A 47-year-old woman presenting with sudden onset of hearing loss. Ax, axial; Cor, coronal; FIESTA , fast imaging employing steady-state acquisition.

A 75-year-old man presenting with progressive left hearing loss, left facial numbness, and worsening balance. Ax, axial; Cor, coronal; FIESTA , fast imaging employing steady-state acquisition.

A 52-year-old woman presenting with new onset of coordination disturbance, worsening headache, and dizziness. Ax, axial; DWI, diffusion-weighted imaging.

A 32-year-old woman presenting with gait imbalance, falls, and blurred vision. Ax, axial; CT, computed tomography; DWI, diffusion-weighted imaging; Sag, sagittal.

Incidental finding in a 58-year-old woman. Ax, axial; Cor, coronal; DWI, diffusion-weighted imaging; FS , fat saturated.


  • 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.


Case A

Vestibular schwannoma with cystic components

Case B

Meningioma with a typical dural tail

Case C

Arachnoid cyst

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