Using 18F-FAPI PET to Detect Metastatic Disease in Patients That Have Gastric or Esophageal Cancer.

Inclusion Criteria: * Male and female adults ≥ 18 years. * Participants with confirmed gastric, esophageal or gastroesophageal malignancy undergoing staging evaluation for treatment planning. * Eastern Cooperative Oncology Group (ECOG) performance status ≤2. * Provided signed, written informed consent prior to any study-related procedures. * Participants are required to have a ceCT scan of chest, abdomen and pelvis as per standard clinical practice and practice guidelines either 21 days or less prior to entry or planned within 21 days of \[¹⁸F\]FAPI-74 administration. * For women who are not postmenopausal (two years of amenorrhea) or surgically sterile (absence of ovaries and/or uterus): agreement to use medically accepted, highly effective methods of contraception (e.g., hormonal implants, combined oral contraceptives, vasectomized partner, during the trial intervention period. Exclusion Criteria: * Unequivocal evidence of metastases at the time of enrollment that would preclude surgery as a treatment option. * Known hypersensitivity to \[¹⁸F\]FAPI-74. * Administration of another investigational diagnostic or therapeutic product within 30 days prior to \[¹⁸F\]FAPI-74 administration. * Prior administration of a radiopharmaceutical within 10 half-lives of that product from the time of \[¹⁸F\]FAPI-74 administration. * Previous cancer (except basal cell carcinoma of the skin or in situ carcinoma of the cervix/uterus (participants treated with curative intent and disease free for more than 5 years are permitted). * Hepatic function: T. bili \>1.5X ULN or alk phos, ALT, or AST \>5X ULN * Renal function: GFR \< 30 mL/min * Pregnant or currently breast feeding (a negative pregnancy test is required in women of childbearing potential). * Inability to undergo the PET/CT scanning procedure. * Inflammatory bowel disease (Crohn's disease, ulcerative colitis) * Sarcoidosis * Treatment, including chemotherapy, radiation, immunotherapy or surgery for curative intent of Gastroesophageal cancers