Design and implementation of multicenter pediatric and congenital studies with cardiovascular magnetic resonance: Big data in smaller bodies.

Cardiovascular magnetic resonance (CMR) has become the reference standard for quantitative and qualitative assessment of ventricular function, blood flow, and myocardial tissue characterization. There is a preponderance of large CMR studies and registries in adults; However, similarly powered studies are lacking for the pediatric and congenital heart disease (PCHD) population. To date, most CMR studies in children are limited to small single or multicenter studies, thereby limiting the conclusions that can be drawn. Within the PCHD CMR community, a collaborative effort has been successfully employed to recognize knowledge gaps with the aim to embolden the development and initiation of high-quality, large-scale multicenter research. In this publication, we highlight the underlying challenges and provide a practical guide toward the development of larger, multicenter initiatives focusing on PCHD populations, which can serve as a model for future multicenter efforts.

High-sensitivity cardiac troponin T in infants exposed to anti-Ro antibodies.

OBJECTIVES: Cardiac involvement in neonatal lupus erythematosis (NLE) can present as myocarditis/endocardial fibroelastosis (EFE). It is unknown whether high-sensitivity cardiac troponin T (hs-cTnT) is useful in identifying subclinical myocardial inflammation in infants exposed prenatally to anti-Ro antibodies. This study reports hs-cTnT levels in infants exposed to anti-Ro antibodies with/without cardiac NLE and reports cardiac MRI (CMR) findings in a subset of these children. METHODS: The study included 45 consecutive infants exposed prenatally to anti-Ro antibodies with (n = 7) or without (n = 38) cardiac NLE, who were seen at the SickKids NLE Clinic between 2012 and 2014. Hs-cTnT levels were measured at least once, and those infants with values of ≥30 ng/l were offered the opportunity to undergo CMR. Descriptive statistics were performed. RESULTS: Of 38 infants without cardiac NLE, 25 had a hs-cTnT level of ≥30 ng/l (including 1 of >113 ng/l); of these, 8 underwent CMR (all without myocarditis/EFE). All 7 infants with cardiac NLE had at least one hs-cTnT level of ≥30 ng/l, but only 2/7 had a level of >113 ng/l; 4/7 infants with cardiac NLE had CMR (all without myocarditis/EFE); 6/7 infants with cardiac NLE had their steroid treatment adjusted based on the trend in their hs-cTnT levels. CONCLUSION: Only 3/45 anti-Ro antibodies-exposed infants had hs-cTnT values outside the reference range reported in healthy infants. None of 12 infants who had CMR had subclinical myocarditis/EFE. Routine measurement of hs-cTnT in every anti-Ro antibody-exposed infant is not indicated. Further studies are needed to define the role of hs-cTnT as a biomarker for cardiac NLE.

Heart transplantation in neonatal Marfan syndrome: Saving life in a rare and fatal condition.

BACKGROUND: Neonatal Marfan syndrome is a rare disease with mortality in the first year of life reported as high as 95% predominantly due to progressive heart failure from valvar regurgitation and cardiomyopathy. Multisystem involvement and uncertain prognosis have historically precluded transplant candidacy, and current management options are of limited success. CASE REPORT: We present a baby girl with a postnatal diagnosis of neonatal Marfan syndrome who at 1 year of age underwent mitral valve and tricuspid valve repair with postoperative profound left ventricular and moderate right ventricular dysfunction necessitating biventricular assist device (BiVAD) support and subsequent heart transplant. A number of noncardiac issues persisted in our patient; however, she enjoyed a good quality of life for the initial 3 years posttransplant. Unfortunately, she subsequently developed rapidly progressive coronary allograft vasculopathy (CAV) with progressive deterioration in function and cardiac arrest. CONCLUSION: To our best knowledge, this is only the second case of neonatal Marfan syndrome to undergo heart transplant reported in the literature and the first with BiVAD support as a bridge to candidacy. This is also the first case of neonatal Marfan syndrome associated with intragenic duplication. This case though demonstrating that earlier listing, ventricular assist device (VAD) support and even primary transplant as treatment in neonatal Marfan syndrome should all be considered viable options but also portends a cautionary tale given the spectrum of comorbidities in this rare and severe disorder.

