New microcannulation technique for imaging contrast and drug delivery via the lymphatics

A technique for drug delivery using the lymphatics was introduced and tested in animals half a century ago, but was never trialed in human subjects. Recently, surgical manipulation of lymphatic vessels for lymphedema treatment has attracted the interest of plastic surgeons. Assessing the lymphatics through imaging plays a vital role in understanding the pathology of lymphedema and planning surgery. Although various lymphatic imaging techniques are currently used, their indirect method of administering contrast media can cause uncontrollable transit and venous contamination. Pilot and preclinical studies were undertaken to simulate microcannulation into the lymphatic vessels using fresh animal and human cadaver models. In the human cadaver model, the target lymphatic vessels were in the dorsal hand and breast. Indocyanine green lymphography was performed to map the lymphatic vessels, after which a prototype microcannula 0.3 mm in diameter was inserted using a surgical microscope via a 5-mm skin incision into the identified lymphatic vessel. A mixture of blue dye and radiocontrast media was injected into the lymphatic vessel through the microcannula manually with a 1-mL syringe, and radiographs were taken to confirm its successful delivery into the lymphatic vessel without leakage from the needle hole. The preclinical study demonstrated that the technique of microcannulation via the lymphatics is an innovative and promising option for an imaging contrast and drug delivery route. This technique has 2 prospective clinical applications: (1) contrast-enhanced lymphatic imaging and (2) delivery of anticancer drugs targeting lymphogenous metastases.