Estimation of Angular Insertion Depth of a Cochlear Implant Electrode Array: Three-Dimensional Reconstruction Versus Spiral Formulae

To describe histologic and radiographic findings associated with insertion of a new lateral wall electrode in human temporal bones, as well as quantify the ease of insertion as characterized by multiple cochlear implant surgeons. Multi-institutional cadaveric study. The Slim J electrode was inserted in cadaveric temporal bones via a standard mastoidectomy and facial recess approach. Insertion was performed by five cochlear implant surgeons with no previous experience with the Slim J electrode array. Electrode array insertion was performed via a round window, an extended round window, or a cochleostomy approach. Intracochlear trauma, and angular insertion depth was assessed histologically and radiologically, respectively, after placement of the Slim J electrode array. Scala tympani insertion was accomplished in all 40 specimens. Thirty-eight specimens (95%) showed minimal trauma (Esrhaghi grade 0 or 1). One patient had rupture of basilar membrane (grade 2 trauma) at 380 degrees. One patient had grade 4 trauma with scalar translocation beginning at 210 degrees. The mean angular insertion depth was 416.4 degrees (range: 338.7-509.2 degrees, SD 44 degrees). Surgical handling was described as easy in 38 cases (95%). In a human cadaveric model the lateral wall Slim J electrode produced minimal intracochlear trauma that was positioned completely within the scala tympani in 97.5% of cases.

To examine the effects of scala tympani (ST) volume, cochlear duct length (CDL), and angular insertion depth (AID) on low-frequency hearing preservation for cochlear implant (CI) recipients of lateral wall electrode arrays. A retrospective review identified 45 adult CI recipients of 24-, 28-, or 31.5-mm lateral wall electrode arrays with preoperative unaided hearing thresholds ≤45 decibel hearing level (dB HL) at 250 Hz. All patients underwent preoperative and postoperative computed tomography to evaluate cochlear morphology and electrode array position. A linear mixed effects model evaluated effects of ST volume, CDL, AID, preoperative low-frequency pure-tone average (LFPTA; 125, 250, and 500 Hz), age at surgery, and biological sex on the postoperative change in LFPTA at activation and 6 months post-activation. There were significant main effects of ST volume (p = 0.044), age (p = 0.028), and biological sex (p = 0.003), indicating better low-frequency hearing preservation for CI recipients with larger ST volumes, younger age at surgery, and female biological sex. Although CDL positively correlated with ST volume (r = 0.74, p < 0.001), there was no significant main effect of CDL (p = 0.367). A broad range in AID of the most apical electrode contact was observed (301.4°-681.8°); however, there was no significant main effect of AID on low-frequency hearing preservation (p = 0.700). During the initial 6 months following implantation, intrinsic factors such as cochlear morphology may have a greater impact on low-frequency hearing preservation than apical positioning of a flexible lateral wall electrode array when using soft surgical techniques. 3 Laryngoscope, 2024.

ObjectiveTo compare hearing preservation outcomes between lateral wall and perimodiolar electrode arrays for cochlear implant patients.Study DesignRetrospective cohort study.SettingA large Western Australian cochlear implant clinicMethodsA total of 311 adult cochlear implant recipients (321 ears) implanted between 2017 and 2022 were included. Of these, 174 presented with postlingual hearing loss and preoperative functional low-frequency hearing. The change in low-frequency pure-tone average was assessed as the difference between preoperative to 3-, 6-, and 12-months postoperative measurements. Data were analyzed through linear mixed-effects modeling and one-way ANOVA.ResultsPreoperative low-frequency, pure-tone average was higher for those implanted with perimodiolar compared with lateral wall electrodes (P < .05). The linear mixed-effects model revealed that change in low-frequency pure-tone average at all postoperative timepoints was similar between lateral wall and perimodiolar electrodes (P > .05).ConclusionThere were similar changes in residual postoperative hearing between all electrode types when controlling for preoperative low-frequency hearing and age implanted. These data suggest that newer, thinner perimodiolar and lateral wall electrodes could be considered for individuals with greater levels of preoperative low-frequency hearing.

