Cone-Beam Computerized Tomography in Cochlear Implant Surgery

Marije de Jong 1 Chen Nadler Ruth Eliahou 3 Michal Kaufman
1Department of Otolaryngology and Head and Neck Surgery, Hadassah Hebrew University Medical Center, Israel
2Oral maxillofacial imaging unit, Oral Medicine Department, the Hebrew University, Hadassah School of Dental Medicine, Israel
3Department of Radiology, Hadassah Hebrew University Medical Center, Israel

PURPOSE: Imaging work-up consisting of Conventional Multi Detector Computed Tomography (MDCT) providing detailed pre-operative anatomy of osseous middle and inner ear structure and the mastoid has become routine for most surgical procedures in this area. It is also the best tool to evaluate middle ear and mastoid pathology in patients with implanted hearing devices or to confirm implant localization in cases of CI failure. Recently at Hadassah Hospital a shift is made to Cone Beam Computerized Tomography (CBCT) as a low-dose imaging technique which uses a cone-shaped x-ray beam to demonstrate high contrast bony structures in the maxillofacial region.

METHODS: We discuss demographics and referral reasons for cases in which CBCT was used at our institution. Demonstrating CBCT scans selected images which show pre-operatively, specific landmarks and pathology and post-operatively, the location of the CI. We evaluated CBCT based on an anatomical scoring system and compare the results to conventional MDCT.

RESULTS: MDCT and or CBCT scans from 10 patients that were implanted with a cochlear hearing device were scored by a radiologist and otolaryngologist. Post-operative CBCT showed precise localization of the CI in all cases and outcomes were relatively similar to MDCT.

CONCLUSION: CBCT provides excellent anatomic evaluation of the middle and inner ear and mastoid in the pre-and post-operative setting. It provides precise localization of the CI post operatively, including implant depth or tip fold over, which is important in CI failures. CBCT has considerable lower radiation dose and should be considered an important alternative for MDCT.

Marije de Jong
Marije de Jong