COVID vaccine-associated myocarditis in an 8-year-old patient.

COVID vaccine-associated myocarditis was first identified in March 2021. There have been numerous case reports that detail the clinical course of paediatric patients older than age 12 with COVID vaccine-associated myocarditis. There are still very few reports of children between the ages of 5 and 11 with COVID vaccine-associated myocarditis. We present an 8 year- old with COVID vaccine-associated myocarditis after his second vaccination against SARS-CoV-2.

Reversal of right ventricular pressure loading improves biventricular function independent of fibrosis in a rabbit model of pulmonary artery banding.

Right ventricular (RV) pressure loading leads to RV and left ventricular (LV) dysfunction through RV hypertrophy, dilatation and fibrosis. Relief of RV pressure load improves RV function. However, the impact and mechanisms on biventricular reverse-remodelling and function are only partially characterized. We evaluated the impact of RV pressure overload relief on biventricular remodelling and function in a rabbit model of reversible pulmonary artery banding (PAB). Rabbits were randomized to three groups: (1) Sham-operated controls (n = 7); (2) PAB (NDef, n = 7); (3) PAB followed by band deflation (Def, n = 5). Sham and NDef animals were sacrificed at 6 weeks after PAB surgery. Def animals underwent PAB deflation at 6 weeks and sacrifice at 9 weeks. Biventricular geometry, function, haemodynamics, hypertrophy and fibrosis were compared between groups using echocardiography, magnetic resonance imaging, high-fidelity pressure-tipped catheters and histology. RV pressure loading caused RV dilatation, systolic dysfunction, myocyte hypertrophy and LV compression which improved after PAB deflation. RV end-diastolic pressure (RVEDP) decreased after PAB deflation, although remaining elevated vs. Sham. LV end-diastolic pressure (LVEDP) was unchanged following PAB deflation. RV and LV collagen volumes in the NDef and Def group were increased vs. Sham, whereas RV and LV collagen volumes were similar between NDef and Def groups. RV myocyte hypertrophy (r = 0.75, P < 0.001) but not collagen volume was related to RVEDP. LV myocyte hypertrophy (r = 0.58, P = 0.016) and collagen volume (r = 0.56, P = 0.031) correlated with LVEDP. In conclusion, relief of RV pressure overload improves RV and LV geometry, hypertrophy and function independent of fibrosis. The long-term implications of persistent fibrosis and increased biventricular filling pressures, even after pressure load relief, need further study. KEY POINTS: Right ventricular (RV) pressure loading in a pulmonary artery banding rabbit model is associated with RV dilatation, left ventricular (LV) compression; biventricular myocyte hypertrophy, fibrosis and dysfunction. The mechanisms and impact of RV pressure load relief on biventricular remodelling and function has not been extensively studied. Relief of RV pressure overload improves biventricular geometry in conjunction with improved RV myocyte hypertrophy and function independent of reduced fibrosis. These findings raise questions as to the importance of fibrosis as a therapeutic target.

Diagnosis and Management of Myocarditis in Children: A Scientific Statement From the American Heart Association.

Myocarditis remains a clinical challenge in pediatrics. Originally, it was recognized at autopsy before the application of endomyocardial biopsy, which led to a histopathology-based diagnosis such as in the Dallas criteria. Given the invasive and low-sensitivity nature of endomyocardial biopsy, its diagnostic focus shifted to a reliance on clinical suspicion. With the advances of cardiac magnetic resonance, an examination of the whole heart in vivo has gained acceptance in the pursuit of a diagnosis of myocarditis. The presentation may vary from minimal symptoms to heart failure, life-threatening arrhythmias, or cardiogenic shock. Outcomes span full resolution to chronic heart failure and the need for heart transplantation with inadequate clues to predict the disease trajectory. The American Heart Association commissioned this writing group to explore the current knowledge and management within the field of pediatric myocarditis. This statement highlights advances in our understanding of the immunopathogenesis, new and shifting dominant pathogeneses, modern laboratory testing, and use of mechanical circulatory support, with a special emphasis on innovations in cardiac magnetic resonance imaging. Despite these strides forward, we struggle without a universally accepted definition of myocarditis, which impedes progress in disease-targeted therapy.

