The Visible Ear Simulator: A Public PC Application for GPU-Accelerated Haptic 3D Simulation of Ear Surgery Based on the Visible Ear Data

Virtual temporal bone simulators and their use in surgical training: a narrative review

OBJECTIVE

Temporal bone dissection is a difficult skill to acquire, and the challenge has recently been further compounded by a reduction in conventional surgical training opportunities during the coronavirus disease 2019 pandemic. Consequently, there has been renewed interest in ear simulation as an adjunct to surgical training for trainees. We review the state-of-the-art virtual temporal bone simulators for surgical training.

MATERIALS AND METHODS

A narrative review of the current literature was performed following a Medline search using a pre-determined search strategy.

RESULTS AND ANALYSIS

Sixty-one studies were included. There are five validated temporal bone simulators: Voxel-Man, CardinalSim, Ohio State University Simulator, Melbourne University's Virtual Reality Surgical Simulation and Visible Ear Simulator. The merits of each have been reviewed, alongside their role in surgical training.

CONCLUSION

Temporal bone simulators have been demonstrated to be useful adjuncts to conventional surgical training methods and are likely to play an increasing role in the future.

Fully immersive virtual reality for skull-base surgery: surgical training and beyond

PURPOSE

A virtual reality (VR) system, where surgeons can practice procedures on virtual anatomies, is a scalable and cost-effective alternative to cadaveric training. The fully digitized virtual surgeries can also be used to assess the surgeon's skills using measurements that are otherwise hard to collect in reality. Thus, we present the Fully Immersive Virtual Reality System (FIVRS) for skull-base surgery, which combines surgical simulation software with a high-fidelity hardware setup.

METHODS

FIVRS allows surgeons to follow normal clinical workflows inside the VR environment. FIVRS uses advanced rendering designs and drilling algorithms for realistic bone ablation. A head-mounted display with ergonomics similar to that of surgical microscopes is used to improve immersiveness. Extensive multi-modal data are recorded for post-analysis, including eye gaze, motion, force, and video of the surgery. A user-friendly interface is also designed to ease the learning curve of using FIVRS.

RESULTS

We present results from a user study involving surgeons with various levels of expertise. The preliminary data recorded by FIVRS differentiate between participants with different levels of expertise, promising future research on automatic skill assessment. Furthermore, informal feedback from the study participants about the system's intuitiveness and immersiveness was positive.

CONCLUSION

We present FIVRS, a fully immersive VR system for skull-base surgery. FIVRS features a realistic software simulation coupled with modern hardware for improved realism. The system is completely open source and provides feature-rich data in an industry-standard format.

What is the Current State of Extended Reality Use in Otolaryngology Training? A Scoping Review

OBJECTIVE

To map current literature on the educational use of extended reality (XR) in Otolaryngology-Head and Neck Surgery (OHNS) to inform teaching and research.

STUDY DESIGN

Scoping Review.

METHODS

A scoping review was conducted, identifying literature through MEDLINE, Ovid Embase, and Web of Science databases. Findings were reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping review checklist. Studies were included if they involved OHNS trainees or medical students who used XR for an educational purpose in OHNS. XR was defined as: fully-immersive virtual reality (VR) using head-mounted displays (HMDs), non-immersive and semi-immersive VR, augmented reality (AR), or mixed reality (MR). Data on device use were extracted, and educational outcomes were analyzed according to Kirkpatrick's evaluation framework.

RESULTS

Of the 1,434 unique abstracts identified, 40 articles were included. All articles reported on VR; none discussed AR or MR. Twenty-nine articles were categorized as semi-immersive, none used occlusive HMDs therefore, none met modern definitions of immersive VR. Most studies (29 of 40) targeted temporal bone surgery. Using the Kirkpatrick four-level evaluation model, all studies were limited to level-1 (learner reaction) or level-2 (knowledge or skill performance).

CONCLUSIONS

Current educational applications of XR in OHNS are limited to VR, do not fully immerse participants and do not assess higher-level learning outcomes. The educational OHNS community would benefit from a shared definition for VR technology, assessment of skills transfer (level-3 and higher), and deliberate testing of AR, MR, and procedures beyond temporal bone surgery. Laryngoscope, 133:227-234, 2023.

Am I doing this right? Structured self-assessment during simulation training of mastoidectomy improves cadaver dissection performance: a prospective educational study

PURPOSE

Temporal bone surgery requires excellent surgical skills and simulation-based training can aid novices' skills acquisition. However, simulation-based training is challenged by early stagnation of performance after few performances. Structured self-assessment during practice might enhance learning by inducing reflection and engagement in the learning task. In this study, structured self-assessment was introduced during virtual reality (VR) simulation of mastoidectomy to investigate the effects on subsequent performance during cadaveric dissection.

METHODS

A prospective educational study with comparison with historical controls (reference cohort). At a temporal bone dissection course, eighteen participants performed structured self-assessment during 3 h of VR simulation mastoidectomy training before proceeding to cadaver dissection (intervention cohort). At a previous course, eighteen participants received identical VR simulation training but without the structured self-assessment (reference cohort). Final products from VR simulation and cadaveric dissection were recorded and assessed by two blinded raters using a 19-point modified Welling Scale.

