Lymphangiography and preliminary evaluation of N-butyl cyanoacrylate, Lipiodol, and ethanol mixtures; sodium tetradecyl sulphate with Lipiodol and air; and ethanol with Lipiodol in rats.

Background: Lymphatic interventional radiology is expanding in scope, with N-butyl 2-cyanoacrylate (NBCA) being one of the only embolic materials currently in use. However, it has drawbacks such as catheter adhesion and non-target embolization. Although alternative agents are needed for lymphatic interventions, optimal substitutes remain unclear. This study aimed to develop a rat model to evaluate the efficacy of NBCA combined with Lipiodol and ethanol (NLE), sodium tetradecyl sulphate (STS) combined with Lipiodol and air, and ethanol and Lipiodol (EL) in lymphatic interventions.

Methods: Twelve Lewis and six Sprague-Dawley male rats were included in this study. Two lymphatic approaches were evaluated: (I) percutaneous transabdominal cisterna chyli/retroperitoneal lymphatic duct puncture at the level of 2nd-3rd lumbar vertebrae using a 25-G needle, as performed in humans (6 rats); and (II) puncture of iliolumbar lymph node (12 rats). For the latter, isosulfan blue was injected subcutaneously into the left and/or right rear foot pad to stain the popliteal lymph nodes, which were then exposed for additional dye injection. A 5.0-cm midline incision was made to expose the blue-stained iliolumbar lymph node. Once lymphangiography was achieved using either approach, embolization was subsequently performed. Two NLE ratios [2:2:1 (NLE221) and 1:5:1 (NLE151)], STS foam (with a ratio of 3:2:3 for air, STS and Lipiodol) and EL (ethanol:Lipiodol =2:1) were used as embolic materials. Their effects were assessed by measuring the travel distance of the embolic mixture.

Results: Using the first approach, lymphangiography was successfully performed in 4 of 6 rats, but embolization could not be achieved due to poor needle stability. Using the second approach, the popliteal and iliolumbar lymph node were visualized in all 12 and 11 rats, respectively. Among the 11 rats with iliolumbar lymph node access, lymphangiography using Lipiodol was performed in one rat, and embolization under fluoroscopy was performed in 10 rats. The thoracic duct was visualized following lymphangiography, and embolization was carried out using NLE221 (n=3), NLE151 (n=2), STS (n=3) and EL (n=2). Lymphatic flow cessation was observed in all 10 cases. The average travel distances were 1.2 cm for NLE221, 3.5 cm for NLE151, 4.3 cm for STS and 4.0 cm for EL21.

Conclusions: The lymph node puncture approach was more technically feasible for conducting preliminary evaluation of NLE, STS and EL in lymphatic embolization. This model may help optimize the development of ideal agents for lymphatic embolization.