TY - JOUR A1 - Taeger, Johannes A1 - Müller-Graff, Franz-Tassilo A1 - Neun, Tilmann A1 - Köping, Maria A1 - Schendzielorz, Philipp A1 - Hagen, Rudolf A1 - Rak, Kristen T1 - Highly precise navigation at the lateral skull base by the combination of flat-panel volume CT and electromagnetic navigation JF - Science Progress N2 - This study aimed to evaluate the feasibility and accuracy of electromagnetic navigation at the lateral skull base in combination with flat panel volume computed tomography (fpVCT) datasets. A mastoidectomy and a posterior tympanotomy were performed on 10 samples of fresh frozen temporal bones. For registration, four self-drilling titanium screws were applied as fiducial markers. Multi-slice computed tomography (MSCT; 600 µm), conventional flat panel volume computed tomography (fpVCT; 466 µm), micro-fpVCT (197 µm) and secondary reconstructed fpVCT (100 µM) scans were performed and data were loaded into the navigation system. The resulting fiducial registration error (FRE) was analysed, and control of the navigation accuracy was performed. The registration process was very quick and reliable with the screws as fiducials. Compared to using the MSCT data, the micro-fpVCT data led to significantly lower FRE values, whereas conventional fpVCT and secondary reconstructed fpVCT data had no advantage in terms of accuracy. For all imaging modalities, there was no relevant visual deviation when targeting defined anatomical points with a navigation probe. fpVCT data are very well suited for electromagnetic navigation at the lateral skull base. The use of titanium screws as fiducial markers turned out to be ideal for comparing different imaging methods. A further evaluation of this approach by a clinical trial is required. KW - electromagnetic navigation KW - fpVCT KW - fiducial registration error KW - lateral skull base KW - otology KW - cochlear implantation Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-250268 SN - 2047-7163 VL - 104 IS - 3 ER - TY - JOUR A1 - Müller-Graff, Franz-Tassilo A1 - Ilgen, Lukas A1 - Schendzielorz, Philipp A1 - Voelker, Johannes A1 - Taeger, Johannes A1 - Kurz, Anja A1 - Hagen, Rudolf A1 - Neun, Tilmann A1 - Rak, Kristen T1 - Implementation of secondary reconstructions of flat-panel volume computed tomography (fpVCT) and otological planning software for anatomically based cochlear implantation JF - European Archives of Oto-Rhino-Laryngology N2 - Purpose For further improvements in cochlear implantation, the measurement of the cochlear duct length (CDL) and the determination of the electrode contact position (ECP) are increasingly in the focus of clinical research. Usually, these items were investigated by multislice computed tomography (MSCT). The determination of ECP was only possible by research programs so far. Flat-panel volume computed tomography (fpVCT) and its secondary reconstructions (fpVCT\(_{SECO}\)) allow for high spatial resolution for the visualization of the temporal bone structures. Using a newly developed surgical planning software that enables the evaluation of CDL and the determination of postoperative ECP, this study aimed to investigate the combination of fpVCT and otological planning software to improve the implementation of an anatomically based cochlear implantation. Methods Cochlear measurements were performed utilizing surgical planning software in imaging data (MSCT, fpVCT and fpVCT\(_{SECO}\)) of patients with and without implanted electrodes. Results Measurement of the CDL by the use of an otological planning software was highly reliable using fpVCT\(_{SECO}\) with a lower variance between the respective measurements compared to MSCT. The determination of the inter-electrode-distance (IED) between the ECP was improved in fpVCT\(_{SECO}\) compared to MSCT. Conclusion The combination of fpVCT\(_{SECO}\) and otological planning software permits a simplified and more reliable analysis of the cochlea in the pre- and postoperative setting. The combination of both systems will enable further progress in the development of an anatomically based cochlear implantation. KW - interelectrode-distance KW - Cochlear duct length KW - Cochlear planning software KW - fpVCT KW - secondary reconstruction KW - MSCT Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-266798 SN - 1434-4726 VL - 279 IS - 5 ER - TY - THES A1 - Ilgen, Lukas T1 - Ermittlung cochleärer Längen- und Winkelmaße mittels Flachdetektor-Volumen-Computertomographie - Evaluation der Anwendung sekundärer Rekonstruktionen T1 - Analysis of the cochlear duct and angular length by flat-panel volume computed tomography - Evaluation of the use of secondary reconstructions N2 - Für die Cochlea-Implantat-Versorgung ist die Kenntnis der individuellen Anatomie der Hörschnecke im perioperativen Kontext essenziell, um ein suffizientes audiologisches Resultat sicherzustellen. Ein akkurates Verfahren hierfür stellt die 3D multiplanare Rekonstruktion (3D-curved MPR) in Schnittbildgebung dar. Notwendige Voraussetzung ist jedoch eine hinreichende Bildqualität. In dieser Arbeit wurde das Augenmerk auf die sekundäre Rekonstruktion von Primärdatensätzen der Flachdetektor-Volumen-Computertomographie (fpVCTSECO) gerichtet. Diese bietet nämlich die Möglichkeit, die Bildqualität zu steigern, ohne jedoch eine als kritisch einzuschätzende Dosissteigerung in Kauf nehmen zu müssen. Es konnte gezeigt werden, dass es für die Messung der Länge von 2 Schneckenwindungen (2TL), der gesamten cochleären Länge (CDL) und dem Winkelmaß (AL) mittels 3D-curved MPR in der fpVCT keinen signifikanten Unterschied gegenüber der Mehrschicht-CT gibt. In beiden Modalitäten wurden alle drei Parameter gegenüber der Referenzbildgebung micro-CT deutlich unterschätzt. Durch die fpVCTSECO war es möglich, die Genauigkeit der Messungen zu steigern und den Werten der Referenz anzunähern. Lediglich für AL muss eine geringfügige systematische Unterschätzung beachtet werden. Postoperativ zeigte sich mit einliegendem Elektrodenträger für 2TL eine ebenso präzise Messung wie präoperativ ohne. Jedoch wurde die CDL um circa 0,5 - 0,7 mm unterschätzt. Ursächlich hierfür dürften vor allem Metallartefakte gewesen sein. Auch wenn die 3D-curved MPR in Kombination mit der fpVCTSECO postoperativ zur Visualisierung der räumlichen Beziehung von Elektrodenträger, Modiolus und ossärer lateraler Wand sehr gut geeignet war, so muss sich der Einfluss dieser Diskrepanz für die audiologische Anpassung in Zukunft erst noch zeigen. N2 - Knowledge of the individual anatomy of the cochlea is essential for optimal hearing perception outcomes in cochlear implantation. 3D-curved multiplanar reconstruction (3D-curved MPR) in cross-sectional imaging is a very precise method. But for this purpose, high-resolution quality is an indispensable requirement. In this study, special attention was turned to secondary reconstruction of primary data of flat-panel volume computed tomography (fpVCTSECO). This postprocessing application provides an opportunity to increase image quality. Beneficially, there is no need of applying additional radiation dose, which should always be regarded critically. For the cochlear duct length (CDL), the two-turn length (2TL) and the angular length (AL), there were no statistically significant differences between fpVCT and multislice computed tomography applying 3D-curved MPR. In contrast to reference imaging modality micro-CT, a clinically relevant underestimation of all three parameters was evident. Using fpVCTSECO, precision of measurements could be increased significantly. It was possible to reach the accuracy of the reference. Only concerning AL, a slight and systematic underestimation must be considered. Postoperatively, after insertion of the electrode into the cochlea, measurement of 2TL was as precise as the preoperative one. For CDL, an underestimation of approximately 0.5 - 0.7 mm was evident. Most likely, this fact was linked to postoperative metal artifacts. Even though 3D-curved MPR in combination with fpVCTSECO is a great possibility to visualize the spatial relation of electrode, modiolus and bony lateral wall, the influence of this difference on audiological fitting procedures has still to be investigated in future studies. KW - Cochlea KW - Anatomie KW - Computertomografie KW - Cochlear-Implantat KW - Dreidimensionale Rekonstruktion KW - cochlear duct length KW - CDL KW - MSCT KW - fpVCT KW - CI Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-327945 ER -