Imaging cochlear implantation with round window insertion in human temporal bones and cochlear morphological variation using high-resolution cone beam CT

Advancing Cochlear Implant Programming: X-ray Guided Anatomy-Based Fitting

BACKGROUND

Anatomy-based fitting (ABF) is a new research area in the field of cochlear implants (CIs). Despite the reported benefits and acceptable levels of ABF among CI recipients, some limitations remain, like the postoperative computed tomography (CT) scan, which is preferred for confirming electrode array insertion.

OBJECTIVE

This study aimed to investigate the feasibility of using plain film radiography (X-ray) for postoperative electrode detection and for building ABF as an alternative to CT.

METHODS

A total of 53 ears with CI were studied. All cases had routine post-insertion X-rays in the cochlear view and additionally underwent postoperative CT. The insertion angles and center frequencies measured by two independent observers were compared for each imaging modality. The angular insertion depth and center frequencies resulting from the X-ray and CT scans were then compared.

RESULTS

No significant differences were observed between the X-ray- and CT-measured angles for the electrode contacts. Radiographic measurements between the two readers showed an almost perfect (≥0.8) or substantial (0.71) intraclass correlation coefficient along the electrode contacts. X-ray images showed a mean difference of 4.7 degrees from CT. The mean semitone deviation of the central frequency between the CT and X-ray images was 0.6.

CONCLUSIONS

X-ray imaging provides a valid and easy-to-perform alternative to CT imaging, with less radiation exposure and lower costs. The radiographs showed excellent concordance with the CT-measured angular insertion depth and consequently with the central frequency for most electrode contacts. Therefore, plain X-ray could be a viable alternative in building ABF for the CI recipients.

Electrode-Modiolus Distance Affects Speech Perception for Lateral Wall Electrodes

OBJECTIVES

The goal of this study was to use cone-beam computed tomography to locate the electrode-modiolus distance (EMD) and correlate this with speech perception in cochlear implant (CI) recipients of the 31.5-mm lateral wall (LW) electrode arrays.

STUDY DESIGN

Retrospective review.

PATIENTS

Forty-five child CI recipients with prelingual profound sensorineural hearing loss of inserted 31.5-mm LW arrays listening with a CI-alone device.

INTERVENTIONS

Stepwise forward multiple linear regression was performed to control and reduce the variability in implant performance to determine whether EMD affects speech perception.

MAIN OUTCOME MEASURES

Electrode location (angular insertion depth [AID], EMD), together with the electrode impedance (EI), surgical approach, sex, CI age, and preimplant hearing aid usage were estimated as independent variables. The dependent variables were the Meaningful Use of Speech Scale (MUSS) and parents' evaluation of children's aural/oral performance (PEACH) assessed with the CI alone at 12 months postactivation.

RESULTS

EMD and CI age were predictive variables for PEACH/MUSS. A negative correlation was found between AID and EMD (r = -0.56, p < 0.01), whereas EMD had a moderately positive correlation with EI (r = 0.32, p < 0.01).

CONCLUSIONS

The best "location-related" predictor of postoperative speech perception was EMD with a 31.5-mm array among CI-alone users.

Enhancement in the Round Window Niche: A Potential Pitfall in High-Resolution MR Imaging of the Internal Auditory Canal

BACKGROUND AND PURPOSE

There is limited discussion in current literature about the normal imaging appearance of the round window. The purpose of this study was to assess the prevalence and imaging characteristics of gadolinium enhancement in the round window niche on MR imaging to the internal auditory canal.

MATERIALS AND METHODS

The presence or absence and laterality of enhancement in the round window niche on MR imaging was retrospectively reviewed in 95 patients from 1 institution. All studies included high-resolution (≤0.5-mm section thickness) pre- and postgadolinium 3D FSE T1 with fat-saturation and postgadolinium 3D FLAIR image sequences. T1 and T2 acquisitions were viewed as coregistered overlays to confirm that enhancement was lateral to the round window membrane within the round window niche. CT was reviewed when available to assess the presence and laterality of soft tissue in the round window niche.

RESULTS

Ninety-five patients with internal auditory canal MRIs were included. Enhancement was present in the round window of 15 of 95 patients (15.8%). Of the 27 patients who underwent CT, 4 (14.8%) had concordant soft tissue on CT and MR imaging enhancement in the round window niche. One patient had MR imaging enhancement within the round window niche without a corresponding abnormality on CT. The absence of soft tissue on CT and the corresponding lack of MR imaging enhancement were present in 22 (81.5%) patients.

