Acute rat lung injury:: Feasibility of assessment with micro-CT

PURPOSE: To evaluate the feasibility of micro-computed tomography (CT) for analysis of the lung fine structure and its alterations during endotoxin-induced lung injury. MATERIALS AND METHODS: Intravital perfusion-fixed rat lungs with (n = 5) and without (n = 5) endotoxin perfusion were scanned with micro-CT. Three imaging modalities (conventional histology, intravital microscopy, and electron microscopy) were used to document the effect of endotoxin and the in vivo application of contrast agent (a mixture of barium sulfate, gelatin, and thymol). The effect of endotoxin on structural changes of the lung was evaluated with analysis of variance. RESULTS: Intravital microscopy, conventional histology, and electron microscopy demonstrated capillary perfusion of contrast agent, inflated alveoli, and no extravasation of barium sulfate in the extravascular space. Systemic application of endotoxin led to a significant increase in the soft-tissue volume of the lungs (ie, tissue edema) (58.09 mum(3) +/- 4.6 [standard error of the mean] vs 8.31 mum(3) +/- 1.63, P < .001) and significant thickening of the alveolar walls (34.01 mum +/- 4.5 vs 14.83 mum 2.5, P < .001) at micro-CT. Simultaneously, endotoxin-treated rat lungs showed a significant reduction in total air space (49.74 mum(3) +/- 1.72 vs 100.99 mum(3) +/- 1.16, P < .001). CONCLUSION: These findings indicate that micro-CT is feasible for structural evaluation of the lung fine structure and its alterations during endotoxin-induced lung injury. (C) 2004 RSNA.