Radionuclide imaging is a visual scanning technique that uses radioactive materials called tracers (radionuclides) to reveal images of internal organs, including those in the digestive tract. These tracers accumulate in certain organs and tissues and emit gamma rays, which are detected by a special camera. A computer then converts this information into clear two- and three-dimensional images of the body. In some cases, extra color is added to enhance clarity of the images.

Analysis of radionuclide images helps physicians diagnose disease. The images are usually analyzed by radiologists (physicians who specialize in the use of radiant energy for diagnostic purposes) or other nuclear medicine expert. The information is then sent to the patient’s physician, and a treatment plan is formulated.

Radionuclide imaging can help diagnose several disorders of the digestive system. For example, these scans can be used to detect abnormalities in the body’s ability to digest food or to reveal damage to organs that may be the source of gastrointestinal bleeding. These tests also are effective at revealing tumors in the digestive tract.

Other conditions detected by radionuclide imaging include:

• Abnormalities in size, shape or position of organs
  
  
• Cancer, both in its site of origin and cancer that has spread to other areas
  
  
• Coronary and vascular problems
  
  
• Thyroid disorders
  
  
• Neurological disorders
  
  
• Blood clots (embolism)
  
  
• Lung, kidney or bladder malfunction
  
  
• Sites of seizures (epilepsy) in the brain
  
  
• Parkinson’s disease (a brain disorder characterized by shaking and difficulty with walking, movement and coordination)
  
  
• Alzheimer’s disease (a degenerative brain disease affecting memory, thought and behavior)

Additionally, radionuclide imaging allows physicians to determine how well newly transplanted organs are functioning. For example, a test known as a cholescintigraphy can help determine whether there is rejection of a transplanted liver.

Radionuclide imaging is often described as being the opposite of an x-ray – instead of radioactive material being directed into the body from the outside, the radioactivity comes from the inside and is projected outward. Although some patients worry about the potentially harmful effects of radioactivity, dosage levels are so low that the risk is minimal for most patients.