Pedal Lymphangiography Remains a Valuable Tool for Percutaneous Thoracic Duct Embolization

Learning Objectives: We intend to describe and visually demonstrate the use of bipedal lymphangiography as a viable technique to visualize the lymphatic circulation. We will also demonstrate its utility for percutaneous thoracic duct embolization (TDE). Background: Pedal lymphangiography was first described by Kinmonth¹ in the 1950’s and remains the gold standard for accessing the lymphatic circulation today. In the past, pedal lymphangiography was used to image lymph nodes for cancer staging but now is primarily used to identify chylous leaks for subsequent percutaneous TDE. Given the relatively low incidence of chylous leaks, pedal lymphangiography is a skill that few newly trained interventional radiologists learn and even fewer have opportunity to master. Several strategies have been suggested to gain access to the lymphatic circulation such as direct nodal injection and retrograde cannulation of the thoracic duct, however, these methods are not without complication. Clinical Findings / Procedure Details: Direct nodal lymphangiogram was attempted as described by Itkin² in 2012. Under ultrasound guidance, suitable lymph nodes in the groin were accessed, however, the needle repeatedly became dislodged due to the patient’s slender body habitus and the direct nodal injection was abandoned in favor of traditional bipedal lymphangiography. Bipedal lymphangiography begins with injection of methylene blue into the web spaces between the toes. The subcutaneous tissue of the dorsal foot is infiltrated with lidocaine and a superficial transverse incision is made. Lymphatic vessels, now a vibrant blue, are gently isolated from the subcutaneous fat and cannulated. Ethiodized oil is infused and periodic fluoroscopy performed to demonstrate progression of contrast to the level of the cisterna chyli. Once visualized fluoroscopically, a 21 gauge Chiba needle is used to puncture the cisterna chyli and the thoracic duct is accessed with a stiff guidewire and microcatheter. Embolization is achieved with coils and a liquid embolic agent such as Onyx (EVOH copolymer). Conclusion and/or Teaching Points: Pedal lymphangiography is a valuable tool in the interventional radiologist’s toolbox. The technique of direct nodal injection used in TDE may theoretically decrease procedure times, however, this technique may be technically more difficult in patients with thin body habitus necessitating the use of pedal lymphangiography