FES PET/MRI for Occult Disease in Lobular Breast Cancer

Inclusion Criteria:

* Adults assigned female sex at birth
* Newly diagnosed ILC confirmed on core-needle biopsy (greater than or equal to 1 percent ER staining per American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) guidelines)
* have undergone or will undergo standard-of-care (SOC) clinical and imaging assessments (e.g., mammography, ultrasound, breast MRI)
* planning for mastectomy or breast-conserving surgery within 12 months of their initial diagnosis
* Provision of signed and dated informed consent form

Exclusion Criteria:

* Patients with history of ipsilateral axillary lymph node dissection
* Patients who received anti-estrogen therapy such as selective estrogen receptor degrader (SERD, e.g., fulvestrant, elacestrant) in the last 28 weeks or selective estrogen receptor modulator (SERM, e.g., tamoxifen, raloxifene) in the last 8 weeks.
* Pregnancy or breastfeeding
* Patients with known allergic or hypersensitivity reactions to previously administered GBCAs or related drug.
* Patients with a contraindication to MRI, or who cannot be positioned within the scanner because their body weight or diameter exceeds the scanner limits.
* Patients requiring intravenous (IV) conscious sedation for imaging are not eligible; patients 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
* Concurrent participation in another clinical study that, in the judgment of the PI, would interfere with study procedures, endpoint assessment, interpretation of imaging findings, or participant safety.