Egg labeling methods for gastric emptying scintigraphy are not equivalent in producing a stable solid meal

A wide range of radiolabeled test meals have been used for gastric emptying scintigraphy. The purpose of this study was to test whether Tc-99m-sulfur colloid-labeled liquid egg white is as stable as 2 fresh whole eggs labeled with Tc-99m-sulfur colloid and whether the cooking method is important. Methods: Whole eggs and liquid egg white were mixed with Tc-99m-sulfur colloid and cooked by either microwaving or frying on a griddle. The cooked eggs were tested for breakdown after 2 and 4 h of incubation in gastric fluid or HCl. Results: Labeled liquid egg white, prepared by either method of cooking, exhibited less breakdown in gastric fluid than whole eggs. Whole eggs cooked in the microwave exhibited significantly more breakdown than liquid egg white. Conclusion: Tc-99m-Sulfur colloid binds better to egg whites compared with whole eggs. These results emphasize the need to evaluate the stability of new radiolabeled test meal preparations, including the method of cooking.