Mapping of Lymphatic Drainage from the Prostate Using Filtered 99mTc-Sulfur Nanocolloid and SPECT/CT

We have developed a practice procedure for prostate lympho-scintigraphy using SPECT/CT and filtered 99mTc-sulfur nanocol-loid, as an alternative to the proprietary product 99mTc-Nanocoll, which is not approved in the United States. Methods: Ten patients were enrolled for this study, and all received radiotracer prepared using a 100-nm membrane filter at a commercial ra-diopharmacy. Whole-body scans and SPECT/CT studies were performed within 1.5–3 h after the radiotracer had been ad-ministered directly into 6 locations of the prostate gland under transrectal ultrasound guidance. The radiation dose was esti-mated from the first 3 patients. Lymphatic drainage mapping was performed, and lymph nodes were identified. Results: The estimated radiation dose ranged from 3.9 to 5.2 mSv/MBq. The locations of lymph nodes draining the prostate gland were similar to those foundusing theproprietary product.Conclusion: When the proprietary radiolabeled nanocolloid indicated for lym-phoscintigraphy is not available, prostate lymph node mapping and identification are still feasible using filtered 99mTc-sulfur nanocolloid. Key Words: prostate cancer; sulfur colloid; SPECT/CT; lymphatic mapping; sentinel nod