Scintimammography using the radioisotope technetium tetrofosmin (Tc-99 tetrofosmin) can detect breast cancer sometimes in situations in which there is considerable uncertainty, as with dense breast tissue. (Dense breast tissue is particularly difficult to decipher by standard mammography.)
Women with dense breasts have a high incidence of false positives with standard mammography -- test results that appear "falsely" positive in the absence of cancer. The false positives lead to unneeded biopsies and anxiety.
The Tc-99 tetrofosmin scan is especially valuable in these women, who are often younger women and have not gone through menopause. Breast malignancies typically show increased uptake of the Tc-99 tetrofosmin as compared to benign growths. In one study, Tc-99 tetrofosmin test had an accuracy of nearly 90%, while standard mammography yielded a significantly lower value.
Scintimammography with technetium tetrofosmin (Tc-99 tetrofosmin) has been approved by the US Food and Drug (FDA) for the diagnosis of breast cancer. The technique is not meant to replace standard mammography and other current tests, but to be used in conjunction with them.