse segmentation strategies were in good agreement, with Dice scores above 0.9 despite using fewer slices (3-6 sparse slices instead of 8-10 contiguous SAX slices). When compared to independent phase-contrast flow measurements, stroke volumes computed from four or six sparse slices had slightly higher precision than conventional SAX segmentation (error standard deviation of 5.4 mL against 6.1 mL) at the cost of slightly lower accuracy (bias of -1.2 mL against 0.2 mL). Functional parameters also showed a trend to improved precision, including end-diastolic volumes, end-systolic volumes, and ejection fractions). CONCLUSION: The postprocessing workflow of 3D isotropic cardiac imaging strategies can be optimized using sparse segmentation and 3D surface reconstruction. Magn Reson Med 79:2665-2675, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Can MRI detect pulmonary hypertension in a population pre-selected by echocardiography?

Background The place of magnetic resonance imaging (MRI) in the assessment of pulmonary hypertension (PH) remains controversial. Several studies proposed to use MRI to assess pulmonary pressure but the level of proof is low. Purpose To evaluate the diagnostic power of cardiac MRI within a non-selected population of patients suspected of PH after an echocardiography. Material and Methods Fifty-six consecutive patients, suspected of PH after an echocardiography, were assessed with right heart catheterization and cardiac MRI (including a high temporal resolution pulmonary flow curve). We extracted from the MRI data the main parameters proposed by all precedent studies available in the literature. We looked for multivariate linear relations between those parameters and the mean pulmonary arterial pressure (mPAP), and eventually assessed with a logit regression the ability of those parameters to diagnose PH in our population. Results The multivariate model retained only two parameters: the right ventricle ejection fraction and the pulmonary trunk minimum area. The prediction of mPAP (r2 = 0.5) yielded limits of agreement of 15 mmHg. However, the prediction of PH within the population was feasible and the method yielded a specificity of 80% for a sensitivity of 100%. Conclusion The performance of MRI to assess mPAP is too low to be used as a replacement for right heart catheterization but MRI could be used as second line examination after echocardiography to avoid right heart catheterization for normal patients.

Adaptive step size LMS improves ECG detection during MRI at 1.5 and 3 T.

OBJECTIVE: We describe a new real-time filter to reduce artefacts on electrocardiogram (ECG) due to magnetic field gradients during MRI. The proposed filter is a least mean square (LMS) filter able to continuously adapt its step size according to the gradient signal of the ongoing MRI acquisition. MATERIALS AND METHODS: We implemented this filter and compared it, within two databases (at 1.5 and 3 T) with over 6000 QRS complexes, to five real-time filtering strategies (no filter, low pass filter, standard LMS, and two other filters optimized within the databases: optimized LMS, and optimized Kalman filter). RESULTS: The energy of the remaining noise was significantly reduced (26 vs. 68%, p < 0.001) with the new filter vs. standard LMS. The detection error of our ventricular complex (QRS) detector was: 11% with our method vs. 25% with raw ECG, 35% with low pass filter, 17% with standard LMS, 12% with optimized Kalman filter, and 11% with optimized LMS filter. CONCLUSION: The adaptive step size LMS improves ECG denoising during MRI. QRS detection has the same F1 score with this filter than with filters optimized within the database.

Nonrigid registration improves MRI T2 quantification in heart transplant patient follow-up.

BACKGROUND: To evaluate the use of a nonrigid registration technique for detecting acute heart transplant rejection by MRI T2 quantification. METHODS: Myocardial T2 quantification was achieved in 279 consecutive examinations from 78 different patients. The protocol consisted of 10 successive black-blood fast spin echo sequences with varying echo times, and a postprocessing based on image registration and exponential fitting. An automatic nonrigid registration method was applied to correct for myocardium misalignment. Finally T2 values were compared with those obtained with a conventional rigid registration followed by manual correction. RESULTS: Nonrigid registration was feasible in 98% of the datasets and was judged of higher quality compared with conventional processing (P < 0.001). No significant difference was found in the clinical outcome (average septal T2 ) between nonrigid and conventional registration (P = 0.66). Interobserver variability was improved with 95% limits of agreement of 2.7 ms (against 3.7 ms with conventional registration). The quality of T2 fitting, as assessed by the coefficient of determination R(2) , was significantly improved (P < 0.001). CONCLUSION: Nonrigid registration improves T2 quantification in heart-transplant patient follow-up.

