March 2018 SPIE Digital Library
Cochlear implants (CIs) are standard treatment for patients who experience sensorineural hearing loss. Although these devices have been remarkably successful at restoring hearing, it is rare to achieve natural fidelity, and some patients experience poor outcomes. Our group has developed image-guided CI programming techniques (IGCIP), in which image analysis techniques are used to locate the intra-cochlear position of CI electrodes to determine patient-customised settings for the CI processor. Clinical studies have shown that IGCIP leads to significantly improved outcomes. A crucial step is the localisation of the electrodes, and rigorously quantifying the accuracy of our algorithms requires dedicated datasets. In this work, we discuss the creation of a ground truth dataset for electrode position and its use to evaluate the accuracy of our electrode localisation techniques. Our final ground truth dataset includes 26 temporal bone specimens that were each implanted with one of four different types of electrode array by an experienced otologist. The arrays were localised in conventional CT images using our automatic methods and manually in high resolution μCT images to create the ground truth. The conventional and μCT images were registered to facilitate comparison between automatic and ground truth electrode localisation results. Our technique resulted in mean errors of 0.13mm in localising the electrodes across 26 cases.