Pulmonary Hypertension SOLAR

Inclusion Criteria: 1. Age ≥ 18 years' old 2. Be on the lung transplant waiting list at Duke University Medical Center. 3. PH as defined by RHC - mPAP \> 20 mmHg, PVR \> 3 WU, PCWP \< 15 mmHg 4. Groups defined as: PAH: Clinical diagnosis of PAH (Group 1 PH) in the absence of severe chronic lung disease, left heart disease, chronic thromboembolism, sarcoidosis, sickle cell disease, or other causes of non-Group 1 PH. COPD-noPH: Clinical diagnosis of COPD in the absence of precapillary PH. COPD-PH: Clinical diagnosis of COPD with precapillary PH. IPF-noPH: Clinical diagnosis of IPF in the absence of precapillary PH. IPF-PH: Clinical diagnosis of IPF with precapillary PH. 5. Willing and able to give informed consent and adhere to visit/protocol schedules (consent must be given before any study procedures are performed). Exclusion Criteria: 1. Moderate to severe heart disease (LVEF \< 45% or severe LV Hypertrophy). 2. Sarcoidosis. 3. Active cancer. 4. Sickle cell anemia. 5. Liver disease (Childs-Pugh class C). 6. Prisoners and pregnant women will not be approached for the study. 7. Inability to obtain consent. 8. Conditions that will prohibit MRI scanning (metal in eye, claustrophobia, inability to lie supine). 9. Medical or psychological conditions which, in the opinion of the investigator, might create undue risk to the subject or interfere with the subject's ability to comply with the protocol requirements