[Qualitative assessment of centrilobular emphysema using computed tomography].

The ability of computed tomography (CT) in the qualitative assessment of centrilobular emphysema (CLE) was studied, with special reference to the morphological relationship between emphysematous change and relatively large bronchovascular bundle forming the margin of secondary pulmonary lobule. Three autopsied lobes with mild, moderate and severe CLE were fixed by the method of Heitzman. Then high resolution CT (HRCT) was applied to those inflation-fixed lobes, which allowed for direct one-to-one pathologic correlation. Furthermore, HRCT findings of these clinical cases with emphysema were analysed. Emphysematous change in CLE was observed as low-attenuation area (LAA) within the homogeneous background on Ct images. In mild and moderate cases, LAA's were round or oval in shape, however in severe case they were observed to be irregular in shape. The border between LAA and parenchyma was not clearly defined, however in severe case LAA was found to be bordered partially or rather subtotally by the bronchovascular bundle. In mild and moderate cases, LAA's were observed to be distant from relatively large bronchovascular bundle. On the other hand, in severe case, only a small amount of lung parenchyma was left between LAA and bronchovascular bundle. These findings correspond to morphologic characteristics of CLE, that is, the process of emphysematous change tends to take place in the center of the secondary lobule, and even if the lobe is severely destroyed, some portion of the peripheral acinus is still preserved at lobular margin. Thus, CT can help to identify the presence of CLE. Furthermore, CT scan analysis of severe grade emphysema may lead to the differentiation between CLE and panlobular emphysema.