RESULTS

The intervention cohort completed fewer procedures (average 4.2) during VR simulation training than the reference cohort (average 5.7). Nevertheless, the intervention cohort achieved a significantly higher average performance score both in VR simulation (11.1 points, 95% CI [10.6-11.5]) and subsequent cadaveric dissection (11.8 points, 95% CI [10.7-12.8]) compared with the reference cohort, who scored 9.1 points (95% CI [8.7-9.5]) during VR simulation and 5.8 points (95% CI [4.8-6.8]) during cadaveric dissection.

CONCLUSIONS

Structured self-assessment is a valuable learning support during self-directed VR simulation training of mastoidectomy and the positive effect on performance transfers to subsequent cadaveric dissection performance.

Mastoidectomy Training: Is Anatomical Variation Needed? A Randomized, Controlled Trial on Performance and Skills Transfer From Virtual Reality to a Three-Dimensional Printed Model

OBJECTIVE

Virtual reality (VR) simulation-based training effectively improves novices' mastoidectomy skills. Unfortunately, learning plateaus at an insufficient level and knowledge on optimizing mastoidectomy training to overcome this plateau is needed. In this study, we aim to investigate how training on anatomically different temporal bone cases affects learning, including the effect on retention and transfer of skills.

STUDY DESIGN

Randomized controlled trial of an educational intervention.

SETTING

The Simulation Center at Copenhagen Academy for Medical Education and Simulation.

PARTICIPANTS

Twenty-four medical students from the University of Copenhagen.

INTERVENTION

Participants were randomized to practice mastoidectomy on either 12 anatomically varying (intervention group) or 12 identical (control group) cases in a VR simulator. At the end of training and again ~ 3 weeks after training (retention), learners were tested on a new VR patient case and a three-dimensional printed model.

MAIN OUTCOME MEASURE

Mastoidectomy performance evaluated by blinded expert raters using a 26-item modified Welling Scale.

RESULTS

The intervention and control groups' performance results were comparable at the end of training. Likewise, retention and transfer performances were similar between groups. The overall mean score at the end of training corresponded to approximately 70% of the possible maximum score.

CONCLUSIONS

Simulation-based training using anatomical variation was equivalent to training on a single case with respect to acquisition, retention, and transfer of mastoidectomy skills. This suggests that efforts to expose novices to variation during initial training are unnecessary as this variation has limited effect, and-conversely-that educators can expose novices to naturally different anatomical variations without worry of hindered learning.

Effect of 3D-Printed Models on Cadaveric Dissection in Temporal Bone Training

Objective

Mastoidectomy is a cornerstone in the surgical management of middle and inner ear diseases. Unfortunately, training is challenged by insufficient access to human cadavers. Three-dimensional (3D) printing of temporal bones could alleviate this problem, but evidence on their educational effectiveness is lacking. It is largely unknown whether training on 3D-printed temporal bones improves mastoidectomy performance, including on cadavers, and how this training compares with virtual reality (VR) simulation. To address this knowledge gap, this study investigated whether training on 3D-printed temporal bones improves cadaveric dissection performance, and it compared this training with the already-established VR simulation.

Study Design

Prospective cohort study of an educational intervention.

Setting

Tertiary university hospital, cadaver dissection laboratory, and simulation center in Copenhagen, Denmark.

Methods

Eighteen otorhinolaryngology residents (intervention) attending the national temporal bone dissection course received 3 hours of mastoidectomy training on 3D-printed temporal bones. Posttraining cadaver mastoidectomy performances were rated by 3 experts using a validated assessment tool and compared with those of 66 previous course participants (control) who had received time-equivalent VR training prior to dissection.

Results

The intervention cohort outperformed the controls during cadaver dissection by 29% (P < .001); their performances were largely similar across training modalities but remained at a modest level (~50% of the maximum score).

Conclusion

Mastoidectomy skills improved from training on 3D-printed temporal bone and seemingly more so than on time-equivalent VR simulation. Importantly, these skills transferred to cadaveric dissection. Training on 3D-printed temporal bones can effectively supplement cadaver training when learning mastoidectomy.

Cochlear implantation: Exploring the effects of 3D stereovision in a digital microscope for virtual reality simulation training - A randomized controlled trial

In cochlear implantation (CI), excellent surgical technique is critical for hearing outcomes. Recent advances in temporal bone Virtual Reality (VR) training allow for specific training of CI and through introduction of new digital microscopes with ultra-high-fidelity (UHF) graphics. This study aims to investigate whether UHF increases performance in VR simulation training of CI electrode insertion compared with conventional, screen-based VR (cVR).

METHODS

Twenty-four medical students completed a randomized, controlled trial of an educational intervention. They performed a total of eight CI electrode insertions each in blocks of four using either UHF-VR or cVR, in randomized order. CI electrode insertion performances were rated by two blinded expert raters using a structured assessment tool supported by validity evidence.

