FAPI-74 PET/CT in Adults With Fibrosis

Inclusion Criteria (by cohort) Head and Neck Cancer Cohort: 1. Participants will be ≥ 21 years of age 2. Diagnosis of oropharyngeal squamous cell carcinoma (OPSCC) 3. Determined to be surgical candidates 4. History of known or suspected fibrosis-inducing medical condition PTLD Cohort: 1. Participants will be ≥ 21 years of age 2. Diagnosed with microbiologically confirmed DS-pTB (culture or PCR positive) 3. History of known or suspected fibrosis-inducing medical condition. 4. Patient-reported completion of TB treatment within 2 years of enrollment. Cardiac Sarcoidosis Cohort: 1. Participants will be ≥ 21 years of age 2. FDG PET/CT scan consistent with metabolically active cardiac sarcoidosis 3. Clinical suspicion of cardiac involvement defined as the presence of any of the following: 1. High degree A-V nodal block 2. Reduced left or right ventricular systolic fusion 3. History of ventricular arrhythmias 4. Unexplained syncope Exploratory Cohort: 1. Participants will be ≥ 21 years of age 2. History of known or suspected fibrosis-inducing medical condition. All Cohorts: 1\. Participants must be informed of the investigational nature of this study and be willing to provide written informed consent and participate in this study in accordance with institutional and federal guidelines prior to study-specific procedures. Exclusion Criteria (by cohort) Head and Neck Cancer Cohort: 1\. Patient is not eligible for tissue resection PTLD Cohort: 1. Diagnosed with TB that is resistant to rifampin per medical record review 2. History of alternative pulmonary disease per medical record review or patient self-report 3. Have been administered corticosteroids or any other systemic investigational agents within 3 months of screening per medical record review or patient self-report 4. Have symptoms or signs suggestive of active TB at the time of pre-screening per patient self-report All Cohorts: 1. Women of childbearing potential may not be pregnant or breast-feeding. A negative pregnancy test will be required before \[F-18\]-FAPI-74injection. 2. Inability to tolerate imaging procedures in the opinion of an investigator or treating physician 3. Any current medical condition, illness, or disorder as assessed by medical record review and/or self-reported that is considered by a physician investigator to be a condition that could compromise participant safety or successful participation in the study 4. Treatment with a therapeutic agent targeting fibroblast activation protein (FAP) within 1 month prior to study enrollment.