These tumors are not malignant, but they do require surgery for removal. The surgical procedures will almost certainly leave the patient will hearing loss in that ear.
I work on a GE scanner that uses a 3D FIESTA sequence, (3D Fast imaging with steady state), non contrast to better visualize the IAC's. An acoustic neuroma will show up "dark" on the images. The 3D FIESTA is also used to visualize other cranial nerves well, not just the VII and VIII. The following website has done a study of the 3D FIESTA images vs. the FSE T2 . http://www.dirjournal.org/pdf/pdf_DIR_115.pdf
I have provided some images showing an acoustic neuroma almost entirely intracanalicular in the patients right IAC.
MRI T2 Axial IAC's
MRI 3D FIESTA Axial
MRI Coronal T1 Pre contrast
MRI T1 Axial pre contrast
MRI T1 Axial post contrast
MRI T1 Coronal post contrast