Lymphatic Abnormalities Research Articles

Refractory Chylothorax and Ventricular Hypertrophy Treated with Trametinib in a Patient with Noonan Syndrome: 18-Month Follow-Up

RASopathies are a group of genetic syndromes caused by germline mutations in genes involved in the RAS/Mitogen-Activated Protein Kinase signaling pathway, which regulates cellular proliferation, differentiation, and angiogenesis. Despite their involvement at different levels of this pathway, RASopathies share overlapping clinical phenotypes. Noonan syndrome is the most prevalent RASopathy, with an estimated incidence of 1 in 2500 live births, and it is typically inherited in an autosomal dominant manner, with 50% of cases involving gain-of-function mutations in the PTPN11 gene. De novo mutations are common, accounting for 60% of cases. The phenotype of Noonan syndrome includes characteristic facial and physical features, congenital cardiac defects, lymphatic and cerebrovascular anomalies, renal malformations, hematological abnormalities, developmental issues, and an increased risk of cancer. Severe congenital cardiac defects and lymphatic abnormalities significantly impact prognosis, contributing to increased morbidity and mortality. Recent therapeutic advancements have introduced trametinib, an MEK1/2 inhibitor, for treating Noonan syndrome patients with severe cardiac and lymphatic complications. To assess its efficacy, here, we present a case of a newborn with Noonan syndrome who exhibited refractory chylothorax, ventricular hypertrophy, and pulmonary stenosis who was treated with trametinib. The patient demonstrated significant improvement in chylothorax and left ventricular hypertrophy, though pulmonary stenosis persisted. This case further confirms trametinib’s potential as a therapeutic option for severe Noonan syndrome complications, emphasizing the need for further clinical trials to optimize treatment protocols and evaluate long-term outcomes.

Magnetic resonance lymphangiography abnormalities as extracardiac biomarkers of pulmonary hypertension and functional phenotype in Fontan-Kreutzer univentricular circulation.

Lymphatic abnormalities have been documented on magnetic resonance lymphangiography in patients with functionally univentricular circulation. The aim of this study is to evaluate associations between findings on magnetic resonance lymphangiography, cardiac catheterisation and functional phenotype in patients with Fontan-Kreutzer circulation. Between January 2017 and October 2019, seven patients with Fontan-Kreutzer circulation (16.57 ± 7.10 years) were enrolled following ethical committee approval and attainment of informed consent. Clinical data, consecutive magnetic resonance imaging and cardiac catheterisation findings were reviewed. Qualitative lymphatic abnormality types were defined as: 1 - Little or none; 2 - Localised to the supraclavicular region; 3 - Extending into the mediastinum; and 4 - Extending into the lung. Pulmonary hypertension was defined as a transpulmonary gradient > 6 mmHg. Quantitative data were assessed using Mann-Whitney U tests, and p < 0.05 was considered statistically significant. Patients with lymphatic abnormalities categorised type 1 or 2 and transpulmonary gradient ≤ 6 mmHg had a normal functional phenotype, while those with type 3 or 4 and transpulmonary gradient > 6 mmHg had a failing functional phenotype. Magnetic resonance lymphangiography in patients with Fontan-Kreutzer circulation and pulmonary hypertension revealed lymphatic abnormalities types 3-4, indicative of a failing functional phenotype compared to patients without pulmonary hypertension. If validated in larger studies, these results suggest the potential utility of this extracardiac biomarker for improving risk stratification. Integration of lymphangiography and transpulmonary gradient with functional class, atrioventricular valve function, and ejection fraction allowed for the categorisation of three distinct functional phenotypes, which may be valuable for future analyses.

Lymphatic magnetic resonance imaging abnormalities in children with repaired tetralogy of Fallot.

