Sentinel node mapping in patients with malignant melanoma using melanoma Tc-99m colloidal rhenium sulfide

PURPOSE: The aim of the study was to localize the sentinel lymph node using lymphoscintigraphy aided by Tc-99m colloidal rhenium sulfide. MATERIALS AND METHODS: Thirty consecutive patients with histologically proved melanoma, but no clinical evidence of metastases, were examined before operation by injecting 20 to 40 MBq (0.5 to 1.1 mCi) Tc-99m colloidal rhenium sulfide with a mean particle size of 100 nm (range, 50 to 200 nm) intradermally around the lesion. Lymphoscintigraphy was performed immediately after injection. In addition, blue dye was injected before operation. A hand-held gamma probe guided the sentinel node biopsy. RESULTS: Lymphoscintigraphy revealed hot spots in all patients. During surgery, the sentinel node was identified in all 30 patients. The number of sentinel nodes per patient ranged from 1 to 4 (mean, 1.9). Histologic examination confirmed the metastatic involvement of the sentinel lymph node in 11 of 30 patients. The sentinel lymph node-positive rate was 22.4%, which was comparable to findings using Tc-99m-labeled nanocolloids. CONCLUSION: The findings indicate that Tc-99m-bound colloidal rhenium sulfide is suitable for sentinel node mapping.