[Analysis of peritumoral edema--with special reference to the value of contrast-enhanced CT scan and dynamic CT scan].

Peritumoral edema, a common occurrence in patients with malignant gliomas and meningiomas, is a major cause of morbidity and mortality. However, the causative mechanism of peritumoral edema has yet to be clarified. In this study, seventy patients with brain tumors (34 glioblastomas, 21 meningiomas and 13 metastatic tumors) were examined by CT scan with and without contrast medium infusion and by postoperative histologic verification in all cases. Peritumoral hypodensity areas on CT scan have generally been interpreted as cerebral edema. Peritumoral edema as seen in CT scan was classified into four grades according to the ratio of the largest diameter of tumor and the size of the zone of edema. Grade 0: no peritumoral low density area is seen in CT scan. Grade I: a small amount of peritumoral low density area is seen in CT scan. Grade II: a moderate amount of peritumoral low density area is seen is CT scan. Grade III: a large amount of peritumoral low density area is seen in CT scan. Twenty-five out of 34 glioblastomas and all of 15 metastatic tumors demonstrated moderate or severe peritumoral edemas such as Grade II or III. However 16 out of 21 meningiomas demonstrated mild peritumoral edemas such as Grade 0 or I. The grade of peritumoral edema was closely related to the degree of malignancy of the brain tumors. 8 out of 9 glioblastomas which demonstrated slight peritumoral edema, Grade I, had large cystic formations which seemed to serve as buffer action to compression mechanism by brain tumors. The grade of peritumoral edema was also related to the location of the tumor and venous involvement.(ABSTRACT TRUNCATED AT 250 WORDS)