TY - JOUR T1 - Gastric Emptying Scintigraphy Egg Radiolabeling Efficiency Pre- and Post-Microwave Cooking JF - Journal of Nuclear Medicine Technology JO - J. Nucl. Med. Technol. DO - 10.2967/jnmt.118.225177 SP - jnmt.118.225177 AU - Jena-Lee D McKee AU - Mary Beth Farrell AU - Kathy T Hunt AU - Vivian Loveless AU - Charity Brannen Y1 - 2019/04/01 UR - http://tech.snmjournals.org/content/early/2019/04/19/jnmt.118.225177.abstract N2 - Introduction: The accuracy and reproducibility of nuclear medicine gastric emptying scintigraphy (GES) require strict adherence to the Society of Nuclear Medicine and Molecular Imaging (SNMMI) standardized protocol. The SNMMI standardized GES protocol contains precise instructions for meal ingredients and preparation. Previous research demonstrated many laboratories were using whole eggs in the test meal as opposed to the guideline-recommended liquid egg white and some laboratories attempted to radiolabel the egg by adding the radiotracer after cooking. This study aimed to document the labeling efficiency of 99mTc-sulfur colloid (SC) added to whole eggs before and after microwave cooking. Methods: Whole eggs were mixed with 99mTc-SC before and after microwave cooking. The radiolabeling stability of the eggs was tested after 2 and 4 hours of incubation in hydrochloric acid (HCl) and simulated gastric fluid with HCl and pepsin. Results: The experiment showed that no matter what the testing condition, radiolabeling by adding 99mTc-SC to whole eggs before microwave cooking resulted in a significantly higher labeling efficiency than radiolabeling when the 99mTc-SC was squirted on eggs after microwave cooking. This finding persisted over time with the pre-cooking radiolabeling method still significantly higher at 2 and 4 hours after the egg was placed for both gastric fluid mediums. Simulated gastric fluid with pepsin at 2 hours, the labeling was significantly higher at 73.3% when the radiotracer was added before microwaving and 43.3% when added after cooking (p<.001). The results of this study further showed that when egg labeling efficiency testing was performed in HCl without pepsin, the labeling was less stable as compared to testing performed in a simulated gastric fluid with HCl and pepsin. In the HCl only medium, the labeling efficiency decreased significantly between 2 and 4 hours for both radiolabeling methods. Conclusion: The results of this study demonstrated the addition of 99mTc-SC to whole eggs after cooking resulted in considerably inferior binding of the radiotracer to the eggs which deteriorated significantly over time. The study further demonstrated that radiolabeling efficiency results vary depending on whether HCl or HCl with pepsin was used to simulate gastric fluid. Radiolabeling stability decreased over time when HCl without pepsin was used. The findings emphasize the criticality of adhering to the standardized meal and preparation as alternate cooking methods have different radiolabeling efficiencies. ER -