[en] 1) CT with pneumomediastinum: 15 patients were examined by CT with pneumomediastinum. The regults were better than CT alone: 9 had tumors separated from surrounding organs and 6 had infiltration or adhesion of tumors to the peripheral region. These findings were useful information in preparing for thoracotomy. 2) Contrast thoracography: Its diagnostic valne was great in all the 24 patients who underwent artificial pneumothorax because of no pleural adhesions. The contrast material collects around a tumor, which projects into the pleural cavity, and the tumor is usually recognized as a ring shadow. The positon, size, and character of the border of the tumor as well as relations between the tumor and the surrounding tissues can be more precisely evaluated than by routine roentgenography. Therefore, usuful information is obtained for thoracotomy. The contrast medium infused was excreted in the urine in 12 hours. There were no complications. (author)