Inclusion Criteria:  Allo-HCT recipients who are at least 18 years of age and have BOS (n=10 patients), BOS 0p (n = 10 patients), or cGVHD of a non-lung organ without evidence of pulmonary impairment (n = 5 patients).  In addition, we will perform only XeMRI imaging on 10 healthy adult volunteers with no medical issues for technical calibration of the XeMRI technology. Members of the study team may serve as healthy volunteers if they have no prior history of lung disease. These data will not be included as part of the analysis.  Exclusion Criteria:  Patients unable to follow up at MD Anderson for routine clinical care Inability or unwillingness to give informed consent Relapsed disease or life expectancy less than 6 months at time of enrollment Severe claustrophobia precluding MRI imaging Active pulmonary infection Pregnant women