However, the indium leukocyte scan will image only the 25% of such cases which are caused by acute infections, while gallium will also localize to other sources of fever, such as chronic infections and tumors. Both the gallium scan and indium leukocyte imaging may be used to image fever of unknown origin (elevated temperature without an explanation). Indium leukocyte imaging is better for acute infections (where neutrophils are still rapidly and actively localizing to the infection), and also for osteomyelitis that does not involve the spine, and for abdominal and pelvic infections. In part this is because gallium binds to neutrophil membranes, even after neutrophil death. In infections, the gallium scan has an advantage over indium leukocyte imaging in imaging osteomyelitis (bone infection) of the spine, lung infections and inflammation, and for chronic infections. For detection of tumors, especially lymphomas, gallium imaging is still in use, but may be replaced by fludeoxyglucose PET imaging in the future. It has been suggested that gallium imaging may become an obsolete technique, with indium leukocyte imaging and technetium antigranulocyte antibodies replacing it as a detection mechanism for infections. Thus, an increased uptake of gallium-67 may indicate a new or old infection, an inflammatory focus from any cause, or a cancerous tumor. Gallium imaging is still used to image inflammation and chronic infections, and it still sometimes locates unsuspected tumors as it is taken up by many kinds of cancer cells in amounts that exceed those of normal tissues. In the past, the gallium scan was the gold standard for lymphoma staging, until it was replaced by positron emission tomography (PET) using fludeoxyglucose (FDG). Gallium citrate scan Gallium scan showing panda (A) and lambda (B) patterns, considered specific for sarcoidosis in the absence of histological confirmation Such scans are useful in locating neuroendocrine tumors and pancreatic cancer. The gallium-68 is bound to an octreotide derivative chemical such as DOTATOC and the positrons it emits are imaged by PET-CT scan. Gallium-68 DOTA scans are increasingly replacing octreotide scans (a type of indium-111 scan using octreotide as a somatostatin receptor ligand). Gallium is particularly useful in imaging osteomyelitis that involves the spine, and in imaging older and chronic infections that may be the cause of a fever of unknown origin. Gallium salts are taken up by tumors, inflammation, and both acute and chronic infection, allowing these pathological processes to be imaged. The gamma emission of gallium-67 is imaged by a gamma camera, while the positron emission of gallium-68 is imaged by positron emission tomography (PET). Gallium can also be used in other forms, for example 68Ga-PSMA is used for cancer imaging. Both 67Ga and 68Ga salts have similar uptake mechanisms. The form of salt is not important, since it is the freely dissolved gallium ion Ga 3+ which is active. Gallium salts like gallium citrate and gallium nitrate may be used. Nuclear medicine test that uses gallium to obtain images of tissues Gallium-67 scanĪ gallium scan is a type of nuclear medicine test that uses either a gallium-67 ( 67Ga) or gallium-68 ( 68Ga) radiopharmaceutical to obtain images of a specific type of tissue, or disease state of tissue.
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