MRI findings of intracranial cystic meningiomas.

AIM: To report the magnetic resonance imaging (MRI) features of intracranial cystic meningiomas and compare these features in intra- and peritumoural cyst groups.
MATERIALS AND METHODS: Fourteen cases of peritumoural cystic meningiomas were compared with 18 cases of intratumoural cystic meningiomas. All patients were examined using non-enhanced and contrast-enhanced MRI. Tumour location, tumour size, signal intensity, enhancement characteristics, and cystic changes were assessed. The MRI features were compared between the intra- and peritumoural cyst groups.
RESULTS: Most cystic meningiomas comprised two or more cysts. The solid parts of the tumours showed moderate or marked enhancement after the injection of contrast material. An enhanced cyst wall was found in six out of 14 cases in the peritumoural cyst group, but not in the intratumoural cyst group. Peritumoural cystic meningiomas were predominately located in the cerebral falx, whereas the intratumoural cystic meningiomas were predominantly found in frontal convexity (X(2)=7.434, p=0.024). The cysts were larger in the peritumoural cyst group than in the intratumoural cyst group (t=5.274, p=0.0258). Peritumoural oedema was more commonly found in the intratumoural cyst group (X(2)=6.863, p=0.008). Cystic meningiomas with solid parts located inside the cyst are reported for the first time.
CONCLUSION: Cystic meningiomas, although uncommon, should be differentiated from other cystic intracranial lesions. Peri- and intratumoural cystic meningiomas have distinct MRI features. The present study provides the first report of two lesions with solid parts located inside the cyst, as well as one lesion with a calcified solid nodule and haemorrhage within the cyst.