Definition

A radiolabeled substance being studied as an imaging agent in breast cancer. Fluorine F 18-16 alpha-fluoroestradiol binds to estrogen receptors and gives off radiation that can be detected by a positron emission tomography (PET) scan. The PET scan forms an image that shows where cancer cells with estrogen receptors can be found in the body. Also called 18F-16 alpha-fluoroestradiol and 18F-FES.