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Cardiovascular magnetic resonance (CMR) and cardiac computed tomography (CCT) are robust cross-sectional imaging modalities that are increasingly being used to guide the diagnosis and management of those born with single-ventricle physiology. The purpose of this review is to acquaint the reader with the wide range of cross-sectional imaging applications that can be applied in this population. Illustrative examples of information provided by CMR and CCT are included, such as delineation of cardiac anatomy, measurement of ventricular volumetry, interrogation of vascular anatomy and flows, evaluation of myocardial viability, and exclusion of thromboembolic disease. Focus is placed on the appropriate selection and timing of advanced cardiac imaging modalities, and differentiations are made between established indications for imaging and emerging applications (such as 4-dimensional [4D] flow assessment and parametric imaging for identification of diffuse fibrosis using CMR). Potential CMR and CCT contributions in the selection of interventional strategies in the child and for surveillance of postoperative complications in the adult are highlighted. Furthermore, the importance of extracardiac cross-sectional imaging in the single-ventricle population is emphasized given the recognition that complications post-Fontan palliation are not limited to the cardiovascular system but will often include extracardiac manifestations of disease (such as hepatic disease or lymphatic abnormalities), While the value of CMR and CCT for contemporary clinical care of individuals born with single-ventricle physiology appears to be well-established, further research will be necessary to explore the impact of risk stratification using imaging biomarkers on clinical outcomes following Fontan palliation.

The impact of fetal echocardiography on the diagnosis and outcomes of vascular ring has not been well examined. We hypothesized that prenatal detection of vascular ring has improved over time and that prenatal diagnosis of vascular ring is associated with earlier intervention and favorable outcomes.This is a single-center, retrospective study of the evolution and outcomes of prenatal diagnosis of vascular ring from 2000 to 2020. We compared clinical presentation, timing of surgical intervention, and outcomes between the prenatally and postnatally diagnosed cases during the same study period.A total of 170 patients were included: 50 with prenatal and 120 with postnatal diagnosis of vascular ring. Prenatal diagnoses included 42 patients (84%) with right aortic arch (RAA), aberrant left subclavian artery (ALSCA), and a left-sided ductus arteriosus and eight (16%) patients with double aortic arch (DAA). The postnatal cohort consisted mainly of 90 patients (75%) with DAA and 22 (18%) with RAA-ALSCA. None of the postnatally diagnosed cases had undergone a fetal echocardiogram. Numbers (percentage) of prenatally diagnosed cases of vascular ring compared with the postnatal cases improved from 4/31 (13%), to 10/29 (34%), to 14/25 (56%), and to 22/35 (69%), respectively, during 2000-2005, 2005-10, 2010-15, and 2015-20 (P = .032). Vascular ring was an isolated abnormality in 84% and 85% of the prenatal and postnatal cohorts, respectively. Compared with the prenatal cohort, postnatally diagnosed patients with an isolated vascular ring were more frequently symptomatic (66% vs 48%, P .03) and underwent cross-sectional imaging (69% vs 44%, P = .009) and surgery more frequently (79% vs 48%, P = .003). Surgery was performed at a later patient age (18 [2-147] months vs 4.8 [0.5-42] months, P = .01) and was more often associated with residual symptoms (27/81 [33%] vs 1/20 [5%], P = .01) in the postnatal cohort than in the prenatal cohort.The diagnosis of vascular ring by fetal echocardiography has improved over time. A significantly higher incidence of RAA-ALSCA in the prenatal compared with the postnatal cohort suggests that patients with this form of vascular ring often do not present to medical attention with significant symptoms postnatally. Prenatal diagnosis of vascular ring was associated with a lower incidence of symptoms, less frequent use of cross-sectional imaging, earlier age at surgical intervention, and lower likelihood of residual symptoms.

BACKGROUND Dynamic contrast-enhanced magnetic resonance imaging (MRI) of the liver in pediatric Fontan patients often shows peripheral reticular areas of hypoenhancement, which has not been studied in detail. OBJECTIVE To semiquantitatively score the hepatic MR perfusion abnormality seen in pediatric Fontan patients, and to correlate the perfusion abnormality with functional clinical and hemodynamic parameters. MATERIALS AND METHODS All children (

OBJECTIVE. The Fontan procedure has significantly improved the survival in children with a functional single ventricle, but it is associated with chronically elevated systemic venous pressure that leads to multisystemic complications. Imaging plays an important role in assessing these complications and guiding management. The pathophysiology, imaging modalities, and current surveillance recommendations are discussed and illustrated. CONCLUSION. Significant improvement in survival of patients with Fontan circulation is associated with ongoing cardiac and extracardiac comorbidities and multisystemic complications. The liver and intestines are particularly vulnerable to damage. In addition, this patient population has been shown to be at increased risk of certain malignancies such as hepatocellular carcinoma and neuroendocrine tumors. Familiarity with imaging findings of Fontan-associated liver disease and other abdominal complications of the Fontan circulation is essential for radiologists because we are likely to encounter these patients in our general practice.

