Lymphatic Intervention, the Frontline of Modern Lymphatic Medicine: Part I. History, Anatomy, Physiology, and Diagnostic Imaging of the Lymphatic System

Computed tomographic mesenteric lymphography by oral iohexol liposomes

Lymphography is a useful technique in the diagnosis of lymphatic diseases. Conventional lymph node imaging methods, such as subcutaneous and footpad injections, are invasive and unable to visualize mesenteric lymph nodes. Liposomes have the potential to increase the oral bioavailability of poorly bioavailable hydrophilic drugs and promote their lymphatic transport in the intestinal lymph. In this study, the iohexol liposome was prepared using cholesterol, soybean lecithin, and iohexol by the reverse-phase evaporation method. It had an encapsulation efficiency of 70.26%, an average particle size diameter of 185.7 nm, a polydispersity index of 0.275, and a zeta potential of -7.697 mV. The iohexol liposomes were stable for five days at 4 °C under static conditions. The iohexol content in the lymph nodes of mice after oral iohexol liposomes initially increased and then gradually decreased over time, with the absorption peak occurring around 50-70 minutes and a peak iohexol content of 5.09 mg/g. After oral administration of iohexol liposomes, mild enhancement (12.46-12.92 HU) was observed in the mesenteric lymph nodes of dogs through CT scanning after a certain period. These results indicate that iohexol liposomes, when administered orally, can effectively achieve imaging of the mesenteric lymph nodes. Overall, we provide a novel noninvasive imaging modality based on liposomes for evaluating mesenteric lymph nodes via lymphography.

MR Lymphangiography: Congenital Lymphatic Flow Disorders

ABSTRACT

Congenital lymphatic flow disorders collectively refer to a heterogeneous group of diseases that manifest as chylothorax, chylous ascites, intestinal lymphangiectasia, protein-losing enteropathy, and peripheral extremity or genital lymphedema, all in the absence of identifiable injury to the lymphatic system. We have only recently begun to understand congenital lymphatic flow disorders through the ability to image lymph flow dynamically. Intranodal dynamic contrast-enhanced magnetic resonance lymphangiography (DCMRL) is a crucial technique for imaging lymphatic flow in pediatric patients with congenital lymphatic flow disorders. However, as lymphatic imaging is still a nascent discipline with many uncertainties regarding optimal imaging and treatment, effective patient management requires a comprehensive understanding of imaging techniques, disease pathophysiology, and multidisciplinary treatment approaches. Above all, a fundamental understanding of the physiological lymphatic flow of the central conducting lymphatics is essential for the correct interpretation of DCMRL images. This knowledge helps to avoid unnecessary examinations, erroneous diagnoses, and potentially harmful treatment approaches. This review provides an overview of the methods, advantages, and precautions for interpreting the DCMRL examination, a state-of-the-art lymphatic system imaging technique, and shares various case studies.

Lymphatic Disorder Management in Pediatric Patients With Congenital Heart Disease in European Pediatric Cardiology Centers: Current Status, Disparities, and Future Considerations

BACKGROUND

Lymphatic disorders such as protein-losing enteropathy, plastic bronchitis, and chylothorax are important complications of the Fontan circulation and ultimately result in an increased risk of early death. Several European centers are now performing lymphatic procedures. The aim of this study is to map the extent of these lymphatic disorders and treatments provided across European pediatric cardiology centers.

METHODS AND RESULTS

A survey was circulated to 49 European pediatric cardiology centers consisting of 37 questions including a mix of binary, categorical, and continuous variables. Thirty-one centers (63%) participated in the study, performing a median of 250 (interquartile range, 178 - 313) cardiopulmonary bypass procedures per year. Chylothorax emerged as the most prevalent lymphatic disorder followed by protein-losing enteropathy and plastic bronchitis. The most common diagnostic investigation method was noncontrast magnetic resonance lymphangiography (52%). Eleven centers (35%) conducted lymphatic interventions with a median of 3 (interquartile range, 1 - 4) procedures per year and 12 (interquartile range, 5 - 15) interventions in total per center.

CONCLUSIONS

This study confirms the rarity of and variation in treatment approaches for lymphatic disorders across Europe. With at least 11 centers offering lymphatic interventions, the adoption of these procedures is on the rise in Europe. To improve the quality of care and treatment outcomes for these complex patients, it is crucial to consider evidence-based lymphatic diagnostics, interventional lymphatic procedures, and the centralization of services in Europe.