RESULTS

Performance scores in cVR were higher than in the UHF-VR simulation although this was not significant (19.8 points, 95% CI [19.3-20.3] vs. 18.8 points, 95% CI [18.2-19.4]; P = 0.09). The decisive factor for performance was participants' ability to achieve stereovision (mean difference = 1.1 points, 95% CI [0.15-2.08], P = 0.02).

DISCUSSION

No additional benefit was found from UHF-VR over cVR training of CI electrode insertion for novices. Consequently, standard cVR simulation should be used for novices' basic skills acquisition in CI surgery. Future studies should instead explore the effects of other improvements in CI surgery training and if the lacking benefit of UHF-VR also applies for more experienced learners.

CONCLUSION

The increased graphical perception and the superior lifelikeness of UHF-VR does not improve early skills acquisition of CI insertion for novices.

Automated summative feedback improves performance and retention in simulation training of mastoidectomy: a randomised controlled trial

OBJECTIVE

This study aimed to investigate the effects of automated metrics-based summative feedback on performance, retention and cognitive load in distributed virtual reality simulation training of mastoidectomy.

METHOD

Twenty-four medical students were randomised in two groups and performed 15 mastoidectomies on a distributed virtual reality simulator as practice. The intervention group received additional summative metrics-based feedback; the control group followed standard instructions. Two to three months after training, participants performed a retention test without learning supports.

RESULTS

The intervention group had a better final-product score (mean difference = 1.0 points; p = 0.001) and metrics-based score (mean difference = 12.7; p < 0.001). At retention, the metrics-based score for the intervention group remained superior (mean difference = 6.9 per cent; p = 0.02). Also at the retention, cognitive load was higher in the intervention group (mean difference = 10.0 per cent; p < 0.001).

CONCLUSION

Summative metrics-based feedback improved performance and lead to a safer and faster performance compared with standard instructions and seems a valuable educational tool in the early acquisition of temporal bone skills.

A novel view of computed tomography images similar to the visual field of otologic surgeons

OBJECTIVES

In preparation for endoscopic sinus surgery (ESS), the most important computed tomography (CT) image for otolaryngologists is the coronal plane image because it has a viewpoint similar to that of the surgical visual field. Contrastingly, otologic surgeons refer to axial and coronal plane images before ear surgery and must imagine the anatomical structure of the temporal bone by reconstructing three-dimensional (3D) images in their minds. We propose a "surgical position view (SPV) image," a novel viewpoint of CT images that enables otologic surgeons to see a perspective similar to the surgical visual field.

METHOD

Sagittal plane CT images of the temporal bone were created from axial plane images with multi-planar reconstruction (MPR). Then, the SPV image was obtained by rotating it 90° to the supine position. The entire process can be performed anywhere in the hospital within 1 minute using the electronic medical record computer's image viewer.

RESULTS

SPV images show anatomical structures of the temporal bone, external ear canal, mastoid cavity, sigmoid vein, facial nerve, ossicles, and cochlea, in a similar view to the actual ear surgery. Soft tissue such as cholesteatoma is depicted in the same concentration as the normal CT image.

CONCLUSION

The SPV image enables an otologic surgeon to see the temporal bone CT image from the actual ear surgery viewpoint simply and quickly. It helps to visualize the 3D anatomical structure of the temporal bone and can be useful for ear surgery planning.

LEVEL OF EVIDENCE

5.

OpenEar Image Data Enables Case Variation in High Fidelity Virtual Reality Ear Surgery

BACKGROUND

Virtual reality (VR) simulation is an established option for temporal bone surgical training. Most VR simulators are based on computed tomography imaging, whereas the Visible Ear Simulator (VES) is based on high-fidelity cryosections of a single temporal bone specimen. Recently published OpenEar datasets combine cone-beam computed tomography (CBCT) and micro-slicing to achieve similar model quality. This study explores integration of OpenEar datasets into VES to enable case variation in simulation with implications for patient-specific modeling based on CBCT.

METHODS

The OpenEar dataset consists of segmented, coregistered, multimodal imaging sets of human temporal bones. We derived drillable bone segments from the dataset as well as triangulated surface models of critical structures such as facial nerve or dura. Realistic visualization was achieved using coloring from micro-slicing, custom tinting, and texture maps. Resulting models were validated by clinical experts.

RESULTS

Six of the eight OpenEar datasets could be integrated in VES complete with instructional guides for various temporal bone surgical procedures. Resulting models were of high quality because of postprocessing steps taken to increase realism including colorization and imaging artifact removal. Bone artifacts were common in CBCT, resulting in dehiscences that most often could not be found in the ground truth micro-slicing data.

CONCLUSION

New anatomy models are included in VES version 3.5 freeware and provide case variation for training which could help trainees to learn more quickly and transferably under variable practice conditions. The use of CBCT for VR simulation models without postprocessing results in bone artifacts, which should be considered when using clinical imaging for patient-specific simulation, surgical rehearsal, and planning.

