State-of-the-art imaging for lymphatic evaluation in children

Complex lymphatic anomalies

Complex lymphatic anomalies are unique diseases marked by abnormal lymphatic vessel development and growth. Imaging is crucial in the evaluation and management of complex lymphatic anomalies, with dynamic contrast-enhanced MR lymphangiography emerging as a valuable modality for visualizing abnormal lymphatic structures and informing treatment decisions. This article gives an overview of complex lymphatic anomalies and their management strategies, focusing specifically on generalized lymphatic anomaly, Gorham-Stout disease, Kaposiform lymphangiomatosis, and central conducting lymphatic anomalies. Simple lymphatic diseases are beyond the scope of this review.

Dynamic contrast-enhanced magnetic resonance lymphangiography: a simple algorithm for image interpretation

Dynamic contrast-enhanced magnetic resonance lymphangiography is a high-resolution imaging technique that has emerged as the preferred method for evaluating lymphatic anatomy and flow dynamics due to its precise anatomical detail. The lymphatic system has a complex anatomical distribution, and variability is common among individuals with cardiac abnormalities, particularly congenital heart disease. Lymphatic imaging has recently been revolutionized by the introduction of MR lymphangiography. However, challenges in interpreting these images persist due to limited availability of this modality, and the expertise required for its performance and interpretation, especially in pediatric patients. We aim to outline a simple algorithm employed in our practice for interpreting MR lymphangiography images for pediatric radiologists.

Systematic Lymphatic Repair for Reduction of Postoperative Lymphatic Leak Following Neuroblastoma Resection

BACKGROUND

Gross total resection of neuroblastoma is associated with lymphatic leaks that can delay postoperative resumption of treatment. To prevent postoperative lymphatic leak, we introduced systematic lymphatic repair (SLR), which involved oversewing the entire edge of the disrupted lymphatic plane after neuroblastoma resection. We sought to study the impact of SLR on postoperative lymphatic leak and time to return to treatment.

METHODS

We reviewed 60 neuroblastoma patients who underwent gross total resection at KK Women's and Children's Hospital. Patient, disease, and operative factors were correlated with surgical drainage, treatment delay and length of stay (LOS). Among patients with sufficient records, the interaction between variables associated with drainage, delay and LOS outcomes were compared in 14 patients who had SLR versus 35 historical controls who had targeted lymphatic repair (TLR).

RESULTS

Postoperative drain duration and volume were significantly higher in tumors with ≥2 image-derived risk factors (IDRFs, P = 0.005 and P = 0.013, respectively) or vessel encasement (P = 0.031 and P = 0.024, respectively). Longer LOS was significantly associated with ≥2 IDRFs (P = 0.006). All forms of suture repair of lymphatics and use of Tachosil™ were associated with significantly longer postoperative drain duration (P < 0.05); the former was also associated with significantly higher total drain volume (P < 0.05) - indicating appropriate use of these adjuncts in patients at risk of chyle leak. In patients who had suture repair of lymphatics, SLR was significantly associated with reduced postoperative interval to chemotherapy resumption (P = 0.014, two-way ANOVA).

CONCLUSION

A systematic approach to repair of lymphatic channels following neuroblastoma resection can significantly reduce time to postoperative resumption of treatment.

TYPE OF STUDY

Clinical Research.

LEVEL OF EVIDENCE

III.

Dynamic Contrast-Enhanced Magnetic Resonance Lymphangiography for Diagnosis and Treatment of Chylopericardium After Cardiac Transplantation

Chylopericardium is a rare complication after cardiac transplantation. We report a case of a 69-year-old woman with persistent chylopericardium after a heart transplantation due to Chagas disease. Failure of conservative treatment led to dynamic contrast-enhanced magnetic resonance lymphangiography and percutaneous radiologic intervention of the lymphatic leakage and symptoms resolution.

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.

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.

