A novel radiomics nomogram based on T2-sampling perfection with application-optimized contrasts using different flip-angle evolutions (SPACE) images for predicting cochlear and vestibular endolymphatic hydrops in Meniere's disease patients.

OBJECTIVES: To construct and validate a radiomics nomogram based on T2-sampling perfection with application-optimized contrasts using different flip-angle evolutions (SPACE) images for predicting cochlear and vestibular endolymphatic hydrops (EH) in Meniere's disease patients. METHODS: A total of 156 patients (312 affected ears) with bilateral definite Meniere's disease who underwent delayed enhancement MRI scans were enrolled in this study. All ears of the patients were divided into a training set (n = 218) and an internal validation set (n = 94). A radiomics nomogram was constructed from radiomics features extracted from the T2-SPACE images, and a radiomics score was calculated. Performance of the radiomics nomogram was assessed using receiver operating characteristics analysis. RESULTS: Five features were selected for the construction of the cochlear radiomics nomogram, and seven features for the vestibular radiomics nomogram. The radiomics nomograms exhibited robust performance in differentiating between EH-positive and EH-negative statuses in both training and validation cohorts, with the area under the receiver operating characteristics curve values for cochlear and vestibular radiomic nomograms being 0.703 and 0.728 in the training set, and 0.718 and 0.701 in the validation set, respectively. CONCLUSION: The novel radiomics nomograms based on T2-SPACE images were successfully constructed to predict cochlear and vestibular EH in Meniere's disease. The models showed a solid and superior performance and may play an important role in the EH prediction. CLINICAL RELEVANCE STATEMENT: We constructed a novel radiomics nomogram, which can be a very useful tool for predicting cochlear and vestibular endolymphatic hydrops in Meniere's disease patients. KEY POINTS: • This is the first T2-SPACE-based nomogram to predict cochlear and vestibular endolymphatic hydrops. • The nomogram is of great value to patients who are unable to undergo delayed enhancement MRI scans.

Development of an Algorithm for Correct Placement of the Basal Electrode Contact in the Context of Anatomy-Based Cochlear Implantation: A Proof of Concept.

BACKGROUND: Correct individual tonotopic frequency stimulation of the cochlea plays an important role in the further development of anatomy-based cochlear implantation. In this context, frequency-specific fitting of the basal electrode contact with a normal insertion depth can be difficult since it is often placed in a frequency range higher than 10 kHz, and current audio processors only stimulate for frequencies up to 8.5 kHz due to microphone characteristics. This results in a mismatch of the high frequencies. Therefore, this study represents a proof of concept for a tonotopic correct insertion and aims to develop an algorithm for a placement of the basal electrode below 8.5 kHz in an experimental setting. METHODS: Pre- and postoperative flat-panel volume CT scans with secondary reconstructions were performed on 10 human temporal bone specimens. The desired frequency location for the most basal electrode contact was set at 8.25 kHz. The distance from the round window to the position where the basal electrode contact was intended to be located was calculated preoperatively using 3D-curved multiplanar reconstruction and a newly developed mathematical approach. A specially designed cochlear implant electrode array with customized markers imprinted on the silicone of the electrode array was inserted in all specimens based on the individually calculated insertion depths. All postoperative measurements were additionally validated using otological planning software. RESULTS: Positioning of the basal electrode contact was reached with only a small mean deviation of 37 ± 399 Hz and 0.06 ± 0.37 mm from the planned frequency of 8.25 kHz. The mean rotation angle up to the basal electrode contact was 51 ± 5°. In addition, the inserted electrode array adequately covered the apical regions of the cochleae. CONCLUSION: Using this algorithm, it was possible to position the basal electrode array contact in an area of the cochlea that could be correctly stimulated by the existing speech processors in the context of tonotopic correct fitting.

Cochlear Implant: Analysis of the Frequency-to-Place Mismatch with the Table-Based Software OTOPLAN® and Its Influence on Hearing Performance.

