Radionuclide imaging is a type of imaging technique that allows physicians to obtain clear images of various parts of the body, including digestive system organs. To obtain the images generated by this technique, tiny amounts of radioactive materials (called “tracers”) are introduced into the patient’s body. The tracers emit a type of energy called gamma rays, which are detected by special devices.

The amount of radiation received during radionuclide imaging is generally considered minimal and safe. For most people, the tracer used in the procedure is harmless and is flushed from the body via urination after the test. Patients are often encouraged to drink plenty of fluids and urinate frequently to help flush the tracer from the body.

Radionuclide imaging can be used to help diagnose various disorders of the digestive system. These include:

• Gallbladder disorders. A cholescintigraphy – also known as a HIDA scan – may reveal acute or chronic gallbladder inflammation and obstruction of the bile ducts.
  
  
• Gastrointestinal bleeding. A radioactive material is injected into a patient to help highlight organs and reveal abnormalities that might be a sign of gastrointestinal (GI) bleeding, particularly in the lower GI tract.
  
  
• Gastroparesis. A gastric emptying study helps the physician examine the rate of emptying from the stomach. Scintigraphic gastric emptying is a different test that allows the physician to observe whether or not poor relaxation of the stomach causes delayed stomach emptying. 

Radionuclide imaging can also be used to detect the source of unexplained pain and a number of conditions and diseases affecting the skeletal system, including bone fractures, arthritis (inflammation of the joints), infections, tumors and others.

Radionuclide imaging is not recommended for certain types of patients, including pregnant or nursing women. Patients should inform their physician of any medications they are taking and any recent testing using a contrast medium (dye) that has been injected or taken orally or rectally. Patients will receive the radioactive material either orally or by injection into a vein anywhere from a few minutes to several days before the test.

Radionuclide imaging is typically performed on an outpatient basis. However, the equipment necessary to perform the test usually requires it to take place in a hospital’s radiology or nuclear medicine department.

During the test, patients are asked to lie on a table (gantry) while a scanner moves over them. Although the test is not generally painful, some patients may become uncomfortable after lying on the table for a long period.

There are no restrictions on daily routine following the test. However, it is recommended that patients drink plenty of fluids to flush the tracer from the body. The radioactive materials in the body release their energy and decay into non-radioactive atoms within a few hours to a few days. Test results are usually available within a few days of the scan and additional tests or appropriate treatment will follow, if necessary.