To improve estimation of cochlear implant (CI) insertion depth in postoperative skull x-rays using synthesized information from preoperative CT scans. Retrospective cohort. Tertiary referral center. Ten adult cochlear implant recipients with preoperative and postoperative temporal bone computed tomography (CT)scans and postoperative skull x-ray imaging. Postoperative x-rays and digitally reconstructed radiographs (DRR) from preoperative CTs were registered using 3D Slicer and MATLAB to enhance localization of the round window and modiolus. Angular insertion depth (AID) was estimated in unmodified and registration-enhanced x-rays and DRRs in the cochlear view. Linear insertion depth (LID) was estimated in registered images by two methods that localized the proximal CI electrode or segmented the cochlea. Ground truth assessments were made in postoperative CTs. Errors of insertion depth estimates were calculated relative to ground truth measurements and compared with paired t t ests. Pearson correlation coefficient was used to assess inter-rater reliability of two reviewer's measurements of AID in unmodified x-rays. In postoperative x-rays, AID estimation errors were similar with and without registration enhancement (-1.3 ± 20.7° and -4.8 ± 24.9°, respectively; mean ± SD; p = 0.6). AID estimation in unmodified x-rays demonstrated strong interrater agreement (ρ = 0.79, p < 0.05) and interrater differences (-15.0 ± 35.3°) comparable to estimate errors. Registering images allowed measurement of AID in the cochlear view with estimation errors of 14.6 ± 30.6° and measurement of LID, with estimate errors that were similar between proximal electrode localization and cochlear segmentation methods (-0.9 ± 2.2 mm and -2.1 ± 2.7 mm, respectively; p = 0.3). 2D-3D image registration allows measurement of AID in the cochlear view and LID using postoperative x-rays and preoperative CT imaging. The use of this technique may reduce the need for postimplantation CT studies to assess these metrics of CI electrode position. Further work is needed to improve the accuracy of AID assessment in the postoperative x-ray view with registered images compared with established methods.

Real-time three-dimensional (3D) reconstruction of real-world environments has many significant applications in various fields, including telepresence technology. When depth sensors, such as those from Microsoft's Kinect series, are introduced simultaneously and become widely available, a new generation of telepresence systems can be developed by combining a real-time 3D reconstruction method with these new technologies. This combination enables users to engage with a remote person while remaining in their local area, as well as control remote devices while viewing their 3D virtual representation. There are numerous applications in which having a telepresence experience could be beneficial, including remote collaboration and entertainment, as well as education, advertising, and rehabilitation. The purpose of this systematic literature review is to analyze the recent advances in 3D reconstruction methods for telepresence systems and the significant related work in this field. Next, we determine the input data and the technological device employed to acquire the input data, which will be utilized in the 3D reconstruction process. The methods of 3D reconstruction implemented in the telepresence system as well as the evaluation of the system, have been extracted and assessed from the included studies. Through the analysis and summarization of many dimensions, we discussed the input data used for the 3D reconstruction method, the real-time 3D reconstruction methods implemented in the telepresence system, and how to evaluate the system. We conclude that real-time 3D reconstruction methods for telepresence systems have progressively improved over the years in conjunction with the advancement of machines and devices such as Red Green Blue-Depth (RGB-D) cameras and Graphics Processing Unit (GPU).

Do Perioperative Systemic Corticosteroids Improve Cochlear Implant Hearing Preservation Outcomes?