OBJECTIVE: The purpose of this study was to compare the originally applied frequency allocation of cochlear implant electrodes assigned by default at the time of activation with a more recent frequency allocation that is anatomy-based by a software called OTOPLAN®. Based on a computed tomography scan of the temporal bone, this software calculates the position of each electrode in the cochlea and its corresponding tonotopic frequency. We also evaluated whether patients with a significant mismatch between these two allocations present poorer speech intelligibility. MATERIALS AND METHODS: Patients who underwent cochlear implantation from 2016 to 2021 at the University Hospital of Liege were included in this retrospective study. We used OTOPLAN® to calculate the tonotopic frequency allocation of each electrode according to its exact position in the cochlear duct. This anatomical frequency mapping was compared with the default frequency mapping at the time of cochlear implant activation. Finally, we compared the mismatch with the patients' auditory performance, represented by the Auditory Capacity Index (ACI). RESULTS: Thirteen patients were included in the study. All patients had a mismatch between the two frequency maps, to a variable extent (200 Hz-1,100 Hz). Frequency shift was significantly inversely correlated with ACI and with the time needed to improve speech intelligibility. CONCLUSION: Our primary results show that patients with a larger mismatch between default frequency mapping and anatomically assigned frequency mapping experience poorer hearing performance and slower adaptation to a cochlear implant.

Analysis of Cochlear Morphology for Cochlear Implantation Using Three-Dimensional Reconstruction of Computed Tomography Images.

INTRODUCTION: Preoperative evaluation of cochlear morphology is important for successful cochlear implantation. This study analyzed the cochlear canal by three-dimensional reconstructions of temporal bones using computed tomography (CT). METHODS: Fifty temporal bones from 25 patients aged 42-74 years were evaluated. The inner spaces of the bony cochlea were reconstructed using a surface rendering technique on the CT images. Eight angular points (P0-P7) every 90° were selected from 0° to 630° from the center of the round window using the reconstructed cochlear canal images. The radius (R) and thickness (T) of the cochlear canal at each point were measured. The cochlear canal length (CoCL) was estimated using an equation based on the radius at each point. The cochlear width and height based on multiplanar CT images were also measured and compared with the length and volume of the cochlear canal. RESULTS: The mean CoCL from 0° to 630° was 31.5 mm, and the cochlear volume was 55.9 mm3. The CoCL to P7 was correlated with the cochlear volume (r = 0.77), coiling ratios (R4/R0, r = 0.47; R5/R1, r = 0.384), cochlear width (long) (r = 0.539), cochlear height (r = 0.385), and total thickness at each point (r = 0.475). The cochlear volume was correlated with CoCL (630°) (r = 0.77), coiling ratio (R4/R0, r = 0.367), cochlear width (long) (r = 0.616), cochlear height (r = 0.447), and total T (r = 0.566). CONCLUSION: Preoperative evaluation using three-dimensional reconstruction can elucidate the size and shape of the cochlear canal before cochlear implantation.

Automatic localization of cochlear implant electrodes using cone beam computed tomography images.

