an imaging test in which a radioactive tracer is put into a vein to help find breast cancer. The tracer accumulates in the breasts, and different tracer patterns can show “hot spots” or areas of greater activity. This test may help evaluate women with abnormal mammograms, and is still being studied as doctors try to improve its usefulness. Also called breast specific gamma imaging (BSGI) or molecular breast imaging (MBI). See also imaging tests, mammogram, nuclear medicine scan, radioisotope.