Aims To quantify thoracic lymphatic burden in paediatric Fontan patients using MRI and correlate with clinical status. Methods and results Paediatric Fontan patients ( 600 mL/m2 was associated with late adverse Fontan status with sensitivity of 57% and specificity of 95%. Conclusion Quantification of MR lymphatic burden is a reliable tool to assess the lymphatics post-Fontan and is associated with clinical status.

OBJECTIVES The hands-on surgical training course utilizes 3-dimensional (3D)-printed heart models to simulate complex congenital heart operations. This study aimed to validate a model and assessment tool in the simulation of 2 techniques of the Norwood operation and investigate whether technical performance improves following rehearsal with or without proctor presence. METHODS Five ‘experienced’ and 5 ‘junior’ surgeons performed 2 techniques of the Norwood operation on 3D-printed models of hypoplastic left heart syndrome. Performances were retrospectively assessed by 10 raters with varying experience in congenital heart surgery (CHS) (Medical Doctorate versus non-Medical Doctorate). Assessments were made with the procedure-specific Hands-On Surgical Training-CHS tool. Results were analysed for technical performance and rater consistency. Following validation, 30 surgeons (24 with proctor guidance and 6 with training videos and objective feedback only) simulated the Norwood operation twice. RESULTS Performance scores were consistently higher for experienced surgeons and raters discriminated clearly between the experienced and junior surgeons (P ≤ 0.001). The hands-on surgical training-CHS tool showed high inter-rater (0.86) and intra-rater (0.80) reliability among all raters. Scores for both experienced and junior surgeons were highly consistent across all raters, with no statistically significant difference (P = 0.50). All surgeons successfully performed the Norwood operation. Sixty attempts were scored in total. Eighty-seven percentage (26/30) of surgeons’ scores (mean: attempt 1 = 92, attempt 2 = 104) and times [mean: attempt 1 = 1:22:00, attempt 2 = 1:08:00 (h:mm:ss)] improved between the 2 attempts by 9% and 15% respectively (P ≤ 0.001). Total scores of all surgeons in the non-proctored subgroup (6) improved by 15% on average (mean: attempt 1 = 86, attempt 2 = 105, P = 0.002). CONCLUSIONS Procedure-specific assessment tools can be developed to evaluate technical performance for complex CHS simulation and be performed reliably by non-expert raters. Rehearsal both under supervision and independently leads to technical skill improvement further supporting its value in CHS training.

Objective Data supporting the use of hands-on simulation in congenital heart surgery are promising but primarily qualitative. This study aimed to demonstrate if there was an objective improvement in time and technical performance of the arterial switch procedure on 3-dimensional printed heart models by surgeons using a validated assessment method. Methods A total of 30 surgeons of varying experience performed the arterial switch procedure twice on 3-dimensional printed models with transposition of the great arteries during the Hands-on Surgical Training courses. Surgeons' performances were recorded and retrospectively assessed for both time and performance using the Hands-on Surgical Training-Congenital Heart Surgery tool, a validated procedure-specific assessment tool for the arterial switch. Results A total of 60 videos were scored. Eighty percent of surgeons (24/30) had improved from their first attempt. The mean total score of the first attempt performance compared with the second was 103 and 120, respectively, with a mean difference in score of 17 (95% confidence interval, 10-24). All surgeons were statistically significantly quicker in their second attempt. The mean time for the first attempt compared with the second was 1 hour, 28 minutes, 4 seconds and 1 hour, 5 minutes, and 45 seconds, respectively, with a mean difference of 0 hours, 22 minutes, 19 seconds (95% confidence interval, 0 hours, 15 minutes, 22 seconds to 0 hours, 25 minutes, 34 seconds). Conclusions This is the first study to demonstrate an objective improvement in time and technical performance of the arterial switch procedure on 3-dimensional printed heart models. This supports the evidence that simulation in the form of deliberate practice with constructive, objective feedback is fundamental in the training of future congenital heart surgeons. These simulations and assessments should be incorporated to create structured, standardized training curricula within congenital heart surgery.