BACKGROUND: Cochlear implants (CI) are implantable medical devices that enable the perception of sounds and the understanding of speech by electrically stimulating the auditory nerve in case of inner ear damage. The stimulation takes place via an array of electrodes surgically inserted in the cochlea. After CI implantation, cone beam computed tomography (CBCT) is used to evaluate the position of the electrodes. Moreover, CBCT is used in research studies to investigate the relationship between the position of the electrodes and the hearing outcome of CI user. In clinical routine, the estimation of the position of the CI electrodes is done manually, which is very time-consuming. RESULTS: The aim of this study was to optimize procedures of automatic electrode localization from CBCT data following CI implantation. For this, we analyzed the performance of automatic electrode localization for 150 CBCT data sets of 10 different types of electrode arrays. Our own implementation of the method by Noble and Dawant (Lecture notes in computer science (Including subseries lecture notes in artificial intelligence and lecture notes in bioinformatics), Springer, pp 152-159, 2015. https://doi.org/10.1007/978-3-319-24571-3_19 ) for automated electrode localization served as a benchmark for evaluation. Differences in the detection rate and the localization accuracy across types of electrode arrays were evaluated and errors were classified. Based on this analysis, we developed a strategy to optimize procedures of automatic electrode localization. It was shown that particularly distantly spaced electrodes in combination with a deep insertion can lead to apical-basal confusions in the localization procedure. This confusion prevents electrodes from being detected or assigned correctly, leading to a deterioration in localization accuracy. CONCLUSIONS: We propose an extended cost function for automatic electrode localization methods that prevents double detection of electrodes to avoid apical-basal confusions. This significantly increased the detection rate by 11.15 percent points and improved the overall localization accuracy by 0.53 mm (1.75 voxels). In comparison to other methods, our proposed cost function does not require any prior knowledge about the individual cochlea anatomy.

Quantum magnetic imaging of iron organelles within the pigeon cochlea.

The ability of pigeons to sense geomagnetic fields has been conclusively established despite a notable lack of determination of the underlying biophysical mechanisms. Quasi-spherical iron organelles previously termed "cuticulosomes" in the cochlea of pigeons have potential relevance to magnetoreception due to their location and iron composition; however, data regarding the magnetic susceptibility of these structures are currently limited. Here quantum magnetic imaging techniques are applied to characterize the magnetic properties of individual iron cuticulosomes in situ. The stray magnetic fields emanating from cuticulosomes are mapped and compared to a detailed analytical model to provide an estimate of the magnetic susceptibility of the individual particles. The images reveal the presence of superparamagnetic and ferrimagnetic domains within individual cuticulosomes and magnetic susceptibilities within the range 0.029 to 0.22. These results provide insights into the elusive physiological roles of cuticulosomes. The susceptibilities measured are not consistent with a torque-based model of magnetoreception, placing iron storage and stereocilia stabilization as the two leading putative cuticulosome functions. This work establishes quantum magnetic imaging as an important tool to complement the existing array of techniques used to screen for potential magnetic particle-based magnetoreceptor candidates.

Multiscale photonic imaging of the native and implanted cochlea.

The cochlea of our auditory system is an intricate structure deeply embedded in the temporal bone. Compared with other sensory organs such as the eye, the cochlea has remained poorly accessible for investigation, for example, by imaging. This limitation also concerns the further development of technology for restoring hearing in the case of cochlear dysfunction, which requires quantitative information on spatial dimensions and the sensorineural status of the cochlea. Here, we employed X-ray phase-contrast tomography and light-sheet fluorescence microscopy and their combination for multiscale and multimodal imaging of cochlear morphology in species that serve as established animal models for auditory research. We provide a systematic reference for morphological parameters relevant for cochlear implant development for rodent and nonhuman primate models. We simulate the spread of light from the emitters of the optical implants within the reconstructed nonhuman primate cochlea, which indicates a spatially narrow optogenetic excitation of spiral ganglion neurons.

Post-operative evaluation of computed tomography imaging following cochlear implantation.

