Inclusion Criteria

Patients will be eligible for the study if they:

• Are non-pregnant, non-lactating females 18 years of age or older(must agree to use an appropriate and effective method of birth control during the study and for 2 weeks after study)
• Are being evaluated for a known or suspected breast tumor (must present with either a mammographic abnormality 10mm or larger or a mammographically occult but palpable abnormality of the breast)
• Have been previously scheduled for biopsy or surgical excision of the known or suspected tumor of the breast
• Have signed an informed consent form

Exclusion Criteria

Patients will not be eligible for this study if they:

• Have a history or suspicion of significant allergic reaction or anaphylaxis to any of the 111In-DAC components
• Have a clinically unstable medical condition or opportunistic infection, a life-threatening disease state, impaired renal or hepatic function or are immunosuppressed
• Are taking or have taken part in any investigational study within 30 days of start of study
• Have received an indium agent within 30 days of start of study
• Are not able to remain immobile during scanning time
• Have taken drugs that may damage the kidneys within 2 weeks of start of study
• Have abnormal laboratory test results: hemoglobin < 9.5 gms/dl, serum creatinine > 1.5 mg/100ml, alkaline phosphatase 2X the upper limit of normal
• Have undergone an excisional and/or needle localization biopsy within 4 days prior to start of study