Microcomputed tomography assessment of lipopolysaccharide-induced acute lung injury in rat

Purpose: High-resolution microcomputed tomography (micro-CT) is an extremely flexible and accurate technique for three-dimensional examination of biological tissues. The aim was to evaluate the feasibility of micro-CT as a noninvasive tool for analyzing the lung structure during lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rats. Materials and Methods: ALI was induced in rats by intratracheal instillation of LPS (2 mg/kg) in 0.3 ml saline, and the control treatment consisted of intratracheal instillation of an equal volume of normal saline. Morphological changes were assessed by using micro-CT and a light microscope at 24 and 48 hours after LPS instillation. Total volume is the sum of all pixels marked as the whole lung and total air volume (Air V) is the sum volume of all air in the lung. Results: The saline groups exhibited no major histological abnormalities, whereas the LPS groups exhibited patchy areas of haemorrhage and thickened alveolar walls with inflammatory cell infiltration at 24 and 48 hours. The LPS groups had significantly smaller Air V and percent total air volume (Air V/TV) compared with those of the saline groups at 24 and 48 hours. Air V/TV was strongly negatively correlated with the lung injury score (r = -0.641, P =.004). Conclusions: Micro-CT is a feasible tool for evaluating the lung structure and lung injury progression during LPS-induced ALI.