PURPOSE: This study utilized an automated segmentation algorithm to assess the cochlear implant electrode array within the cochlea and investigate its impact on audiologic outcomes as measured by post-operative speech perception scores. Furthermore, manual evaluations of electrode placement were compared to automatic segmentation methods to determine their accuracy in predicting post-operative audiologic outcomes. MATERIALS AND METHODS: This retrospective chart review was conducted at a tertiary care referral center involving adult post-lingually deafened cochlear implant recipients implanted from 2015 to 2019. Patients with appropriate postoperative imaging and speech testing were included. Patients were excluded if non-English speaking, had a cognitive deficit, or a labyrinthine malformation. Automated and manual methods were used to analyze computed tomography (CT) scans and correlate the findings with post-operative speech perception scores and detection of electrode translocation. RESULTS: Among the 47 patients who met inclusion criteria, 15 had electrode translocations confirmed by automatic segmentation methods. Controlling for CI usage and pre-operative AzBio scores, patients with translocation exhibited significantly lower consonant-nucleus consonant (CNC) and AzBio scores at 6-months post-implantation compared to patients with ST insertions. Moreover, the number of translocated electrode contacts was significantly associated with post-operative CNC scores. Manual evaluations of electrode location were predictive but less sensitive to electrode translocations when compared with automated 3D segmentation. CONCLUSIONS: Placement of CI electrode contacts within ST without translocation into SV, leads to improved audiologic outcomes. Manual assessment of electrode placement via temporal bone CT, without 3D reconstruction, provides a less sensitive method to determine electrode placement than automated methods. LEVEL OF EVIDENCE: Level 4. LAY SUMMARY: This study investigated the impact of electrode placement on speech outcomes for cochlear implant recipients. Using advanced imaging techniques, the researchers compared automated and manual methods for evaluating electrode position and examined the relationship between electrode translocation and audiologic outcomes. The findings revealed that proper placement within the cochlea without translocation into inappropriate compartments inside the cochlea improves speech understanding. Manual evaluations were somewhat accurate but less sensitive in detecting translocations compared to automated methods, which offer more precise predictions of patient outcomes. These results contribute to our understanding of factors influencing cochlear implant success and highlight the importance of optimizing electrode placement for improved speech outcomes.

Third window lesions of the inner ear: A pictorial review.

PURPOSE: Radiographic review of pathologies that associate with third window syndrome. METHODS: Case series and literature review. RESULTS: Eight unique third window conditions are described and illustrated, including superior, lateral, and posterior semicircular canal dehiscence; carotid-cochlear, facial-cochlear, and internal auditory canal-cochlear dehiscence, labyrinthine erosion from endolymphatic sac tumor, and enlarged vestibular aqueduct. CONCLUSION: The present study highlights the characteristic imaging features and symptoms to differentiate third window pathologies for expedient diagnosis and management planning.

Intralabyrinthine schwannoma: Surgical management and cochlear lumen preservation.

The present video reports the surgical removal of an intralabyrinthine schwannoma. The video contains patient's medical history, preoperative radiological evaluations and detailed description of surgical steps of the procedure, consisting in labyrinthectomy, cochleostomy and insertion of a dummy electrode in the preserved cochlear lumen within the context of a subtotal petrosectomy.

Comparing linear and non-linear models to estimate the appropriate cochlear implant electrode array length-are current methods precise enough?

PURPOSE: In cochlear implantation with flexible lateral wall electrode arrays, a cochlear coverage (CC) range between 70% and 80% is considered ideal for optimal speech perception. To achieve this CC, the cochlear implant (CI) electrode array has to be chosen according to the individual cochlear duct length (CDL). Here, we mathematically analyzed the suitability of different flexible lateral wall electrode array lengths covering between 70% and 80% of the CDL. METHODS: In a retrospective cross-sectional study preoperative high-resolution computed tomography (HRCT) from patients undergoing cochlear implantation was investigated. The CDL was estimated using an otosurgical planning software and the CI electrode array lengths covering 70-80% of the CDL was calculated using (i) linear and (ii) non-linear models. RESULTS: The analysis of 120 HRCT data sets showed significantly different model-dependent CDL. Significant differences between the CC of 70% assessed from linear and non-linear models (mean difference: 2.5 mm, p < 0.001) and the CC of 80% assessed from linear and non-linear models (mean difference: 1.5 mm, p < 0.001) were found. In up to 25% of the patients none of the existing flexible lateral wall electrode arrays fit into this range. In 59 cases (49,2%) the models did not agree on the suitable electrode arrays. CONCLUSIONS: The CC varies depending on the underlying CDL approximation, which critically influences electrode array choice. Based on the literature, we hypothesize that the non-linear method systematically overestimates the CC and may lead to rather too short electrode array choices. Future studies need to assess the accuracy of the individual mathematical models.

