Implementation of secondary reconstructions of flat-panel volume computed tomography (fpVCT) and otological planning software for anatomically based cochlear implantation

Abstract

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 (fpVCTSECO) 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 fpVCTSECO) of patients with and without implanted electrodes. Results Measurement of the CDL by the use of an otological planning software was highly reliable using fpVCTSECO 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 fpVCTSECO compared to MSCT. Conclusion The combination of fpVCTSECO 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.

Cochlear Duct Length Measurements in Computed Tomography and Magnetic Resonance Imaging Using Newly Developed Techniques

“…But in clinical imaging, there is a dependence of the CDL on the resolution. The CDL measured in flat‐panel volume CT (resolution, 100 µm) resulted in a significantly longer CDL when compared with standard flat‐panel volume CT (460 µm) and CT (600 µm) 34 . Furthermore, there was a tendency toward a longer CDL in CT data sets with higher resolution 35 .…”

“…The CDL measured in flat-panel volume CT (resolution, 100 mm) resulted in a significantly longer CDL when compared with standard flat-panel volume CT (460 mm) and CT (600 mm). 34 Furthermore, there was a tendency toward a longer CDL in CT data sets with higher resolution. 35 To exclude the variability of the resolution, the slice thickness was set to 600 mm for both MRI and CT in the present study.…”

Vermessung der Cochlea mittels eines Tablet-basierten Softwarepakets: Einfluss der Bildgebungsmodalität und des Untersucherhintergrunds

“…So ergeben sich in der Synchrotron-Phasenkontrast-Bildgebung (SR-PCI), der aktuell höchstauflösenden Methode, Werte für die CDL OC von 32,1 mm und CDL LW von 39,0 mm [ 20 ]. Messungen anhand von Flachdetektor-Volumen- Computertomographien (fpVCT) zeigen eine CDL OC von 34,63 ± 1,47 mm [ 27 ]. Die CDL OC ist dabei in Zusammenhang mit der Greenwood-Funktion für die Frequenzbestimmung von zentraler Bedeutung [ 16 ].…”

“…Dazu sind fpVCT in der postoperativen Lagekontrolle weniger artefaktanfällig [ 19 ]. Optimale Messbedingungen können sich dabei aus einer Kombination aus sekundär rekonstruierten fpVCT und der Nutzung der Software OTOPLAN ergeben [ 27 ]. Die MRT erfolgt zum Ausschluss einer retrocochleären Pathologie, der Beurteilung des Hörnervs und der Flüssigkeitsfüllung der Cochlea sowie zur Detektion bindegewebiger Obliterationen und früher Stadien der Ossifikation [ 38 ].…”

Cochlea-Implantation: Bestimmung der Cochlear Duct Length (CDL)

“…2b).Postoperatives ProzedereDie postoperativ durchgeführte radiologische Lagekontrolle kann auch dazu genutzt werden, die Cochlea zu vermessen und die CDL zu berechnen. Untersuchungen haben gezeigt, dass eine höher auflösende Bildgebung hierfür insbesondere bei einliegender Elektrode von Vorteil ist und die cochleären Parameter trotz möglicher Artefakte weniger verfälscht werden[28,35].Aus den CDL-Berechnungen kann dann die Lage jedes Elektrodenkontakts individuell bestimmt und eine 3-dimensionale Darstellung der inserierten Elektrode erreicht werden (▶ Abb. 4).…”