Tetralogy of Fallot patients face an elevated risk of developing chylothorax and pleural effusions post-surgery. This patient group exhibits risk factors known to compromise the lymphatic system, such as elevated central venous pressure, pulmonary flow changes, and hypoxia. This study investigates the morphology and function of the lymphatic system in tetralogy of Fallot patients through lymphatic magnetic resonance imaging and near-infrared fluorescence imaging, respectively. Post-repair tetralogy of Fallot patients aged 6-18 years were recruited, along with age and gender-matched controls. Magnetic resonance imaging was used to assess the morphology of the thoracic lymphatic vessels and the thoracic, while near-infrared fluorescence imaging was used to assess lymphatic activity utilising lymph rate, velocity, and pressure. Nine patients and 10 controls were included. Echocardiography revealed that 2/3 of the patients had moderate-severe pulmonary regurgitation, while none displayed signs of elevated central venous pressure. Magnetic resonance imaging identified three patients with type 3 (out of 4 types) lymphatic abnormalities, while controls had none. The thoracic ducts showed severe (one patient) and moderate (one patient) tortuosity. Mean thoracic duct diameters were 3.3 mm ±1.1 in patients and 3.0 mm ± 0.8 in controls (p-value = 0.53). Near-infrared fluorescence imaging revealed no anomalous patterns. Despite no presence of clinical lymphatic disease, 3/9 of the repaired tetralogy of Fallot patients exhibited lymphatic morphological abnormalities. The significance of these anomalies remains uncertain currently. Further research is needed to determine whether these lymphatic alterations in this patient cohort are a result of congenital malformations, haemodynamic shifts, or prenatal and early-life saturation levels.

The Lymphatic Highway: How Lymphatics Drive Lung Health and Disease.

The pulmonary lymphatic system has emerged as a critical regulator of lung homeostasis and a key contributor to the pathogenesis of respiratory diseases. As the primary conduit responsible for maintaining fluid balance and facilitating immune cell trafficking, the integrity of lymphatic vessels is essential for preserving normal pulmonary structure and function. Lymphatic abnormalities manifest across a broad spectrum of pulmonary disorders, underscoring their significance in respiratory health and disease. This review provides an overview of pulmonary lymphatic biology and delves into the involvement of lymphatics in four major lung diseases: chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), asthma, and lung transplant rejection. We examine how lymphatic abnormalities manifest in each of these conditions and investigate the mechanisms through which lymphatic remodeling and dysfunction contribute to disease progression. Furthermore, we explore the therapeutic potential of targeting the lymphatic system to ameliorate these debilitating respiratory conditions. Despite the current knowledge, several crucial questions remain unanswered, such as the spatial and temporal dynamics of lymphatic changes, the molecular crosstalk between lymphatics and the lung microenvironment, and the distinction between protective versus detrimental lymphatic phenotypes. Unraveling these mysteries holds the promise of identifying novel molecular regulators, characterizing lymphatic endothelial phenotypes, and uncovering bioactive mediators. By harnessing this knowledge, we can pave the way for the development of innovative disease-modifying therapies targeting the lymphatic highway in lung disorders.

Association between lymphatic abnormalities in the neck and thorax in primary chylopericardium and surgical outcomes evaluated by non-enhanced magnetic resonance (MR) lymphangiography.

Chylopericardium refers to the accumulation of chylous fluid in the pericardial cavity. Non-enhanced magnetic resonance lymphangiography (MRL) can show neck and thoracic lymphatic abnormalities in the primary chylopericardium. It is not clear whether there is a relationship between neck and thoracic lymphatic abnormalities in primary chylopericardium and thoracic duct terminal release surgery. This study aimed to explore the correlation between the severity of neck and thoracic lymphatic abnormalities observed in non-enhanced MRL and the surgical outcomes in primary chylopericardium. This is a retrospective cohort study. A retrospective analysis was conducted on fifty-six patients diagnosed with primary chylopericardium between January 2016 and December 2021, all of whom underwent thoracic duct terminal release surgery. Ultrasonography, chest computed tomography (CT) and non-enhanced MRL were performed prior to the surgical intervention. Patients were categorized into four types based on the severity of neck and thoracic lymphatic abnormalities observed in the non-enhanced MRL. Clinical and laboratory examinations and surgical outcomes were compared across different types using χ 2-test or Fisher's exact test, t-test, and Kruskal-Wallis H-test. Additionally, independent factors influencing surgical outcomes were analyzed. Among primary chylopericardium cases (n=56), 22 (39.2%) were classified as type I or II, 17 (30.4%) as type III, and 17 (30.4%) as type IV. Surgical outcomes were more favorable for type I or II patients than those with type III or IV, accompanied by a reduction in postoperative primary chylopericardium volume (P=0.002). Postoperative chest CT scans indicated that type I or II patients had fewer instances of large grid shadows, small grid shadows, and bronchovascular bundle thickening compared to preoperative scans (P=0.001, P=0.02, P=0.03). Age and bronchomediastinal trunk dilation emerged as independent factors influencing surgical outcomes [odds ratio (OR) 0.03, 95% confidence interval (CI): 0.003-0.220, P=0.001; OR 11.10, 95% CI: 1.70-72.39, P=0.01, respectively]. A more severe degree of neck and thoracic lymphatic abnormalities is associated with worse surgical outcomes. Moreover, age and bronchomediastinal trunk dilatation are independent predictors of surgical outcomes. Preoperative utilization of non-enhanced MRL for severity of lymphatic abnormalities classification in primary chylopericardium patients offers a noninvasive means of assessing surgical risk.