Social media to enhance engagement and science dissemination during in-person and virtual medical conferences: the SCMR 2020 and 2021 experiences: a report of the SCMR social media task force.

Most cardiac imaging conferences have adopted social media as a means of disseminating conference highlights to a global audience well beyond the confines of the conference location. A deliberate and thoughtful social media campaign has the potential to increase the reach of the conference and allow for augmented engagement. The coronavirus disease 2019 (COVID-19) pandemic triggered a radical transformation in not just the delivery of healthcare but also the dissemination of science within the medical community. In the past, in-person medical conferences were an integral annual tradition for most medical professionals to stay up to date with the latest in the field. Social distancing requirements of the COVID-19 pandemic resulted in either cancelling medical conferences or shifting to a virtual format. Following suit, for the first time in its history, the 2021 Society for Cardiovascular Magnetic Resonance (SCMR) annual meeting was an all-virtual event. This called for a modified social media strategy which aimed to re-create the sociability of an in-person conference whilst also promoting global dissemination of the science being presented. This paper describes the employment of social media as well as the evolution through the SCMR scientific sessions for 2020 and 2021 that serves as a model for future cardiovascular conferences.

Adverse fibrosis remodeling and aortopulmonary collateral flow are associated with poor Fontan outcomes.

BACKGROUND: The extent and significance in of cardiac remodeling in Fontan patients are unclear and were the subject of this study. METHODS: This retrospective cohort study compared cardiovascular magnetic resonance (CMR) imaging markers of cardiac function, myocardial fibrosis, and hemodynamics in young Fontan patients to controls. RESULTS: Fifty-five Fontan patients and 44 healthy controls were included (median age 14 years (range 7-17 years) vs 13 years (range 4-14 years), p = 0.057). Fontan patients had a higher indexed end-diastolic ventricular volume (EDVI 129 ml/m2 vs 93 ml/m2, p < 0.001), and lower ejection fraction (EF 45% vs 58%, p < 0.001), circumferential (CS - 23.5% vs - 30.8%, p < 0.001), radial (6.4% vs 8.2%, p < 0.001), and longitudinal strain (- 13.3% vs - 24.8%, p < 0.001). Compared to healthy controls, Fontan patients had higher extracellular volume fraction (ECV) (26.3% vs 20.6%, p < 0.001) and native T1 (1041 ms vs 986 ms, p < 0.001). Patients with a dominant right ventricle demonstrated larger ventricles (EDVI 146 ml/m2 vs 120 ml/m2, p = 0.03), lower EF (41% vs 47%, p = 0.008), worse CS (- 20.1% vs - 25.6%, p = 0.003), and a trend towards higher ECV (28.3% versus 24.1%, p = 0.09). Worse EF and CS correlated with longer cumulative bypass (R = - 0.36, p = 0.003 and R = 0.46, p < 0.001), cross-clamp (R = - 0.41, p = 0.001 and R = 0.40, p = 0.003) and circulatory arrest times (R = - 0.42, p < 0.001 and R = 0.27, p = 0.03). T1 correlated with aortopulmonary collateral (APC) flow (R = 0.36, p = 0.009) which, in the linear regression model, was independent of ventricular morphology (p = 0.9) and EDVI (p = 0.2). The composite outcome (cardiac readmission, cardiac reintervention, Fontan failure or any clinically significant arrhythmia) was associated with increased native T1 (1063 ms vs 1026 ms, p = 0.029) and EDVI (146 ml/m2 vs 118 ml/m2, p = 0.013), as well as decreased EF (42% vs 46%, p = 0.045) and worse CS (- 22% vs - 25%, p = 0.029). APC flow (HR 5.5 CI 1.9-16.2, p = 0.002) was independently associated with the composite outcome, independent of ventricular morphology (HR 0.71 CI 0.30-1.69 p = 0.44) and T1 (HR1.006 CI 1.0-1.13, p = 0.07). CONCLUSIONS: Pediatric Fontan patients have ventricular dysfunction, altered myocardial mechanics and increased fibrotic remodeling. Cumulative exposure to cardiopulmonary bypass and increased aortopulmonary collateral flow are associated with myocardial dysfunction and fibrosis. Cardiac dysfunction, fibrosis, and collateral flow are associated with adverse outcomes.