CONCLUSIONS

Enhancement can be visualized within the round window niche on MR imaging as an incidental finding. This enhancement probably represents postinflammatory granulation tissue and does not require further intervention. However, the potential for this enhancement to be misdiagnosed as a pathologic process can be a pitfall in MR imaging.

In vitro measurements of radiation exposure with different modalities (computed tomography, cone beam computed tomography) for imaging the petrous bone with a pediatric anthropomorphic phantom

BACKGROUND

Various imaging modalities, such as multi-detector computed tomography (CT) and cone beam CT are commonly used in infants for the diagnosis of hearing loss and surgical planning of implantation hearing aid devices, with differing results.

OBJECTIVE

We compared three different imaging modalities available in our institution, including a high-class CT scanner, a mid-class CT scanner and an angiography system with a cone beam CT option, for image quality and radiation exposure in a phantom study.

MATERIALS AND METHODS

While scanning an anthropomorphic phantom imitating a 1-year-old child with vendor-provided routine protocols, organ doses, surface doses and effective doses were determined for these three modalities with thermoluminescent dosimeters. The image quality was evaluated using the signal difference to noise ratio (SDNR) and the spatial resolution of a line-pair insert in the phantom head. The dose efficiency, defined as the ratio of SDNR and effective dose, was also compared.

RESULTS

The organ and surface doses were lowest with the high-class CT protocol, but the image quality was the worst. Image quality was best with the cone beam CT protocol, which, however, had the highest radiation exposure in this study, whereas the mid-class CT was in between.

CONCLUSION

Based on our results, high-end CT should be used for surgical planning because it has the lowest dose, while the image quality is still sufficient for this purpose. However, if highest image quality is needed and required, e.g., by ENT surgeons, the other modalities should be considered.

Evaluating cochlear insertion trauma and hearing preservation after cochlear implantation (CIPRES): a study protocol for a randomized single-blind controlled trial

Background

In order to preserve residual hearing in patients with sensorineural hearing loss (SNHL) who receive a cochlear implant (CI), insertion trauma to the delicate structures of the cochlea needs to be minimized. The surgical approach comprises the conventional mastoidectomy-posterior tympanotomy (MPT) to arrive at the middle ear, followed by either a cochleostomy (CO) or the round window (RW) approach. Both techniques have their benefits and disadvantages. Another important aspect in structure preservation is the design of the electrode array. Two different designs are used: a “straight” lateral wall lying electrode array (LW) or a “pre-curved” perimodiolar lying electrode array (PM). Interestingly, until now, the best surgical approach and design of the implant is uncertain. Our hypothesis is that there is a difference in hearing preservation outcomes between the four possible treatment options.

Methods

We designed a monocenter, multi-arm, randomized controlled trial to compare insertion trauma between four groups of patients, with each group having a unique combination of an electrode array type (LW or PM) and surgical approach (RW or CO). In total, 48 patients will be randomized into one of these four intervention groups. Our primary objective is the comparison of postoperative hearing preservation between these four groups. Secondly, we aim to assess structure preservation (i.e., scalar translocation, with basilar membrane disruption or tip fold-over of array) for each group. Thirdly, we will compare objective outcomes of hearing and structure preservation by way of electrocochleography (ECochG).

Discussion

Cochlear implantation by way of a cochleostomy or round window approach, using different electrode array types, is the standard medical care for patients with severe to profound bilateral sensorineural hearing loss, as it is a relatively simple and low-risk procedure that greatly benefits patients. However, loss of residual hearing remains a problem. This trial is the first randomized controlled trial that evaluates the effect of cochlear insertion trauma of several CI treatment options on hearing preservation.

Trial registration

Netherlands Trial Register (NTR) NL8586. Registered on 4 May 2020. Retrospectively registered; 3/48 participants were included before registration.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05878-2.

