الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 122 |  |  |
| | | from | 122 | | |
Abstract
Although atypical and malignant meningiomas are rare; they constitute health problem as they tend to have aggressive behavior as well as high recurrence rate after surgical removal. In our study we aimed to evaluate the role magnetic resonance imaging not only in diagnosis, pre-operative planning but also in predicting pathological type.Reviewing the literature, meninigiomas were graded histopathologically by WHO into three groups WHO grade I (benign), WHO grade II (atypical) and WHO garde III (malignant). Typically meningiomas are unilobular peripheral dural based masses with smooth well-defined borders. It are usually isointense or mildly hypointense to normal grey matter on T1 WI and isoentense or mildly hyperintense to normal gerey matter on T2 WI. After IV contrast administration, typical meningiomas show intense homogenous enhancement. Multiple dural lesions mimic meningioma in their MR appearance such as metastases, lymphoma, hemangiopericytoma, gliosarcoma, sarcoidosis, plasmacytoma and others. We studied 28 case that shows atypical feature on routine MR examinations. Our imaging protocol involved routine MR examination including diffusion weighted imagion with additional perfusion study as well as MR spectroscopy. from overall view of 16 case of atypical and malignant meningiomas and 12 case of typical meningioma we found that, atypical and malignant types tend to have atypical radiological feature by routine MRI such as heterogeneous signal intensity, heterogeneous pattern of enhancement, irregular tumor margins, marked amount of perifocal edema, bone or parenchymal invasion. Three or more of above mentioned atypical findings could not be seen in the typical group being unique for the atypical and malignant group.