Innominate Vein Turndown Procedure as Another Option for Lymphatic Abnormalities in Fontan Patients.

Innominate Vein Turndown Procedure as Another Option for Lymphatic Abnormalities in Fontan Patients.

Noncontrast MR Lymphangiography to Identify Progression of Lymphatic Abnormalities over the Course of Fontan Completion.

Noncontrast MR Lymphangiography to Identify Progression of Lymphatic Abnormalities over the Course of Fontan Completion.

Targeting lymphatic function in cardiovascular-kidney-metabolic syndrome: preclinical methods to analyze lymphatic function and therapeutic opportunities.

The lymphatic vascular system spans nearly every organ in the body and serves as an important network that maintains fluid, metabolite, and immune cell homeostasis. Recently, there has been a growing interest in the role of lymphatic biology in chronic disorders outside the realm of lymphatic abnormalities, lymphedema, or oncology, such as cardiovascular-kidney-metabolic syndrome (CKM). We propose that enhancing lymphatic function pharmacologically may be a novel and effective way to improve quality of life in patients with CKM syndrome by engaging multiple pathologies at once throughout the body. Several promising therapeutic targets that enhance lymphatic function have already been reported and may have clinical benefit. However, much remains unclear of the discreet ways the lymphatic vasculature interacts with CKM pathogenesis, and translation of these therapeutic targets to clinical development is challenging. Thus, the field must improve characterization of lymphatic function in preclinical mouse models of CKM syndrome to better understand molecular mechanisms of disease and uncover effective therapies.

Exploring New Drug Repurposing Opportunities for MEK Inhibitors in RASopathies: A Comprehensive Review of Safety, Efficacy, and Future Perspectives of Trametinib and Selumetinib.

The RASopathies are a group of syndromes caused by genetic variants that affect the RAS-MAPK signaling pathway, which is essential for cell response to diverse stimuli. These variants functionally converge towards the overactivation of the pathway, leading to various constitutional and mosaic conditions. These syndromes show overlapping though distinct clinical presentations and share congenital heart defects, hypertrophic cardiomyopathy (HCM), and lymphatic dysplasia as major clinical features, with highly variable prevalence and severity. Available treatments have mainly been directed to target the symptoms. However, repurposing MEK inhibitors (MEKis), which were originally developed for cancer treatment, to target evolutive aspects occurring in these disorders is a promising option. Animal models have shown encouraging results in treating various RASopathy manifestations, including HCM and lymphatic abnormalities. Clinical reports have also provided first evidence supporting the effectiveness of MEKi, especially trametinib, in treating life-threatening conditions associated with these disorders. Nevertheless, despite notable improvements, there are adverse events that occur, necessitating careful monitoring. Moreover, there is evidence indicating that multiple pathways can contribute to these disorders, indicating a current need to more accurate understand of the underlying mechanism of the disease to apply an effective targeted therapy. In conclusion, while MEKi holds promise in managing life-threatening complications of RASopathies, dedicated clinical trials are required to establish standardized treatment protocols tailored to take into account the individual needs of each patient and favor a personalized treatment.

Sequential MRI Evaluation of Lymphatic Abnormalities over the Course of Fontan Completion.