Progressive right ventricular outflow tract fibrosis after repair of tetralogy of Fallot.

OBJECTIVES: The objective of this study was to determine the evolution of fibrosis over time and its association with clinical status. METHODS: Children with repaired tetralogy of Fallot who had undergone at least two cardiac magnetic resonance examinations including T1 mapping at least 1 year apart were included. RESULTS: Thirty-seven patients (12.7 ± 2.6 years, 61% male) were included. Right ventricular free wall T1 increased (913 ± 208 versus 1023 ± 220 ms; p = 0.02). Baseline cardiac magnetic resonance parameters did not predict a change in imaging markers or exercise tolerance. The right ventricular free wall per cent change correlated with left ventricular T1% change (r = 0.51, p = 0.001) and right ventricular mass Z-score change (r = 0.51, p = 0.001). T1 in patients with late gadolinium enhancement did not differ from the rest. CONCLUSION: Increasing right ventricular free wall T1 indicates possible progressive fibrotic remodelling in the right ventricular outflow tract in this pilot study in children and adolescents with repaired tetralogy of Fallot. The value of T1 mapping both at baseline and during serial assessments will need to be investigated in larger cohorts with longer follow-up.

Right ventricular function in patients with pulmonary regurgitation with versus without tetralogy of Fallot.

BACKGROUND: Right ventricular (RV) dilation from pulmonary valve regurgitation (PR) is common after intervention(s) for pulmonary stenosis (PS) or atresia and intact ventricular septum (PA/IVS). It is not well established whether PR and RV dilation have similar effects on RV function and exercise capacity in these patients compared to patients after repair of tetralogy of Fallot (rToF). The aims of this study were to compare exercise tolerance, RV function and myocardial mechanics in non-ToF versus rToF children with significantly increased and comparable RV volumes. METHODS: Thirty PS or PA/IVS children after intervention(s) with significant PR and RV dilation (non-ToF group) were retrospectively matched for RV end-diastolic volume index (RVEDVi) and age with 30 rToF patients. Clinical characteristics, RV function by echocardiography and CMR, ECG and exercise capacity were compared between groups. RESULTS: The groups were well matched for RVEDVi and age. Global RV function (RVEF: 48.7 ±â€¯6.4% vs. 48.5 ±â€¯7.2%, P = .81) and exercise capacity (% predicted peak VO2:82.5 ±â€¯17.7% vs. 75.6 ±â€¯20.4%, P = .27) were similarly reduced between groups. RVEDVi correlated inversely with RVEF in both groups (non-ToF:r = -0.39, P = .04, rToF:r = -0.40, P = .03). QRS duration was wider in rToF patients, and in both groups inversely correlated with RVEF (non-ToF:r = -0.77, P < .001, rToF:r = -0.69, P < .001). In contrast to global function, longitudinal RV strain was lower in rTOF vs non-TOF (-20.1 ±â€¯3.9 vs.-25.7 ±â€¯4.4, P < .001). CONCLUSIONS: Global RV function and exercise capacity are similarly reduced in non-ToF and rToF patients with severely dilated RV, after matching by RVEDVi, suggesting a comparable impact of RV dilation on RV global function. The significance of reduced RV longitudinal function and worse dyssynchrony in rToF patients require further exploration.