Evaluation of insertion quality of a slim perimodiolar electrode array.

OBJECTIVES: The influence of cochlear morphology and electrode array design on scalar position and dislocation rates is of great interest in CI surgery. The aim of this study is to evaluate scalar position and specific points of dislocation in relation to cochlear morphology in patients implanted with a new slim perimodiolar electrode array. MATERIALS AND METHODS: Patients were implanted using the slim modiolar electrode array (= SMA) (= 532/632 electrode array of Cochlear™). Postoperative imaging was performed via cone beam computed tomography (CBCT) and the scans were analyzed regarding cochlear morphology (distances A and B and cochlear height), scalar location of the electrode array, basal insertion depth and apical insertion angle. Furthermore, electrode array design and surgical protocols were evaluated. RESULTS: 81 ears implanted with the SMA were retrospectively included. We evaluated 3 electrode array tip fold over intraoperatively via X-ray imaging and performed revision during the same surgery. The CBCT scans showed 76 initial scala tympani (ST) insertions without dislocation. Two ears showed a dislocated array, one at 77° and the other at 163°. Three arrays were inserted into scala vestibuli (SV) via cochleostomy. These patients showed no signs of obliteration. Cochlear morphology showed no influence on angular insertion depth and scalar position. CONCLUSIONS: The SMA showed a very low rate of scalar dislocations due to its slim electrode array design (2.7%). We could find a learning curve regarding the handling and the risk of dislocation and tip fold over with this electrode array. The rate of intraoperative tip fold over detection via X-ray imaging was 3.7%. Therefore, we highly recommend X-ray imaging and transimpedance matrix measurements within the surgery protocol. Scala vestibuli insertions happened in patients with cochleostomy only. We could identify two specific points of dislocation depending on electrode array design.

Comparison of depth of electrode insertion between cochleostomy and round window approach: a cadaveric study.

INTRODUCTION: Round window approach and cochleostomy approach can have different depth of electrode insertion during cochlear implantation which itself can alter the audiological outcomes in cochlear implant. OBJECTIVE: The current study was conducted to determine the difference in the depth of electrode insertion via cochleostomy and round widow approach when done serially in same temporal bone. METHODOLOGY: This is a cross-sectional study conducted in the Department of Otorhinolaryngology in conjunction with Department of Anatomy and Department of Diagnostic and Interventional Radiology over a period of 1 year. 12-electrode array insertion was performed via either approach (cochleostomy or round window) in the cadaveric temporal bone. HRCT temporal bone scan of the implanted temporal bone was done and depth of insertion and various cochlear parameters were calculated. RESULT: A total of 12 temporal bones were included for imaging analysis. The mean cochlear duct length was 32.892 mm; the alpha and beta angles were 58.175° and 8.350°, respectively. The mean angular depth of electrode insertion via round window was found to be 325.2° (SD = 150.5842) and via cochleostomy 327.350 (SD = 112.79) degree and the mean linear depth of electrode insertion via round window was found to be 18.80 (SD = 4.4962) mm via cochleostomy 19.650 (SD = 3.8087) mm, which was calculated using OTOPLAN 1.5.0 software. There was a statically significant difference in linear depth of insertion between round window and cochleostomy. Although the angular depth of insertion was higher in CS group, there was no statistically significant difference with round window type of insertion. CONCLUSION: The depth of electrode insertion is one of the parameters that influences the hearing outcome. Linear depth of electrode insertion was found to be more in case of cochleostomy compared to round window approach (p = 0.075) and difference in case of angular depth of electrode insertion existed but not significant (p = 0.529).

Machine learning-based prediction of the outcomes of cochlear implantation in patients with inner ear malformation.