Purpose To evaluate lymphatic abnormalities before and after Fontan completion using noncontrast lymphatic imaging and relate findings with postoperative outcomes. Materials and Methods This study is a retrospective review of noncontrast T2-weighted lymphatic imaging performed at The Children's Hospital of Philadelphia from June 2012 to February 2023 in patients with single ventricle physiology. All individuals with imaging at both pre-Fontan and Fontan stages were eligible. Lymphatic abnormalities were classified into four types based on severity and location of lymphatic vessels. Classifications were compared between images and related to clinical outcomes such as postoperative drainage and hospitalization, lymphatic complications, heart transplant, and death. Results Forty-three patients (median age, 10 years [IQR, 8-11]; 20 [47%] boys, 23 [53%] girls) were included in the study. Lymphatic abnormalities progressed in 19 individuals after Fontan completion (distribution of lymphatic classifications: type 1, 23; type 2, 11; type 3, 6; type 4, 3 vs type 1, 10; type 2, 18; type 3, 10; type 4, 5; P = .04). Compared with individuals showing no progression of lymphatic abnormalities, those progressing to a high-grade lymphatic classification had longer postoperative drainage (median time, 9 days [IQR, 6-14] vs 17 days [IQR, 10-23]; P = .04) and hospitalization (median time, 13 days [IQR, 9-25] vs 26 days [IQR, 18-30]; P = .03) after Fontan completion and were more likely to develop chylothorax (12% [three of 24] vs 75% [six of eight]; P < .01) and/or protein-losing enteropathy (0% [0 of 24] vs 38% [three of eight]; P < .01) during a median follow-up of 8 years (IQR, 5-9). Progression to any type was not associated with an increased risk of adverse events. Conclusion The study demonstrated that lymphatic structural abnormalities may progress in select individuals with single ventricle physiology after Fontan completion, and progression of abnormalities to a high-grade classification was associated with worse postoperative outcomes. Keywords: Congenital Heart Disease, Glenn, Fontan, Lymphatic Imaging, Cardiovascular MRI Supplemental material is available for this article. Published under a CC BY 4.0 license.

State-of-the-art imaging for children with central lymphatic disorders

Lymphatic imaging plays a crucial role in novel lymphatic interventions, offering valuable insights into central lymphatic drainage. Lymphatic system abnormalities may appear in various pediatric disorders, and accurate imaging is crucial for effective diagnosis and tailored therapeutic interventions. Traditional imaging modalities have offered valuable insights, but the demand for non-invasive, high-resolution techniques has fueled the development of innovative lymphatic imaging methods. In this review, we explore the state of the art in lymphatic imaging specifically within the context of pediatric surgery.

Indocyanine green lymphography in the congenital chylothorax and chylous ascites.

The prognosis of congenital chylothorax and ascites ranges from spontaneous resolution to death, but no established examination exists to predict the prognosis. We aimed to develop a clinically useful method to evaluate lymphatic abnormalities using indocyanine green (ICG) lymphography in infants with congenital chylothorax and ascites. We retrospectively evaluated infants with congenital chylothorax and chylous ascites who underwent ICG lymphography in our hospital between 2012 and 2022. The ICG lymphography findings was evaluated. We defined the dermal backflow in the trunk as the lymphatic flow from the end of the limb back through the lymphatic vessels on the surface of the trunk. The association between the dermal backflow in the trunk and clinical outcomes, as follows, are investigated: the duration of the drainage period, the duration of endotracheal intubation, and the length of hospital stay. Twenty infants had a dermal backflow in the trunk, and ten did not. Clinical outcomes in infants with and without dermal backflow in the trunk were as follows (median): the duration of the drainage period (20 vs. 0 days, p = 0.001), the duration of endotracheal intubation (12 vs. 2 days, p = 0.04), and the length of hospital stay (62 vs. 41 days, p = 0.04), respectively. In multivariate linear regression analysis adjusted for gestational age, the duration of the drainage period was correlated with the dermal backflow in the trunk [exp(B) = 2.62; p = 0.003]. The dermal backflow in the trunk in ICG lymphography was useful in predicting the clinical course of congenital chylothorax and ascites.

Infliximab modifies CD74-mediated lymphatic abnormalities and adipose tissue alterations in creeping fat of Crohn's disease.