Cochlear implant surgery: Learning curve in virtual reality simulation training and transfer of skills to a 3D-printed temporal bone - A prospective trial

OBJECTIVE

Mastering Cochlear Implant (CI) surgery requires repeated practice, preferably initiated in a safe - i.e. simulated - environment. Mastoidectomy Virtual Reality (VR) simulation-based training (SBT) is effective, but SBT of CI surgery largely uninvestigated. The learning curve is imperative for understanding surgical skills acquisition and developing competency-based training. Here, we explore learning curves in VR SBT of CI surgery and transfer of skills to a 3D-printed model.

METHODS

Prospective, single-arm trial. Twenty-four novice medical students completed a pre-training CI inserting test on a commercially available pre-drilled 3D-printed temporal bone. A training program of 18 VR simulation CI procedures was completed in the Visual Ear Simulator over four sessions. Finally, a post-training test similar to the pre-training test was completed. Two blinded experts rated performances using the validated Cochlear Implant Surgery Assessment Tool (CISAT). Performance scores were analyzed using linear mixed models.

RESULTS

Learning curves were highly individual with primary performance improvement initially, and small but steady improvements throughout the 18 procedures. CI VR simulation performance improved 33% (p < 0.001). Insertion performance on a 3D-printed temporal bone improved 21% (p < 0.001), demonstrating skills transfer.

DISCUSSION

VR SBT of CI surgery improves novices' performance. It is useful for introducing the procedure and acquiring basic skills. CI surgery training should pivot on objective performance assessment for reaching pre-defined competency before cadaver - or real-life surgery. Simulation-based training provides a structured and safe learning environment for initial training.

CONCLUSION

CI surgery skills improve from VR SBT, which can be used to learn the fundamentals of CI surgery.

Patient-specific Virtual Temporal Bone Simulation Based on Clinical Cone-beam Computed Tomography

OBJECTIVES

Patient-specific surgical simulation allows presurgical planning through three-dimensional (3D) visualization and virtual rehearsal. Virtual reality simulation for otologic surgery can be based on high-resolution cone-beam computed tomography (CBCT). This study aimed to evaluate clinicians' experience with patient-specific simulation of mastoid surgery.

METHODS

Prospective, multi-institutional study. Preoperative temporal bone CBCT scans of patients undergoing cochlear implantation (CI) were retrospectively obtained. Automated processing and segmentation routines were used. Otologic surgeons performed a complete mastoidectomy with facial recess approach on the patient-specific virtual cases in the institution's temporal bone simulator. Participants completed surveys regarding the perceived accuracy and utility of the simulation.

RESULTS

Twenty-two clinical CBCTs were obtained. Four attending otologic surgeons and 5 otolaryngology trainees enrolled in the study. The mean number of simulations completed by each participant was 16.5 (range 3-22). "Overall experience" and "usefulness for presurgical planning" were rated as "good," "very good," or "excellent" in 84.6% and 71.6% of the simulations, respectively. In 10.7% of simulations, the surgeon reported to have gained a significantly greater understanding of the patient's anatomy compared to standard imaging. Participants were able to better appreciate subtle anatomic findings after using the simulator for 60.4% of cases. Variable CBCT acquisition quality was the most reported limitation.

CONCLUSION

Patient-specific simulation using preoperative CBCT is feasible and may provide valuable insights prior to otologic surgery. Establishing a CBCT acquisition protocol that allows for consistent segmentation will be essential for reliable surgical simulation.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:1855-1862, 2021.

Training in temporal bone drilling

Acquiring surgical experience in the operating room is increasingly difficult. Simulation of temporal bone drilling is therefore essential, and more and more widely used. The aim of this review is to clarify the limitations of classical surgical training, and to describe the different types of simulation available for temporal bone drilling. Systematic Medline search used the terms: "temporal bone" and training and surgery; "temporal bone" and training and drilling. Seventy-one of the 467 articles identified were relevant for this review. Various temporal bone simulators have been created to get around the limitations (ethical, financial, cultural, working time) of temporal bone drilling. They can be classified as cadaver, animal, physical or virtual models. The main advantages of physical and virtual prototyping are their ease of access, the possibility of repeating gestures on a standardised model, and the absence of ethical issues. Validation is essential before these simulators can be included in the curriculum, to ensure efficacy and thus improve patient safety in the operating room.

Reliable Assessment of Surgical Technical Skills Is Dependent on Context: An Exploration of Different Variables Using Generalizability Theory

PURPOSE

Reliable assessment of surgical skills is vital for competency-based medical training. Several factors influence not only the reliability of judgments but also the number of observations needed for making judgments of competency that are both consistent and reproducible. The aim of this study was to explore the role of various conditions-through the analysis of data from large-scale, simulation-based assessments of surgical technical skills-by examining the effects of those conditions on reliability using generalizability theory.

METHOD

Assessment data from large-scale, simulation-based temporal bone surgical training research studies in 2012-2018 were pooled, yielding collectively 3,574 assessments of 1,723 performances. The authors conducted generalizability analyses using an unbalanced random-effects design, and they performed decision studies to explore the effect of the different variables on projections of reliability.