Increased extracellular volume in the liver of pediatric Fontan patients.

BACKGROUND: Patients with single ventricle physiology are at increased risk for developing liver fibrosis. Its extent and prevalence in children with bidirectional cavopulmonary connection (BCPC) and Fontan circulation are unclear. Extracellular volume fraction (ECV), derived from cardiovascular magnetic resonance (CMR) and T1 relaxometry, reflect fibrotic remodeling and/or congestion in the liver. The aim of this study was to investigate whether pediatric patients with single ventricle physiology experience increased native T1 and ECV as markers of liver fibrosis/congestion. METHODS: Hepatic native T1 times and ECV, using a cardiac short axis modified Look-Locker inversion recovery sequence displaying the liver, were measured retrospectively in children with BCPC- and Fontan circulations and compared to pediatric controls. RESULTS: Hepatic native T1 time were increased in Fontan patients (n = 62, 11.4 ± 4.4 years, T1 762 ± 64 ms) versus BCPC patients (n = 20, 2.8 ± 0.9 years, T1 645 ± 43 ms, p = 0.04). Both cohorts had higher T1 than controls (n = 44, 13.7 ± 2.9 years, T1 604 ± 54 ms, p < 0.001 for both). ECV was 41.4 ± 4.8% in Fontan and 36.4 ± 4.8% in BCPC patients, respectively (p = 0.02). In Fontan patients, T1 values correlated with exposure to cardiopulmonary bypass time (R = 0.3, p = 0.02), systolic and end diastolic volumes (R = 0.3, p = 0.04 for both) and inversely with oxygen saturations and body surface area (R = -0.3, p = 0.04 for both). There were no demonstrable associations of T1 or ECV with central venous pressure or age after Fontan. CONCLUSION: Fontan and BCPC patients have elevated CMR markers suggestive of hepatic fibrosis and/or congestion, even at a young age. The tissue changes do not appear to be related to central venous pressures. TRIAL REGISTRATION: Retrospectively registered data.

Mapping versus source methods for quantifying myocardial T1 in controls and in repaired tetralogy of Fallot: interchangeability and reproducibility in children.

BACKGROUND: Myocardial T1 relaxometry can be performed by contouring on individual T1-weighted source images (source method) or on a single T1 map (mapping method). OBJECTIVE: This study compares (a) agreement between native T1 and extracellular volume results of the two methods and (b) interobserver reproducibility of the two methods in children without heart disease and those with tetralogy of Fallot (TOF). MATERIALS AND METHODS: We retrospectively analyzed pediatric patients (controls and those with repaired TOF) with cardiac magnetic resonance examinations including extracellular volume quantification using the modified Look-Locker inversion recovery (MOLLI) sequence. We compared native T1 and extracellular volume of the entire left ventricle and interventricular septum derived using the source and the mapping approaches. RESULTS: In the control group (n=25, median age 14.0 years, interquartile range [IQR] 11.5-16.5 years), the mapping method produced lower native T1 values than the source method in the interventricular septum (mean difference ± standard deviation [SD] = 12±15 ms, P<0.001). In the TOF group (n=50, median age 13.3 years, IQR 9.9-15.0 years), the mapping method produced lower values for native T1 and extracellular volume in the interventricular septum (mean difference 9±14 ms and 0.6±1.1%, P<0.001). In 6-12% of the children, differences were >3 standard deviations from the mean difference. Interobserver reproducibility between the two methods by intraclass correlation coefficients were clinically equivalent. CONCLUSION: T1 and extracellular volume values generated by the source and mapping methods show systematic differences and can vary significantly in an individual child, and thus cannot be used interchangeably in clinical practice. The source method might allow for easier detection and, in some cases, mitigation of artifacts that are not infrequent in children and can be difficult to appreciate on the T1 map.

Dual phase infusion with bolus tracking: technical innovation for cardiac and respiratory navigated magnetic resonance angiography using extracellular contrast.

