Lagekontrolle von Cochlear Implantaten mittels Digitaler Volumentomographie. Eine vergleichende histologische und radiologische Untersuchung an anatomischen Felsenbeinpräparaten

Introduction: For development of cochlear implant devices, postoperative follow-up, handling of complications and quality control, radiological evaluation of the position of implanted Cochlear Implant (CI) devices is extremely important. Digital Volume Tomography (DVT; 3D Accu-I-Tomo, Morita, Kyoto, Japan) is a flat panel computed tomography system which was first introduced for use in dental medicine. Especially in imaging of the middle and inner ear and regarding image quality, slice thickness, and radiation dose, it showed superiority over Computed Tomography (CT) in the past. Objective: To evaluate if DVT is a appropriate method for postoperative imaging of CI-patients and to identify the exact position of the implant array within the cochlear by multiple measurements. Methods: 13 formalin fixated temporal bone specimens were implanted with a Contour Advance (Cochlear, Sydney, Australia) and scanned in DVT. To determine the exact electrode position temporal bones were ground histological and acted as referee for exact measurements. Analysis was performed using DVT software idixel, Adobe Photoshop, and a stereomicroscope with measurement software. Moreover analysis criteria used for conventional CT scans were applied to evaluate the electrode position. Position measurements in DVT and grindings were statistically compared using Bland-Altman-Method to proof the agreement between measurements. Results showed a good agreement between DVT scans and histological reference. The mean difference between measurements in DVT and grindings was -36.26 µm. Conclusion: DVT offers a supreme image quality with low artefacts and is a good instrument for position evaluation after cochlear implantation.