Technetium is a chemical element with the symbol Tc and atomic number 43. It is the lightest element whose isotopes are all radioactive. All available technetium is produced as a synthetic element. Naturally occurring technetium is a spontaneous fission product in uranium ore and thorium ore, the most common source, or the product of neutron capture in molybdenum ores. This silvery gray, crystalline transition metal lies between manganese and rhenium in group 7 of the periodic table, and its chemical properties are intermediate between those of both adjacent elements. The most common naturally occurring isotope is 99Tc, in traces only.
Nuclear medicine or nucleology is a medical specialty involving the application of radioactive substances in the diagnosis and treatment of disease. Nuclear imaging, in a sense, is "radiology done inside out" because it records radiation emitting from within the body rather than radiation that is generated by external sources like X-rays. In addition, nuclear medicine scans differ from radiology, as the emphasis is not on imaging anatomy, but on the function. For such reason, it is called a physiological imaging modality. Single photon emission computed tomography (SPECT) and positron emission tomography (PET) scans are the two most common imaging modalities in nuclear medicine.
A radioactive tracer, radiotracer, or radioactive label is a chemical compound in which one or more atoms have been replaced by a radionuclide so by virtue of its radioactive decay it can be used to explore the mechanism of chemical reactions by tracing the path that the radioisotope follows from reactants to products. Radiolabeling or radiotracing is thus the radioactive form of isotopic labeling. In biological contexts, use of radioisotope tracers are sometimes called radioisotope feeding experiments.
Scintigraphy, also known as a gamma scan, is a diagnostic test in nuclear medicine, where radioisotopes attached to drugs that travel to a specific organ or tissue (radiopharmaceuticals) are taken internally and the emitted gamma radiation is captured by external detectors to form two-dimensional images in a similar process to the capture of x-ray images. In contrast, SPECT and positron emission tomography (PET) form 3-dimensional images and are therefore classified as separate techniques from scintigraphy, although they also use gamma cameras to detect internal radiation. Scintigraphy is unlike a diagnostic X-ray where external radiation is passed through the body to form an image.
A technetium-99m generator, or colloquially a technetium cow or moly cow, is a device used to extract the metastable isotope 99mTc of technetium from a decaying sample of molybdenum-99. 99Mo has a half-life of 66 hours and can be easily transported over long distances to hospitals where its decay product technetium-99m is extracted and used for a variety of nuclear medicine diagnostic procedures, where its short half-life is very useful.
The pertechnetate ion is an oxyanion with the chemical formula TcO−
4. It is often used as a convenient water-soluble source of isotopes of the radioactive element technetium (Tc). In particular it is used to carry the 99mTc isotope which is commonly used in nuclear medicine in several nuclear scanning procedures.
A bone scan or bone scintigraphy is a nuclear medicine imaging technique of the bone. It can help diagnose a number of bone conditions, including cancer of the bone or metastasis, location of bone inflammation and fractures, and bone infection (osteomyelitis).
Sodium pertechnetate is the inorganic compound with the formula NaTcO4. This colourless salt contains the pertechnetate anion, TcO−
4. The radioactive 99m
Tc
O−
4 anion is an important radiopharmaceutical for diagnostic use. The advantages to 99m
Tc
include its short half-life of 6 hours and the low radiation exposure to the patient, which allow a patient to be injected with activities of more than 30 millicuries. Na[99m
Tc
O
4] is a precursor to a variety of derivatives that are used to image different parts of the body.
Technetium compounds are chemical compounds containing the chemical element technetium. Technetium can form multiple oxidation states, but often forms in the +4 and +7 oxidation states. Because technetium is radioactive, technetium compounds are extremely rare on Earth.
Technetium (99mTc) sulesomab is a radio-pharmaceutical composed of anti-human mouse monoclonal antibody that targets the granulocyte associated NCA-90 cell antigen and a conjugated technetium-99m radionuclide. After intravenous administration, Leukoscan enables sensitive and specific whole body measurement of granulocyte infiltration and activation by gamma camera imaging of 99mTc-antibody bound cells. Total clearance of LeukoScan from blood samples after administration and imaging has been reported at 48 hour time points indicating limited retention of the agent in circulation
Technetium-99m (99mTc) is a metastable nuclear isomer of technetium-99, symbolized as 99mTc, that is used in tens of millions of medical diagnostic procedures annually, making it the most commonly used medical radioisotope in the world.
Technetium (99mTc) arcitumomab is a drug used for the diagnostic imaging of colorectal cancers, marketed by Immunomedics. It consists of the Fab' fragment of a monoclonal antibody and a radionuclide, technetium-99m.
Technetium (99mTc) nofetumomab merpentan is a mouse monoclonal antibody derivative used in the diagnosis of lung cancer, gastrointestinal, breast, ovary, pancreas, kidney, cervix, and bladder carcinoma. The antibody part, nofetumomab, is attached to the chelator merpentan, which links it to the radioisotope technetium-99m (99mTc).
Technetium 99mTc albumin aggregated (99mTc-MAA) is an injectable radiopharmaceutical used in nuclear medicine. It consists of a sterile aqueous suspension of Technetium-99m (99mTc) labeled to human albumin aggregate particles. It is commonly used for lung perfusion scanning. It is also less commonly used to visualise a peritoneovenous shunt and for isotope venography.
An octreotide scan is a type of SPECT scintigraphy used to find carcinoid, pancreatic neuroendocrine tumors, and to localize sarcoidosis. It is also called somatostatin receptor scintigraphy (SRS). Octreotide, a drug similar to somatostatin, is radiolabeled with indium-111, and is injected into a vein and travels through the bloodstream. The radioactive octreotide attaches to tumor cells that have receptors for somatostatin. A gamma camera detects the radioactive octreotide, and makes pictures showing where the tumor cells are in the body, typically by a SPECT technique. A technetium-99m based radiopharmaceutical kit is also available.
Medronic acid, also known as methylene diphosphonate, is the smallest bisphosphonate. Its complex with radioactive technetium, 99mTc medronic acid, is used in nuclear medicine to detect bone abnormalities, including metastases.
A germanium-68/gallium-68 generator is a device used to extract the positron-emitting isotope 68Ga of gallium from a source of decaying germanium-68. The parent isotope 68Ge has a half-life of 271 days and can be easily utilized for in-hospital production of generator produced 68Ga. Its decay product gallium-68 is extracted and used for certain positron emission tomography nuclear medicine diagnostic procedures, where the radioisotope's relatively short half-life and emission of positrons for creation of 3-dimensional PET scans, are useful.
Technetium (99mTc) mebrofenin is a diagnostic radiopharmaceutical used for imaging of the liver and the gallbladder. Under the brand name Choletec it is available from Bracco Diagnostic. Supplied as a sterile kit of mebrofenin and dehydrated stannous fluoride. The vial is reconstituted with 1 to 5 mL up to 3.7 gigabecquerels (100 mCi) of sodium pertechnetate solution to form the final radio labeled 99mTc mebrofenin.
A DPD scan is a type of nuclear medicine imaging test which uses radioactive technetium-99m (99mTc) and 3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) to diagnose cardiac amyloidosis. The radiopharmaceutical is taken up only in patients with ATTR amyloidosis, making it a useful tool to differentiate from AL amyloidosis.
Organotechnetium chemistry is the science of describing the physical properties, synthesis, and reactions of organotechnetium compounds, which are organometallic compounds containing carbon-to-technetium chemical bonds. The most common organotechnetium compounds are coordination complexes used as radiopharmaceutical imaging agents.
