Atypical and malignant meningiomas: evaluation of different radiological criteria based on CT and MRI.

The following are our results of a retrospective analysis of 214 patients, operated on meningiomas, in order to investigate radiological criteria of malignancy. Among these cases there were 31 patients with a histologically confirmed diagnosis of malignant subtypes. As uncertain signs of malignancy of ensuing radiological features are an irregular enhancement of contrast-media and the size of cerebral edema. Based upon CT and MR images we have developed a standardised, computerised evaluation method which enables us to study in detail the internal architecture of meningiomas.