A gallbladder scan is a specialized radiology procedure used to assess the function and structure of the gallbladder. This procedure may also be referred to as a liver-biliary scan because the liver often is examined as well due to its proximity and close functional relationship to the gallbladder.
A gallbladder scan is a type of nuclear radiology procedure. This means that a tiny amount of a radioactive substance is used during the procedure to assist in the examination of the gallbladder. The radioactive substance, called a radionuclide (radiopharmaceutical or radioactive tracer), is absorbed by normal gallbladder tissue.
The radionuclide used in gallbladder scans is usually a form of technetium. Once absorbed into the gallbladder tissue, the radionuclide emits a type of radiation, called gamma radiation. The gamma radiation is detected by a scanner, which processes the information into a picture of the gallbladder.
By measuring the behavior of the radionuclide in the body during a nuclear scan, the doctor can assess and diagnose various conditions, such as obstruction of bile ducts from gallstones, tumors, abscesses, hematomas, organ enlargement, or cysts. A nuclear scan may also be used to assess organ function.
The areas where the radionuclide collects in greater amounts are called "hot spots." The areas that do not absorb the radionuclide and appear less bright on the scan image are referred to as "cold spots."
Gallbladder disease may be caused by infection or by a blockage within the gallbladder or the ducts of the liver/gallbladder system (the biliary tree). If the gallbladder is infected or obstructed, the radionuclide cannot pass into the gallbladder. If there is a blockage within the biliary tree, passage of the radionuclide will stop at the point of the obstruction.