MRI manifestations and pathological basis of atypical meningioma

  Objective  To investigate the magnetic resonance imaging (MRI) characteristics and pathological basis of atypical meningiomas.

  Methods  The MRI materials of 20 patients with atypical meningioma confirmed by surgery and pathology were retrospectively analyzed, including imaging features (cystic degeneration, lobulation, enhancement mode and degree, tumor-brain interface, adjacent skull signs) and pathological basis.

  Results  The tumors were located on convex surface in 12 cases, beside falciform surface in 6 cases, and beside sigmoid sinus in 2 cases. Typical MRI findings showed clear boundary soft tissue masses. The lesion showed iso-signal or hypo-signal on T₁WI, and hyper-signal on T₂WI. The space-occupying effect was more significant than edema. Cystic degeneration and necrosis were found in the tumors. Enhanced scan showed heterogeneous enhancement.

  Conclusion  The incidence rate of atypical meningioma is low, and its MRI manifestations has certain characteristics. Preoperative localization and qualitative diagnosis of tumors can be achieved by plain and enhanced MRI scans.