Unmanned aerial vehicle remote sensing images are easy to acquire and cost-effective. Their application provides a new approach for the maintenance of offshore wind farms. To obtain an accurate model of wind turbines, thereby improving detection efficiency and mitigating the risks associated with high-altitude workings, a low-cost method for wind turbine three-dimensional (3D) reconstruction is proposed. The main advantages of deep learning-based Multi-View Stereo Network (MVSNet) include high accuracy, fast processing speed, and ease of extension to multiple viewpoints. Most networks utilize multi-scale 3D Convolutional Neural Network (CNN) for regularization. However, when dealing with images that have high depth and resolution, CNN regularization strategy leads to a significant increase in memory usage. In this paper, the two-dimensional cost maps are regularized along the depth dimension sequentially using Stacked Convolutional Gated Recurrent Unit (Stacked Conv-GRU), instead of reducing the 3D cost volume all at once. Localized convolution operations replace undifferentiated fully connected operations, substantially reducing memory consumption and enabling high-resolution reconstruction. We conduct comparisons and model evaluations on the ”Nordtank” wind turbine remote sensing image dataset. Experimental results demonstrate that, compared to other 3D reconstruction methods, Stacked Conv-GRU regularized MVSNet reduces run time and hardware requirements while maintaining similar accuracy.

Objective To study the image segmentation, three-dimensional (3D) reconstruction and simulation operation of choledocholithotomy and T-tube drainage based on the computed tomagraphy (CT) data of patient with choledocholithiasis. Methods Patient with choledocholithiasis underwent 64-slice spiral CT imaging. The images segmentation and 3D reconstruction were performed by Medical Image Process System (MIPS) to construct the 3D model of the hepatobiliary system. The model was modified by FreeForm Modeling System. The virtual surgical instruments were developed by GHOST SDK software, and were imported to the virtual surgery. Results The data of plain, arterial phase, venous phase and portal venous phase scanning were collected, and the data stored in DICOM format were transformed to BMP format. A model of the hepatobiliary system was constructed after the data was segmented by MIPS, and then the model was exported in the STL format. The data in STL format were imported to FreeForm Modeling System for smoothing the model. Different structures were assigned different colors to make the model more vivid. The self-developed virtual surgical instruments were imported to the system, and the virtual surgery for choledocholithiasis was performed with PHANToM. Conclusions With the help of MIPS, the image segmentation and 3D reconstruction of the model are finished rapidly and effectively. After the virtual surgical instruments are developed in FreeForm Modeling System, the virtual surgery can be achieved in the 3D model with the assistance of PHANToM. Key words: Choledocholithiasis; Three-dimensional reconstruction; Virtual surgery

An optimal protocol for clearing the cervical spine in unconscious patients with traumatic brain injury remains controversial. Protocols include plain radiographs and computed tomography (CT), and ligamentous injury may be identified with flexion-extension radiographs. We questioned whether cervical CT with three-dimensional (3D) reconstructions may obviate the need for flexion-extension radiology in the detection of occult ligamentous injury. Between July 1999 and November 2001, 276 unconscious traumatic brain injured patients admitted to The Alfred Hospital received cervical spine plain radiographs, CT with 3D reconstructions, and dynamic flexion-extension X-ray studies with fluoroscopy as part of a routine protocol. These patients were identified from a prospective intensive care unit database and all radiology reports were reviewed. Dynamic flexion-extension X-ray studies with fluoroscopy identified no new fractures or instability; there were no instances of true-positive results. Dynamic flexion-extension was true-negative in 260 of 276 (94%) patients, falsely positive in six patients (2.2%) and falsely negative in one (0.4%) patient. In nine patients, dynamic flexion-extension was inadequate. Dynamic flexion-extension X-ray studies with fluoroscopy delayed cervical spine clearance and were almost always reported as normal. In a cervical spine clearance protocol for unconscious traumatic brain injury patients, dynamic flexion-extension X-ray studies with fluoroscopy did not identify any patients with cervical fracture or instability not already identified by plain radiographs and fine-cut CT (C0 to T2) with 3D reconstructions.

We herein describe the case of an adult with a complicated huge lymphangioma of the small bowel mesentery. Computed tomography (CT) confirmed a 45 × 30 × 14 cm multiple and separate, mixed and solid cystic tumor without enhancement by contrast medium in the abdominal cavity. Mesenteric CT angiography with three-dimensional (3D) reconstruction showed that the tumor did not involve the first jejunal artery, although the tumor did involve the subsequent jejunal and ileal arteries and the corresponding segment of the small bowel. Under anatomic guidance based on mesenteric CT angiography with 3D reconstruction, we were able to successfully excise the tumor. Mesenteric lymphangioma should be excised even when the tumor is asymptomatic. Mesenteric CT angiography with 3D reconstruction is useful for the surgical treatment of huge mesenteric tumors.