Diagnostic and prognostic value of MRI T2 quantification in heart transplant patients.

This study was designed retrospectively to assess the value of myocardial T2 to detect or predict ongoing acute heart rejection, in heart transplant patients, with a 1.5-T MRI magnet. One hundred and ninety-six myocardial T2 quantifications were performed on sixty consecutive heart transplant patients during routine follow-up. T2 values were assessed (i) with regard to the results of concomitant biopsies and (ii) with a Cox multivariate model for the prediction of subsequent rejections, defined by a ≥ grade 2 at biopsy or highly suspected in the absence of biopsy (>10% drop in ejection fraction with subsequent reversibility under treatment). T2 values were proposed as main covariate, after logit transformation and adjustment for other confounding parameters such as delay since graft surgery and delay before biopsy. T2 values were strongly linked (i) to the presence of rejection on concomitant biopsy (P < 0.0001) and (ii) to the risk of subsequent rejection on Cox multivariate model (P < 0.001). T2 values above 60 ms were associated with relative risk of rejection higher than 2.0 and rapidly increasing. In conclusion, myocardial T2 yields a high diagnostic and prognostic value for graft rejection in heart transplant patients.

Longitudinal myocardial peak velocities using high temporal resolution phase-contrast and simple averaging are comparable to tissue Doppler echocardiography.

OBJECT: Phase contrast imaging is widely used to measure blood velocity. However tissue Doppler imaging (TDI) echocardiography is the reference for myocardial velocity assessment. This study aims at validating the ability of phase contrast (PC) sequences to correctly assess myocardial velocities and to compare these velocities to TDI. The phase contrast sequence was performed with breath-hold parameters and with parameters tuned to increase temporal resolution in free breathing. MATERIALS AND METHODS: Left and Right auriculo-ventricular annuluses longitudinal velocities were recorded on six healthy volunteers with different temporal resolutions (TDI: 5 ms, breath-hold PC: 94 ms and free-breathing PC: 19 ms). Free-breathing PC was obtained by averaging of three excitations. Amplitudes of four standard echocardiographic and clinically relevant myocardial longitudinal velocity waves were compared: Early filling and auricular, systolic and isovolumic contractions. RESULTS: Isovolumic contraction waves were only visible with free-breathing PC and TDI. The differences with the reference TDI wave velocities were lower (p = 0.02) for free-breathing PC (19.2 ± 2.6%) than for breath-hold PC (28.1 ± 2.9%). These differences for free-breathing PC were close to (p = 0.21) the coefficient of variation of the measurements provided by TDI (14.8 ± 1.2%). CONCLUSION: Myocardial longitudinal peak velocities can be assessed with a PC sequence tuned to optimize temporal resolution.

Surface-length index: a novel index for rapid detection of right ventricles with abnormal ejection fraction using cardiac MRI.

OBJECTIVE: To validate a new index, the surface-length index (SLI) based on area change in a short-axis view and length reduction in the horizontal long-axis view, which is used to quickly (<1 min) detect right ventricles with an abnormal ejection fraction (EF) during a cardiac MRI examination. SLI can be used to avoid a complete delineation of the endocardial contours of normal right ventricles. METHODS: Sixty patients (group A) were retrospectively included to calibrate the SLI formula by optimisation of the area under the ROC curves and SLI thresholds were chosen to obtain 100 % sensitivity. Another 340 patients (group B) were prospectively recruited to test SLI's capacity to detect right ventricles (RVs) with an abnormal EF (<0.5). RESULTS: The appropriate threshold to obtain 100 % sensitivity in group A was 0.58. In group B, with the 0.58 threshold, SLI yielded a sensitivity of 100 % and specificity of 51 %. SLI would have saved 35 % of the RV studies in our population, without inducing any diagnostic error. SLI and EF correlation was good (r (2) = 0.64). CONCLUSION: SLI combines two simple RV measures, and brings significant improvement in post-processing efficiency by preselecting RVs that require a complete study. KEY POINTS: • Assessment of right ventricle ejection fraction (RVEF) with cine-MRI is time consuming. • Therefore, RVEF is not always assessed during cardiac MRI. • Surface-length index (SLI) allows rapid detection of abnormal RVEF during cardiac MRI. • SLI saves one third of the operator time. • Every cardiac MRI could include RVEF assessment by means of SLI.