RESULTS

Overall, 5 observations were needed to achieve a generalizability coefficient > 0.8. Several variables modified the projections of reliability: increased learner experience necessitated more observations (5 for medical students, 7 for residents, and 8 for experienced surgeons), the more complex cadaveric dissection required fewer observations than virtual reality simulation (2 vs 5 observations), and increased fidelity simulation graphics reduced the number of observations needed from 7 to 4. The training structure (either massed or distributed practice) and simulator-integrated tutoring had little effect on reliability. Finally, more observations were needed during initial training when the learning curve was steepest (6 observations) compared with the plateau phase (4 observations).

CONCLUSIONS

Reliability in surgical skills assessment seems less stable than it is often reported to be. Training context and conditions influence reliability. The findings from this study highlight that medical educators should exercise caution when using a specific simulation-based assessment in other contexts.

The Effect of Simulator-Integrated Tutoring for Guidance in Virtual Reality Simulation Training

INTRODUCTION

Simulation-integrated tutoring in virtual reality (VR) simulation training by green lighting is a common learning support in simulation-based temporal bone surgical training. However, tutoring overreliance can negatively affect learning. We therefore wanted to investigate the effects of simulator-integrated tutoring on performance and learning.

METHODS

A prospective, educational cohort study of a learning intervention (simulator-integrated tutoring) during repeated and distributed VR simulation training for directed, self-regulated learning of the mastoidectomy procedure. Two cohorts of novices (medical students) were recruited: 16 participants were trained using the intervention program (intermittent simulator-integrated tutoring) and 14 participants constituted a nontutored reference cohort. Outcomes were final-product performance assessed by 2 blinded raters and simulator-recorded metrics.

RESULTS

Simulator-integrated tutoring had a large and positive effect on the final-product performance while turned on (mean difference = 3.8 points, P < 0.0001). However, this did not translate to a better final-product performance in subsequent nontutored procedures. The tutored cohort had a better metrics-based score, reflecting higher efficiency of drilling (mean difference = 3.6%, P = 0.001). For the individual metrics, simulator-integrated tutoring had mixed effects both during procedures and on the tutored cohort in general (learning effect).

CONCLUSIONS

Simulator-integrated tutoring by green lighting did not induce a better final-product performance but increased efficiency. The mixed effects on learning could be caused by tutoring overreliance, resulting from a lack of cognitive engagement when the tutor function is on. Further learning strategies such as feedback should be explored to support novice learning and cognitive engagement.

Understanding the effects of structured self-assessment in directed, self-regulated simulation-based training of mastoidectomy: A mixed methods study

Objective

Self-directed training represents a challenge in simulation-based training as low cognitive effort can occur when learners overrate their own level of performance. This study aims to explore the mechanisms underlying the positive effects of a structured self-assessment intervention during simulation-based training of mastoidectomy.

Methods

A prospective, educational cohort study of a novice training program consisting of directed, self-regulated learning with distributed practice (5x3 procedures) in a virtual reality temporal bone simulator. The intervention consisted of structured self-assessment after each procedure using a rating form supported by small videos. Semi-structured telephone interviews upon completion of training were conducted with 13 out of 15 participants. Interviews were analysed using directed content analysis and triangulated with quantitative data on secondary task reaction time for cognitive load estimation and participants’ self-assessment scores.

Results

Six major themes were identified in the interviews: goal-directed behaviour, use of learning supports for scaffolding of the training, cognitive engagement, motivation from self-assessment, self-assessment bias, and feedback on self-assessment (validation). Participants seemed to self-regulate their learning by forming individual sub-goals and strategies within the overall goal of the procedure. They scaffolded their learning through the available learning supports. Finally, structured self-assessment was reported to increase the participants’ cognitive engagement, which was further supported by a quantitative increase in cognitive load.

Conclusions

Structured self-assessment in simulation-based surgical training of mastoidectomy seems to promote cognitive engagement and motivation in the learning task and to facilitate self-regulated learning.

Evaluation of an Infant Temporal-Bone Model as Training Tool

Objective:

Evaluation of the face validity of a new artificial model of an infant temporal bone (TB) suitable for surgical training, including cochlear implantation.

Subject:

Micro-computer-tomography images were obtained from a TB specimen of a 1-year-old normal infant available in an anatomical collection. The TB model was designed and constructed using these images and techniques known from similar models of adult TB.

Intervention:

Fifteen otology departments in Austria, Germany, and Switzerland rated the infant TB model and compared it with the established adult TB model manufactured commercially by the same company.

Main Outcome Measure:

The otologists responded to a semi-quantitative questionnaire with a rating scale ranging from 1 (strongly disagree) to 5 (strongly agree). Macroscopic and microscopic anatomic details, drilling experience, and surgical landmarks were rated. The surgical procedures included mastoidectomy, posterior tympanotomy, cochleostomy, and insertion of a cochlear electrode.

Results:

Overall ratings were similar (3.9) for both the infant and the adult TB models, with ranges of 3.47 to 4.47 (infant model) and 3.5 to 4.33 (adult model). Ratings of specific anatomical details differed as a function of type of model, but without preference of one model over the other.

