Extra-axial mass in the right cerebellopontine angle. The lesion has low to intermediate signal on T2 weighted images and intermediate T1 signal. There is homogeneous enhancement post administration of contrast. There is a possibility of peripheral nonenhancing cystic elements around the more solid enhancing lesion. The lesion bulges into the porus acousticus which appears mildly expanded.
On the high resolution FIESTA images the nerves in the internal acoustic meatus can be seen separately to the mass. The superior aspect of the lesion abuts the undersurface of the tentorium with a possible dural tail in this region.
Laterally the lesion abuts the petrous ridge, extending to the region of the jugular foramen.
There is moderate oedema in the adjacent cerebellar hemisphere and there is moderate mass effect on the right middle cerebral peduncle. Compressed vessels are seen around the lesion. There is distortion of the fourth ventricle and mild hydrocephalus seen involving the lateral and third ventricles.
Conclusion: Right cerebellopontine angle mass with moderate local mass effect. The differential diagnosis is between meningioma and vestibular schwannoma, with meningioma slightly favoured on the imaging appearance but both lesions remain in the differential diagnosis.