In vivo imaging of the progression of acute lung injury using hyperpolarized [1‐13C] pyruvate

Purpose To investigate pulmonary metabolic alterations during progression of acute lung injury. Methods Using hyperpolarized [1‐13C] pyruvate imaging, we measured pulmonary lactate and pyruvate in 15 ventilated rats 1, 2, and 4 h 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 1 ml/kg and another 5 rats (injured‐2) received 2 ml/kg hydrochloric acid (pH 1.25) in the trachea at 70 min. Results The mean lactate‐to‐pyruvate ratio of the injured‐1 cohort was 0.15 ± 0.02 and 0.15 ± 0.03 at baseline and 1 h after the injury, and significantly increased from the baseline value 3 h 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 1 h after the injury and further decreased to 0.07 ± 0.02 (P = 0.08) 3 h after injury. No significant change was observed in the control group. Compliance in both injured groups decreased significantly after the injury (P