In vivo Hahn spin-echo decay (Hahn-T-2) observation of regional changes inthe time course of oleic acid lung injury

We studied the time course of changes in the Hahn spin-echo decay (Hahn-T-2 ) in lungs of spontaneously breathing living rats at 1 hour, 3 hours, and 7 days following oleic acid injection. Motion artifacts were minimized by us ing the motion-insensitive interleaved rapid line scan (ILS) imaging techni que. Prior to injury, the lungs exhibited two resolvable exponential Hahn-T -2 components, One and 3 hours after injury the decay showed a regionally n onuniform behavior, which was fit with one, two, or three exponential compo nents. The short and medium components increased at 1 and 3 hours after inj ection. The third, much longer, component is probably due to intraalveolar pulmonary edema. After 7 days the Hahn decay was similar to that observed b efore injury, probably reflecting resolution of the edema. Our data suggest that Hahn-T-2 measurements can be used to characterize the time course and regional distribution of lung injury in living animals, (C) 2000 Wiley-Lis s, Inc.