OBJECTIVE: The objectives of this study are twofold: first, to visualize the structure of malformed cochleae through image reconstruction; and second, to develop a predictive model for postoperative outcomes of cochlear implantation (CI) in patients diagnosed with cochlear hypoplasia (CH) and incomplete partition (IP) malformation. METHODS: The clinical data from patients diagnosed with cochlear hypoplasia (CH) and incomplete partition (IP) malformation who underwent cochlear implantation (CI) at Beijing Tongren Hospital between January 2016 and August 2020 were collected. Radiological features were analyzed through 3D segmentation of the cochlea. Postoperative auditory speech rehabilitation outcomes were evaluated using the Categories of Auditory Performance (CAP) and the Speech Intelligibility Rating (SIR). This study aimed to investigate the relationship between cochlear parameters and postoperative outcomes. Additionally, a predictive model for postoperative outcomes was developed using the K-nearest neighbors (KNN) algorithm. RESULTS: In our study, we conducted feature selection by using patients' imaging and audiological attributes. This process involved methods such as the removal of missing values, correlation analysis, and chi-square tests. The findings indicated that two specific features, cochlear volume (V) and cochlear canal length (CDL), significantly contributed to predicting the outcomes of hearing and speech rehabilitation for patients with inner ear malformations. In terms of hearing rehabilitation, the KNN classification achieved an accuracy of 93.3%. Likewise, for speech rehabilitation, the KNN classification demonstrated an accuracy of 86.7%. CONCLUSION: The measurements obtained from the 3D reconstruction model hold significant clinical relevance. Despite the considerable variability in cochlear morphology across individuals, radiological features remain effective in predicting cochlear implantation (CI) prognosis for patients with inner ear malformations. The utilization of 3D segmentation techniques and the developed predictive model can assist surgeons in conducting preoperative cochlear structural measurements for patients with inner ear malformations. This, in turn, can offer a more informed perspective on the anticipated outcomes of cochlear implantation.

Cochlear implantation for rare Streptococcus suis meningitis with hearing loss.

OBJECTIVES: This study aimed to explore the diagnostic sensitivity of 3D heavily weighted T2-weighted MRI (T2MRI) and high-resolution computed tomography (HRCT) in patients with cochlear fibrosis associated with Streptococcus suis (S. suis) meningitis and the practicality of Cochlear implantation (CI) treatments. METHODS: Between January 2020 and December 2022, we enrolled four patients with rare cochlear S. suis meningitis with associated hearing loss despite aggressive or non-aggressive follow-up antibiotic treatment. Clinical imaging data, surgical performances and post-surgical-electrode impedance were evaluated. RESULTS: Combined with HRCT and T2MRI, the cochlea had varying degrees of fibrosis and ossification in different cases. However, the electrodes were successfully and wholly inserted after intraoperative removal of the ossified and fibrotic foci. Post-surgical electrode impedance values of MP1 + 2 mode were normal in all 4 cases at initial activation. CONCLUSION: In patients with S. suis meningitis and associated cochlear fibrosis, T2MRI examination of the inner ear was more sensitive than HRCT. This research highlights the feasibility of CI treatment in S. suis meningitis patients with severe cochlear fibrosis.

Relationship between vestibular schwannoma and endolymphatic hydrops.

BACKGROUND: Both vestibular schwannoma (VS) and Meniere's disease (MD) patients underwent hydrops MRI to clarify the relationship between VS and endolymphatic hydrops (EH). METHODS: Eighty patients with VS or MD underwent an inner ear test battery followed by hydrops MRI, and were then divided into 3 groups. Group A comprised 58 MD patients (62 ears) with positive EH but negative VS. Group B included 18 VS patients (18 ears) with negative EH, while Group C consisted of 4 patients (4 ears) who had VS concomitant with EH. Another 14 MD patients who tested negative for EH on hydrops MRI were initially excluded from this cohort, but were later included for comparison. RESULTS: The decreasing prevalence of EH at the cochlea, saccule and utricle in Group A was identified in 59 (95%), 42 (68%) and 40 (65%) ears, respectively, mimicking a declining sequence of abnormality rates running from audiometry (86%), cervical vestibular-evoked myogenic potential (cVEMP) test (55%) to the ocular (oVEMP) test (53%). However, such decreasing trend was not identified in Groups B and C. In Groups C and A combined, 4 (6%) of 62 EH patients had concomitant VS. Conversely, 4 (18%) of 22 VS patients in Groups C and B combined had concurrent EH. CONCLUSION: A very low (6%) rate of VS in EH patients indicates that VS in EH patients may be coincidental. In contrast, EH was identified in 18% prevalence of VS patients, mirroring the 22% prevalence of cochlear EH demonstrated in VS donors through histopathological studies.