Conclusions:

Infant TB models can be used similarly as adult TB models for surgical training, including cochlear implantation. They may deserve a more important role in surgical training because cadaveric human temporal bones of infants are not available.

Morphological analysis of sigmoid sinus anatomy: clinical applications to neurotological surgery

OBJECTIVES

The primary objective of this study was to use high-resolution micro-CT images to create accurate three-dimensional (3D) models of several intratemporal structures, and to compare several surgically important dimensions within the temporal bone. The secondary objective was to create a statistical shape model (SSM) of a dominant and non-dominant sigmoid sinus (SS) to provide a template for automated segmentation algorithms.

METHODS

A free image processing software, 3D Slicer, was utilized to create three-dimensional reconstructions of the SS, jugular bulb (JB), facial nerve (FN), and external auditory canal (EAC) from micro-CT scans. The models were used to compare several clinically important dimensions between the dominant and non-dominant SS. Anatomic variability of the SS was also analyzed using SSMs generated using the Statismo software framework.

RESULTS

Three-dimensional models from 38 temporal bones were generated and analyzed. Right dominance was observed in 74% of the paired SSs. All distances were significantly shorter on the dominant side (p < 0.05), including: EAC - SS (dominant: 13.7 ± 3.4 mm; non-dominant: 15.3 ± 2.7 mm), FN - SS (dominant: 7.2 ± 1.8 mm; non-dominant: 8.1 ± 2.3 mm), 2nd genu FN - superior tip of JB (dominant: 8.7 ± 2.2 mm; non-dominant: 11.2 ± 2.6 mm), horizontal distance between the superior tip of JB - descending FN (dominant: 9.5 ± 2.3 mm; non-dominant: 13.2 ± 3.5 mm), and horizontal distance between the FN at the stylomastoid foramen - JB (dominant: 5.4 ± 2.2 mm; non-dominant: 7.7 ± 2.1). Analysis of the SSMs indicated that SS morphology is most variable at its junction with the transverse sinus, and least variable at the JB.

CONCLUSIONS

This is the first known study to investigate the anatomical variation and relationships of the SS using high resolution scans, 3D  models and statistical shape analysis. This analysis seeks to guide neurotological surgical approaches and provide a template for automated segmentation and surgical simulation.

The OpenEar library of 3D models of the human temporal bone based on computed tomography and micro-slicing

Virtual reality surgical simulation of temporal bone surgery requires digitized models of the full anatomical region in high quality and colour information to allow realistic texturization. Existing datasets which are usually based on microCT imaging are unable to fulfil these requirements as per the limited specimen size, and lack of colour information. The OpenEar Dataset provides a library consisting of eight three-dimensional models of the human temporal bone to enable surgical training including colour data. Each dataset is based on a combination of multimodal imaging including Cone Beam Computed Tomography (CBCT) and micro-slicing. 3D reconstruction of micro-slicing images and subsequent registration to CBCT images allowed for relatively efficient multimodal segmentation of inner ear compartments, middle ear bones, tympanic membrane, relevant nerve structures, blood vessels and the temporal bone. Raw data from the experiment as well as voxel data and triangulated models from the segmentation are provided in full for use in surgical simulators or any other application which relies on high quality models of the human temporal bone.

The effect of distributed virtual reality simulation training on cognitive load during subsequent dissection training

BACKGROUND

Complex tasks such as surgical procedures can induce excessive cognitive load (CL), which can have a negative effect on learning, especially for novices.

AIM

To investigate if repeated and distributed virtual reality (VR) simulation practice induces a lower CL and higher performance in subsequent cadaveric dissection training.

METHODS

In a prospective, controlled cohort study, 37 residents in otorhinolaryngology received VR simulation training either as additional distributed practice prior to course participation (intervention) (9 participants) or as standard practice during the course (control) (28 participants). Cognitive load was estimated as the relative change in secondary-task reaction time during VR simulation and cadaveric procedures.

RESULTS

Structured distributed VR simulation practice resulted in lower mean reaction times (32% vs. 47% for the intervention and control group, respectively, p < 0.01) as well as a superior final-product performance during subsequent cadaveric dissection training.

CONCLUSIONS

Repeated and distributed VR simulation causes a lower CL to be induced when the learning situation is increased in complexity. A suggested mechanism is the formation of mental schemas and reduction of the intrinsic CL. This has potential implications for surgical skills training and suggests that structured, distributed training be systematically implemented in surgical training curricula.

Accuracy and precision of manual segmentation of the maxillary sinus in MR images-a method study

OBJECTIVE

To assess the accuracy and precision of segmentation of the maxillary sinus in MR images to evaluate the potential usefulness of this modality in longitudinal studies of sinus development.

METHODS

A total of 15 healthy subjects who had been both craniofacial CT and MR scanned were included and the 30 maxillary sinus volumes were evaluated using segmentation. Two of the authors did segmentation of MRI and one of these authors did double segmentation. Agreement in results between CT and MRI as well as inter- and intraexaminer errors were evaluated by statistical and three-dimensional analysis.