Monitor four-point impedance in cochlear implant recipients over time and determine if implant type, surgical approach, and electrode positioning affected impedance measurements. Prospective observational. Hospital. Adult cochlear implant recipients implanted with a perimodiolar or lateral wall cochlear implant. Mean values for four-point impedances were calculated for all electrode contacts at perioperative and 3 months after surgery. Linear mixed models were applied to the impedance data to compare between implant types and time points. The angular insertion depth and electrode position relative to the medial and lateral wall, commonly termed the Intracochlear Position Index (ICPI), were collected and compared with impedance measurements. Perioperatively, the four-point impedance was similar between implant types, with perimodiolar implants having marginally higher impedance values in the basal region. At 3 months after surgery, impedances significantly increased in the basal half of the electrode array for both implants, with higher impedance values for CI532 implants. There were no significant differences in insertion angle depth between implant types. The ICPI values for the seven most basal electrodes were similar for both implants; however, CI532 arrays were significantly more medially placed along the remaining apical portion of the array, which is expected. ICPI values did not correlate with impedance measurements for either implant. Four-point impedance increases at 3 months after surgery may reflect fibrous tissue formation after cochlear implantation. The higher impedance values in perimodiolar implants may reflect a more extensive fibrosis formation as a result of surgical approaches used, requiring drilling of the cochlea bone.

The primary aim of this study was to compare outcomes of adult cochlear implant recipients receiving either perimodiolar or lateral wall electrode arrays. A prospective randomized controlled study was conducted to investigate final electrode array position, speech perception, and vestibular symptoms. Tertiary referral center. One hundred forty-four adults were assessed for the study. Inclusion criteria were bilateral postlingual severe to profound sensorineural hearing loss, with 500-Hz threshold in the implant ear of 75 dB HL or greater. Subjects were randomized to receive either perimodiolar or lateral wall electrode arrays. Postoperative electrode array position was assessed by cone-beam computed tomography. Speech perception was measured preoperatively in best-aided conditions, and 3 and 12 months postoperatively. Vestibular symptoms were assessed using two self-reported questionnaires and/or clinician reports. Postoperative speech perception results for 124 implants in 123 adults showed significant improvement from preoperative scores and from 3 to 12 months postoperatively. Multiple regression analysis indicated no significant effect of electrode array position for any speech perception results at 3 and 12 months postoperatively. Auditory alone, monosyllabic word, and phoneme scores at 12 months were 48.4 and 71.4% for lateral wall electrode arrays and 49.8% and 72.0% for perimodiolar electrode arrays, respectively. No relationships between angle (depth) of electrode array insertion and speech perception outcomes were detected. There was no significant difference in incidence of vestibular symptoms between the groups. Correct scala tympani placement of either the perimodiolar or lateral wall electrode arrays used in this study provides excellent speech perception outcomes, with no significant difference demonstrated between groups.

