EF5 is a nitroimidazole

Nitroimidazole

4-Nitroimidazole is an imidazole derivative that contains a nitro group.Several derivatives of nitroimidazole constitute the class of nitroimidazole antibiotics that have been used to combat anaerobic bacterial and parasitic infections. Perhaps the most common example is metronidazole . Other...

 used in oncology research. Due to its similarity in chemical structure to etanidazole

Etanidazole

Etanidazole is a nitroimidazole drug used for its radiosensitizing properties. Administration of etanidazole results in a decrease of glutathione concentration and inhibits glutathione S-transferase. The result is that tissues become more sensitive to the ionizing radiation used in cancer treatment....

, EF5 binds in cells displaying hypoxia.

The ¹⁸F

Fluorine-18

Fluorine-18 is a fluorine radioisotope which is an important source of positrons. It has a mass of 18.0009380 u and its half-life is 109.771 minutes....

-radiolabeled

Isotopic labeling

Isotopic labeling is a technique for tracking the passage of a sample of substance through a system. The substance is 'labeled' by including unusual isotopes in its chemical composition...

 derivative

Derivative (chemistry)

In chemistry, a derivative is a compound that is derived from a similar compound by some chemical or physical process. In the past it was also used to mean a compound that can be imagined to arise from another compound, if one atom is replaced with another atom or group of atoms, but modern...

 of EF5 is being studied for its possibility to be used in positron emission tomography

Positron emission tomography

Positron emission tomography is nuclear medicine imaging technique that produces a three-dimensional image or picture of functional processes in the body. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide , which is introduced into the body on a...

 (PET) to detect low levels of oxygen in brain tumors. This can help show how a tumor will respond to treatment.