Precise evaluation of the postoperative cochlear duct length by flat-panel volume computed tomography – Application of secondary reconstructions

Schendzielorz, Philipp; Ilgen, Lukas; Müller-Graff, Franz-Tassilo; Noyalet, Laurent; Völker, Johannes; Taeger, Johannes; Hagen, Rudolf; Neun, Tilmann; Zabler, Simon; Althoff, Daniel; Rak, Kristen

doi:10.1080/14670100.2021.1973208

Cited by 5 publications

(6 citation statements)

References 45 publications

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“…Previous studies have shown that fpVCT SECO with a resolution of 99 μm facilitates highly accurate CDL measurements comparable to an experimental micro-CT scan with 18 μm resolution (6,38). For this reason, no micro-CT scans were part of the present analysis and fpVCT was considered suitable to serve as the reference standard.…”

Section: Discussionmentioning

confidence: 99%

The Photon-Counting CT Enters the Field of Cochlear Implantation: Comparison to Angiography DynaCT and Conventional Multislice CT

Rak,

Spahn,

Müller-Graff

et al. 2024

Otol Neurotol

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Introduction Cochlear duct length (CDL) measurement plays a role in the context of individualized cochlear implant (CI) surgery regarding an individualized selection and implantation of the CI electrode carrier and an efficient postoperative anatomy-based fitting process. The level of detail of the preoperative temporal bone CT scan depends on the imaging modality with major impact on CDL measurements and CI electrode contact position determination. The aim of this study was to evaluate the accuracy of perioperative CDL measurements and electrode contact determination in photon-counting CT (PCCT). Methods Ten human fresh-frozen petrous bone specimens were examined with a first-generation PCCT. A clinically applicable radiation dose of 27.1 mGy was used. Scans were acquired before and after CI insertion. Postoperative measurement of the CDL was conducted using an otological planning software and 3D-curved multiplanar reconstruction. Investigation of electrode contact position was performed by two respective observers. Measurements were compared with a conventional multislice CT and to a high-resolution flat-panel volume CT with secondary reconstructions. Results Pre- and postoperative CDL measurements in PCCT images showed no significant difference to high-resolution flat-panel volume CT. Postoperative CI electrode contact determination was also as precise as the flat-panel CT-based assessment. PCCT and flat-panel volume CT were equivalent concerning interobserver variability. Conclusion CDL measurement with PCCT was equivalent to flat-panel volume CT with secondary reconstructions. PCCT enabled highly precise postoperative CI electrode contact determination with substantial advantages over conventional multislice CT scanners.

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Section: Discussionmentioning

confidence: 99%

The Photon-Counting CT Enters the Field of Cochlear Implantation: Comparison to Angiography DynaCT and Conventional Multislice CT

Rak,

Spahn,

Müller-Graff

et al. 2024

Otol Neurotol

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“…Most of these studies based their AID estimations on preoperative CDL estimations. Thus, underestimating the CDL may lead to an overestimation of AID and result in rather too short electrode choices that do not achieve the aimed CC of 70% to 80% (17,19,34).…”

Section: Discussionmentioning

confidence: 99%

“…Besides possible inaccuracies caused by underlying calculation methods, the prediction error may be influenced by several sources, e.g., imaging artifacts, observer variances, discrepancies in the surgical outcome, or landmark inaccuracies (35,36). It has been shown that there were smaller prediction errors for the CDL and, thus, AID prediction when the image resolution is higher (17,(33)(34)(35). This is consistent with our clinical impression that defining landmarks on the HRCT requires a high resolution of the cochlear borders.…”

Section: Discussionmentioning

confidence: 99%

Accuracy of Preoperative Cochlear Duct Length Estimation and Angular Insertion Depth Prediction

et al. 2023

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Objective In cochlear implantation with flexible lateral wall electrodes, a cochlear coverage of 70% to 80% is assumed to yield an optimal speech perception. Therefore, fitting the cochlear implant (CI) to the patient’s individual anatomy has gained importance in recent years. For these reasons, the optimal angular insertion depth (AID) has to be calculated before cochlear implantation. One CI manufacturer offers a software that allows to visualize the AID of different electrode arrays. Here, it is hypothesized that these preoperative AID models overestimate the postoperatively measured insertion angle. This study aims to investigate the agreement between preoperatively estimated and postoperatively measured AID. Study Design Retrospective cross-sectional study. Setting Single-center tertiary referral center. Patients Patients undergoing cochlear implantation. Intervention Preoperative and postoperative high-resolution computed tomography (HRCT). Main Outcome Measures The cochlear duct length was estimated by determining cochlear parameters (A value and B value), and the AID for the chosen electrode was (i) estimated by elliptic circular approximation by the software and (ii) measured manually postoperatively by detecting the electrode contacts after insertion. Results A total of 80 HRCT imaging data sets from 69 patients were analyzed. The mean preoperative AID estimation was 662.0° (standard deviation [SD], 61.5°), and the mean postoperatively measured AID was 583.9° (SD, 73.6°). In all cases (100%), preoperative AID estimation significantly overestimated the postoperative determined insertion angle (mean difference, 38.1°). A correcting factor of 5% on preoperative AID estimation dissolves these differences. Conclusions The use of an electrode visualization tool may lead to shorter electrode array choices because of an overestimation of the insertion angle. Applying a correction factor of 0.95 on preoperative AID estimation is recommended.

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“…Vergleichende Bestimmungen der CDL mithilfe der 3 D-Rekonstruktion zwischen MSCT, fpVCT und fpVCT SECO mit der als Goldstandard geltenden Micro-CT ergaben, dass Messungen mithilfe der fpVCT SECO die Genauigkeit von denjenigen der Micro-CT erreichen [27]. Auch in postoperativen Evaluationen konnten die sekundären Rekonstruktionen für eine präzise CDL-Messung trotz einliegender Elektrode verwendet werden, auch wenn eine leichte systemische Unterschätzung der postoperativen CDL zu beachten ist [28].…”

Section: Vergleichende Bestimmungen Der CDLunclassified

“…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).…”

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

Müller-Graff¹,

Rak²

2022

Laryngorhinootologie

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Bei Cochlea-Implantationen gewinnt die personalisierte Versorgung zunehmend an Bedeutung. Die Wahl einer für den individuellen Patienten passenden Elektrode könnte das Sprachverstehen verbessern. Die Messung der cochleären Länge ist dabei wichtig: präoperativ für die Wahl der geeigneten Elektrodenlänge und postoperativ, um die korrekte Elektrodenlage zu kontrollieren und ein „anatomisches“ Fitting der Elektrodenkontakte zu ermöglichen.

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Precise evaluation of the postoperative cochlear duct length by flat-panel volume computed tomography – Application of secondary reconstructions

Cited by 5 publications

References 45 publications

The Photon-Counting CT Enters the Field of Cochlear Implantation: Comparison to Angiography DynaCT and Conventional Multislice CT

The Photon-Counting CT Enters the Field of Cochlear Implantation: Comparison to Angiography DynaCT and Conventional Multislice CT

Accuracy of Preoperative Cochlear Duct Length Estimation and Angular Insertion Depth Prediction

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

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