The effect of virtual reality on temporal bone anatomy evaluation and performance

Purpose There is only limited data on the application of virtual reality (VR) for the evaluation of temporal bone anatomy. The aim of the present study was to compare the VR environment to traditional cross-sectional viewing of computed tomography images in a simulated preoperative planning setting in novice and expert surgeons. Methods A novice (n = 5) and an expert group (n = 5), based on their otosurgery experience, were created. The participants were asked to identify 24 anatomical landmarks, perform 11 distance measurements between surgically relevant anatomical structures and 10 fiducial markers on five cadaver temporal bones in both VR environment and cross-sectional viewings in PACS interface. The data on performance time and user-experience (i.e., subjective validation) were collected. Results The novice group made significantly more errors (p < 0.001) and with significantly longer performance time (p = 0.001) in cross-sectional viewing than the expert group. In the VR environment, there was no significant differences (errors and time) between the groups. The performance of novices improved faster in the VR. The novices showed significantly faster task performance (p = 0.003) and a trend towards fewer errors (p = 0.054) in VR compared to cross-sectional viewing. No such difference between the methods were observed in the expert group. The mean overall scores of user-experience were significantly higher for VR than cross-sectional viewing in both groups (p < 0.001). Conclusion In the VR environment, novices performed the anatomical evaluation of temporal bone faster and with fewer errors than in the traditional cross-sectional viewing, which supports its efficiency for the evaluation of complex anatomy.

Automated Registration-Based Temporal Bone Computed Tomography Segmentation for Applications in Neurotologic Surgery

Objective This study investigates the accuracy of an automated method to rapidly segment relevant temporal bone anatomy from cone beam computed tomography (CT) images. Implementation of this segmentation pipeline has potential to improve surgical safety and decrease operative time by augmenting preoperative planning and interfacing with image-guided robotic surgical systems. Study Design Descriptive study of predicted segmentations. Setting Academic institution. Methods We have developed a computational pipeline based on the symmetric normalization registration method that predicts segmentations of anatomic structures in temporal bone CT scans using a labeled atlas. To evaluate accuracy, we created a data set by manually labeling relevant anatomic structures (eg, ossicles, labyrinth, facial nerve, external auditory canal, dura) for 16 deidentified high-resolution cone beam temporal bone CT images. Automated segmentations from this pipeline were compared against ground-truth manual segmentations by using modified Hausdorff distances and Dice scores. Runtimes were documented to determine the computational requirements of this method. Results Modified Hausdorff distances and Dice scores between predicted and ground-truth labels were as follows: malleus (0.100 ± 0.054 mm; Dice, 0.827 ± 0.068), incus (0.100 ± 0.033 mm; Dice, 0.837 ± 0.068), stapes (0.157 ± 0.048 mm; Dice, 0.358 ± 0.100), labyrinth (0.169 ± 0.100 mm; Dice, 0.838 ± 0.060), and facial nerve (0.522 ± 0.278 mm; Dice, 0.567 ± 0.130). A quad-core 16GB RAM workstation completed this segmentation pipeline in 10 minutes. Conclusions We demonstrated submillimeter accuracy for automated segmentation of temporal bone anatomy when compared against hand-segmented ground truth using our template registration pipeline. This method is not dependent on the training data volume that plagues many complex deep learning models. Favorable runtime and low computational requirements underscore this method’s translational potential.

Image-guided Temporal Bone Dissection Course

Introduction Temporal bone anatomy is complex and demands a profound anatomical knowledge. Association between surgery and imaging helps in the process of learning three-dimensional (3D) anatomy and surgical techniques. High definition temporal bone imaging can play an important role in dissection training. Objective To describe a computed tomography (CT) image-guided temporal bone dissection course for surgical training in otolaryngology and to verify the satisfaction level of the students with the course. Methods Descriptive research. The course took place at a research laboratory, with three experienced temporal bone surgeons. The participants were 12 otolaryngology residents. The laboratory has 7 modern workstations with microscope and monitors linked with a computerized video system. Cadaveric temporal bones were donated to the university. Imaging acquisition of the cadaveric temporal bones used in the course was performed in a multislice CT scanner. The CT images of cadaveric temporal bones were available with real-time access on the laboratory monitor's screens during dissections. Results A total of 13 temporal bones were included for dissection. Students had the opportunity to view on the same screen, simultaneously, both the dissection video and the respective CT images of their temporal bone anatomical specimens. This allowed correlating surgical and imaging aspects of temporal bone anatomy. At the end of the course, participants answered a satisfaction survey. Conclusion Considering imaging methods are routinely used during most otologic surgeries, detailed knowledge of CT imaging should be explored in conjunction with the temporal bone anatomical dissection.

