Inclusion Criteria:

• 1. Participants will be ≥ 18 years of age
• 2. Known or suspected, in the opinion of an investigator, primary breast or metastatic breast cancer. For subjects with primary breast cancer we will target lesion size of 1.0 cm or greater on at least one type of standard imaging.
• 3. Participants must be informed of the investigational nature of this study and be willing to provide written informed consent and participate in this study in accordance with institutional and federal guidelines prior to study-specific procedures.

Exclusion Criteria:

• 1. Females who are pregnant or breast feeding at the time of enrollment will not be eligible for this study; a urine pregnancy test will be performed in women of child-bearing potential prior to FTT injection.
• 2. Inability to tolerate imaging procedures in the opinion of an investigator or treating physician
• 3. Any current medical condition, illness, or disorder as assessed by medical record review and/or self-reported that is considered by a physician investigator to be a condition that could compromise participant safety or successful participation in the study