ObjectivesAlthough a life-preserving surgery for children with single ventricle physiology, the Fontan palliation is associated with striking morbidity and mortality with advancing age. Our primary objective was to evaluate the impact of non-invasive, external, thoraco-abdominal ventilation on pulmonary blood flow (PBF) and cardiac output (CO) as measured by cardiovascular magnetic resonance (CMR) imaging in adult Fontan subjects.MethodsAdults with a dominant left ventricle post-Fontan palliation (lateral tunnel or extracardiac connections) and healthy controls matched by sex and age were studied. We evaluated vascular flows using phase-contrast CMR imaging during unassisted breathing, negative pressure ventilation (NPV) and biphasic ventilation (BPV). Measurements were made within target vessels (aorta, pulmonary arteries, vena cavae and Fontan circuit) at baseline and during each ventilation mode.ResultsTen Fontan subjects (50% male, 24.5 years (IQR 20.8–34.0)) and 10 matched controls were studied. Changes in PBF and CO, respectively, were greater following BPV as compared with NPV. In subjects during NPV, PBF increased by 8% (Δ0.20 L/min/m2 (0.10–0.53), p=0.011) while CO did not change significantly (Δ0.17 L/min/m2 (−0.11–0.23), p=0.432); during BPV, PBF increased by 25% (Δ0.61 L/min/m2 (0.20–0.84), p=0.002) and CO increased by 16% (Δ0.47 L/min/m2 (0.21–0.71), p=0.010). Following BPV, change in PBF and CO were both significantly higher in subjects versus controls (0.61 L/min/m2 (0.2–0.84) vs −0.27 L/min/m2 (−0.55–0.13), p=0.001; and 0.47 L/min/m2 (0.21–0.71) vs 0.07 L/min/m2 (−0.47–0.33), p=0.034, respectively).ConclusionExternal ventilation acutely augments PBF and CO in adult Fontan subjects. Confirmation of these findings in larger populations with longer duration of ventilation and extended follow-up will be required to determine sustainability of haemodynamic effects.

Digital reality is an emerging platform for three-dimensional representation of medical imaging data. In this technical innovation paper, the authors evaluated the accuracy and utility of mixed-reality technology in the morphological evaluation of complex congenital heart disease. The authors converted CT datasets of 12 heart specimens with different subtypes of double-outlet right ventricle to stereoscopic images and interrogated them using a mixed-reality system. The morphological features identified on the stereoscopic models were compared with findings at macroscopic examination of the actual heart specimens. The results showed that the mixed-reality system provided highly accurate stereoscopic display of spatially complex congenital cardiac lesions, with interactive features that might enhance 3-D understanding of morphology. Additionally, the authors found that high-resolution digital reproduction of cardiac specimens using clinical CT scanners is feasible for preservation and educational purposes.

This paper reports a unique case of anomalous origin of the left coronary artery from the right pulmonary artery associated with scimitar syndrome. The presence of pulmonary hypertension may have contributed to maintain coronary perfusion, which likely prevented early significant coronary steal. This study reports the clinical course, diagnosis challenges, and management strategy. (Level of Difficulty: Intermediate.), Graphical abstract, This paper reports a unique case of anomalous origin of the left coronary artery from the right pulmonary artery associated with scimitar syndrome. The…

Congenital heart surgery is a technically demanding specialty resulting in a prolonged training period. With the growing expectation of perfect patient outcomes, there is a need for improved training methods by implementing simulation. We assess the utilization of simulation in the training of congenital heart surgeons and discuss its future implications. A keyword-based PubMed literature search was conducted for hands-on surgical simulation in congenital heart surgery. The abstracts/titles of the search were reviewed and papers using simulation specific to congenital cardiac surgery were selected. Studies that did not include surgeons operating on the simulator, or did not incorporate assessment methods were excluded. Analysis included the problem addressed, simulator-type, methodology, assessment methods, results, benefits/limitations, and reproducibility. Five papers fulfilled our selection criteria of hands-on surgical simulation in congenital heart surgery with an assessment of the simulator or procedural performance. One simulation used animal models and 4 utilized 3D-printed models. Simulators covered either single or multiple complex procedures. All studies highlight usefulness of simulation; however, only 1 study has been replicated with >10 participants. The studies demonstrate how hands-on surgical simulation is possible within congenital heart surgery. Although primarily proof of concept studies, the next step would involve using a greater number of participants and demonstrate how repetition and deliberate practice will improve outcomes. Congenital heart surgery is one of the most technically demanding surgical specialties; therefore, we should lead the way in utilizing simulation to complement the training of our surgeons as we face the challenges ahead.