RESULTS

The intraclass correlation coefficient for volume measurements for both method error, inter- and intraexaminer agreement were > 0.9 [maximal 95% confidence interval of 0.989-0.997, p < 0.001] and the limit of agreement for all parameters were < 5.1%. Segmentation errors were quantified in terms of overlap [Dice Coefficient (DICE) > 0.9 = excellent agreement] and border distance [95% percentile Hausdorff Distance (HD) < 2 mm = acceptable agreement]. The results were replicable and not influenced by systematic errors.

CONCLUSION

We found a high accuracy and precision of manual segmentation of the maxillary sinus in MR images. The largest mean errors were found close to the orbit and the teeth. Advances in knowledge: MRI can be used for 3D models of the paranasal sinuses with equally good results as CT and allows longitudinal follow-up of sinus development.

Otologic Skills Training

This article presents a summary of the current simulation training for otologic skills. There is a wide variety of educational approaches, assessment tools, and simulators in use, including simple low-cost task trainers to complex computer-based virtual reality systems. A systematic approach to otologic skills training using adult learning theory concepts, such as repeated and distributed practice, self-directed learning, and mastery learning, is necessary for these educational interventions to be effective. Future directions include development of measures of performance to assess efficacy of simulation training interventions and, for complex procedures, improvement in fidelity based on educational goals.

Orthopaedic tumors: What problems are we solving, and are universities and major medical centers doing enough?

Little has been published about the complexity of orthopaedic tumors compared to others tumors. The current study in the literature treated this problem in terms of classification, surgical intervention and impact on the patient. In this article, factors risks of tumors will be we identified. A strategy based on three dimensional simulations will be explained in order to improve the clinical trials.

Creating an Optimal 3D Printed Model for Temporal Bone Dissection Training

Objective:

Making a 3-dimensional (3D) temporal bone model is simple using a plaster powder bed and an inkjet printer. However, it is difficult to reproduce air-containing spaces and precise middle ear structures. The objective of this study was to overcome these problems and create a temporal bone model that would be useful both as a training tool and for preoperative simulation.

Methods:

Drainage holes were made to remove excess materials from air-containing spaces, ossicle ligaments were manually changed to bony structures, and small and/or soft tissue structures were colored differently while designing the 3D models. The outcomes were evaluated by 3 procedures: macroscopic and endoscopic inspection of the model, comparison of computed tomography (CT) images of the model to the original CT, and assessment of tactile sensation and reproducibility by 20 surgeons performing surgery on the model.

Results:

Macroscopic and endoscopic inspection, CT images, and assessment by surgeons were in agreement in terms of reproducibility of model structures. Most structures could be reproduced, but the stapes, tympanic sinus, and mastoid air cells were unsatisfactory. Perioperative tactile sensation of the model was excellent.

Conclusions:

Although this model still does not embody perfect reproducibility, it proved sufficiently practical for use in surgical training.

The effect of implementing cognitive load theory-based design principles in virtual reality simulation training of surgical skills: a randomized controlled trial

Background

Cognitive overload can inhibit learning, and cognitive load theory-based instructional design principles can be used to optimize learning situations. This study aims to investigate the effect of implementing cognitive load theory-based design principles in virtual reality simulation training of mastoidectomy.

Methods

Eighteen novice medical students received 1 h of self-directed virtual reality simulation training of the mastoidectomy procedure randomized for standard instructions (control) or cognitive load theory-based instructions with a worked example followed by a problem completion exercise (intervention). Participants then completed two post-training virtual procedures for assessment and comparison. Cognitive load during the post-training procedures was estimated by reaction time testing on an integrated secondary task. Final-product analysis by two blinded expert raters was used to assess the virtual mastoidectomy performances.

Results

Participants in the intervention group had a significantly increased cognitive load during the post-training procedures compared with the control group (52 vs. 41 %, p = 0.02). This was also reflected in the final-product performance: the intervention group had a significantly lower final-product score than the control group (13.0 vs. 15.4, p < 0.005).

Conclusions

Initial instruction using worked examples followed by a problem completion exercise did not reduce the cognitive load or improve the performance of the following procedures in novices. Increased cognitive load when part tasks needed to be integrated in the post-training procedures could be a possible explanation for this. Other instructional designs and methods are needed to lower the cognitive load and improve the performance in virtual reality surgical simulation training of novices.

A review of simulation platforms in surgery of the temporal bone

BACKGROUND

Surgery of the temporal bone is a high-risk activity in an anatomically complex area. Simulation enables rehearsal of such surgery. The traditional simulation platform is the cadaveric temporal bone, but in recent years other simulation platforms have been created, including plastic and virtual reality platforms.

OBJECTIVE OF REVIEW

To undertake a review of simulation platforms for temporal bone surgery, specifically assessing their educational value in terms of validity and in enabling transition to surgery.

TYPE OF REVIEW

Systematic qualitative review.

SEARCH STRATEGY

Search of the Pubmed, CINAHL, BEI and ERIC databases.