Gray-Scale Inversion on High Resolution Computed Tomography of the Temporal Bone: An Observational Study

Objectives: This is a qualitative study to explore the utility of gray-scale inversion or the “invert” function of high-resolution computed tomography (HRCT) scans in the diagnosis of temporal bone anatomy and pathology. Methods: This is a case series describing an innovative application of an existing image processing tool to visualize temporal bone anatomy and pathology. Illustrative patients at a tertiary referral center with otologic symptoms and findings leading to HRCT scans of the temporal bone were included. Diagnostic HRCT scans were evaluated utilizing the gray-scale inversion function (invert function). Results: Nine illustrative cases which demonstrate conditions such as persistent stapedial artery, membranous stapes footplate, total ossicular prosthesis migration into the vestibule, third window syndrome such as superior semicircular canal dehiscence (SSCD) and cochlea-facial nerve dehiscence, otosclerosis, and ossicular chain discontinuity are included. The enhanced visualization was confirmed surgically in 3 cases, and 1 had physiological confirmation using cervical vestibular evoked myogenic potentials (cVEMP). Conclusions: Gray-scale inversion can be used to improve visualization of temporal bone anatomy and pathologic changes when diagnoses are in doubt. The invert function is a useful adjunct in the armamentarium of both radiologists and otologists when evaluating HRCT of the temporal bone.

Retrospective analysis of difficulties during mastoid surgeries in tertiary referral center in Nepal

<p class="abstract"><strong>Background:</strong> Complications can occur during and following mastoidectomy because of the variation in the temporal bone anatomy and surgical factors. The operating surgeon needs to be aware of potential difficulties and their clinical relevance to avoid the dread complication. This study aims to study various per-operative difficulties and complications encountered during mastoid surgery.</p><p class="abstract"><strong>Methods:</strong> A retrospective study was conducted, including 152 cases of chronic otitis media squamous type who underwent mastoidectomy from June 2017 to January 2019. Revision cases and cases with missing records on per-operative findings, early postoperative status, hearing assessment were excluded from the study. </p><p class="abstract"><strong>Results:</strong> Out of 152 cases, there were 80 males and 72 females with a mean of 27.5 years. Dural plate breach was recognized in 19 cases (12.5%) with iatrogenic injury in 16 cases. Breach of sinus plate and exposure of sigmoid sinus was noted in 11 cases (7.24%) and all were iatrogenic. Korner’s septum was noted in five cases (3.29%). The facial canal was dehiscence in 25 cases (16.4%) with the majority in the horizontal segment, but the sheath was intact in all cases. Immediate postoperative facial nerve palsy was seen in four cases (2.6%). Fistula in the lateral semi-circular canal was noted in two cases. Taste disturbance was noted in 13 cases. Local complications related to the surgical site was seen in 19 cases.</p><p class="abstract"><strong>Conclusions:</strong> The anatomic variations and surgical difficulty are common in mastoid surgery. The major complication rate is around 2-3% despite various mastoid variation and difficulties.</p>

Temporal bone dysplasia in Coffin-Siris syndrome

We report a child, diagnosed with Coffin-Siris syndrome (CSS), with chronic right otorrhoea. CT and DR-MRI were performed to further investigate, diagnose and determine relevant surgical anatomy. CT temporal bones assessment was performed, and the measurements compared with previously published data for normal temporal bone anatomy. These comparisons highlighted various differences which were not initially expected; it showed that there were multiple inner ear abnormalities in addition to middle ear disease. This case highlights the importance of considering temporal bone abnormalities in all children with CSS or any dysmorphia, when they may require mastoid procedures. Reviewing the management of this case provides relevant learning opportunities for both primary, secondary and tertiary care institutions.