Flat-panel conebeam CT in the clinic: history and current state

Research into conebeam CT concepts began as soon as the first clinical single-slice CT scanner was conceived. Early implementations of conebeam CT in the 1980s focused on high-contrast applications where concurrent high resolution ( < 200    μ m ), for visualization of small contrast-filled vessels, bones, or teeth, was an imaging requirement that could not be met by the contemporaneous CT scanners. However, the use of nonlinear imagers, e.g., x-ray image intensifiers, limited the clinical utility of the earliest diagnostic conebeam CT systems. The development of consumer-electronics large-area displays provided a technical foundation that was leveraged in the 1990s to first produce large-area digital x-ray detectors for use in radiography and then compact flat panels suitable for high-resolution and high-frame-rate conebeam CT. In this review, we show the concurrent evolution of digital flat panel (DFP) technology and clinical conebeam CT. We give a brief summary of conebeam CT reconstruction, followed by a brief review of the correction approaches for DFP-specific artifacts. The historical development and current status of flat-panel conebeam CT in four clinical areas-breast, fixed C-arm, image-guided radiation therapy, and extremity/head-is presented. Advances in DFP technology over the past two decades have led to improved visualization of high-contrast, high-resolution clinical tasks, and image quality now approaches the soft-tissue contrast resolution that is the standard in clinical CT. Future technical developments in DFPs will enable an even broader range of clinical applications; research in the arena of flat-panel CT shows no signs of slowing down.

Cochlear morphometry in healthy ears of a mexican population: A comparison of measurement techniques

OBJECTIVE

This study describes the cochlear morphometry of a mexican population analysed by laterality and sex. The objective is to compare Cochlear Length (CL) evaluation between Alexiades et al. formula and manual method described by Würfel et al. PATIENTS: Hispanic patients from Mexico, with an age of 18 years or older, were included. Morphometric examination was performed retrospectively on 200 subjects who underwent previously temporal bone imaging for clinical purposes.

MATERIALS AND METHODS

Horos for Mac program was used to measure CL, cochlear height, distance A, and distance B. WorkStation AW Volume Share 2 was used to obtain volume. CL was measured in 400 temporal bones (228 females, 172 males).

RESULTS

The mean CL was 34.02mm±2.15mm. A significant difference was found in all variables between sex (P=≤0.05) and laterality (P=≤0.05). The Alexiades equation was used for determining CL and compared with the manual formula, with no significant differences (κ=0.71). However, the time consumption was 5 times faster with the calculated method. The Alexiades formula was demonstrated to be a reliable method measurement.

CONCLUSION

Preoperative Computed Tomography evaluation of the internal ear helps to plan the Cochlear Implants (CI) surgical approach and allows to choose an appropriate electrode length for each necessity. Our findings may be useful to facilitate and adapt preoperative management of CI surgery by considering the characteristics of cochlear morphology of Latin-American populations.

Feasibility of Cochlea High-frequency Ultrasound and Microcomputed Tomography Registration for Cochlear Computer-assisted Surgery: A Testbed

INTRODUCTION

There remains no standard imaging method that allows computer-assisted surgery of the cochlea in real time. However, recent evidence suggests that high-frequency ultrasound (HFUS) could permit real-time visualization of cochlear architecture. Registration with an imaging modality that suffers neither attenuation nor conical deformation could reveal useful anatomical landmarks to surgeons. Our study aimed to address the feasibility of an automated three-dimensional (3D) HFUS/microCT registration, and to evaluate the identification of cochlear structures using 2D/3D HFUS and microCT.

METHODS

MicroCT, and 2D/3D 40 MHz US in B-mode were performed on ex vivo guinea pig cochlea. An automatic rigid registration algorithm was applied to segmented 3D images. This automatic registration was then compared to a reference method using manual annotated landmarks placed by two senior otologists. Inter- and intrarater reliabilities were evaluated using intraclass correlation coefficient (ICC) and the mean registration error was calculated.

RESULTS

3D HFUS/microCT automatic registration was successful. Excellent levels of concordance were achieved with regards intra-rater reliability for both raters with micro-CT and US images (ICC ranging from 0.98 to 1, p < 0.001) and with regards inter-rater reliability (ICC ranging from 0.99 to 1, p < 0.001). The mean HFUS/microCT automated RE for both observers was 0.17 ± 0.03 mm [0.10-0.25]. Identification of the basilar membrane, modiolus, scala tympani, and scala vestibuli was possible with 2D/3D HFUS and micro-CT.

CONCLUSIONS

HFUS/microCT image registration is feasible. 2D/3D HFUS and microCT allow the visualization of cochlear structures. Many potential clinical applications are conceivable.

