To identify gastrointestinal stromal tumors (GISTs), Mayo Clinic doctors perform a comprehensive physical exam. This exam may include imaging studies of the tumor, blood tests, endoscopy and biopsies.
Imaging studies may include:
- X-rays. X-rays generate one-dimensional images of the body that help your doctor locate internal abnormalities.
- CT scans. CT scans generate detailed cross-sectional images of your body that may show the location and size of your tumor and whether it has spread to other tissues or organs.
- MRI scans. MRI scans use magnetic fields and radio waves to make 3-D images that can reveal abnormalities. Doctors also use MRI scans to determine whether your tumor has spread.
- Positron emission tomography (PET). PET is a noninvasive technique that creates 3-D images of your organs.
- Upper endoscopy. During upper endoscopy, a gastroenterologist or surgeon looks into your esophagus, stomach and small intestine using a thin lighted tube with a small video camera at the tip. Small samples of tissue (biopsies) may be taken if an abnormality is found. A biopsy may not identify GISTs that lie beneath the lining of the gastrointestinal tract, and other tests may be needed.
- Endoscopic ultrasound. During this procedure, an endoscope with an ultrasound probe at the end is passed down your throat and into your stomach and, if necessary, into the upper part of your small intestine. The probe emits high-frequency sound waves that generate images of the inside of your stomach and intestine. This may help reveal a tumor not evident with upper endoscopy alone.
Your Mayo Clinic doctors also may sample and analyze tumor cells (biopsy) to confirm the diagnosis and determine the stage of your tumor. Staining your tissue sample with a special dye can show the presence of an abnormality that appears in almost all GISTs.