抄録
Fifty-five patients who were suspected to have a tumor invasion in the pterygopalatine fossa, pterygoid fossa, infratemporal fossa, lateral and posterior pharyngeal wall were examined using EMI Scanner 1010. A line joining the lower edge of the orbit to the uppermost part of the external auditory canal (Reid's base line) is adopted as a base and cuts were obtained below and above this line. The place examined in the present study was included in the slices from 1 to 4cm below the base line. Soft tissues in the pterygopalatine fossa and its vicinity are grossly divided into two parts, namely the high density and the low density area. The former mainly represents muscles like the lateral pterygoid or the medial pterygoid muscles and the latter indicates the fatty soft tissues locating among muscles and bones. In addition to the destruction of the bone and the deformity of the air filled cavity, changes in the soft tissues are very important to determine the presence or absence of the tumor invasion. Although the tumor, in general, has an almost same density as the muscles, the extension of the tumor can be demonstrated by the loss of the low density area and the deformity of the muscle shadow. CT scan revealed a tumor invasion in the pterygopalatine fossa and its vicinity in 18 out of 25 cases of maxillary carcinoma and these findings were confirmed by surgery. CT scan is most usefull for determination of the size and location of the tumor and we propose that findings on CT scan should be taken into consideration when attempting to determine TNM classification of tumors.