Three-dimensional (3D) imaging and image reconstruction play a prominent role in the diagnosis, treatment planning, and post-therapeutic monitoring of patients with congenital heart disease. More interactive and realistic medical experiences take advantage of advanced visualization techniques like augmented, mixed, and virtual reality. Further, 3D printing is now used in medicine. All these technologies improve the understanding of the complex morphologies of congenital heart disease. In this review article, we describe the technical advantages and disadvantages of various advanced visualization techniques and their medical applications in the field of congenital heart disease. In addition, unresolved issues and future perspectives of these evolving techniques are described.

The pulmonary circulation after one and one-half ventricle repair is complex because of the direct connection of two sources of blood flow. Associated pulmonary regurgitation further complicates the pulmonary circulation. We report the complex hemodynamics depicted by phase-contrast magnetic resonance imaging in a patient with one and one-half ventricle circuit and severe pulmonary regurgitation. Antegrade superior vena caval flow occurred almost exclusively during diastole and regurgitated into the right ventricle. Consequently, the entire systemic venous return reached the right ventricle during diastole and is pumped back into the pulmonary arteries in systole. The case highlights the importance of analyzing flow patterns phase-by phase throughout the cardiac cycle instead of relying on the net flow volumes through each source of pulmonary blood flow.

Congenital heart surgery (CHS) is technically demanding, and its training is extremely complex and challenging. Training of the surgeon's technical skills has relied on a preceptorship format in which the trainees are gradually exposed to patients in the operating room under the close tutelage of senior staff surgeons. Training in the operating room is an inefficient process and the concept of a learning curve is no longer acceptable in terms of patient outcomes. The benefits of surgical simulation in training of congenital heart surgeons are well known and appreciated. However, adequate surgical simulation models and equipment for training have been scarce until the recent development of three-dimensionally (3D) printed models. Using comprehensive 3D printing and silicone-molding techniques, realistic simulation training models for most congenital heart surgical procedures have been produced. Newly developed silicone-molded models allow efficient CHS training in a stress-free environment with instantaneous feedback from the proctors and avoids risk to patients. The time has arrived when all congenital heart surgeons should consider surgical simulation training before progressing to real-life operating in a similar fashion to the aviation industry where all pilots are required to complete simulation training before flying a real aircraft. It is argued here that simulation training is not an option anymore but should be a mandatory component of CHS training.

PURPOSE: To assess regional blood flow in fasting pediatric patients with Fontan circulation by using MRI and to explore associations with clinical parameters. MATERIALS AND METHODS: In this retrospective study, pediatric patients who had undergone the Fontan procedure (

Three-dimensional (3D) printed models are widely accepted for use in training of various surgical procedures for congenital heart disease; however, their physical properties have been considered suboptimum for procedures. We created silicone molded models produced using a novel "parting and assembly" strategy and compared their suitability for hands-on training with that of conventional 3D printed models.Computed tomography imaging data from 2 patients with transposition of the great arteries were used. The heart was divided into multiple parts (atria, ventricles, great arteries, coronary arteries, and valves), and molds of each part were created. The parts reproduced by silicone molding were assembled using an adhesive agent. In an online course, 2 silicone molded models and 1 3D printed model were used for training of 34 surgeons. A questionnaire was distributed to these surgeons aimed at assessing the suitability of the models for the arterial switch operation (ASO).The silicone molded models showed excellent anatomic detail, high elasticity, and high resistance to tearing. The cost per model, based on the production of 50 models, was slightly higher for the silicone molded models compared with the 3D printed models. All 26 surgeons who completed the questionnaire reported that the silicone molded models provided sufficient anatomic information, but only 19% said the same for the 3D printed models. All surgeons also considered the silicone models to be realistic when passing a needle, cutting vessels, suturing, and excision of the coronary buttons, as opposed to46% for the 3D printed models.Silicone molding of models for the ASO is feasible by applying a "parting and assembly" strategy. Silicone molded models provide excellent physical properties that are far superior to those of 3D printed models for surgical simulation.

