FFNP-PET/MR Imaging of Progesterone Receptor Expression in Invasive Breast Cancer

Inclusion Criteria:

1. Women 18 years of age or older
2. Diagnosis of biopsy-proven invasive breast cancer measuring at least 1.0 cm in diameter by any imaging modality
3. Biopsy-proven PR-positive (N=23) or PR-negative (N=5) invasive breast cancer
4. Undergoing diagnostic breast MRI ordered by the referring clinician for staging and extent of disease

Exclusion Criteria:

1. Inability or unwillingness to provide informed consent to the study
2. Participants currently undergoing neoadjuvant chemotherapy/endocrine therapy or those who have received chemotherapy/endocrine therapy within 6 months prior to the MRI
3. Participants who have had neoadjuvant chemotherapy/endocrine therapy, surgical intervention, or radiation for the current biopsy-proven malignancy
4. Participants with breast expanders
5. Participants who are or might be pregnant or lactating
6. Participant girth exceeds the bore of the PET/MRI scanner
7. Participants with a contraindication to gadolinium based contrast agents, including allergy or impaired renal function (per University of Wisconsin Health Guidelines)
8. Participants with a history of allergic reaction attributable to compounds of similar chemical or biologic composition to FFNP
9. Participants in liver failure as judged by the patient's physician
10. Participants with standard contraindications to MRI, including claustrophobia and metallic implants incompatible with MRI

Participants requiring intravenous (IV) conscious sedation for imaging are not eligible; participants requiring mild, oral anxiolytics for the clinical MRI will be allowed to participate as long as the following criteria are met:

1. The subject has their own prescription for the medication
2. The informed consent process is conducted prior to the self-administration of this medication
3. They come to the research visit with a driver
4. Participants unable to lie prone for 30 minutes for imaging