Nuclear Pharmacy

Objective: The purpose of this study was to retrospectively evaluate microwave heating preparations of "'Tc-sulfur colloid during a 4-wk period. Methods: The mTc-SC kit preparation was performed according to the package insert with microwave heating modifications. Results: During the first 2 wk, patient studies (n = 14) showed excellent images, however during the last 2 wk patient studies (n = 18) demonstrated lung uptake with clumping (n = 16). The average radiochemical purity of the microwaved "'Tc-SC preparations for the first and second 2-wk periods were 98.9% ± 0.9% (n = 9) and 99.3% ± 0.4% (n = 9), respectively. Eight of 18 microwaved 99"'Tc-SC kits were used in 16 patient studies which showed lung uptake. The 99m"fc radioactivity of the prepared "'Tc-SC ranged from 51-241 mCi for the first 2 wk, and 62-242 mCi during the last 2 wk. There is no particular day of the week associated with the use of "'Tc eluates. The preparation and injection of the microwaved "'Tc-SC were all randomly performed by different nuclear medicine technologists. When comparing lot numbers of the cold kits, two kits came from one lot number, whereas 16 kits from another lot number. Conclusions: Our findings showed the microwave heating method may not be an optimal method to prepare 99m"fc-SC, although the reason for the lung uptake is not clear.