A new lymphography protocol and interpretation principles based on functional lymphatic anatomy in lower limb lymphedema

Indirect lymphatic system imaging is essential for diagnosing lymphatic diseases. The basic methodology involves intradermal or subcutaneous injection of a contrast agent into the surrounding lymphatic capillary, and the flow of the contrast agent is identified using a detector. Many contrast agents that use near-infrared dye, including indocyanine green (ICG) fluorescent lymphography, are available. ICG is rapidly spreading as a convenient and safe lymphedema diagnostic method, because it does not involve radiation exposure, and the imaging equipment is more compact than other devices. The lymphatic system is a semi-open circulatory system with numerous lymphatic capillaries acting as blind ends. Anatomical information on the injection site and observation of specific lymphatic vessels and nodes is important. However, this anatomical information is lacking. Recent reports suggest that ICG fluorescent lymphography can be applied to cadavers in the same manner as living bodies. Furthermore, these reports have demonstrated the functional aspects of the capillary lymph vessel networks as well as their relationship with lymphatic vessels and lymph nodes. This review article describes the historical progression from the old to the new functional lymphatic anatomy and introduces a new functional lymphography technique for the lower limbs.