[Progress of research on cone beam CT in cochlear implantation]

Cochlear implant, as the most successful artificial auditory implant, brings tens of thousands of patients with severe or profound sensorineural hearing loss back to the world of sound every year. With the expansion of surgical indications, a large number of difficult cases bring new challenges for cochlear implantation. As a new technology, cone beam CT has the double advantages of high spatial resolution and low radiation. It is considered as the second revolution of CT technology, which shows unique value in the application of cochlear implantation. This article reviews the basic principles of cone beam CT and its application and research progress in cochlear implantation.

Evaluation of the relationship between tympanic plate morphology and degenerative bone changes of condyle and articular eminence

INTRODUCTION

This study aimed to evaluate the relationship between tympanic plate morphology and degeneration of temporomandibular joint (TMJ) condyle and articular eminence (AE).

MATERIAL AND METHODS

Cone beam computed tomography images of 700 patients (345 males, 355 females) were evaluated. The prevalence and location of tympanic plate pneumatization (TPP) and foramen tympanicum (FT) were recorded. Sagittal scans of the TMJs were classified according to the degenerative bone changes of condyle and AE (flattening, osteophytes, erosion, sclerosis, and subcortical cysts).

RESULTS

TPP was found in 106 of 700 patients (15.2%) while FT was found in 165 (23.2%) of the patients. TPP and FT were bilateral in 52 (49.1%) patients and 46 (27.9%) patients, respectively. The mean axial diameter of FT was 2.53mm and the mean sagittal diameter was 2.52mm. The most common degenerative changes for condyle and AE were flattening.

CONCLUSION

To know these structures is important for surgical operations in the region of TMJ and ear to prevent complications. CBCT is useful to evaluate these anatomical landmarks and the relationship between them and the degenerative bone changes of condyle and AE.

Auditory performance of post-lingually deafened adult cochlear implant recipients using electrode deactivation based on postoperative cone beam CT images

PURPOSE

The use of image processing techniques to estimate the position of intra-cochlear electrodes has enabled the creation of personalized maps to meet the individual stimulation needs of cochlear implant (CI) recipients. The aim of this study was to evaluate a novel technique of electrode deactivation based on postoperative cone beam computed tomography (CBCT) images in post-lingually deafened adult CI recipients.

METHODS

Based on postoperative CBCT images, the positioning of the electrodes was estimated in relation to the modiolus in 14 ears of 13 post-lingually deafened adult CI recipients. The electrodes sub-optimally positioned or involved in kinking and tip fold-over were deactivated. Speech perception scores in silence and in noise were obtained from subjects using the standard map and were followed up 4 weeks after image-based electrode deactivation reprogramming technique (IBEDRT). The participants selected their preferred map after 4 weeks of IBEDRT use.

RESULTS

There were statistically significant improvements in the speech recognition tests in silence and noise when comparing IBEDRT performance to the standard map. All participants elected the IBEDRT as their new preferred map.

CONCLUSIONS

IBEDRT is a promising technique for fitting CI recipients and minimizing channel interaction increased by the positioning of the electrodes sub-optimally placed, thereby improving their auditory performance. We propose a novel electrode deactivation technique based on postoperative CBCT imaging, with a limited number of deactivated electrodes and a low-dosing scanning which could be applied for clinical routine.

Radiologic anatomy of the round window relevant to cochlear implantation and inner ear drug delivery

Objective

To determine anatomic relationships and variation of the round window membrane to bony surgical landmarks on computed tomography.

Study design

Retrospective imaging review.

Methods

100 temporal bone images were evaluated. Direct measurements were obtained for membrane position. Vector distances and angulation from umbo and bony annulus were calculated from image viewer software coordinates.

Results

The angle of round window membrane at junction with cochlear basal turn was (42.1 ± 8.6)°. The membrane's position relative to plane of the facial nerve through facial recess was (14.7 ± 5.2)° posterior from a reference line drawn through facial recess to carotid canal. Regarding transtympanic drug delivery, the round window membrane was directed 4.1 mm superiorly from the inferior annulus and 5.4 mm anteriorly from the posterior annulus. The round window membrane on average was angled superiorly from the inferior annulus (77.1 ± 27.9)° and slightly anteriorly from the posterior annulus (19.1 ± 11.1°). The mean distance of round window membrane from umbo was 4 mm and posteriorly rotated 30° clockwise from a perpendicular drawn from umbo to inferior annulus towards posterior annulus. Together, these measurements approximate the round window membrane in the tympanic membrane's posteroinferior quadrant.

Conclusions

These radiologic measurements demonstrate normal variations seen in round window anatomy relative to facial recess approach and bony tympanic annulus, providing a baseline to assess round window insertion for cochlear implantation and outlines anatomic factors affecting transtympanic drug delivery.