Preliminary report of a thoracic duct-to-pulmonary vein lymphovenous anastomosis in swine: A novel technique and potential treatment for lymphatic failure

OBJECTIVE

The thoracic duct is the largest lymphatic vessel in the body, and carries fluid and nutrients absorbed in abdominal organs to the central venous circulation. Thoracic duct obstruction can cause significant failure of the lymphatic circulation (i.e., protein-losing enteropathy, plastic bronchitis, etc.). Surgical anastomosis between the thoracic duct and central venous circulation has been used to treat thoracic duct obstruction but cannot provide lymphatic decompression in patients with superior vena cava obstruction or chronically elevated central venous pressures (e.g., right heart failure, single ventricle physiology, etc.). Therefore, this preclinical feasibility study sought to develop a novel and optimal surgical technique for creating a thoracic duct-to-pulmonary vein lymphovenous anastomosis (LVA) in swine that could remain patent and preserve unidirectional lymphatic fluid flow into the systemic venous circulation to provide therapeutic decompression of the lymphatic circulation even at high central venous pressures.

METHODS

A thoracic duct-to-pulmonary vein LVA was attempted in 10 piglets (median age 80 [IQR 80-83] days; weight 22.5 [IQR 21.4-26.8] kg). After a right thoracotomy, the thoracic duct was mobilized, transected, and anastomosed to the right inferior pulmonary vein. Animals were systemically anticoagulated on post-operative day 1. Lymphangiography was used to evaluate LVA patency up to post-operative day 7.

RESULTS

A thoracic duct-to-pulmonary vein LVA was successfully completed in 8/10 (80.0%) piglets, of which 6/8 (75.0%) survived to the intended study endpoint without any complication (median 6 [IQR 4-7] days). Initially, 2/10 (20.0%) LVAs were aborted intraoperatively, and 2/10 (20.0%) animals were euthanized early due to post-operative complications. However, using an optimized surgical technique, the success rate for creating a thoracic duct-to-pulmonary vein LVA in six animals was 100%, all of which survived to their intended study endpoint without any complications (median 6 [IQR 4-7] days). LVAs remained patent for up to seven days.

CONCLUSION

A thoracic duct-to-pulmonary vein LVA can be completed safely and remain patent for at least one week with systemic anticoagulation, which provides an important proof-of-concept that this novel intervention could effectively offload the lymphatic circulation in patients with lymphatic failure and elevated central venous pressures.

Surgical management of chronic lymphatic pleural effusions and chronic lymphatic ascites

Patients with central lymphatic conduction disorders commonly have recalcitrant pleural effusions and or ascites. These conditions cause a profound deterioration in the patient's quality of life. Support measures such as low-fat diet and diuretics alone hardly ever provide meaningful improvement. New understanding of the pathophysiology of these disorders has opened the door in recent years to the development of several surgical procedures that have remarkable success rates. However, these patients must be managed by expert multidisciplinary teams.

Lymphatic failure and lymphatic interventions: Knowledge gaps and future directions for a new frontier in congenital heart disease

Lymphatic failure is a broad term that describes the lymphatic circulation's inability to adequately transport fluid and solutes out of the interstitium and into the systemic venous circulation, which can result in dysfunction and dysregulation of immune responses, dietary fat absorption, and fluid balance maintenance. Several investigations have recently elucidated the nexus between lymphatic failure and congenital heart disease, and the associated morbidity and mortality is now well-recognized. However, the precise pathophysiology and pathogenesis of lymphatic failure remains poorly understood and relatively understudied, and there are no targeted therapeutics or interventions to reliably prevent its development and progression. Thus, there is growing enthusiasm towards the development and application of novel percutaneous and surgical lymphatic interventions. Moreover, there is consensus that further investigations are needed to delineate the underlying mechanisms of lymphatic failure, which could help identify novel therapeutic targets and develop innovative procedures to improve the overall quality of life and survival of these patients. With these considerations, this review aims to provide an overview of the lymphatic circulation and its vasculature as it relates to current understandings into the pathophysiology and pathogenesis of lymphatic failure in patients with congenital heart disease, while also summarizing strategies for evaluating and managing lymphatic complications, as well as specific areas of interest for future translational and clinical research efforts.