[Comprehensive literature review on the application of the otological-surgical planning software OTOPLAN® for cochlear implantation. German version]. / Umfassender Literaturüberblick über die Anwendung der otologisch-chirurgischen Planungssoftware OTOPLAN® bei der Cochleaimplantation.

BACKGROUND: The size of the human cochlear, measured by the diameter of the basal turn, varies between 7 and 11 mm. For hearing rehabilitation with cochlear implants (CI), the size of the cochlear influences the individual frequency map and the choice of electrode length. OTOPLAN® (CAScination AG [Bern, Switzerland] in cooperation with MED-EL [Innsbruck, Austria]) is a software tool with CE marking for clinical applications in CI treatment which allows for precise pre-planning based on cochlear size. This literature review aims to analyze all published data on the application of OTOPLAN®. MATERIALS AND METHODS: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were applied to identify relevant studies published in the PubMed search engine between January 2015 and February 2023 using the search terms "otoplan" [title/abstract] OR "anatomy-based fitting" [title/abstract] OR "otological software tool" [title/abstract] OR "computed tomography-based software AND cochlear" [title/abstract]. RESULTS: The systematic review of the literature identified 32 studies on clinical use of OTOPLAN® in CI treatment. Most studies were reported from Germany (7 out of 32), followed by Italy (5), Saudi Arabia (4), the USA (4), and Belgium (3); 2 studies each were from Austria and China, and 1 study from France, India, Norway, South Korea, and Switzerland. In the majority of studies (22), OTOPLAN® was used to assess cochlear size, followed by visualizing the electrode position using postoperative images (5), three-dimensional segmentation of temporal bone structures (4), planning the electrode insertion trajectory (3), creating a patient-specific frequency map (3), planning of a safe drilling path through the facial recess (3), and measuring of temporal bone structures (1). CONCLUSION: To date, OTOPLAN® is the only DICOM viewer with CE marking in the CI field that can process pre-, intra-, and postoperative images in the abovementioned applications.

The spectrum of cochlear malformations in CHARGE syndrome and insights into the role of the CHD7 gene during embryogenesis of the inner ear.

PURPOSE: We reviewed the genotypes and the imaging appearances of cochleae in CHARGE patients from two large tertiary centres and analysed the observed cochlear anomalies, providing detailed anatomical description and a grading system. The goal was to gain insight into the spectrum of cochlear anomalies in CHARGE syndrome, and thus, in the role of the CHD7 gene in otic vesicle development. METHODS: We retrospectively reviewed CT and/or MR imaging of CHARGE patients referred to our institutions between 2005 and 2022. Cochlear morphology was analysed and, when abnormal, divided into 3 groups in order of progressive severity. Other radiological findings in the temporal bone were also recorded. Comparison with the existing classification system of cochlear malformation was also attempted. RESULTS: Cochlear morphology in our CHARGE cohort ranged from normal to extreme hypoplasia. The most common phenotype was cochlear hypoplasia in which the basal turn was relatively preserved, and the upper turns were underdeveloped. All patients in the cohort had absent or markedly hypoplastic semicircular canals and small, misshapen vestibules. Aside from a stenotic cochlear aperture (fossette) being associated with a hypoplastic or absent cochlear nerve, there was no consistent relationship between cochlear nerve status (normal, hypoplasia, or aplasia) and cochlear morphology. CONCLUSION: Cochlear morphology in CHARGE syndrome is variable. Whenever the cochlea was abnormal, it was almost invariably hypoplastic. This may shed light on the role of CHD7 in cochlear development. Accurate morphological description of the cochlea contributes to proper clinical diagnosis and is important for planning surgical treatment options.

