Chronic delayed gastric emptying (gastroparesis) is most often caused by an intrinsic disturbance in gastric or upper gastrointestinal motility. It may be associated with other systemic diseases (e.g. diabetes) or may be due to a primary dysfunction of the stomach. The typical symptoms of delayed gastric emptying include early satiety, nausea, and vomiting.

The imaging study of choice is the solid gastric emptying study. Most nuclear medicine laboratories use radiolabeled egg sandwich which is readily available, easy to prepare, and firmly labeled with radiotracer when prepared.

In our clinic, two eggs are mixed with 1.0 mCi of Tc-99m-sulfur colloid. The mixture is then cooked until firm in a Teflon-coated pan and is given to the patient to eat with two slices of white bread as an egg sandwich. Ingestion of the meal should be completed within 10 minutes which is followed by acquisition of anterior and posterior images of the left upper quadrant of the abdomen every 15 minutes up to 90 minutes. These images are used to assess the gastric emptying visually.

Normally, the radiolabeled meal moves progressively from the proximal to the distal stomach, and then it empties steadily in a linear fashion into the small bowel following a brief period of lagging due to trituration of food at the antral part of stomach.

The quantitative analysis of the gastric emptying is done as the following:

First, the region of interest is drawn around the stomach in each anterior and posterior image and secondly, corrected for radioisotope decay. Finally, the geometric mean method, which is a square root of the product of decay corrected counts in anterior and posterior stomach, is utilized to calculate the gastric emptying.

The radiolabeled meal retained at time zero is considered 100%, and then subsequently the gastric retained at each time interval is calculated based on the counts retained in the stomach at each time interval divided by the counts at time zero.

The patient's percentage of radiolabeled meal retained at 90 minutes was 81% which is markedly delayed in emptying (normal is less than 50% retained at 90 minutes).