Pattern recognition in radiographs of excised air-inflated human lungs. II. Acute inflammation in non-emphysematous lungs.

To evaluate the patterns of bronchiolitis, alveolar pneumonia, usual interstitial pneumonia, and local interstitial inflammation in radiographs of excised air-inflated lungs at autopsy the distribution of these findings in 89 lungs was determined histologically on 441 sections sampled systematically. Pathologic-radiologic correlations were then studied on the basis of 33 sections from 24 lungs selected to represent unequivocally the features in question. Discrete alveolar pneumonic infiltrates measuring 2 mm or more in diameter appeared as coarse unhomogeneous macular opacities exhibiting indistinct borders and often following bronchi or bronchioli. Smaller infiltrates or pure bronchiolitis were not distinguishable radiographically. Infiltrates measuring more than 1 cm in diameter appeared confluent with a dense homogeneous centre and indistinct borders. In the midst of the opacities air-bronchograms were often and abscess cavities sometimes visible. Fulminant acute interstitial pneumonia of the usual type showed centrally a dense opacity with air-bronchograms and peripherally trabecular densities distributed non-anatomically. Between the trabecular densities there were uneven punctate opacities and expansion by air-inflation was incomplete. Local interstitial inflammation that caused thickening of the alveolar walls up to 4 time of normal was not distinguishable radiographically.