T2 of endotoxin lung injury with and without methylprednisolone treatment.

NMR relaxation times (T1 and T2) and the water content (WC) of in vitro rat lungs were measured during the course of endotoxin lung injury in rats. Measurements of normal lungs, untreated endotoxin-injured lungs, and endotoxin-injured lungs treated with methylprednisolone (MPSL) were compared. The untreated endotoxin lungs showed prolongation of the fast and slow T2 components (T2f and T2s), but no significant changes in T1 or water content. Also, there was no correlation between 1/WC and relaxation rates or between T1 and T2. MPSL treatment prevented T2f and T2s prolongation; however, the duration of MPSL effectiveness was limited. Animals which were treated with MPSL more than 7 h prior to measurements showed T2 prolongation. This study indicates that NMR relaxation times, particularly T2, can be useful in evaluating lung injuries and their treatments.