This technical innovation paper describes a technique for performing cardiac-gated, respiratory-navigated cardiovascular magnetic resonance angiography using an extracellular gadolinium-based contrast agent at 1.5 Tesla (T) with a dual phase bolus injection and slow infusion technique.

Increased Arterial Stiffness Adversely Affects Left Ventricular Mechanics in Patients With Pediatric Takayasu Arteritis From a Toronto Cohort.

BACKGROUND/OBJECTIVE: Takayasu arteritis (TA) is characterized by extensive aortic, large and midsize arterial wall inflammation. The aim of this study was to assess the morphological and elastic properties of the aorta and large arteries and the impact on left ventricular (LV) mechanics in children with TA. METHODS: Seven pediatric TA patients (6 female patients, 13.8 ± 3.2 years) were assessed with magnetic resonance imaging, vascular ultrasound, applanation tonometry, and echocardiography from February 2015 until July 2017 and compared with 7 age- and sex-matched controls. Takayasu arteritis disease activity was assessed clinically by the Pediatric Vasculitis Activity Score (PVAS). RESULTS: Pediatric TA patients showed increased carotid-to-radial artery pulse wave velocity (8.1 ± 1.8 vs. 6.4 ± 0.6 m/s, p = 0.03) and increased carotid-to-femoral artery pulse wave velocity (8.3 ± 1.9 vs. 5.1 ± 0.8 m/s, p < 0.01) when compared with controls. Patients demonstrated increased LV mass index (74.3 ± 18.8 vs. 56.3 ± 10.9 g/m, p = 0.04), altered myocardial deformation with increased basal rotation (-9.8 ± 4.5 vs. -4.0 ± 2.0 degrees, p = 0.01) and torsion (19.9 ± 8.1 vs. 9.1 ± 3.1 degrees, p = 0.01), and impaired LV diastolic function with decreased mitral valve E/A ratio (1.45 ± 0.17 vs. 2.40 ± 0.84, p = 0.01), increased mitral valve E/E' ratio (6.8 ± 1.4 vs. 4.9 ± 0.7, p < 0.01), and increased pulmonary vein A-wave velocity (26.7 ± 5.7 vs. 16.8 ± 3.3 cm/s, p = 0.03). Carotid-to-radial artery pulse wave velocity was associated with systolic (R = 0.94, p < 0.01), diastolic (R = 0.85, p = 0.02), and mean blood pressure (R = 0.91, p < 0.01), as well as disease activity by PVAS (R = 0.75, p = 0.05). The PVAS was associated with carotid-to-radial artery pulse wave velocity (R = 0.75, p = 0.05), as well as systolic (R = 0.84, p = 0.02), diastolic (R = 0.82, p = 0.03), and mean blood pressure (R = 0.84, p = 0.02). CONCLUSIONS: Increased arterial stiffness is present in pediatric TA patients and associated with increased blood pressure and TA disease activity. Pediatric TA patients demonstrate altered LV mechanics, LV hypertrophy, and impaired diastolic function.

How many versus how much: comprehensive haemodynamic evaluation of partial anomalous pulmonary venous connection by cardiac MRI.

OBJECTIVES: The objective of this study was to investigate the effect of location and number of anomalously connected pulmonary veins and any associated atrial septal defect (ASD) on the magnitude of left-to-right shunting in patients with partial anomalous pulmonary venous connection (PAPVC), and how that influences right ventricular volume loading. METHODS AND RESULTS: The cardiac magnetic resonance (CMR) and echocardiography examinations of 26 paediatric patients (mean age, 11.2 ± 5.1 years) with unrepaired PAPVC were analysed. Fourteen patients had right-sided, 11 left-sided and 1 patient bilateral PAPVC. An ASD was present in 11 patients, of which none had a Qp/Qs < 1.5 and 8 had a Qp/Qs≥ 2.0. No patient with isolated left upper PAPVC experienced a Qp/Qs ≥ 2.0 compared to 9/12 patients with right upper PAPVC. Qp/Qs correlated with indexed right ventricle (RV) end-diastolic volume (RVEDVi, r = 0.59, p = 0.002) by CMR and with echocardiographic right ventricular end-diastolic dimension (RVED) z-score (r = 0.68, p = 0.003). A RVEDVi >124 ml/m2 by CMR and a RVED z-score >2.2 by echocardiography identified patients with a Qp/Qs ≥1.5 with good sensitivity and specificity. CONCLUSIONS: An asymptomatic patient with a single anomalously connected left upper pulmonary vein and without an ASD is unlikely to have a significant left-to-right shunt. On the other hand, right-sided PAPVC is frequently associated with a significant left-to-right shunt, especially when an ASD is present. KEY POINTS: • Patients with PAPVC and ASD routinely have a significant left-to-right shunt. • Patients with right PAPVC are likely to have a significant left-to-right shunt. • Patients with left PAPVC are unlikely to have a significant left-to-right shunt. • CMR is helpful in decision-making for patients with PAPVC.

