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.