Assessment of right ventricle volumes and function by cardiac MRI: quantification of the regional and global interobserver variability.

Reproducibility of the manual assessment of right ventricle volumes by short-axis cine-MRI remains low and is often attributed to the difficulty in separating the right atrium from the ventricle. This study was designed to evaluate the regional interobserver variability of the right ventricle volume assessment to identify segmentation zones with the highest interobserver variability. Short-axis views of 90 right ventricles (30 hypertrophic, 30 dilated, and 30 normal) were acquired with 2D steady-state free precession sequences at 1.5 T and were manually segmented by two observers. The two segmentations were compared and the variations were quantified with a variation score based on the Hausdorff distance between the two segmentations and the interobserver 95% limits of concordance of the global volumes. The right ventricles were semiautomatically split into four subregions: apex, mid-ventricle, tricuspid zone, and infundibulum. These four subregions represented 11%, 34%, 36%, and 19% of the volume but, respectively, yielded variation scores of 8%, 16%, 42%, and 34%. The infundibulum yielded the highest interobserver regional variability although its variation score remained comparable to the tricuspid zone due to its lower volume. These results emphasize the importance of standardizing the segmentation of the infundibulum and the tricuspid zone to improve reproducibility.

Severe neonatal hypercalcemia caused by subcutaneous fat necrosis without any apparent cutaneous lesion.

UNLABELLED: Subcutaneous fat necrosis is a classic, albeit uncommon, cause of neonatal hypercalcemia. It occurs in newborn infants within the first month of life following a complicated delivery. The diagnosis is usually easy because of the presence of red-purple plaques in fatty areas along with firm subcutaneous nodules. A 1-month-old neonate, born strangled by her umbilical cord, presented with diarrhea and hypercalcemia (3.46 mM) with an initial physical examination considered normal. Her biological evaluations were as follows: P = 1.37 mM (1.6-2.2); PTH = 3 ng/L (12-65); 25-OH vitamin D = 87 nM (23-113); (1,25)-OH(2) vitamin D = 192 ng/L (20-46). The third day, a careful exam of the whole cutaneous surface revealed small firm subcutaneous nodules in the ischial region. Despite the absence of any visible skin modification, the association of perinatal stress and high (1,25)-OH(2) vitamin D level with subcutaneous nodules led to the diagnosis of subcutaneous fat necrosis. She was treated with oral prednisone for 45 days. Serum calcium levels normalized within a week, and the nodules disappeared without complications. CONCLUSION: Subcutaneous fat necrosis may induce severe hypercalcemia without any visible cutaneous lesion.

Isotropic Reconstruction of MR Images Using 3D Patch-Based Self-Similarity Learning.

Isotropic three-dimensional (3D) acquisition is a challenging task in magnetic resonance imaging (MRI). Particularly in cardiac MRI, due to hardware and time limitations, current 3D acquisitions are limited by low-resolution, especially in the through-plane direction, leading to poor image quality in that dimension. To overcome this problem, super-resolution (SR) techniques have been proposed to reconstruct a single isotropic 3D volume from multiple anisotropic acquisitions. Previously, local regularization techniques such as total variation have been applied to limit noise amplification while preserving sharp edges and small features in the images. In this paper, inspired by the recent progress in patch-based reconstruction, we propose a novel isotropic 3D reconstruction scheme that integrates non-local and self-similarity information from 3D patch neighborhoods. By grouping 3D patches with similar structures, we enforce the natural sparsity of MR images, which can be expressed by a low-rank structure, leading to robust image reconstruction with high signal-to-noise ratio efficiency. An Augmented Lagrangian formulation of the problem is proposed to efficiently decompose the optimization into a low-rank volume denoising and a SR reconstruction. Experimental results in simulations, brain imaging and clinical cardiac MRI, demonstrate that the proposed joint SR and self-similarity learning framework outperforms current state-of-the-art methods. The proposed reconstruction of isotropic 3D volumes may be particularly useful for cardiac applications, such as myocardial infarction scar assessment by late gadolinium enhancement MRI.

