| Objeetive:To determine whether the semi-quantification of pulmonary inflamation and fibrosis in rat peplomycin induced-pulmonary fibrosis using multislice computed tomography(MSCT) is feasible, and correlation between MSCT and pathologic scores.Methods:Sixty mature healthy Sprague-Dawley rats were randomly divided into experimental group(3d,7d,14d,28d and 56d) and control group. Ten rats were in each groups. After the rats were anesthetized and fixed, CT-guided percutaneous trachea punctures were conducted with a abacterial single-use syringe. The former were given intratracheally 5mg/ml peplomycin solution 1ml/kg weight and the control group were given physiological saline solution 1 ml/kg weight. To ensure a homogenous distribution,0.5 ml air was injected twice after peplomycin administration and immediately rotated the animals erectly.All rats were scaned with MSCT in vivo in the supine position at follow-up of 3 to 56 days. Baseline CT examinations were performed prior to and immediately after drug instillation to monitor the distribution of peplomycin in the lungs. All CT scans were obtained with a Aquilion 16 scanner (TOSHIBA Medical Systems, Japan), with use of a 512 x 512-pixel matrix, and the high spatial frequency algorithm. The technical parameters of each scan were 120kVp,100mA,0.5s/r. Images were reconstructed from the apex of the lung to the base with 1.0-mm thickness and 0.5-mm interval, and with window settings appropriate for assessment of pulmonary parenchyma (level,-350Hu; width,1350Hu).On CT images,6 findings were scored in a semiquantitative fashion, ie, ground-glassopacity(GGO), consolidation, nodule, pleural thickening, and parenchymal lines were scored on a scale of zero to 5 depending on area involved. Peripheral bronchial dilatation was scored on a scale of 0 to 2 depending on severity.All sections were stained by haematoxylin and eosin or by Masson's trichrome. On each pathologic slide,5 field of vision were selected at random,11 findings were scored in a semiquantitative fashion, severity of alveolar wall cellular infiltration, extent of alveolar wall cellular infiltration, severity of alveolar space inflammatory cell and intra-alveolar amorphous materials, extent of alveolar space inflammatory cell and intra-alveolar amorphous materials, interstitial fibrosis, honeycombing were scored on a scale of 0 to 5, alveolar wall metaplastic cells lining air space, smooth muscle in stroma, myointimal thickening in vessel wall, severity of bronchial mural fibrosis, and extent of bronchial mural fibrosis were scored on a scale of 0 to 2. Inflammation score was obtained by summing the scores of former four findings, Fibrosis score was obtained by summing the scores of the latter seven findings.Results:Pathologic inflammation scores of the experimental groups were highest in the 7d group (11.53±2.81,p<0.001), whereas fibrosis scores were highest in the 56d group(7.06±1.69,p<0.001). On experimental groups, the CT scores of GGO (1.77±0.61, p<0.001) and consolidation (2.35±0.80,p<0.001) were highest in the 7d group, and fibrosis scores were highest in the 56d group (7.06±1.69,p<0.001). the CT scores of nodule and pleural thickening were not significant difference. GGO (r=0.637, P<0.001) and consolidation (r=0.780, P< 0.001) by CT showed fair to moderate correlation with pathologic inflammation scores, parenchymal lines (r=0.761, P<0.001) showed good and peripheral bronchial dilatation (r=0.628, P< 0.001) showed good correlation with pathologic fibrosis scores.Conclusion:(1) It was feasible that the rats pulmnary fibrosis model were duplicated by intratracheally injected peplomycin under CT-guided percutaneous puncturation. (2) The various period PF models of rats could reflect the development of experimental pulmonary fibrosis. (3) MSCT could reflect radiologic diversification of pulmonary fibrosis of rats in different stages. (4) The MSCT scores correlated with pathologic scorws to some extent in pulmonary fibrosis model of rats.
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