1. A method for providing MRI data of pulmonary gas exchange and/or alveolar-capillary barrier status, comprising: transmitting an RF MRI excitation pulse sequence configured to excite dissolved phase hyperpolarized 129 Xe in a gas exchange region of a lung of a subject; and obtaining MRI image data of dissolved phase 129 Xe in a red blood cell (RBC) compartment in the gas exchange region of the lung of the subject based on the transmission of the RF MRI excitation pulse sequence.