Accuracy of subject-specific prediction of end-systolic time in MRI across a range of RR intervals.

BACKGROUND: Prediction of End-Systole time is of utmost importance for cardiac MRI to correctly associate acquired k-space lines during reconstruction of cine acquisitions. This prediction is usually based on the patient's heart rate using Weissler's formula, which was calibrated by linear regression within a population and cannot account for individual variability. OBJECTIVE: We propose an automatic method to build a personalized model that better predicts end-systole. METHODS: A phase contrast sequence was modified to acquire only central k-space line with 6.6ms temporal resolution, in a slice passing through the aorta during 128 heartbeats in 35 subjects. Segmentation of aorta and detection of end of systolic ejection was automatic. Duration of electromechanical systole duration as function of heart rate was determined for each subject separately. RESULTS: In comparison with the global models, the adapted cardiac model predicted significantly better both echocardiographic end-systolic reference (bias = 0ms vs 17ms, p<0.001) and MRI measurements (bias = 6.8ms vs 17ms). Favorable impact was shown on the cine reconstruction of the 5 subjects with the higher cardiac variability (p = 0.02). CONCLUSIONS: Personalization of cardiac model to the subject is feasible in MRI and reduces the error of prediction of systole.

Design and Validation of a Novel MR-Compatible Sensor for Respiratory Motion Modeling and Correction.

GOAL: A novel magnetic resonance (MR) compatible accelerometer for respiratory motion sensing (MARMOT) is developed as a surrogate of the vendors' pneumatic belts. We aim to model and correct respiratory motion for free-breathing thoracic-abdominal MR imaging and to simplify patient installation. METHODS: MR compatibility of MARMOT sensors was assessed in phantoms and its motion modeling/correction efficacy was demonstrated on 21 subjects at 3 T. Respiration was modeled and predicted from MARMOT sensors and pneumatic belts, based on real-time images and a regression method. The sensor accuracy was validated by comparing motion errors in the liver/kidney. Sensor data were also exploited as inputs for motion-compensated reconstruction of free-breathing cardiac cine MR images. Multiple and single sensor placement strategies were compared. RESULTS: The new sensor is compatible with the MR environment. The average motion modeling and prediction errors with MARMOT sensors and with pneumatic belts were comparable (liver and kidney) and were below 2 mm with all tested configurations (belts, multiple/single MARMOT sensor). Motion corrected cardiac cine images were of improved image quality, as assessed by an entropy metric (p  <  10-6), with all tested configurations. Expert readings revealed multiple MARMOT sensors were the best (p  <  0.03) and the single MARMOT sensor was similar to the belts (nonsignificant in two of the three readers). CONCLUSION: The proposed sensor can model and predict respiratory motion with sufficient accuracy to allow free-breathing MR imaging strategy. SIGNIFICANCE: It provides an alternative sensor solution for the respiratory motion problem during MR imaging and may improve the convenience of patient setup.

Specifics of cardiac magnetic resonance imaging in children.

This review points out three specific features of cardiac magnetic resonance imaging (MRI) in children: the small size of the heart modifies the usual balance between signal-to-noise ratio and spatial resolution; the higher and more variable heart rate limits tissue characterization and temporal resolution; and motion artefacts (notably respiratory motions) must be dealt with. In the second part of this review, we present the current and future practices of cardiac magnetic resonance (CMR) in children, based on the experience of all French paediatric cardiac MRI centres.