Pattern recognition in radiographs of excised air-inflated human lungs. IV Emphysema alone and with other common lesions.

To evaluate at autopsy the radiographic pattern of emphysema alone and with alveolar oedema, haemorrhage or pneumonia in excised air-inflated lungs the distribution of these findings in 89 lungs was determined histologically on 441 sections sampled systematically. Pathologic-radiologic correlations were studied on the basis of 58 sections from 30 lung selected to represent most clearly the features in question. In mild centrilobular emphysema (CLE) the number and calibre of small blood vessels was often reduced. Small translucencies could appear. In moderate CLE vascular changes were always visible and unevenly distributed translucencies in most cases. Some lungs looked slightly rounded. In severe CLE the number of blood vessels was greatly reduced, they were displayed between extensive tissue defects, and the lung looked always rounded. Only mild panlobular emphysema occurred in the material. This was difficult to distinguish radiologically but could show up as a coarse reticular background with a reduced number of blood vessels, and the lung could look rounded. Paracicatricial emphysema appeared as translucent areas around scars. Simultaneous alveolar processes often obscured the blood vessel changes of CLE and could accentuate or hide the tissue defect translucencies. The same alveolar processes were more unevenly distributed in emphysematous than in non-emphysematous lungs.