Investigations

Imaging for suspected meningioma/glioma

• standard structural MRI (defined as T2 weighted, FLAIR, DWI series and T1 pre- and post-contrast volume) should be offered as the initial diagnostic test for suspected meningioma/glioma, unless MRI is contraindicated
  
  
• consider CT imaging for meningioma (if not already performed) to assess bone involvement if this is suspected.

Notes:

• skull x-ray - 15% of meningiomas show areas of calcification; look for hyperostosis of adjacent bone; dilatation of the middle meningeal groove in the parasagittal and convex regions; demineralisation of the dorsum sella from long standing raised intracranial pressure.
  
  
• CT scan
  • calcification evident in 20-30% of cases; characteristically, there is a well circumscribed lesion of iso- or hyper-density with a surrounding area of hypodensity due to cerebral oedema
  • non-contrast CT
    • 60% slightly hyperdense to normal brain, the rest are more isodense (2)
    • 20-30% have some calcification
  • post-contrast CT
    • 72% brightly and homogeneously contrast enhance (2)
    • malignant or cystic variants demonstrate more heterogeneity/less intense enhancement
  • hyperostosis (5%) (3)
    • typical for meningiomas that abut the base of the skull need to distinguish reactive hyperostosis from:
      • direct skull vault invasion by adjacent meningioma
      • primary intraosseous meningioma
  • enlargement of the paranasal sinuses (pneumosinus dilatans) has also been suggested to be associated with anterior cranial fossa meningiomas
  • lytic/destructive regions may be seen in higher grade tumours
    • however should also consider alternative pathology (e.g. haemangiopericytoma or metastasis)
      
      
• angiography - indicates the vascular supply of the tumour and confirms the diagnosis. Characteristically this demonstrates 'blushing' which is a result of the tumour's vascularity and a blood supply from the external carotid artey

Reference:

• NICE (July 20180. Brain tumours (primary) and brain metastases in adults
• Greenberg H, Chandler WF, Sandler HM. Brain tumors. Oxford University Press, USA. (1999) ISBN:019512958X
• Parizel PM, Carpentier K, Van Marck V et-al. Pneumosinus dilatans in anterior skull base meningiomas. Neuroradiology. 2013;55 (3): 307-11. doi:10.1007/s00234-012-1106-9
• Lee JH. Meningiomas. Springer. (2008) ISBN:1846287847