Dynamic contrast-enhanced magnetic resonance imaging (MRI) of the liver in pediatric Fontan patients often shows peripheral reticular areas of hypoenhancement, which has not been studied in detail.To semiquantitatively score the hepatic MR perfusion abnormality seen in pediatric Fontan patients, and to correlate the perfusion abnormality with functional clinical and hemodynamic parameters.All children ( 18 years old) after Fontan palliation with combined clinical cardiac and liver MRI performed between May 2017 and April 2019 were considered for inclusion. A semiquantitative perfusion score was used to assess the severity of the hepatic reticular pattern seen on dynamic contrast-enhanced liver imaging. The liver was divided into four sections: right posterior, right anterior, left medial and left lateral. Each liver section was assigned a score from 0 to 4 depending on the amount of abnormal reticular hypoenhancement. Scoring was assigned for each section of the liver across eight successive dynamic contrast-enhanced modified spoiled gradient echo runs. Scores were correlated with clinical and hemodynamic parameters.All Fontan children showed hepatic reticular hypoenhancement by MRI, most severe in the early portal venous phase with a median maximum total perfusion abnormality score of 12 (range: 9-14). All perfusion abnormalities progressively resolved during the hepatic venous phase. Perfusion abnormality scores were greatest in the right compared to left hepatic lobes (7 range: [6-8] vs. 5 [range: 3-6], P 0.01). The maximum left hepatic lobe perfusion abnormality scores were greatest in children with versus without imaging signs of portal hypertension (8 [range: 7-8] vs. 4 [range: 3-5], P 0.01). High unconjugated bilirubin and low platelets correlated with greater perfusion abnormality (R = 0.450, P = 0.024, and R = - 0.458, P 0.01, respectively). Age at MRI, time from Fontan, focal liver lesions and cardiac MRI hemodynamic parameters did not show significant correlations with the severity of the liver perfusion abnormality.All Fontan children have hepatic reticular hypoenhancement abnormalities seen with MRI that are most severe in the right hepatic lobe and universally show gradual resolution through the hepatic venous phase. Perfusion abnormality in the left hepatic lobe is worse in children with portal hypertension.

Left main coronary artery ostial atresia (LMCAOA) is a rare congenital anomaly of the coronary arteries. The published literature regarding the current diagnostic and management recommendations are limited. We present three case series of LMCAOA from our institution, including one with a unique association with anomalous origin of left coronary artery (LCA) from pulmonary artery. In addition, this report includes a review of 50 pediatric and 43 adult cases from literature. The majority of the patients were symptomatic. Sudden cardiac death occurred in 10% of pediatric patients and 7% of adult patients. Almost half of pediatric patients had additional cardiac lesions. At the time of diagnosis, 82% of patients had abnormal exercise stress test and 73% had abnormal myocardial perfusion imaging (MPI). The diagnosis of LMCAOA was suspected by echocardiography in 47% of pediatric patients, while 26% were initially misdiagnosed as anomalous origin of LCA from pulmonary artery. Coronary angiography confirmed the diagnosis in most cases and 70.5% of pediatric patients had small collaterals, while 80.5% of adult patients had large collaterals. Nine pediatric patients had no revascularization surgery with five deaths. Revascularization surgery was performed in 39 pediatric patients with four deaths. After 2005, there is a gradual shift toward performing coronary osteoplasty rather than coronary artery bypass grafting. Eighteen adult patients had revascularization surgery and all survived. Fifteen adult patients had no revascularization surgery, of which there were five deaths. In patients with LMCAOA, revascularization surgery is currently recommended in the presence of symptoms, ischemic changes on electrocardiogram or exercise stress test, myocardial perfusion defect on MPI, global left ventricular systolic dysfunction on echocardiogram, severe mitral regurgitation, or small-sized collaterals in coronary angiography. Short-term and mid-term outcomes are encouraging.

There are a number of techniques used in the surgical treatment of supravalvular aortic stenosis with excellent results; however, junior surgeons’ experience may be limited due to its rare nature. Simulation with 3D-printed models provides a safe platform for surgeons to rehearse surgical techniques prior to patient application but must replicate all features of surgical anatomy. Here, we describe how software manipulation can be used to accurately reproduce the surgical anatomy in supravalvular aortic stenosis and be used to train surgeons in 2 different techniques.

