A procedure used to locate the place where a biopsy specimen will be taken from the breast. Using mammography, the radiologist finds the precise area from which the biopsy sample will be taken and marks the skin directly above it. A thin, hollow needle containing a wire about the size of a strand of hair is inserted into the spot and then removed, leaving the wire in the breast. The function of the wire is to show the surgeon performing the biopsy where the “suspicious” tissue is, because it cannot be seen with the naked eye.