129Xe Gas Exchange Imaging in IPF and cHP: A Reliability Study

Inclusion Criteria: * Adults \> 18 years of age * Diagnosis of progressive chronic HP, IPF as determined by MDD discussion (historical or during screening period) OR normal control (no history of known lung disease, no abnormal parenchymal or airway findings on CT examination and no values outside of the normal for FVC, FEV1, TLC, and DLCO.) * FVC % Predicted \>45% * DLCO % Predicted \>30% * Progressive lung disease as defined by one of the following criteria within 24 months of screening visit * Relative decline in the FVC ≥ 10% of the predicted value * Relative decline in the FVC of ≥ 5% - \< 10% of the predicted value and worsening of respiratory symptoms * Relative decline in the FVC of ≥ 5% - \< 10% of the predicted value and an increased extent of fibrosis on prior clinical high-resolution CT * Worsening of respiratory symptoms and an increased extent of fibrosis on high-resolution CT. Exclusion Criteria: * Stable FVC over 2-year period as determined by study physician * Unstable cardiac condition within 6 months of screening as determined by study physician