Coloured radionuclide or gamma scan of a normal liver (triangularshaped red and blue). Radionuclide scanning is a diagnostic technique based on the detection of radiation emitted by radioactive substances introduced into the body. The images provided reflect the functioning of an organ better than other techniques, although they provide less anatomical detail. The liver is the largest internal organ and regulates the levels of most of the main chemicals in blood. It produces important proteins for blood plasma, regulates the blood level of amino acids and, along with the kidneys, clears the blood of drugs and other poisonous substances.