Correlation between High-Resolution Computed Tomography Scan Findings and Histological Findings in Human Vestibular End Organs and Surgical Implications

BACKGROUND

Histological study of vestibular end organs has been challenging due to the difficulty in preserving their structures for histological analysis and due to their complex geometry. Recently, radiology advances have allowed to deepen the study of the membranous labyrinth.

SUMMARY

A review and analysis of surgical implications related to the anatomy of the vestibular end organ is performed. Radiological advances are key in the advancement of the knowledge of the anatomy and pathology of the vestibule. Thus, application of such knowledge in the development or improvement of surgical procedures may facilitate the development of novel techniques. Key Messages: During the last few decades, the knowledge of the anatomy of the auditory system through histology and radiology had improved. Technological advances in this field may lead to a better diagnosis and therapeutic approach of most common and important diseases affecting the inner ear.

Cone beam CT for perioperative imaging in hearing preservation Cochlear implantation - a human cadaveric study

Background

Knowledge of the cochlear implant array’s precise position is important because of the correlation between electrode position and speech understanding. Several groups have provided recent image processing evidence to determine scalar translocation, angular insertion depth, and cochlear duct length (CDL); all of which are being used for patient-specific programming. Cone beam computed tomography (CBCT) is increasingly used in otology due to its superior resolution and low radiation dose. Our objectives are as followed:

Validate CBCT by measuring cochlear metrics, including basal turn diameter (A-value) and lateral wall cochlear duct length at different angular intervals and comparing it against microcomputed CT (uCT).

Explore the relationship between measured lateral wall cochlear duct length at different angular intervals and insertion depth among 3 different length electrodes using CBCT.

Methods

The study was performed using fixed human cadaveric temporal bones in a tertiary academic centre. Ten temporal bones were subjected to the standard facial recess approach for cochlear implantation and imaged by CBCT followed by uCT. Measurements were performed on a three-dimensional reconstructed model of the cochlea. Sequential insertion of 3 electrodes (Med-El Flex24, 28 and Soft) was then performed in 5 bones and reimaged by CBCT. Statistical analysis was performed using Pearson’s correlation.

Results

There was good agreement between CBCT and uCT for cochlear metrics, validating the precision of CBCT against the current gold standard uCT in imaging. The A-value recorded by both modalities showed a high degree of linear correlation and did not differ by more than 0.23 mm in absolute values. For the measurement of lateral wall CDL at various points along the cochlea, there was a good correlation between both modalities at 360 deg and 720 deg (r = 0.85, p < 0.01 and r = 0.79, p < 0.01). The Flex24 electrode displayed consistent insertion depth across different bones.

Conclusions

CBCT reliably performs cochlear metrics and measures electrode insertion depth. The low radiation dose, fast acquisition time, diminished metallic artifacts and portability of CBCT make it a valid option for imaging in cochlear implant surgery.

Applicability of vital staining and tissue clearing to vascular anatomy and melanocytes' evaluation of temporal bone in six laboratory species

The purpose of the present study was to define the applicability of tissue clearing to the field of otology. We combined tissue clearing with vital staining perfusion via a pumping system to examine the vascular anatomy of temporal bones in laboratory animals. We used six different types of species including Korean wild mouse, mouse, Mongolian gerbil, hamsters and Guinea pigs. A mixture of Alcian blue reagent and 4% paraformaldehyde was circulated throughout the entire circulatory system of the animal via a perfusion pump system. Transparency images were obtained from the temporal bones according to the protocol of the SunHyun 3D Imaging Kit. In examining the inner surface of the tympanic membrane, flaccid part (pars flaccida) was positioned along the entire marginal area in Guinea pig. In the Guinea pig, unlike the other species, the cortical bone of the mastoid (bullae) was easily removed using cold instruments, allowing a direct approach to the enclosed structures. The distribution and pattern of cochlea melanocytes were compared among the species. "Mobius strip"-like accumulated melanocytes in vestibules were shown in both the Korean wild mouse and mouse. The collateral blood supply to the cochlea in six different species was checked in various pattern. Combining dye infusion with tissue-clearing techniques, we documented the middle ear and transparent inner ear structures in six different species. The information and associated images will help other researchers to develop hypotheses and design experimental investigations.

