Obtaining regional alveolar pO2 is a coveted goal in pulmonary medicine, as it reflects both ventilation and perfusion. Hyperpolarized gases, mostly 3He were used to map pAO2. For 3He this is straightforward as helium is virtually insoluble in tissue. Xe, however, dissolves into tissue and blood and is carried away from the alveolar space, thus contributes to the loss of the 129Xe MRI signal. To date no attempt has been made to address this issue. Here we report a novel use of SB-XTC to measure pAO2 in vivo while simultaneously measuring and taking into account xenon gas exchange on the signal decay.