The Efficacy of Radiolabeling the Albumin in Egg Whites with 99m Tc-Sulfur Colloid.

In 2009, the Society of Nuclear Medicine and Molecular Imaging published a standardized protocol guideline for gastric emptying scintigraphy that contains specific instructions on the exact meal and preparation procedure. Previous research has shown that the standardized meal and proper preparation of the meal for gastric emptying scintigraphy are not being adopted by some facilities. This research explores the differences of radiolabeling in the method of preparation of 99m Tc-sulfur colloid (SC)-radiolabeled eggs. Methods: Liquid egg whites were mixed with 99m Tc-SC before cooking in conjunction with the standardized protocol. A second sample set was prepared by adding the 99m Tc-SC to eggs after they were cooked. Each sample set was placed in a solution of HCl and pepsin to simulate gestation. Radiolabeling efficacy was tested on each sample set at 2 and 4 h after gestating in HCl and pepsin. Results: 99m Tc-SC added to the liquid egg whites before microwave cooking yielded radiolabeling efficacy of 70% 99m Tc-SC after 2 and 4 h of simulated gastric fluid gestation. In contrast, radiolabeling after cooking the egg whites yielded 50% radiolabeling after simulated gestation. Conclusion: The results from this experiment showed that the method of mixing the 99m Tc-SC with liquid egg whites before microwave cooking has higher binding efficacy than when adding 99m Tc-SC onto already cooked egg whites. These results highlight the importance of following the standardized protocol for the meal preparation of a gastric emptying study.