Cochlear implants: Insertion assessment by computed tomography

BACKGROUND AND OBJECTIVES

Imaging exams play a key role in cochlear implants with regard to both planning implantation before surgery and quality control after surgery. The ability to visualize the three-dimensional location of implanted electrodes is useful in clinical routines for assessing patient outcome. The aim of this study was to evaluate linear and angular insertion depth measurements of cochlear implants based on conventional computed tomography.

METHODS

Tools for linear and angular measurements of cochlear implants were used in computed tomography exams. The tools realized the insertion measurements in an image reconstruction of the CIs, based on image processing techniques. We comprehensively characterized two cochlear implant models while obviating possible changes that can be caused by different cochlea sizes by using the same human temporal bones to evaluate the implant models.

RESULTS

The tools used herein were able to differentiate the insertion measurements between two cochlear implant models widely used in clinical practice. We observed significant differences between both insertion measurements because of their different design and construction characteristics (p = 0.004 and 0.003 for linear and angular measurements, respectively; t-test). The presented methodology showed to be a good tool to calculate insertion depth measurements, since it is easy to perform, produces high-resolution images, and is able to depict all the landmarks, thus enabling measurement of the angular and linear insertion depth of the most apical electrode contacts.

CONCLUSION

The present study demonstrates practical and useful tools for evaluating cochlear implant electrodes in clinical practice. Further studies should measure preoperative and postoperative benefits in terms of speech recognition and evaluate the preservation of residual hearing in the implanted ear. Such studies can also determine correlations between surgical factors, electrode positions, and performance. In addition to refined surgical techniques, the precise evaluation of cochlear length and correct choice of cochlear implant characteristics can play an important role in postoperative outcomes.

Possibility of differentiation of cochlear electrodes in radiological measurements of the intracochlear and chorda-facial angle position

Due to an increasing number of cochlear implantations, quality control has become more important. In addition to intraoperative biophysical measurements, radiological imaging is another possibility. An upcoming technique regarding this is Cone Beam CT (CBCT). Sixty-five data sets (35 Nucleus Contour Advance–Cochlear; 30 Flex Soft–MedEl) of postoperative imaging by CBCT (Accu-I-tomo F17, Morita, Kyoto, Japan) underwent further evaluation. Insertion angle, height of the cochlea, distance of the electrode to the medial or lateral wall, angle between chorda tympani and facial nerve and the precise position of the electrode cable in the facial-chordal angle were determined. The typical difference between the perimodiolar and lateral course of the electrodes could also be shown in radiological measurements. This demonstrates the accuracy and advantage of CBCT in visualisation of small structures with fewer metal artifacts. Furthermore, in 75% of patients, the angle of the chorda and facial nerve could be visualised. Significant differences in dependence of the electrode type for the relation of them to the facial nerve could be seen. In conclusion, CBCT achieves reliable visualisation and detailed imaging-based measurements of the intracochlear position of different cochlea electrodes. Additionally, clinically known differences can be reproduced. Even visualisation of the position of the electrode in the chorda-facial angle is possible. Therefore, CBCT is a useful tool in intra- and postoperative control of cochlear implants.

Clinically relevant human temporal bone measurements using novel high-resolution cone-beam CT

OBJECTIVE

To test the feasibility of measuring fine temporal bone structures using a newly established cone-beam computed tomography (CBCT) system.

MATERIALS AND METHODS

Six formalin-fixed human cadaver temporal bones were imaged using a high-resolution CBCT system that has 900 frames and copper + aluminum filtration. Fine temporal bone structures, including those of the facial nerve canal and vestibular structures, were identified and measured.

RESULTS

The fine structures of the middle ear, including the tympanic membrane, tendon of the tensor tympani, cochleariform process of the semicanal of the tensor tympani, pyramidal eminence, footplate of the stapes, full path of the facial nerve within the temporal bone, supralabyrinthine space, semicircular canals, pathway of the subarcuate canal, and full path of the vestibular aqueduct, were clearly demonstrated. The vestibular aqueduct has a midpoint width of 0.4 ± 0.0 mm and opercular width of 0.5 ± 0.1 mm (mean ± SD). The length of the internal acoustic meatus was 10.6 ± 1.2 mm (mean ± SD), and the diameter of the internal acoustic meatus was 3.7 ± 0.3 mm (mean ± SD).

CONCLUSION

This novel high-resolution CBCT system has potentially broad applications in the diagnosis of inner ear disease and in monitoring associated pathological changes, surgical planning, navigation for the ear surgery, and temporal bone training.