Lymphoscintigraphic sentinel node imaging and gamma probe defection in breast cancer with Tc-99m nanocolloidal albumin - Results of an optimized protocol

Purpose: The purpose of this study was to aid in the standardization of lym phoscintigraphy for detecting the sentinel node (SN) in breast cancer using Tc-99m-labeled nanocolloidal albumin. Materials and Methods: One hundred twenty-three women with proved breast ca ncer were enrolled. Four injections of 10 to 15 MBq (0.27 to 0.41 mCi) Tc-9 9m nanocolloid in 0.1 mi physiologic saline were administered intra- and su bdermally at the margin of the skin overlying the tumor. Planar scintigraph ic images in the lateral and anterior projections were obtained 2.5 to 18 h ours after tracer administration. With a gamma probe used as a guide, all r adioactive lymph nodes in the axilla were resected, Complete dissection the n followed. Results: In 116 of the 123 (94%) women, axillary nodal tracer uptake was re vealed. Six of the 7 women in whom detection failure occurred had histologi cally proved tumor infiltration of the lymphatics and axillary involvement. In 36 (31%) of the patients with visualized lymph nodes, the SN was metast atic. The remaining 80 patients with negative SN included three cases with axillary involvement. The sensitivity of the SN with respect to the histolo gic status of the entire axilla thus was 92.3%, and the negative predictive value was 96.3%. The overall accuracy of the method was 97.4%. The number of hot nodes in women with and without axillary involvement was significant ly different. Conclusions: The described protocol represents an easily reproduced and rel iable method for SN detection in breast cancer. Furthermore, the number of visualized axillary nodes reflects the histologic status of the axilla.