The HRCT image and histopathology were examined in 23 lung cancer that touched to pleural. The useful findings to determine the presence of pleural invasion were 1) whether or not the lesion touches to pleura widely (>3cm), 2) presence of costal destruction, 3) presence of the disappearance of an extrapleural fat layr. All of lesions which had 1) or 2) findings showed pleural infiltration histrogically. However, it was difficult to diagnose a presence of the invasion to the visceral pleura precisely, in the cases that an extrapleural fat layr disappears and a tumor touches with the pleura 3cm or less. HRCT images of 3-1.5mm thickness was able to diagnose the disappearance of a fat layr precisely, because it is able to detect more trifing fat in comparison with a CT image of 10mm thickness.
On the other hand, pleural indentation and pleural thickening were not useful to the evaluation of the presence of pleural infiltration. The tumor which abutted on the visceral pleura and pleural indentation were seen submacroscopically, however, tumor was not infiltrating to visceral pleura, and increase of fibrous tissue and infiltration of inflammatory cells as reaction were recognized on the microscopic specimen. The histopathologic findings corresponding to the soft tissue density lesion that exists between the tumor and parietal pleura on HRCT was not recognized. It was considered little pleural fluid pooled between the tumor and parietal pleura.
HRCT image reflected a pathological findings precisely. There fore it was a useful diagnosis method in the evaluation of a presence of pleural infiltration.