Lymphatic abnormalities are essential for pathophysiologic changes of creeping fat (CrF) in Crohn's disease (CD). Anti-tumor necrosis factor (TNF) therapy has been proved to alleviate CrF lesions, however, whether it achieves these by remodeling lymphatics is unknown. CD74 expression was detected in CrF and uninvolved mesentery of CD patients. Lymphatic functions in vitro were evaluated and lymphatic endothelium barrier were checked by transendothelial electrical resistance (TEER) and FITC-Dextran permeability. Protein level of tight junction and signaling pathways were detected by western blotting. CD74 was upregulated in LECs of CrF and positively correlated with TNF-α synthesis. This was suppressed by IFX administration. In vitro, TNF-α stimulated LECs to express CD74 through NF-κB signaling pathway, and this was rescued by IFX. CD74 downregulation suppressed the abilities of LECs in proliferation, migration and tube formation. Interaction of CD74-MIF impaired LECs' barrier via reducing tight junction proteins in an ERK1/2-dependent manner, which was reversed by CD74 downregulation. Consistently, the CD patients receiving IFX therapy displayed decreased lymphangiogenesis and improved mesenteric lymphatic endothelium barrier, companied with reduced adipocyte size and adipokine levels in CrF. Anti-TNF therapy could modify pathological changes in CrF by alleviating CD74-mediated lymphatic abnormalities.

Anesthetic challenges in patients with multicompartmental lymphatic failure after Fontan palliation undergoing transcatheter thoracic duct decompression.

Lymphatic flow abnormalities are central to the development of protein losing enteropathy, plastic bronchitis, ascites and pleural effusions in patients palliated to the Fontan circulation. These complications can occur in isolation or multicompartmental (two or more). The treatment of multicompartmental lymphatic failure aims at improving thoracic duct drainage. Re-routing the innominate vein to the pulmonary venous atrium decompresses the thoracic duct, as atrial pressure is lower than systemic venous pressure in Fontan circulation. Transcatheter thoracic duct decompression is a new minimally invasive procedure that involves placing covered stents from the innominate vein to the atrium. Patients undergoing this procedure require multiple general anesthetics, presenting challenges in managing the sequelae of disordered lymphatic flow superimposed on Fontan physiology. We reviewed the first 20 patients at the Center for Lymphatic Imaging and Intervention at a tertiary care children's hospital presenting for transcatheter thoracic duct decompression between March 2018 and February 2023. The patients ranged in age from 3 to 26 years. The majority had failed prior catheter-based lymphatic intervention, including selective embolization of abnormal lympho-intestinal and lympho-bronchial connections to treat lymphatic failure in a single compartment. Fourteen had failure in three lymphatic compartments. Patients were functionally impaired (ASA 3-5) with significant comorbidities. Concurrent with thoracic duct decompression, three patients required fenestration closure for the resultant decrease in oxygen saturation. Ten patients had improvement in symptoms, seven had no changes and three have limited follow up. Five (25%) of these patients were deceased as of January 2024 due to non-lymphatic complications from Fontan failure.

Central conducting lymphatic anomaly: from bench to bedside.

Central conducting lymphatic anomaly (CCLA) is a complex lymphatic anomaly characterized by abnormalities of the central lymphatics and may present with nonimmune fetal hydrops, chylothorax, chylous ascites, or lymphedema. CCLA has historically been difficult to diagnose and treat; however, recent advances in imaging, such as dynamic contrast magnetic resonance lymphangiography, and in genomics, such as deep sequencing and utilization of cell-free DNA, have improved diagnosis and refined both genotype and phenotype. Furthermore, in vitro and in vivo models have confirmed genetic causes of CCLA, defined the underlying pathogenesis, and facilitated personalized medicine to improve outcomes. Basic, translational, and clinical science are essential for a bedside-to-bench and back approach for CCLA.

Interventional treatment of refractory non-traumatic chylous effusions in patients with lymphoproliferative disorders

To report results of interventional treatment of refractory non-traumatic abdomino-thoracic chylous effusions in patients with lymphoproliferative disorders. 17 patients (10 male; mean age 66.7 years) with lymphoproliferative disorders suffered from non-traumatic chylous effusions (chylothorax n = 11, chylous ascites n = 3, combined abdomino-thoracic effusion n = 3) refractory to chemotherapy and conservative therapy. All underwent x-ray lymphangiography with iodized-oil to evaluate for and at the same time treat lymphatic abnormalities (leakage, chylo-lymphatic reflux with/without obstruction of central drainage). In patients with identifiable active leakage additional lymph-vessel embolization was performed. Resolution of effusions was deemed as clinical success. Lymphangiography showed reflux in 8/17 (47%), leakage in 2/17 (11.8%), combined leakage and reflux in 3/17 (17.6%), lymphatic obstruction in 2/17 (11.8%) and normal findings in 2/17 cases (11.8%). 12/17 patients (70.6%) were treated by lymphangiography alone; 5/17 (29.4%) with leakage received additional embolization (all technically successful). Effusions resolved in 15/17 cases (88.2%); 10/12 (83.3%) resolved after lymphangiography alone and in 5/5 patients (100%) after embolization. Time-to-resolution of leakage was significantly shorter after embolization (within one day in all cases) than lymphangiography (median 9 [range 4–30] days; p = 0.001). There was no recurrence of symptoms or post-interventional complications during follow-up (median 445 [40–1555] days). Interventional-radiological treatment of refractory, non-traumatic lymphoma-induced chylous effusions is safe and effective. Lymphangiography identifies lymphatic abnormalities in the majority of patients and leads to resolution of effusions in > 80% of cases. Active leakage is found in only a third of patients and can be managed by additional embolization.

