[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)