High-resolution computed tomography-based length assessments of the cochlea – an accuracy evaluation

Abstract

Conclusion: The length of the cochlea can be determined with good precision using a 3D-curved multiplanar reconstruction analysis technique and linear reconstruction of the cochlea. The method is not time-consuming and can be applied during clinical routine. Objective: A preoperative prediction of the best cochlear implant electrode length can help reduce the risk of intraoperative cochlear trauma in patients who need to retain residual acoustic hearing for electric-acoustic stimulation or in patients with anatomical anomalies or malformations. The goal of this study was to evaluate the accuracy and reliability of length measurement of the cochlea after linear reconstruction using 3D-curved multiplanar reconstrucion analysis of high resolution computed tomography (CT) scans. Methods: Human cadaveric temporal bone specimens underwent cochlear implantation using custom-made electrodes with two radiopaque markers of a defined length before CTscans were made. Length measurement was performed by four readers and the results were compared to the true value. Inter-reader reliability was calculated. The time needed for analysis was recorded. Results: The mean time needed for analysis of one specimen’s radiologic data was 6.1 (± 3.4) min. The mean deviation of the length measurement from the true value was 0.8 (± 0.7) mm. Inter-reader reliability was excellent (0.76, p = 0.006).

Keywords::

• Multiplanar reconstruction
• cochlear implant
• temporal bone

Acknowledgments

We thank Claude Jolly PhD, Med-El Director of Electrode Design, and Anandhan Dhanasingh (Med-El, Innsbruck, Austria) for development, production and supply of the electrodes used in this study.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.