One of the indications for lymphoscintigraphy in patients with melanoma is to determine the lymphatic drainage pattern and position of the first draining lymph node--the sentinel node. Metastasis in the sentinel node indicates the need for therapeutic lymph node dissection. The purpose of the present study was to examine the reproducibility of lymphoscintigraphy in assessing the location and number of sentinel nodes.
Methods: Twenty-five patients with clinically localized melanoma were investigated. The same investigator performed two scintigraphic studies with a 2-4 wk interval in each patient, in an identical manner. A 60-MBq dose of 99mTc-nanocolloid was injected intradermally at the primary tumor site. The lymph flow was studied dynamically, complemented by lateral/oblique views. The images were evaluated by a panel of three observers.
Results: The sentinel node was visualized within 20 min in all patients. A difference in number of sentinel nodes depicted on the first and second study was noted in three patients (12%). The melanoma was situated on the head (two patients) and arm (one patient) in these patients. Otherwise, the images were identical for number and location of nodes.
Conclusions: Reproducibility of lymphoscintigraphy with 99mTc-nanocolloid was high in this study. However, some sentinel nodes may be missed in lymphoscintigraphy for melanoma.