The 25 th International Conference on Auditory Display (ICAD 2019) 23–27 June 2019, Northumbria University AUDIO GUIDANCE FOR OPTIMAL PLACEMENT OF AN AUDITORY BRAINSTEM IMPLANT WITH MAGNETIC NAVIGATION AND MAXIMUM CLINICAL APPLICATION ACCURACY Ognjen Miljic, Zoltan Bardosi, Wolfgang Freysinger 4D Visualization Laboratory University ENT Hospital Medical University of Innsbruck, Austria ognjen.miljic@student.i-med.ac.at ABSTRACT For patients with ineffective auditory nerve and complete hearing loss, Auditory Brainstem Implant (ABI) [1] presents diversity of hearing sensations to help with sound consciousness and commu- nication. At present, during the surgical intervention, surgeons use pre- operative patient images to determine optimal position of an ABI on cochlear nucleus on brainstem. When found, the optimal posi- tion is marked and mentally mapped by the surgeon; Next, the sur- geon tries to locate the optimal position in patient’s head again and places the ABI. The aim of this project is to provide the surgeon with maximum clinical application accuracy guidance to store the optimal position for the implant, and to provide intuitive audio guidance for positioning the implant at the stored optimal posi- tion. By using three audio methods, in combination with visual in- formation on Image-Guided Surgery (IGS), surgeon should spend less time looking at the screen, and more time focused on the pa- tient. 1. INTRODUCTION This work presents a dynamic audio feedback system for po- sitional guidance in real-time during surgical procedure of ABI placement. ABI is a solution for individuals with hearing loss due to an ineffective auditory nerve, and it is implanted on cochlear nucleus which is located on the anterior part of the brainstem. By- passing both, the inner ear and the auditory nerve ABI stimulates the cochlear nucleus and provides the patient with a hearing sen- sation, which can improve communication and consciousness. At present, during the surgical intervention, surgeons use pre- operative patient images, usually including Magnetic Resonance Imaging (MRI) and/or Computed Tomography (CT), to determine the optimal position for the ABI on the cochlear nucleus. The main purpose of this project is: • Providing support for better spatial accuracy in preoperative planning of the ABI implementation • Remembering the spatial position that is localised with an Electronic Auditory Brainstem Response (E-ABR) This work is licensed under Creative Commons Attribution Non Commercial 4.0 International License. The full terms of the License are available at http://creativecommons.org/licenses/by-nc/4.0 • Final positioning of the ABI with maximum possible accu- racy in the appropriate position During the IGS, location of the surgical probe is visualized by tracking and mapping its location to the pre-operative model of patient anatomy. Nevertheless, the main issue during IGS is that the surgeon often has to divert attention from patient to the screen (navigation system). By using auditory cues, surgeon should spend less time looking at the screen and more time focused on the pa- tient. Combining audio guidance signals with existing IGS visual information, may result in greater accuracy when locating a given target in a 3D volume [2]. 2. METHODS The proposed audio guidance system is comprised of the follow- ing elements: (i) NavABI software for IGS developed in house - basis of this software is Rhinospider Technology [3] developed by the University Hospital for ENT at the Medical University of Inns- bruck (ii) custom NavABI audio plug-in software developed using OpenAL(Open Audio Library) software interface to audio hard- ware (iii) Electromagnetic Tracking System - Aurora NDI [4] (iv) SoundWear Companion speaker BOSE - 2.0 wearable Bluetooth speaker for presenting audio guidance. In this work three different types of audio guidances are used. The main difference between following methods lies in complex- ity and cognitive effort used to understand audio signals. From the simplest, Pulsed Tone sonification distance guidance that most of the participants are familiar with (car parking assistant), over Sig- nal To Noise sonification (participants should recognize it as tun- ing the old radio) which also represent distance information, to the method designed for guidance in all three axes of Euclidean space by using three different perceptions of the sound Pitch, Loudness and Duration. To avoid perceptual inaccuracies on the part of the listener, amplitude scale (frequency as a function of amplitude) according to the Fletcher-Munson Curve [5] is taken into account for each tone in all three methods. 2.1. Pitch, Loudness and Duration Sonification (PLD) This solution is based on the idea that three different perceptions of the sound (Pitch, Loudness and Duration) guides the surgeon along the X, Y and Z axes of the operating table. https://doi.org/10.21785/icad2019.075 313