sentinel node detection failure due to defective labeling and large particle size of tc-99m antimony sulfide colloid

introduction: many radiotracers have been used for sentinel node mapping with acceptable results. the main difference between these radiotracers is the particle size. in the current study, we reported defective labeling of tc-99m antimony sulfide colloid which resulted in large particle size. methods: tc-99m-antimony sulfide colloid was used for axillary sentinel node mapping of 45 breast cancer patients. the prepared kits were turbid and were used for the first 15 patients. for the remaining 30 patients, we used a filter (gyrodisc ca-pc cellulose acetate membrane; 30 mm; pore size: 0.2 µm) after labeling to remove the possible large particles of the prepared kits. results: on the lymphoscintigraphy images, at least one sentinel node could be identified in 5 and 29 patients of the unfiltered and filtered groups respectively (p=0.00001). sentinel node detection by gamma probe was successful in 5 and 30 patients in the unfiltered and filtered groups respectively (p=0.000001). conclusion: tc-99-antimopny sulfide colloid is a suitable radiotracer for sentinel node mapping of the breast cancer patients. in case of any unusual turbidity of the labeled kit, it should not be used or at least be filtered before injection.