How does a gastric emptying study work?
A gastric emptying study involves the ingestion of a standardized meal consisting of some food source that is tagged with a radioactive label. The most common meal utilized for the study consists of egg whites tagged with 99m Tc sulfur colloid. Meals must be standardized for content and calories so that adequate comparisons can be made. Imaging is usually performed over 90 to 180 minutes. Images may be obtained throughout that time period or at regular intervals, usually with either anterior and posterior projections or with a single left anterior oblique projection. The importance of these views is that food enters the stomach posteriorly and moves anteriorly. Images must take into account movement of ingested material within the stomach and differentiate it from actual emptying.