4DX Functional Lung Imaging in the Diagnosis of Chronic Lung Allograft Dysfunction After Lung Transplantation

Inclusion Criteria: 1. Greater than or equal to 18 years of age at the time of written informed consent 2. Recipient of a first bilateral lung transplantation performed at Duke University at least one year prior to written informed consent 3. Computed tomography (CT) scan of the chest performed at Duke as standard of care after transplantation but within 1 year prior to written informed consent 4a. CLAD grades 1, 2,or 3 (per ISHLT 2014 criteria \[Meyer et al 2014\]) prior to or at the time of screening * Grade 1 is defined as a fractional decrease in FEV1 to 66-80% of post-transplant baseline FEV1 * Grade 2 is defined as a fractional decrease in FEV1 to 51%-65% of post-transplant baseline FEV1 * Grade 3 is defined as a fractional decrease in FEV1 to \<= 50% of post-transplant baseline FEV14b. CLAD free status (defined as most recent FEV1 at the time of screening \>90% of post-transplant baseline FEV1) Exclusion Criteria: 1. Recipients of a single lung transplant 2. Recipients of a redo-lung transplant 3. Recipients of bone marrow or stem cell transplant 4. Recipients of a multi-organ transplant 5. Patients with hospital admissions(excluding admissions for planned treatment of the CLAD and/or rejection)within one month of screening. 6. Patients who are unable to lie flat on the fluoroscopy table 7. Pregnant women (by subject's verbal report). Lung transplant recipients are routinely counseled to avoid pregnancy due to the teratogenic effects of necessary immunosuppressant medications. Pregnancy after lung transplantation is therefore extremely rare. As this is a minimal risk study which does not involve an experimental therapy, invasive devices, or increased risk procedures, pregnancy testing is deemed unnecessary for this population for this study.