Correction to: Clinical recommendations for cardiovascular magnetic resonance mapping of T1, T2, T2* and extracellular volume: A consensus statement by the Society for Cardiovascular Magnetic Resonance (SCMR) endorsed by the European Association for Cardiovascular Imaging (EACVI).

CORRECTION TO: J CARDIOVASC MAGN RESON (2017) 19: 75. DOI: 10.1186/S12968-017-0389-8: In the original publication of this article [1] the "Competing interests" section was incorrect. The original publication stated the following competing interests.

Magnetic resonance imaging of cardiovascular thrombi in children.

Cardiovascular thrombosis is rare in children and usually occurs in the presence of predisposing conditions, such as indwelling vascular catheters, tumors, aneurysms, ventricular dysfunction, or after surgery. Clots can occur in the cardiac chambers, arteries or veins, or inside conduits. Detection of thrombi is feasible with a variety of magnetic resonance imaging (MRI) techniques, including unenhanced methods but also contrast-enhanced MR angiography. In this essay we illustrate the MRI appearance of cardiovascular thrombosis in children and suggest an imaging protocol based on our clinical experience.

Splanchnic, Thoracoabdominal, and Cerebral Blood Flow Volumes in Healthy Children and Young Adults in Fasting and Postprandial States: Determining Reference Ranges by Using Phase-Contrast MR Imaging.

Purpose To estimate reference ranges for blood flow volume (BFV) in major splanchnic, thoracoabdominal, and neck vessels by using phase-contrast magnetic resonance (MR) imaging in children and young adults in fasting and postprandial states. Materials and Methods In this institutional research ethics board-approved prospective study, healthy volunteers underwent phase-contrast MR imaging in a fasting state and again after a standardized meal. BFV values were reported as medians and ranges, and postmeal to premeal BFV ratios were calculated. BFVs in volunteers divided into two groups according to age (≤18 years old and >18 years old) were compared by using the Mann-Whitney test adjusted for multiple comparisons. Linear regression for internal validation of BFV and Pearson correlation and Bland-Altman analysis for interobserver agreement were used. Results Reference ranges for BFVs were estimated in 39 volunteers (23 male and 16 female; mean age, 21.2 years ± 8.5; range, 9-40 years) and were indexed according to body surface area, with internal validation (R2 = 0.84-0.92) and excellent interobserver agreement (R2 = 0.9928). There was an almost 30% increase in total abdominal BFV (P < .0001) in response to a meal, which was the result of a threefold increase in superior mesenteric artery BFV (P < .0001). BFV after the meal remained unaffected in the celiac artery and cerebral circulation. Significantly higher normalized BFVs in the cerebral circulation were measured in children with both preprandial (P = .039) and postprandial (P = .008) status than those in adults. Conclusion Reference ranges for BFVs and changes in BFVs in response to a meal in major splanchnic, thoracoabdominal, and neck vessels were estimated by using phase-contrast MR imaging in healthy volunteers to allow hemodynamic assessment of children and young adults with various diseases. © RSNA, 2017 Online supplemental material is available for this article.