Abstract
Objective: The purpose of this study was to retrospectively evaluate microwave heating preparations of 99mTc-sulfur colloid during a 4-wk period.
Methods: The 99mTc-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 99mTc-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 99mTc-SC kits were used in 16 patient studies which showed lung uptake. The 99mTc radioactivity of the prepared 99mTc-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 99mTc eluates. The preparation and injection of the microwaved 99mTc-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 99mTc-SC, although the reason for the lung uptake is not clear.