An Accurate and Individualized Preoperative Estimation Method for the Linear Insertion Depth of Cochlear Implant Electrode Arrays Based on Computed Tomography.

OBJECTIVES: Cochlear implantation or auditory brainstem implantation is currently the only accepted method for improving severe or profound sensorineural hearing loss. The length of the electrodes implanted during cochlear implantation is closely related to the degree of hearing improvement of hearing after the surgery. We aimed to explore new methods to accurately estimate the electrode array (EA) linear insertion depth based on computed tomography (CT) images prior surgery, which could help surgeons select the appropriate EA length for each patient. DESIGN: Previous studies estimated the linear insertion depth by measuring the length of the lateral wall of the cochlea rather than the electrode's path in the cochlea duct. Here, we determined the actual position of the EA on the CT image after cochlear surgery in order to predict the path of the EA, and the length of the predicted EA path was measured by the contouring technique (CoT) to estimate the linear insertion depth of the EA. Because CoT can only measure the length of the estimated EA path on a two-dimensional plane, we further modified the measurement by weighting the height of the cochlea and the length of the EA tail (the length of the last stimulating electrode to the end, which cannot be displayed on the CT image), which we termed the modified CoT + height + tail (MCHT) measurement. RESULTS: Based on our established method, MCHT could reduce the error to the submillimeter range (0.67 ± 0.37 mm) when estimating the linear insertion depth of various kinds of EAs compared with the actual implant length. The correlation coefficient between the linear insertion depth as predicted by MCHT and the actual was 0.958. The linear insertion depth estimated by this method was more accurate than that estimated using the classical CoT technique ( R = 0.442) and using the modified Escudé's method ( R = 0.585). CONCLUSIONS: MCHT is a method based on CT images that can accurately predict the linear insertion depth of cochlear implants preoperatively. This is the first report that we are aware of a method for predicting linear insertion depth before cochlear implantation with only submillimeter errors and that is tailored to different types of EAs.

Comprehension of Cochlear Duct Length for Incomplete Partition Types.

OBJECTIVE: Preoperative assessment of the cochlear duct length (CDL) and cochlear dimensions allows the selection of optimized implants. We aimed to evaluate the CDL measurements in incomplete partition (IP) defect patients and to create a reference to the literature. METHODS: Forty-one patients with IP (13 IP I, 23 IP II, and 5 IP III) and 30 controls were included in the study. The standardized cochlear image showing the basal turn in the most expansive plane was reconstructed from temporal high-resolution computed tomography images. Cochlear duct length measured manually (CDL-M) was measured by points placed consecutively on the lateral wall of the cochlea. The defined equations for estimating CDL (CDL measured according to Schurzig et al formula [CDL-Ɵ], CDL measured according to Escudé et al formula [CDL-E], CDL measured according to Alexiades et al formula [CDL-A]) were calculated from the same images. Cochlear duct length mean values obtained by each method were compared for each IP type. RESULTS: The longest CDL value was found in the control group, irrespective of the calculation method. Incomplete partition II cases had the most extended mean CDL among IP types. Incomplete partition III had the shortest CDL among all groups' CDL-M values. However, the mean CDL-M values of IP types I and III showed close results. There was no significant difference between the CDL-E and CDL-M values of the control group. Similarly, no significant difference was found between CDL-Ɵ and CDL-M values in IP type III cases. However, the results of other estimating formulations of all groups differed significantly from CDL-M values. CONCLUSION: Cochlear duct length differences were detected between the control group and IP subtypes. These differences should be considered when choosing the appropriate electrode length. Because the results of formulas estimating CDL may differ from CDL-M in both control and IP cases, it would be more appropriate to use manual measurements in clinical practice.