Advanced Imaging to Assess the Effect of Immunosuppression on Progressive Fibrosis

Inclusion Criteria:

1. Age 18-80 with a diagnosis of chronic hypersensitivity pneumonitis, connective tissue-associated ILD (due to rheumatoid arthritis, systemic sclerosis, mixed connective tissue disease), or undifferentiated ILD.
2. Starting immunosuppression treatment with mycophenolate mofetil, mycophenolate sodium, and / or prednisone for clinically indicated non-IPF ILD treatment.
3. Pulmonary fibrosis, defined as honeycombing, traction bronchiectasis, or reticular opacities on high-resolution computed tomography (HRCT) performed within 1 year to or at Visit 1.
4. Forced vital capacity (FVC) of \>/= 45% and diffusing capacity of the lungs for carbon monoxide (DLCO) \>/= 25% predicted on PFTs performed at Visit 1.

Exclusion criteria:

1. Current or prior exposure to FDA approved anti-fibrotic therapy.
2. Extent of emphysema greater than extent of fibrosis.
3. Pregnancy or plans to become pregnant at baseline or during follow-up.
4. Contraindications to MRI.
5. Contraindications to receiving gadolinium-based contrast agents.
6. Research-related radiation exposure exceeds 50 millisievert (mSv) in the prior year.
7. Estimated glomerular filtration rate (eGFR) \< 30 mL/min (only for individuals with a history of chronic kidney disease).
8. Clinically significant pulmonary hypertension (PH) defined by use of pulmonary vasodilatory therapy.
9. Respiratory infection within the prior 6 weeks.
10. Smoking of any kind within the prior 6 months.