In Vivo Imaging Of The Progression Of Acute Lung Injury Using Hyperpolarized [1-C-13] Pyruvate

PurposeTo investigate pulmonary metabolic alterations during progression of acute lung injury.MethodsUsing hyperpolarized [1-C-13] pyruvate imaging, we measured pulmonary lactate and pyruvate in 15 ventilated rats 1, 2, and 4h after initiation of mechanical ventilation. Lung compliance was used as a marker for injury progression. 5 untreated rats were used as controls; 5 rats (injured-1) received 1ml/kg and another 5 rats (injured-2) received 2ml/kg hydrochloric acid (pH1.25) in the trachea at 70min.ResultsThe mean lactate-to-pyruvate ratio of the injured-1 cohort was 0.150.02 and 0.15 +/- 0.03 at baseline and 1h after the injury, and significantly increased from the baseline value 3h after the injury to 0.23 +/- 0.02 (P=0.002). The mean lactate-to-pyruvate ratio of the injured-2 cohort decreased from 0.14 +/- 0.03 at baseline to 0.08 +/- 0.02 1h after the injury and further decreased to 0.07 +/- 0.02 (P=0.08) 3h after injury. No significant change was observed in the control group. Compliance in both injured groups decreased significantly after the injury (P<0.01).ConclusionsOur findings suggest that in severe cases of lung injury, edema and hyperperfusion in the injured lung tissue may complicate interpretation of the pulmonary lactate-to-pyruvate ratio as a marker of inflammation. However, combining the lactate-to-pyruvate ratio with pulmonary compliance provides more insight into the progression of the injury and its severity. Magn Reson Med 78:2106-2115, 2017. (c) 2017 International Society for Magnetic Resonance in Medicine.