3D printing allows the most realistic perception of the surgical anatomy of congenital heart diseases without the requirement of physical devices such as a computer screen or virtual headset. It is useful for surgical decision making and simulation, hands-on surgical training (HOST) and cardiovascular morphology teaching. 3D-printed models allow easy understanding of surgical morphology and preoperative surgical simulation. The most common indications for its clinical use include complex forms of double outlet right ventricle and transposition of the great arteries, anomalous systemic and pulmonary venous connections, and heterotaxy. Its utility in congenital heart surgery is indisputable, although it is hard to “scientifically” prove the impact of its use in surgery because of many confounding factors that contribute to the surgical outcome. 3D-printed models are valuable resources for morphology teaching. Educational models can be produced for almost all different variations of congenital heart diseases, and replicated in any number. HOST using 3D-printed models enables efficient education of surgeons in-training. Implementation of the HOST courses in congenital heart surgical training programs is not an option but an absolute necessity. In conclusion, 3D printing is entering the stage of maturation in its use for congenital heart surgery. It is now time for imagers and surgeons to find how to effectively utilize 3D printing and how to improve the quality of the products for improved patient outcomes and impact of education and training.

Funding Acknowledgements Type of funding sources: None. Background The performance of fetal echocardiogram in diagnosing vascular ring (VR) and its impact on postnatal outcomes has not been well examined. Methods We reviewed all patients with VR diagnosis from 2000-2020. Results 50 patients with antenatal diagnosis of VR; 42(84%) with right aortic arch aberrant left subclavian artery and left-sided ductus arteriosus ((RAA-ALS) and 8(16%) with double aortic arch (DAA) were compared to 120 patients with postnatal diagnosis; 90(75%) with DAA, 22(18%) with RAA-ALS (Table 1). Prenatal diagnosis of VR increased over study period; 4 vs 31, 10 vs 29, 14 vs 25, 22 vs 35 between 2000-2005, 2005-2010, 2010-2015, and 2015-2020 respectively, p< 0.01. Prenatal diagnosis of VR was associated with less symptoms [26(52%) vs 72(60%), p Conclusion Prenatal diagnosis of VR has evolved over time. RAA-ALS versus DAA were dominant in the prenatally and postnatally diagnosed cohorts respectively. Prenatal diagnosis of VR was associated less symptoms, less cross-sectional imaging, earlier age of surgical intervention and less residual symptoms. Table 1 Prenatal Diagnosis (N = 50) Postnatal Diagnosis (N = 120) p-value Gestational Age (weeks) 39 ± 3 38 ± 2 0.9 Male (%) 31 (62%) 69(58%) 0.8 Subtype of vascular ring: Double aortic arch RAA-ALSA Others 8 (16%) 42 (80 %) 0 (0 %) 90 (72%) 22 (17%) 8 (11%) 0.002 0.01 Associated intracardiac CHD: VSD TOF DORV AVSD Coarctation of aorta Others 11 (22%) 1 1 3 0 3 3 24 (20%) 5 7 2 2 3 5 0.8 Associated genetic diagnosis: 22q11 deletion Trisomy 21 Others 9 (18%) 6 3 0 32 (26%) 29 3 0 0.1 Symptomatic presentation: Respiratory Gastrointestinal 26 (52 %) 15 11 72 (60 %) 57 15

Introduction: The importance of the lymphatic circulation in Fontan physiology is incompletely understood and may have implications in Fontan ‘failure’. Non-invasive imaging of the lymphatic system with heavily T2-weighted MRI sequences could be a useful tool for patient surveillance and prognostication. We sought to quantify lymphatic burden in Fontan patients and correlate with clinical status. Methods: Consecutive pediatric Fontan patients, Results: There were 48 patients (27 males) with median age at MRI of 12.9 (9.4-14.7) years, age at Fontan of 3.3 (2.9-3.8) years, and time from Fontan at MRI of 9.2 (5.9-10.4) years. Inter-rater agreement for lymphatic burden was excellent (ICC 0.96 [0.94-0.98]). Greater lymphatic burden correlated with hospital length of stay and duration of chest tube drainage post-Fontan (r =0.423, p=0.003 and r=0.419, p=0.003). Median lymphatic burden was greater in patients that had chylous effusions post-Fontan (286 (157-492) ml vs 123 (60-271) ml, p=0.011) and in patients with composite adverse outcome (n=12) defined by heart failure (n=3), transplant assessment (n=2), recurrent effusions (n=8), Fontan thrombus (n=2), and/or PLE (n=6) post-Fontan; (458 (266-2016) ml vs 130 (272-256) ml, p=0.005). Pre-Fontan mean PA pressure and time from Fontan did not correlate with lymphatic burden (r=0.062, p=0.676 and r=0.139, p= 0.343). Conclusion: Quantification of MR lymphatic burden is a reliable tool to assess lymphatic status post-Fontan and is associated with clinical outcomes.