Role of 99mTc Sestamibi Scintimammography for the Evaluation of Breast

Breast cancer is the second most common malignancy among women in the United States, with a projected 180,200 cases in 1997. In 1974, Siegel et al. reported increased breast uptake of Tc-HEDSPA during routine bone scanning of patients with known breast cancer, The sensitivity for the detection of breast carcinoma was generally high, but the specificity was low using these tracers, limiting their clinical use. Attempts to formulate radiotracers more specific for breast carcinoma have included biologically active peptides such as indium-labeled somatostatin analogs which are targeted to specific receptors and radiolabeled monoclonal antibodies to breast cancer cells. Mitochondrial retention of MIBI does not appear to be organ-specific and may thus account for MIBI accumulation in tumors such as breast carcinoma. Hallmarks of breast carcinoma, like many malignancies, include increased mitotic activity of tumor cells, the development of neovascularization as a means of obtaining nutrients for growth and invasion, and the development of intense fibrosis.