Hyperpolarized 129Xe MRI for the Assessment of BOS With Late Onset LONIPC

Inclusion Criteria: * For participants who have known LONIPC at enrollment (cross-sectional group): * Patient is 18 - 70 years old * Patient has received an allogenic HSCT * Diagnosed LONIPC For participants who have no known LONIPC, but are at risk by virtue of recently-diagnosed cGVHD: * Patient is 18 - 70 years old * Patient has received an allogenic HSCT in the last 24 months * Patient has a new diagnosis of cGVHD within the last 6 months by criteria of: * Moderate- or severe- cGVHD as per NIH consensus criteria, determined by a treating hematologist or * cGVHD requiring immunosuppression with prednisone at a dose of \> 0.5mg/kg/day, or alternate steroid-sparing agent Exclusion Criteria: * For participants who have known LONIPC at enrollment (cross-sectional group): * Age less than 18 years or greater than 70 years of age * Current smoker (quit in the last 3 months) * Smoking history greater than 20 pack years * Presence of contraindications to pulmonary function testing including myocardial infarction within the last one month, hemoptysis, active communicable disease (e.g. TB), inability to follow commands, thoracic/abdominal/eye surgery within the last 3 months, pneumothorax, uncontrolled hypertension (SBP \> 180, DBP \> 110) or pulmonary embolism, other contraindication as determined by technical staff. * Pregnancy prior to or during study * In the opinion of the investigator, subject is mentally or legally incapacitated, preventing inform…