COMPUTERIZED TOMOGRAPHY SCANNING APPEARANCES OF INTRACRANIAL MENINGIOMAS - ATTEMPT TO PREDICT THE HISTOLOGICAL FEATURES

The computerized tomography (CT) scans of 102 patients with meningiomas confirmed at operation and histologically were reviewed, and the features displayed by the tumors were correlated with their histology. There were 54 transitional, 17 fibroblastic, 13 mixed transitional and fibroblastic, 10 angioblastic, and eight syncytial meningiomas. It was found that each of these meningioma variants exhibited common CT features that could be helpful in predicting the probable histology. These common features were: visible calcium aggregates, degree of surrounding edema, tumor density before and after contrast medium enhancement, homogeneity, and definition of outline. Visible calcium aggregates pointed to a diagnosis of either transitional or fibroblastic meningioma. None of the angioblastic or syncytial variants exhibited this feature. Most of the tumors were surrounded by edema of varying degrees (92%) but this was not considered to be a specific feature except perhaps in the fibroblastic type where the edema was almost invariably of moderate degree. Tumor attentuation values unenhanced by contrast medium were also nonspecific but in enhanced scans a homogeneous density distribution pointed to the tumor being most probably of the transitional type. The angioblastic and syncytial variants showed a marked tendency to exhibit low-density non- enhancing 'cystic' areas or poorly defined, irregular tumor margins or fringes. All of the fibroblastic, transitional, or mixed fibroblastic and transitional variants were well defined with more or less regular shapes. The presence of marked edema, absence of visible calcium aggregates, non-homogeneous contrast enhancement with non-enhancing 'cystic' components and poorly defined irregular borders point to aggressive or invasive characteristics more commonly found in the angioblastic and syncytial variants.