Effect of Surgery and Radiation Therapy on Tc-99M Sestamibi Uptake Patterns in Molecular Breast Imaging

Inclusion Criteria:

* Women who have planned surgical excision of a lesion or have had a baseline MBI study as part of another MBI research protocol who are within 6-12 months of completing breast surgery who are able and willing to return to Mayo Clinic for a follow up MBI study once the 6-12 month interval is complete.
* Women who plan BCT for a malignant lesion or who are within 6-12 months of completing breast conserving treatment and have had a baseline MBI study as part of another MBI research protocol and are able and willing to return to Mayo Clinic for a follow up MBI study.

Exclusion Criteria:

* Women who do not require surgical excision of a breast lesion or breast conserving treatment for breast cancer.
* Patients undergoing mastectomy.
* Women who are pregnant or lactating.
* Women who are taking hormonal contraception or hormone replacement therapy (vaginal estrogen is permitted), or have used these agents within the previous 3 months.
* Women who have received chemotherapy within the previous 6 months or receive chemotherapy as part of their cancer treatment.
* Men (due to the very low incidence of male breast cancer and the lack of any available data regarding the use of scintimammography or MBI in men).
* Women under the age of 18 years.
* Women unable to sit comfortably during image acquisition.
* Women who are unable to return to Mayo Clinic for a follow up MBI scan 6-12 months after surgical excision or 6-12 months after completing radiation therapy for breast conservation.