A gastric emptying scan is an imaging test. It measures how quickly food travels from the stomach into the small bowel (intestine). During the test, you're given a meal to eat that contains a small amount of radioactive substance (tracer). Then scans of the stomach are done. The tracer shows up clearly on the scans and tracks the food's movement through your stomach. This test is most often needed if you have symptoms that suggest a motility problem. Motility refers to the movement of the muscles in the digestive tract. The test takes about 4 hours.