Background:The accuracy of three-dimensional (3D) reconstructions from cone-beam computed tomography (CBCT) has been particularly important in dentistry, which will affect the effectiveness of diagnosis, treatment plan, and outcome in clinical practice. The aims of this study were to assess the linear, volumetric, and geometric accuracy of 3D reconstructions from CBCT and to investigate the influence of voxel size and CBCT system on the reconstructions results.Methods:Fifty teeth from 18 orthodontic patients were assigned to three groups as NewTom VG 0.15 mm group (NewTom VG; voxel size: 0.15 mm; n = 17), NewTom VG 0.30 mm group (NewTom VG; voxel size: 0.30 mm; n = 16), and VATECH DCTPRO 0.30 mm group (VATECH DCTPRO; voxel size: 0.30 mm; n = 17). The 3D reconstruction models of the teeth were segmented from CBCT data manually using Mimics 18.0 (Materialise Dental, Leuven, Belgium), and the extracted teeth were scanned by 3Shape optical scanner (3Shape A/S, Denmark). Linear and volumetric deviations were separately assessed by comparing the length and volume of the 3D reconstruction model with physical measurement by paired t-test. Geometric deviations were assessed by the root mean square value of the imposed 3D reconstruction and optical models by one-sample t-test. To assess the influence of voxel size and CBCT system on 3D reconstruction, analysis of variance (ANOVA) was used (α = 0.05).Results:The linear, volumetric, and geometric deviations were −0.03 ± 0.48 mm, −5.4 ± 2.8%, and 0.117 ± 0.018 mm for NewTom VG 0.15 mm group; −0.45 ± 0.42 mm, −4.5 ± 3.4%, and 0.116 ± 0.014 mm for NewTom VG 0.30 mm group; and −0.93 ± 0.40 mm, −4.8 ± 5.1%, and 0.194 ± 0.117 mm for VATECH DCTPRO 0.30 mm group, respectively. There were statistically significant differences between groups in terms of linear measurement (P < 0.001), but no significant difference in terms of volumetric measurement (P = 0.774). No statistically significant difference were found on geometric measurement between NewTom VG 0.15 mm and NewTom VG 0.30 mm groups (P = 0.999) while a significant difference was found between VATECH DCTPRO 0.30 mm and NewTom VG 0.30 mm groups (P = 0.006).Conclusions:The 3D reconstruction from CBCT data can achieve a high linear, volumetric, and geometric accuracy. Increasing voxel resolution from 0.30 to 0.15 mm does not result in increased accuracy of 3D tooth reconstruction while different systems can affect the accuracy.

Evaluate, based on morphologic and histologic parameters, the atraumaticity of 2 electrode arrays implanted in 10 human temporal bones. Atraumatic surgery and electrode arrays are current topics in otologic surgery. The preservation of cochlear anatomy and its functions is a priority and morphologic evaluation of the surgical trauma is essential to continue improving in this field. Ten preserved human temporal bones (TB) without anatomic alterations were used in this study. They were divided into 2 groups of 5, and atraumatic surgery was performed to insert HiFocus 1J (group A) and HiFocus Helix (group B) electrode arrays. Anatomic comparisons were performed using computed tomography and histologic analysis. Group A: the mean length for the cochlear longitudinal axis was 10.30 mm, and the cochlear transversal axis was 7.2 mm. Scala tympani insertion was achieved in 4/5 TB studied, with a mean depth and angle of insertion of 19.2 mm and 325.5°, respectively. Lateral location of the electrode array was achieved in all specimens. No significant correlation was observed between these dimensions and depth of insertion. Group B: the mean length for the cochlear longitudinal axis was 9.52 mm, and cochlear transversal axis was 6.38 mm. Scala tympani insertion was achieved in 4/5 TB studied, with a mean depth and angle of insertion of 17.5 mm and 352°, respectively. Modiolar location of the electrode array was achieved in all specimens. A positive correlation was established between the linear and angular insertion depths (p = 0.044). In summary, it is safe to state that neither electrode array shows significant insertion trauma.

In modern medicine, 3D reconstruction plays an important role in improving the accuracy of disease detection and treatment especially in the process of robot-assisted surgery. Accordingly, the choice of 3D reconstruction method is of great importance, which provides real-time visualization. This study analyses and compares two types of methods in 3D medical image reconstruction and visualization: Surface Rendering and Volume Rendering. To be more specific, four algorithms including Contour Filter (CF), Marching Cubes (MC), Composite Volume Rendering (CVR) and Texture Mapping Hardware (TMH) were implemented and compared from the perspective of the rendering effect, speed and interactivity, in which the former two algorithms belong to the concept of Surface Rendering and the latter two algorithms are in the range of Volume Rendering. These algorithms were implemented by Microsoft Visual Studio with Visualization Toolkit (VTK) to reconstruct the 3D images of patients CT image data. The mechanism and realization of these algorithms were described, and the merits and shortcomings of these different rendering methods were compared. Based on the comparison results, the 3D reconstruction and rendering method can be determined according to the specific requirements of robot-assisted surgery.