The Gastric Emptying Scan (GEC) measures how well the stomach performs its muscular function, a process known as motility. This procedure determines the rate at which food moves from the stomach into the small intestine. While the GEC is highly effective for diagnosing disorders of stomach movement, it is not a dedicated tool for identifying cancer. The scan measures function, but a physical mass might indirectly influence the results.
Understanding the Gastric Emptying Scan
The Gastric Emptying Scan is a nuclear medicine test that provides a quantitative assessment of gastric motility. The process involves the patient eating a standardized meal, such as scrambled eggs, which contains a small, tasteless amount of a radioactive tracer. A specialized device called a gamma camera is positioned over the abdomen to take images at set time intervals, typically over four hours. By measuring the amount of radioactivity remaining in the stomach, technicians calculate the percentage of the meal that has exited. This procedure fundamentally analyzes the function of the stomach muscles, providing a detailed rate of emptying, rather than visualizing the structure of the stomach wall.
Primary Conditions Diagnosed by the Scan
The primary purpose of the GEC is to diagnose specific disorders related to the speed of stomach emptying. The most common condition identified is gastroparesis, or delayed gastric emptying, which occurs when the stomach muscles do not contract effectively. This muscular failure means food is retained in the stomach for too long, leading to symptoms like nausea, vomiting, bloating, and a feeling of fullness. Gastroparesis is frequently associated with long-term conditions like diabetes, which can cause nerve damage. The scan is also used to diagnose dumping syndrome, characterized by rapid gastric emptying, often seen after certain types of stomach surgery.
How Cancer Can Affect Gastric Emptying Results
A Gastric Emptying Scan cannot directly visualize or diagnose a cancerous tumor. The test tracks a radioactive meal, not the physical structure of the stomach lining or surrounding organs. However, a tumor can indirectly cause an abnormal GEC result by creating a mechanical blockage. A mass located near the pylorus—the muscular valve that controls food flow—can physically obstruct the exit pathway, resulting in delayed gastric emptying. An abnormal GEC result simply indicates that the stomach is emptying too slowly, which could be due to gastroparesis or a physical cause like a tumor. If the scan shows significant delay, a physician must order anatomical imaging tests to determine if the cause is functional or obstructive.
Dedicated Diagnostic Tools for Gastric Cancer
When a physical obstruction or cancer is suspected, dedicated anatomical imaging and diagnostic tools are required, as the GEC is not appropriate for this purpose. The definitive method for diagnosing gastric cancer is an upper endoscopy, also known as esophagogastroduodenoscopy (EGD). During an EGD, a thin, flexible tube equipped with a light and camera is passed down the throat to visually inspect the lining of the esophagus, stomach, and the first part of the small intestine. If the endoscopist observes any suspicious areas, they can perform a biopsy. A biopsy involves taking a small tissue sample, which is then examined under a microscope by a pathologist; this cellular analysis is the only way to definitively confirm the presence of cancer. Imaging tests like Computed Tomography (CT) scans or Positron Emission Tomography (PET) scans are also used, primarily for staging the cancer, which means determining its size and whether it has spread to other parts of the body.