Brief summary

Background: Injury or diseases of the heart and lung can sometimes cause scar tissue (fibrosis) to build up in those organs. Current imaging scans can see this scar tissue once it has formed, but researchers want to find a way to detect the fibrosis in its earliest stages, while there might still be time to prevent serious damage. A new tracer (a radioactive substance injected during imaging scans) may be able to help. Objective: To test a new tracer (18F-FAPI-74) during imaging scans in people with heart or lung disease. Eligibility: People aged 18 years and older with lung or heart disease that may cause scarring in those organs. Design: Participants will have 6 clinic visits over 2 years. Participants will be screened: They will have blood tests and tests of their heart and lung function. Those with heart disease will have a magnetic resonance imaging (MRI) scan of the heart. The study tracer will be used with positron emission tomography (PET)/computed tomography (CT) scans. The study tracer will be injected into a vein in the arm. Participants will lie on a padded bed that slides through a donut-shaped machine. Participants will have scans with the study tracer 2 times, 8 to 12 months apart. They will also have standard CT scans and blood tests during these visits. They will also have blood tests at 3 and 6 months between these visits. Participants will have a follow-up visit after 18 to 24 months. The study scans, MRI and standard CT scans, and lung function tests may be repeated....