Fig. 14.

Vascular lesions. A patient with progressive, pulsatile tinnitus, some hearing loss and a subtle facial nerve deficit was referred for imaging. MRI revealed a large, vividly enhancing mass with intralesional flow voids (a: axial T1; b: coronal post-contrast T1) at the fundus of the IAC, extending into the temporal fossa and middle ear. On CT, destruction of the surrounding bone is seen (arrows in c). Biopsy showed the lesion to be a hemangiopericytoma. This tumour is rarely seen intracranial and arises from pericytes, surrounding capillaries, in the meninges [29]. Only a few cases have been reported in the temporal bone. Patient 2 shows the typical imaging appearance of an arteriovascular malformation: flow voids due to enlarged feeding and draining vessels are present in the pons, CPA and prepontine cistern on T2 (d) with enhancement on post-contrast T1 (e)