This is a prospective exploratory biodistribution study in patients with interstitial lung disease (ILD).

The purpose of this research study is to determine where and to which degree the FAPI tracer (68Ga-FAPI-46) accumulates in normal and fibrotic lung tissues of patients with interstitial lung disease.

The study will include patients with interstitial lung disease who have or will initiate a new ILD medication OR will undergo tissue biopsy or surgery of the lung.

The study will include 30 patients, the upper limit for PET imaging studies conducted under the Radioactive Drug Research Committee (RDRC) purview.

Participants will be injected with up to 7 mCi of 68-GaFAPi and will undergo one PET/CT scan and one High Resolution CT of the lungs.

The study is sponsored by Ahmanson Translational Theranostic Division at UCLA.

ILD is a group of respiratory diseases that affect the interstitium of the lungs. A major problem is the highly variable course of fibrosing ILD: some patients remain stable without treatment, and others progress rapidly despite pharmacotherapy.

Novel diagnostic approaches for risk stratification with more accurate prediction of the course of fibrosing ILD could potentially improve prognostication and ultimately lead to better survival in these patients.

Persistent activation and local accumulation of myofibroblasts is a common feature of fibrotic diseases. FAP is a promising target for molecular imaging of fibroblast activation and detection of sites of active tissue remodeling.

Small molecule inhibitors of FAP have been labeled with positron-emitting isotopes for PET imaging. 68Ga-FAPi-46 can serve as diagnostic biomarker in ILD.

In this study, the investigators will evaluate the 68Ga-FAPi-46 biodistribution in patients with ILD and observe the correlation of FAP expression and FAPi radiopharmaceutical uptake.

The primary objective of this study is to evaluate the biodistribution of the new FAP-targeted PET tracer, 68Ga-FAPi- 46, in patients with ILD.

OUTLINE:

1. Participants with Interstitial Lung Disease will be asked to undergo a 68Ga-FAPi-46 PET/CT and one High Resolution CT of the lungs
2. Patients will be followed until pathology is obtained during clinical care. (if undergoing surgery or biopsy)
3. Biodistribution results will be assessed comparing pathological findings and PET/CT results

Inclusion criteria

• Patients with ILD confirmed by CT at time of staging
• Patients who have initiated or will initiate a new ILD medication with 3 months of enrollment OR Patients who are scheduled to undergo tissue biopsy or surgery of the lung
• Patients are ≥ 18 years old at the time of the radiotracer administration
• Patient can provide written informed consent

Exclusion criteria

• Patient is pregnant or nursing
• Patients with active infectious lung disease
• Patients not expected to comply with the protocol requirements, not able to understand or follow trial procedures