A cochlear implant, sometimes called a "bionic ear," allows patients with congenital hearing loss to bypass the problem and again perceive sound. Surgeons conduct radiologic studies using either an MRI or CT scan prior to implantation to determine abnormalities in the inner ear, conditions of related nerves and any obstructions in the ear ducts.

In the first head-to-head comparison, a research team led by Dr. Peter Roland, professor and chairman of otolaryngology, found that MRIs offered a more detailed view and better information on specifics. The results are reported online in the journal Otology & Neurotology.

"Thirty percent of patients we evaluated had abnormalities on MRI we would not have seen on CT, whereas in none of the patients were there findings on CT that we wouldn't have seen on MRI," said Dr. Roland, the study's senior author.

Some of those specifics help determine which surgical technique is used, the specific electrode arrays employed and can impact in which ear the cochlear implant is placed.

"In half the patients who had abnormalities on MRI that weren't seen on CT, it made a difference in which ear was selected for implantation," he said.

In the study, researchers evaluated the records of 56 implantation candidates, imaging 112 temporal bones. CT scans found as few as 6 percent of certain abnormalities.

On average, testing and anesthesiology costs for MRIs are 40 percent to 50 percent higher than those associated with CTs.

The implant is essentially a bionic ear, Dr. Roland said. The ear normally translates sound waves a mechanical form of energy to electrical impulses, which the brain perceives as sound. Implants bypass the dysfunctional inner ear and mirror the natural mechanical-to-electrical-impulse tr
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Contact: Russell Rian
Russell.rian@utsouthwestern.edu
214-648-3404
UT Southwestern Medical Center
11-Jan-2006