Pertechnetate

The structure of the technetate(VII) ion.

The pertechnetate (technetate(VII)) ion is an oxoanion with the chemical formula TcO₄⁻. 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 Tc-99m isotope (half-life 6 hours) which is commonly used in nuclear medicine in several nuclear scanning procedures.

A technetate(VII) is a compound containing this ion. Pertechnetates are salts of technetic(VII) acid. Pertechnetate is analogous to permanganate but it has little oxidizing power.

Use of pertechnetate to carry technetium-99m

A technetium-99m generator, also known as a cow, provides the pertechnetate containing the short-lived isotope Tc-99m for medical uses. This compound is generated directly from molybdate held on alumina within the generator (see this topic for detail).

Uses in nuclear medicine

Perechnetate has a wide variety of uses in diagnostic nuclear medicine. Since technetate(VII) can substitute for iodine in the Na/I Symporter (NIS) Channel in follicular cells of the thyroid gland, inhibiting uptake of iodine into the follicular cells, Tc^99m-pertechnetate can be used as an alternative to I¹²³ in imaging of the thyroid, although it specifically measures uptake and not organification.^[1] It has also been used historically to evaluated for testicular torsion, although ultrasound is more commonly used in current practice, as it does not deliver a radiation dose to the testes. It is also used in labeling of autologus red blood cells for MUGA scans to evaluate left ventricular cardiac function, localize of gastrointestinal bleeding prior to embolization or surgical management, and in damaged red blood cells to detect ectopic splenic tissue. Technetate(VII) radiolabeled with Tc99m is also the marker injected into the body looking for ectopic gastric tissue as is found in a Meckel's diverticulum with Meckel's Scans.^[2]

Uses of pertechnetate which do not rely on its radioactivity

All technetium salts are mildy radioactive, but some of them have explored use of the element for its chemical properties. In these uses, its radioactivity is incidental, and generally the least radioactive (longest lived) isotopes of Tc are used. In particular, Tc-99 (half-life 211,000 years) is used in corrosion research, because it is the decay product of the easily-obtained commercial Tc-99m isotope^{[citation needed]}, which is its nuclear isomer. In theory, the longest-lived technetium isotope, Tc-97 (half-life 2.6 million years), would be the optimal isotope for this use.

Solutions of technetate(VII) react with the surface of iron to form technetium dioxide, in this way it is able to act as an anodic corrosion inhibitor.

References

See also

• Sodium pertechnetate