Magnetic resonance lymphangiography: Establishing normal

BackgroundDespite an increased interest in visualizing the lymphatic vessels with magnetic resonance lymphangiography (MRL), little literature is available describing their appearance in nonlymphedematous individuals. To determine lymphatic abnormalities, an understanding of how healthy lymphatic vessels appear and behave needs to be established. Therefore, in this study, MRL of individuals without a history of lymphatic disease was performed. MethodsA total of 25 individuals (15 women) underwent MRL of their lower limbs using a 3.0 T Philips magnetic resonance imaging scanner (Philips Medical Systems). The first nine participants were recruited to establish the concentration of gadolinium-based contrast agent (GBCA) to administer, with the remainder imaged before and after interdigital forefoot GBCA injections at the optimized dose. Outcomes, including lymphatic vessel diameter, tortuosity, and frequency of drainage via particular drainage routes, were recorded. ResultsHealthy lymphatic vessels following the anteromedial pathway were routinely observed in post-contrast T1-weighted images (average tortuosity, 1.09 ± 0.03), with an average of 2.16 ± 0.93 lymphatic vessels with a diameter of 2.47 ± 0.50 mm crossing the anterior ankle. In six limbs, vessels following the anterolateral pathways were observed. No vessels traversing the posterior of the legs were seen. In a subset of 10 vessels, the lymphatic signal, measured at the ankle, peaked 29 minutes, 50 seconds ± 9 minutes, 29 seconds after GBCA administration. No lymphatic vessels were observed in T2-weighted images. ConclusionsContrast-enhanced MRL reliably depicts the lymphatic vessels in the legs of healthy controls. Following interdigital contrast injection, anteromedial drainage appears dominant. Quantitative measures related to lymphatic vessel size, tortuosity, and drainage rate are readily obtainable and could be beneficial for detecting even subtle lymphatic impairment.

Long-term efficacy and safety of netakimab in patients with active ankylosing spondylitis: results of three years of use in the international multicentre, randomized, double-blind, phase III clinical trial BCD-085-5/ASTERA

The article presents the results of the three-year use of netakimab (NTK) in patients with ankylosing spondylitis (AS) as part of the phase III BCD-085-5/ASTERA study.Objective: to evaluate the long-term efficacy and safety of NTK over a three-year period in patients with active AS.Material and methods. BCD-085-5/ASTERA – double-blind, multicenter, randomized phase III clinical trial that enrolled patients with active AS (BASDAI ≥4) and a back pain intensity ≥4 on a numeric rating scale with inefficacy or intolerance of non-steroidal anti-inflammatory drugs or biologic drugs. A total of 228 patients were randomized in a 1:1 ratio and assigned to either the NTK group or the placebo/NTK group. Starting at week 16, patients who did not achieve ASAS20 (20% improvement according to ASAS criteria) received NTK 120 mg once every 2 weeks in an open-label regimen. Patients who achieved ASAS20 response at week 52 in the NTK group and week 68 in the placebo/NTK group continued to receive NTK (120 mg every 2 weeks) until week 156 in the NTK group and until week 172 in the placebo/NTK group.Results and discussion. Over the course of three years of NTK use, most patients experienced a sustained decline in AS activity (according to ASDAS-CRP, BASDAI) with sustained response (ASAS20/40, ASAS5/6) to therapy. Most adverse events reported were mild to moderate. 36.7% of patients had adverse events, which were mainly laboratory abnormalities, blood and lymphatic system abnormalities and infectious complications.Conclusion. The clinical effect of NTK was maintained in most patients with AS over a three-year period, with no significant loss of response. NTK was well tolerated and the safety profile remained favorable.

