18F-FDG Kinetics Parameters Depend on the Mechanism of Injury in Early Experimental Acute Respiratory Distress Syndrome

PET with 18F-FDG allows for noninvasive assessment of regional lung metabolism reflective of neutrophilic inflammation. This study aimed at determining during early acute lung injury whether local 18F-FDG phosphorylation rate and volume of distribution were sensitive to the initial regional inflammatory response and whether they depended on the mechanism of injury: endotoxemia and surfactant depletion. Methods: Twelve sheep underwent homogeneous unilateral surfactant depletion (alveolar lavage) and were mechanically ventilated for 4 h (pos-itive end-expiratory pressure, 10 cm H2O; plateau pressure, 30 cm H2O) while receiving intravenous endotoxin (lipopolysaccharide-positive [LPS1] group; n 5 6) or not (lipopolysaccharide-negative group; n 5 6). 18F-FDG PET emission scans were then acquired. 18F-FDG phosphory-lation rate and distribution volumewere calculated with a 4-compartment model. Lung tissue expression of inflammatory cytokines was measured using real-time quantitative reverse transcription polymerase chain reac