Radiology and Imaging Tests for Colorectal Disease
Your doctor may want to use one, or a combination of, any of the following diagnostic imaging and radiology tests to determine if your symptoms are due to colorectal disease:
Colorectal transit study: This test shows how well food moves through the colon. The patient swallows capsules containing small markers which are visible on X-ray. The movement of the markers through the colon is monitored with abdominal X-rays taken.
Computed tomography scan (CT or CAT scan): This diagnostic imaging procedure uses a combination of X-rays and computer technology to produce horizontal, or axial, images (often called slices) of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general X-rays.
One version of the CT scan, known as “virtual colonoscopy,” involves the use of computed tomography and can produce a three dimensional view of the colon. The technology involves some radiation though the physicians have designed ways to reduce exposure. The same rules for preparing the colon apply in this procedure as with a normal colonoscopy or a barium enema.
Lower GI (gastrointestinal) series (also called barium enema): A lower GI series is a procedure that examines the rectum, the large intestine, and the lower part of the small intestine. Barium is given into the rectum as an enema. An X-ray of the abdomen shows strictures (narrowed areas), obstructions (blockages), and other problems.
Upper GI (gastrointestinal) series: Upper GI series is a diagnostic test that examines the organs of the upper part of the digestive system: the esophagus, stomach, and duodenum (the first section of the small intestine). Barium is swallowed and X-rays are then taken to evaluate the digestive organs.
Magnetic resonance enterography (MRE): MRE is a diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body. The patient lies on a bed that moves into the cylindrical MRI machine. The machine takes a series of pictures of the inside of the body using a magnetic field and radio waves. The computer enhances the pictures produced.
One of the newest technologies used for viewing the abdomen, MR enterography uses a large magnet and computers to create images of the intestines and surrounding structures instead of radiation.
Radioisotope gastric-emptying scan: During this test, the patient eats food containing a radioisotope, which is a slightly radioactive substance that will show up on a scan. The dosage of radiation from the radioisotope is very small and not harmful, but allows the radiologist to see the food in the stomach and how quickly it leaves the stomach, while the patient lies under a machine. This procedure is only available at Beaumont Hospital, Troy.
Ultrasound: Ultrasound is a diagnostic imaging technique that uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels. Gel is applied to the area of the body being studied, such as the abdomen, and a wand called a transducer is placed on the skin. The transducer sends sound waves into the body that bounce off organs and return to the ultrasound machine, producing an image on the monitor. A picture or videotape of the test is also made so it can be reviewed in the future.
Magnetic resonance cholangiopancreatography (MRCP): This test uses magnetic resonance imaging (MRI) to obtain pictures of the bile ducts. The machine uses radio waves and magnets to scan internal organs and tissues.