Comparison of Preoperative and Postoperative Lymphatic Function is Essential to Understand the Changes in Lymphatic Function
Silva and Chang suggested referring to the article that we had reported.2,3 Indocyanine green lymphography is an alternative method of examination, which is less invasive and inexpensive. Subtle changes in lymphatic function can be detected at higher resolution using indocyanine green lymphography compared with lymphoscintigraphy. In our comparative study on secondary lower extremity lymphedema patients, earlier and less severe lymphatic dysfunction was detected by indocyanine green lymphography than by lymphoscintigraphy.3
As the authors proposed, it is very important to compare preoperative and postoperative lymphatic function of the upper extremities in breast cancer patients. In our previous study, lymphatic function of the upper extremities was examined periodically in breast cancer patients using indocyanine green lymphography before surgery and 1, 3, 6, 9, and 12 months after surgery.4 In some of these patients in whom lymphatic function became impaired following surgery, collateral lymphatic routes developed and dermal backflow patterns subsequently disappeared with conservative treatment. In patients whose collecting lymphatics along the cephalic artery to the supraclavicular nodes develop without passing through the axial nodes, accumulation at axillary nodes may not indicate lymphatic function (Fig. 2). In our previous study, no preoperative pattern predicting the postoperative occurrence of lymphedema could be detected. Perioperative changes in the velocity of lymphatic flow should be investigated in future studies.
There is an important disadvantage to indocyanine green lymphography. Morbidly obese patients cannot be evaluated well by this modality because it is impossible to observe lymphatic vessels located more than 2 cm deep in the subcutaneous tissue. Because of the limited ability of indocyanine green lymphography, scintigraphy is still considered the gold standard for evaluating lymphatic function. When combined with single-photon emission computed tomography, the function of the deep lymphatic system can be investigated in greater detail. The investigations of the physiology of lymphatic function using various modalities should be continued in the future.