Dissolved 129Xe imaging holds promise for the detection of early functional decline due to radiation-induced lung injury through the extraction of regional quantitative parameters relating to lung physiology and gas exchange. In this work a spiral-IDEAL imaging technique was used with a partial-lung irradiation rat model to investigate regional changes lung function associated with injury and compare to histology. A significant reduction in capillary hematocrit (HCT) was observed in the vicinity of irradiation. These results were in agreement with quantitative histology of red blood cells. Imaging results were more sensitive than whole-lung spectroscopy, which was performed simultaneously.