Surgical management of thoracic duct anomalies

The development of new imaging techniques for the study of the central lymphatic system allows us to understand the anatomy and pathophysiology of all the disorders of the thoracic duct. With the help of catheters placed percutaneously in the thoracic duct, we can do now complex operations on the thoracic duct to restore its functionality. Advance imaging, expert percutaneous skills, and expert microsurgical skills are critical to the success of these interventions.

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.

MR Lymphangiography in Lymphatic Disorders: Clinical Applications, Institutional Experience, and Practice Development

Lymphatic flow and anatomy can be challenging to study, owing to variable lymphatic anatomy in patients with diverse primary or secondary lymphatic pathologic conditions and the fact that lymphatic imaging is rarely performed in healthy individuals. The primary components of the lymphatic system outside the head and neck are the peripheral, retroperitoneal, mesenteric, hepatic, and pulmonary lymphatic systems and the thoracic duct. Multiple techniques have been developed for imaging components of the lymphatic system over the past century, with trade-offs in spatial, temporal, and contrast resolution; invasiveness; exposure to ionizing radiation; and the ability to obtain information on dynamic lymphatic flow. More recently, dynamic contrast-enhanced (DCE) MR lymphangiography (MRL) has emerged as a valuable tool for imaging both lymphatic flow and anatomy in a variety of congenital and acquired primary or secondary lymphatic disorders. The authors provide a brief overview of lymphatic physiology, anatomy, and imaging techniques. Next, an overview of DCE MRL and the development of an MRL practice and workflow in a hybrid interventional MRI suite incorporating cart-based in-room US is provided, with an emphasis on multidisciplinary collaboration. The spectrum of congenital and acquired lymphatic disorders encountered early in an MRL practice is provided, with emphasis on the diversity of imaging findings and how DCE MRL can aid in diagnosis and treatment of these patients. Methods such as DCE MRL for assessing the hepatic and mesenteric lymphatic systems and emerging technologies that may further expand DCE MRL use such as three-dimensional printing are introduced. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Surgical Management of Central Lymphatic Conduction Disorders: A Review

AIM

Recent advances in lymphatic imaging allow understanding the pathophysiology of lymphatic central conduction disorders with great accuracy. This new imaging data is leading to a wide range of novel surgical interventions. We present here the state-of-the-art imaging technology and current spectrum of surgical procedures available for patients with these conditions.

METHOD

Descriptive report of the newest lymphatic imaging technology and surgical procedures and retrospective review of outcome data.

RESULTS

There are currently two high-resolution imaging modalities for the central lymphatic system: multi-access dynamic contrast-enhanced MR lymphangiogram (DCMRL) and central lymphangiography (CL). DCMRL is done by accessing percutaneously inguinal and mesenteric lymph nodes and periportal lymphatics vessels. DCMRL provides accurate anatomical and dynamic data on the progression, or lack thereof, of the lymphatic fluid throughout the central lymphatic system. CL is done by placing a catheter percutaneously in the thoracic duct (TD). Pleural effusions are managed by pleurectomy and intraoperative lymphatic glue embolization guided by CL. Anomalies of the TD are managed by TD-to-vein anastomosis and/or ligation of aberrant TD branches. Chylous ascites and organ-specific chylous leaks are managed by intraoperative glue embolization, surgical lymphocutaneous fistulas, and ligation of aberrant peripheral lymphatic channels, among several other procedures.

CONCLUSION

The surgical management of lymphatic conduction disorders is a new growing field within pediatric general surgery. Pediatric surgeons should be familiar with the newest imaging modalities of the lymphatic system and with the surgical options available for patients with these complex surgical conditions to provide prompt treatment or referral.

LEVEL OF EVIDENCE

V.