Dynamic Contrast-enhanced CT Lymphangiography to Quantify Thoracic Duct Lymphatic Flow.

Background CT lymphangiography has been used to image the lymphatic anatomy and assess lymphatic abnormalities. There is, however, a need to develop a method for quantification of lymphatic flow rate in the thoracic duct (TD). Purpose To develop and validate a TD lymphatic flow measurement technique using dynamic contrast-enhanced CT lymphangiography. Materials and Methods Lymphatic flow rate was measured with two techniques: a first-pass analysis technique based on a single compartment model and a thresholding technique distinguishing between opacified and nonopacified voxels within the TD. The measurements were validated in a swine animal model between November 2021 and September 2022. CT images were acquired at 100 kV and 200 mA using a fast-pitched helical scan mode covering the entire TD following contrast material injection into the bilateral inguinal lymph nodes. Two helical CT scans, acquired at the base and peak contrast enhancement of the TD, were used to measure lymphatic flow rate. A US flow probe surgically placed around the TD provided the reference standard measurement. CT lymphatic flow measurements were compared with the reference US flow probe measurements using regression and Bland-Altman analysis. Repeatability was determined using repeated flow measurements within approximately 10 minutes of each other. Results Eleven swine (10 male; mean weight, 43.6 kg ± 2.6 [SD]) were evaluated with 71 dynamic CT acquisitions. The lymphatic flow rates measured using the first-pass analysis and thresholding techniques were highly correlated with the reference US flow probe measurements (r = 0.99 and 0.91, respectively) and showed good agreement with the reference standard, with Bland-Altman analysis showing small mean differences of 0.04 and 0.05 mL/min, respectively. The first-pass analysis and thresholding techniques also showed good agreement for repeated flow measurements (r = 0.94 and 0.90, respectively), with small mean differences of 0.09 and 0.03 mL/min, respectively. Conclusion The first-pass analysis and thresholding techniques could be used to accurately and noninvasively quantify TD lymphatic flow using dynamic contrast-enhanced CT lymphangiography. © RSNA, 2023 See also the editorial by Choyke in this issue.

Abstract 16011: Lymphatic Intervention Following Superior Cavo-Pulmonary Anastomosis Potentially Allows for Successful Fontan Completion

Introduction: Superior cavopulmonary anastomosis (SCPC) inevitably exposes the thoracic duct to higher venous pressure, potentially triggering disordered lymphatic perfusion manifesting as chylothorax (CT) and/or plastic bronchitis (PB) . Though outcomes following lymphatic interventions after Fontan completion (FC) are well described, they are not well described in patients after SCPC. Methods: A single-center retrospective study of patients who underwent lymphatic intervention for PB or CT following SCPC 1/1/2011-12/31/2021 was performed, excluding those with planned two ventricle or 1.5 ventricle repair, patients who underwent thoracic duct ligation, and those in whom interventions were performed either prior to SCPC or following FC. Results: In total, 27 patients (56% male) were studied, of which 22% had PB and 78% with CT, 7% with Noonan’s syndrome and 19% with heterotaxy syndrome. Median age at intervention was 11.3 months (IQR 7.4 - 33.5). Median time following SCPC was 3.5 months (IQR 2.1 - 24.2). In terms of interventions, 41% (n=11) underwent selective lymphatic channel embolization. Of these 36% (4/11) underwent subsequent thoracic duct embolization (TDE). The remaining 59% (n=16) patients underwent TDE. The thoracic duct was able to be accessed in 23 patients (85.2%). Twenty-four patients (19/21 with CT, 5/6 with PB) had resolution of symptoms following transcatheter intervention at our center. Following intervention, seven patients (all of whom were of the type IV lymphatic subtype) were successfully referred for FC, ten are currently awaiting FC, five are not Fontan candidates and five passed away from non-procedural comorbidities. Median duration of post-operative chest tubes following FC was 7 days (IQR 6-8) and median follow up is 39.1 months (IQR 15.1 - 45.1). Conclusions: Selective lymphatic embolization and TDE are feasible in SCPC recipients with CT and PB, with most patients experiencing symptomatic improvement. Subsequent FC has been achieved in some patients with type IV lymphatic abnormalities, suggesting that these interventions may alter the unnatural history of lymphatic dysfunction in single ventricle patients. Future research is needed to define longer term outcomes of this high-risk cohort.