[68Ga]Ga DOTA-5G as a Diagnostic Imaging Agent for Metastatic/Advanced Invasive Lobular Breast Cancer (LBC)

Inclusion Criteria:

* (Ability to understand and willingness to sign a written informed consent document.
* Men and women age ≥ 18 yrs
* Confirmed presence of metastatic/advanced invasive lobular breast cancer and measurable disease per RECIST (version 1.1) or PERCIST
* Available archival tumor tissue
* Eastern Cooperative Oncology Group Performance Status ≤ 2
* Hematologic parameters defined as: Absolute neutrophil count (ANC) ≥ 1000 cells/mm3,Platelet count ≥ 100,000/mm3, Hemoglobin ≥ 8 g/dL.
* Blood chemistry levels defined as: AST, ALT, alkaline phosphatase ≤ 5 times upper limit of normal (ULN), Total bilirubin ≤ 2 times ULN, eGFR \>60 mL/min/1.73m\*2
* Anticipated life expectancy ≥ 3 months
* Able to remain motionless for up to 30-60 minutes per scan.

Exclusion Criteria:

* Pregnant and lactating women
* Prisoners
* Concurrent malignancy of a different histology that could confound imaging interpretation.
* Patients who cannot undergo PET/CT scanning because of weight limits(\>350lbs)