The utility of dynamic contrast-enhanced intranodal magnetic resonance lymphangiography (MRL) in the investigation of primary lymphatic anomalies

AIM

The aim of this study was to describe the technique of DCMRL to identify central lymphatic abnormalities in patients with primary lymphatic anomalies and discuss utility of the findings.

MATERIALS AND METHODS

Twenty-eight patients with primary lymphatic abnormalities underwent dynamic magnetic resonance imaging (MRI) following injection of gadolinium directly into inguinal lymph nodes at a tertiary lymphovascular referral center.

RESULTS

Technical success was achieved in 23 patients (82.1%). Pathological imaging findings included obstructed, hypoplastic, or absent lymphatic channels with collateralization/rerouting or reflux of flow, lymphangiectasia, lymphatic pseudoaneurysms, and lymph leaks. Protocol modifications for improved imaging are highlighted including technical aspects of lymph node injection, image acquisition and MRI parameters. In two patients, imaging findings warranted embolization of the abnormal lymphatic channels with subsequent symptomatic improvement.

CONCLUSION

DCMRL has been shown to be a safe, reproducible technique in patients with primary lymphatic anomalies enabling imaging of the central lymphatic system.

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.

Revolutionizing lymph node metastasis imaging: the role of drug delivery systems and future perspectives

The deployment of imaging examinations has evolved into a robust approach for the diagnosis of lymph node metastasis (LNM). The advancement of technology, coupled with the introduction of innovative imaging drugs, has led to the incorporation of an increasingly diverse array of imaging techniques into clinical practice. Nonetheless, conventional methods of administering imaging agents persist in presenting certain drawbacks and side effects. The employment of controlled drug delivery systems (DDSs) as a conduit for transporting imaging agents offers a promising solution to ameliorate these limitations intrinsic to metastatic lymph node (LN) imaging, thereby augmenting diagnostic precision. Within the scope of this review, we elucidate the historical context of LN imaging and encapsulate the frequently employed DDSs in conjunction with a variety of imaging techniques, specifically for metastatic LN imaging. Moreover, we engage in a discourse on the conceptualization and practical application of fusing diagnosis and treatment by employing DDSs. Finally, we venture into prospective applications of DDSs in the realm of LNM imaging and share our perspective on the potential trajectory of DDS development.

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.

Thoracic Duct Embolization for Treatment of Chyle Leakage After Thyroidectomy and Neck Dissection

OBJECTIVE

This study aimed to evaluate the safety and efficacy of intranodal lymphangiography and thoracic duct embolization (TDE) for chyle leakage (CL) after thyroid surgery.

MATERIALS AND METHODS

Fourteen patients who underwent intranodal lymphangiography and TDE for CL after thyroid surgery were included in this retrospective study. Among the 14 patients, 13 underwent bilateral total thyroidectomy with neck dissection (central compartment neck dissection [CCND], n = 13; left modified radical neck dissection (MRND), n = 11; bilateral MRND, n = 2), and one patient underwent left hemithyroidectomy with CCND. Ten patients (76.9%) had high-output CL (> 500 mL/d). Before the procedure, surgical intervention was attempted in three patients (thoracic duct ligation, n = 1; lymphatic leakage site ligation, n = 2). Lymphangiographic findings, technical and clinical successes, and complications were analyzed. Technical success was defined as the successful embolization of the thoracic duct after access to the lymphatic duct via the transabdominal route. Clinical success was defined as the resolution of CL or surgical drain removal.

RESULTS

On lymphangiography, ethiodized oil leakage near the surgical bed was identified in 12 of 14 patients (85.7%). The technical success rate of TDE was 78.6% (11/14). Transabdominal antegrade access was not feasible due to the inability to visualize the identifiable cisterna chyli or a prominent lumbar lymphatic duct. Among patients who underwent a technically successful TDE, the clinical success rate was 90.1% (10/11). The median time from the procedure to drain removal was 3 days (with a range of 1-13 days) for the 13 patients who underwent surgical drainage. No CL recurrence was observed during the follow-up period (ranging from 2-44 months; median, 8 months). There were no complications, except for one case of chylothorax that developed after TDE.

CONCLUSION

TDE appears to be a safe and effective minimally invasive treatment option for CL after thyroid surgery, with acceptable technical and clinical success rates.