Macaroni & cheese as an alternative meal for gastric emptying procedures

Purpose: Many nuclear medicine departments use oatmeal as an alternative to eggs for gastric emptying (GE) studies, however it has been suggested that oatmeal does not truly represent a solid-based meal. One type of food that may better represent a solid-based meal is macaroni & cheese. Published literature has shown that the binding ability of 99mTc-sulfur colloid to melted cheddar cheese is very similar to that provided by eggs. The purpose of this study is to determine if a macaroni & cheese meal will provide gastric emptying rates comparable to our current standardized egg-based meal.

Methods: Seven healthy participants from various age groups and genders with normal gastric function, determined by a physician approved questionnaire, each underwent GE procedures utilizing two different meal protocols. Meal 1 consisted of two beaten eggs mixed with 1 mCi of 99mTc-sulfur colloid cooked in a skillet and served with 2 slices of buttered bread and 300 mL of water. For Meal 2, a bowl containing two slices of cheddar cheese and 1 mCi of 99mTc-sulfur colloid was heated in a microwave for 15 seconds. The prepared macaroni & cheese (Kraft Easy Mac Original) was mixed with the cheddar cheese and served to the patient with 300 mL of water. Patients were instructed to consume each meal within 10 minutes. Images of the digestive tract were taken at 0, 30, 60, 90, 120, 180, and 240 minutes after ingestion of each meal. Regions of interest were drawn around the stomach on each anterior image and emptying percentages at each time frame were determined using the geometric mean.

Results: The average emptying percentage at each time frame for the macaroni & cheese and egg meals were compared and a T-test revealed that the meals were not significantly different (p = 0.0005). Additionally, these emptying percentages are within the normal limits established by the SNMMI, which were converted from gastric retention to gastric emptying values. Conclusion: The T-test revealed that the average emptying percentages between the two types of meals was not significantly different and fell within the normal limits specified by the SNMMI. Therefore, a meal of cheddar cheese mixed with macaroni & cheese could be considered a feasible alternative for patients undergoing a GE study for whom eggs are contraindicated. There does appear, however, to be a variation among the individual patient emptying percentages at each time point between the two meals. These differences could be due to the small number of participants in the study, meal composition, and/or the binding ability of 99mTc-sulfur colloid to cheddar cheese versus eggs. Since this study is ongoing, we intend to provide more definitive results in the near future.