The effect of pulmonary edema on proton nuclear magnetic resonance relaxation times

This study was done to determine the effect of permeability pulmonary edema on proton nuclear magnetic resonance (NMR) relaxation times. Permeability edema was induced in rats by the intravenous injection of alloxan in saline. Control animals received only saline. The rats were ventilated through a tracheostomy; and after a time sufficient for the edema to become uniform, they were sacrificed. T1, and T2 and extravascular lung water were measured on lung samples. A linear relationship was found between the relaxation times and the extravascular lung water. Any diffuse alveolar process including pulmonary edema can increase proton density as well. The T1 and T2 relaxation times may be used to distinguish among different causes of increased proton density in the lung.