Cerebellopontine Angle Cisterns

MRI scans demonstrate five typical CPA pathologies with mass effect on the adjacent brainstem and cerebellum.

In Case A, the images show a T2 heterogeneously hyperintense and avidly enhancing mass with cystic components in the CPA with mass effect on the adjacent right cerebellum, middle cerebellar peduncle, and the pons. The mass extends into and expands the internal auditory canal (IAC).

In Case B, the images demonstrate a T1 isointense, T2 isointense, and homogeneously enhancing mass with a dural tail in the left CPA, without obvious extension into the IAC.

Case C features a nonenhancing extraaxial CPA mass with mild mass effect on adjacent structures. The signal intensity of this mass follows the CSF signal on all sequences, including DWI.

Case D features an ill-defined nonenhancing extraaxial left CPA mass insinuating around the nerves and vessels. On the postcontrast axial CT image, the mass is shown to encase the adjacent basilar artery. On the axial T2 image, the mass is shown to encase the traversing left trigeminal nerve. Although the mass is heterogeneously T2 bright and T1 dark, it does not follow CSF signal intensity. The mass is markedly hyperintense on the DWI image.

Case E features a T1 hyperintense nonenhancing mass in the right CPA. Suppression of signal is noted on the fat-saturated sequence. The mass encases the visualized anterior inferior cerebellar artery. The mass is hypointense on DWI.