Computer-aided Surgical Planning for Implantation of Hearing Aids Based on CT Data in a VR Environment

Abstract

A study was undertaken to assess the feasibility of a preoperative fitting test for an implantable hearing aid in a virtual reality (VR) environment. High-resolution spiral computed tomography (CT) of the mastoid bone was performed, and the results of a mastoidectomy were simulated with manual segmentation on a standard medical workstation. CT was also performed on a temporal bone specimen obtained at real mastoidectomy, and the bone margins were segmented automatically with threshold-based techniques. A triangulated surface representation of the bone structures including the mastoid cavity was generated. These data as well as the computer-aided design (CAD) files of the medical devices were transferred into a VR environment. The CAD components of the hearing aid were manipulated to simulate the surgical implantation procedure. Merging CAD data of an implantable hearing aid with CT data of the temporal bone in a VR environment was shown to be a feasible method of providing three-dimensional information for the presurgical determination of fit and mountability. Advances in hardware and software are expected to improve the usability of this method. Although clinical studies are needed, these results may serve as an impetus for exploring the use of low-cost, widely available VR computer equipment in a potentially broad field of clinical applications.

Comparison of the Implantability of Electronic Hearing Devices in a Virtual Reality Planning Environment and in Human Temporal Bones

“…Using Schueller's X-ray alone, there may be a risk of attempting impossible implantations and judgment would be difficult in problematic cases. Those inherent deficits, however, may be overcome using the presented VR implantation simulation technique (25).…”

Preoperative planning of a complete mastoidectomy: semiautomatic segmentation and evaluation

“…On the other hand, as we stated in the introduction, our application aims at replacing the manual milling process involved in the conventional surgery by a robotic-assisted milling. For a successful milling of the inner contents of the mastoid, an accurate delineation of the interior spongious bone is required [1]. To the best of our knowledge, no automatic approach has been proposed for the segmentation of this structure.…”

“…Despite major technical improvements in recent years, these types of hearing aid devices still have several technical limitations and, for several reasons, are not helpful for every patient case [1,2]. Therefore, totally implantable hearing aid devices have been introduced that allow an amplified auditory signal to be transmitted directly to the middle ear [3,4].…”

3D-Darstellung des Mittelohres mittels computergestützter Nachverarbeitung helikaler Mehrschicht-CT-Daten

“…Die 3D-Darstellung erleichtert allerdings das Erlangen einer 3D-Vorstellung, da sie Informationen über die räumliche Beziehung der anatomischen Strukturen zueinander bündelt und so der Analyseprozess vereinfacht wird [15]. Die computergestützte 3D-Nachverarbeitung von CT-Daten ist daher sowohl in der Diagnostik als auch in der präoperativen Planung bei komplexen Mittelohrpathologien hilfreich [16].…”