Cochlear helix and duct length identification – Evaluation of different curve fitting techniques

Schurzig, Daniel; Timm, Max; Lexow, G. Jakob; Majdani, Omid; Lenarz, Thomas; Rau, Thomas S.

doi:10.1080/14670100.2018.1460025

Cited by 40 publications

(70 citation statements)

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“…Since the first (or basal) turn of the cochlea is the most visible part of the cochlea in clinical computed tomography (CT) images (see Figure 1 ), spiral equations were developed that rely on the measurement of basal turn parameters. 11…”

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confidence: 99%

A Novel Method for Clinical Cochlear Duct Length Estimation toward Patient‐Specific Cochlear Implant Selection

et al. 2018

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ObjectiveIn the field of cochlear implantation, the current trend toward patient-specific electrode selection and the achievement of optimal audiologic outcomes has resulted in implant manufacturers developing a large portfolio of electrodes. The aim of this study was to bridge the gap between the known variability of cochlea length and this electrode portfolio.DesignRetrospective analysis on cochlear length and shape in micro–computed tomography and cone beam computed tomography data.SettingTertiary care medical center.Subjects and MethodsA simple 2-step approach was developed to accurately estimate the individual cochlear length as well as the projected length of an electrode array inside the cochlea. The method is capable of predicting the length of the cochlea and the inserted electrode length at any specific angle. Validation of the approach was performed with 20 scans of human temporal bones (micro–computed tomography) and 47 pre- and postoperative clinical scans (cone beam computed tomography).ResultsMean ± SD absolute errors in cochlear length estimations were 0.12 ± 0.10 mm, 0.38 ± 0.26 mm, and 0.71 ± 0.43 mm for 1, 1.5, and 2 cochlea turns, respectively. Predicted insertion angles based on clinical cone beam computed tomography data showed absolute deviations of 27° ± 18° to the corresponding postoperative measurements.ConclusionWith accuracy improvements of 80% to 90% in comparison with previously proposed approaches, the method is well suited for the use in individualized cochlear implantation.

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confidence: 99%

A Novel Method for Clinical Cochlear Duct Length Estimation toward Patient‐Specific Cochlear Implant Selection

et al. 2018

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“…The fundamental data used for the investigation was previously presented in two earlier studies from our group [6,15]. It consists of 15 micro CT datasets in which cross sections of scala tympani (ST), scala vestibuli (SV), basilar membrane (BM) and helicotrema (HT) region were manually segmented using a custom software tool specifically designed for this task [32].…”

Section: Geometrical Averaging Of Scala Tympani Contoursmentioning

confidence: 99%

“…In terms of sufficiently accurate modelling, studies on the insertion forces occurring during electrode array insertion are most likely the most demanding investigations. The artificial cochlea models (ACM) used within these investigations must reliably feature the Life 2021, 11, 373 2 of 11 spiral shape of the cochlea itself [15][16][17][18], but also accurately represent the outer shape of the ST which interacts with the array during insertion [11]. Furthermore, these models should be filled with a fluid which mimics the perilymph in terms of viscosity and the frictional properties of the array sliding along the ST walls during insertion.…”

Section: Introductionmentioning

confidence: 99%

Uncoiling the Human Cochlea—Physical Scala Tympani Models to Study Pharmacokinetics Inside the Inner Ear

Schurzig

Fröhlich

Raggl

et al. 2021

Life

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In the field of cochlear implantation, artificial/physical models of the inner ear are often employed to investigate certain phenomena like the forces occurring during implant insertions. Up to now, no such models are available for the analysis of diffusion processes inside the cochlea although drug delivery is playing an increasingly important role in this field. For easy access of the cochlea along its whole profile, e.g., for sequential sampling in an experimental setting, such a model should ideally be longitudinal/uncoiled. Within this study, a set of 15 micro-CT imaging datasets of human cochleae was used to derive an average representation of the scala tympani. The spiral profile of this model was then uncoiled along different trajectories, showing that these trajectories influence both length and volume of the resulting longitudinal model. A volumetric analysis of the average spiral model was conducted to derive volume-to-length interrelations for the different trajectories, which were then used to generate two tubular, longitudinal scala tympani models with volume and length properties matching the original, spiral profile. These models can be downloaded for free and used for reproducible and comparable simulative and experimental investigations of diffusion processes within the inner ear.

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“…The goal of the present study was to evaluate the variability of modiolar parts of the cochlea and compare it to the variations observed with measures obtained from the lateral wall. Three groups of specimen were compared: corrosion casts 8 , micro computer tomography (µCT) datasets 35 and clinical measurements obtained with cone beam computer tomography (CT) in a clinical setting ( 36 . The data show that the variability in cochlear microanatomy is similar in modiolar and lateral portions of the cochlea.…”

Section: Introductionmentioning

confidence: 99%

Variations in Microanatomy of the Human Modiolus: Implications for Cochlear Implants

Pietsch

Schurzig

Salcher

et al. 2021

Preprint

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Human cochlear anatomy is highly variable. The phenomenon has been first described qualitatively, followed by a quantitative variability assessment with detailed anatomical models of the human cochlea. However, all previous work focused on lateral cochlear wall. Few information is available on the variability of the modiolar wall. Modiolar variability, likely determined by variability in the spiral ganglion, provides key information on when during ontogenesis the individual cochlear morphology is established: before and/or after neuronal structures are formed. In the present study we analyzed 108 corrosion casts, 95 clinical cone beam computer tomographies and 15 µCTs of human cochleae and observed modiolar variability of similar and larger extent than the lateral wall variability. Lateral wall measures correlated with modiolar wall measures significantly. ~49% of the variability has a common cause, very likely established already during the time when the spiral ganglion is formed. Proximity of other neuronal and vascular structures, defining the remaining variability in scalar spaces, are determined later in ontogenesis, when the scalae are formed. The present data further allows implications for perimodiolar cochlear implants and their tip fold-overs. In particular, the data demonstrate that tip fold-overs of preformed implants likely result from the morphology of the modiolus (with radius changing from base to apex), and that optimal cochlear implantation of perimodiolar arrays cannot be guaranteed without an individualized surgical technique.

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Cochlear helix and duct length identification – Evaluation of different curve fitting techniques

Abstract: Spline curve reconstructions appear to be the best option for anatomical diagnostics in clinical practice. Retrospective studies can be performed to further evaluate model-based evaluations.

Cited by 40 publications

References 46 publications

A Novel Method for Clinical Cochlear Duct Length Estimation toward Patient‐Specific Cochlear Implant Selection

A Novel Method for Clinical Cochlear Duct Length Estimation toward Patient‐Specific Cochlear Implant Selection

Uncoiling the Human Cochlea—Physical Scala Tympani Models to Study Pharmacokinetics Inside the Inner Ear

Variations in Microanatomy of the Human Modiolus: Implications for Cochlear Implants

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