T2-weighted MR characteristics of internal auditory canal masses.

PURPOSE To determine whether masses of the internal auditory canal are hypointense relative to cerebrospinal fluid, and therefore visible, on fast spin-echo T2-weighted MR images.

METHODS Forty-six patients had 50 masses of the internal auditory canal, identified initially on contrast-enhanced MR images, that were evaluated retrospectively for signal intensity of the mass with respect to cerebrospinal fluid and for visibility of the neural elements within the internal auditory canal on T2-weighted images.

RESULTS Forty-seven of 50 masses were clearly identified on T2-weighted images. Three small abnormalities (2 to 4 mm) were not seen with confidence on T2-weighted images. However, on close inspection of these three masses, the small abnormality on contrast-enhanced MR images corresponded to a hypointense focus on T2-weighted images. All 50 masses were hypointense relative to cerebrospinal fluid on T2-weighted images.

CONCLUSION All masses of the internal auditory canal in this study were hypointense relative to cerebrospinal fluid on T-2 weighted images, and were therefore visible.