EVALUATION METHOD

Assessment of reported outcomes in terms of educational value.

RESULTS

A total of 49 articles were included, covering cadaveric, animal, plastic and virtual simulation platforms. Cadaveric simulation is highly rated as an educational tool, but there may be a ceiling effect on educational outcomes after drilling 8-10 temporal bones. Animal models show significant anatomical variation from man. Plastic temporal bone models offer much potential, but at present lack sufficient anatomical or haptic validity. Similarly, virtual reality platforms lack sufficient anatomical or haptic validity, but with technological improvements they are advancing rapidly.

CONCLUSIONS

At present, cadaveric simulation remains the best platform for training in temporal bone surgery. Technological advances enabling improved materials or modelling mean that in the future plastic or virtual platforms may become comparable to cadaveric platforms, and also offer additional functionality including patient-specific simulation from CT data.

Integration of high-resolution data for temporal bone surgical simulations

PURPOSE

To report on the state of the art in obtaining high-resolution 3D data of the microanatomy of the temporal bone and to process that data for integration into a surgical simulator. Specifically, we report on our experience in this area and discuss the issues involved to further the field.

DATA SOURCES

Current temporal bone image acquisition and image processing established in the literature as well as in house methodological development.

REVIEW METHODS

We reviewed the current English literature for the techniques used in computer-based temporal bone simulation systems to obtain and process anatomical data for use within the simulation. Search terms included "temporal bone simulation, surgical simulation, temporal bone." Articles were chosen and reviewed that directly addressed data acquisition and processing/segmentation and enhancement with emphasis given to computer-based systems. We present the results from this review in relationship to our approach.

CONCLUSIONS

High-resolution CT imaging ([Formula: see text] voxel resolution), along with unique image processing and rendering algorithms, and structure-specific enhancement are needed for high-level training and assessment using temporal bone surgical simulators. Higher-resolution clinical scanning and automated processes that run in efficient time frames are needed before these systems can routinely support pre-surgical planning. Additionally, protocols such as that provided in this manuscript need to be disseminated to increase the number and variety of virtual temporal bones available for training and performance assessment.

Cognitive Load in Mastoidectomy Skills Training: Virtual Reality Simulation and Traditional Dissection Compared

OBJECTIVE

The cognitive load (CL) theoretical framework suggests that working memory is limited, which has implications for learning and skills acquisition. Complex learning situations such as surgical skills training can potentially induce a cognitive overload, inhibiting learning. This study aims to compare CL in traditional cadaveric dissection training and virtual reality (VR) simulation training of mastoidectomy.

DESIGN

A prospective, crossover study. Participants performed cadaveric dissection before VR simulation of the procedure or vice versa. CL was estimated by secondary-task reaction time testing at baseline and during the procedure in both training modalities.

SETTING

The national Danish temporal bone course.

PARTICIPANTS

A total of 40 novice otorhinolaryngology residents.

RESULTS

Reaction time was increased by 20% in VR simulation training and 55% in cadaveric dissection training of mastoidectomy compared with baseline measurements. Traditional dissection training increased CL significantly more than VR simulation training (p < 0.001).

CONCLUSIONS

VR simulation training imposed a lower CL than traditional cadaveric dissection training of mastoidectomy. Learning complex surgical skills can be a challenge for the novice and mastoidectomy skills training could potentially be optimized by employing VR simulation training first because of the lower CL. Traditional dissection training could then be used to supplement skills training after basic competencies have been acquired in the VR simulation.

Lamb Temporal Bone as a Surgical Training Model of Round Window Cochlear Implant Electrode Insertion

OBJECTIVE

The preservation of residual hearing in cochlear implantation opens the door for optimal functional results. This atraumatic surgical technique requires training; however, the traditional human cadaveric temporal bones have become less available or unattainable in some institutions. This study investigates the suitability of an alternative model, using cadaveric lamb temporal bone, for surgical training of atraumatic round window electrode insertion.

INTERVENTION

A total of 14 lamb temporal bones were dissected for cochlear implantation by four surgeons. After mastoidectomy, visualization, and drilling of the round window niche, an atraumatic round window insertion of a Medel Flex24 electrode was performed. Electrode insertion depth and position were verified by computed tomography scans.

MAIN OUTCOME MEASURE

All cochleas were successfully implanted using the atraumatic round window approach; however, surgical access through the mastoid was substantially different when compared human anatomy. The mean number of intracochlear electrode contacts was 6.5 (range, 4-11) and the mean insertion depth 10.4 mm (range, 4-20 mm), which corresponds to a mean angular perimodiolar insertion depth of 229 degrees (range 67-540°). Full insertion of the electrode was not possible because of the smaller size of the lamb cochlea in comparison to that of the human.

CONCLUSION

The lamb temporal bone model is well suited as a training model for atraumatic cochlear implantation at the level of the round window. The minimally pneumatized mastoid as well as the smaller cochlea can help prepare a surgeon for difficult cochlear implantations. Because of substantial differences to human anatomy, it is not an adequate training model for other surgical techniques such as mastoidectomy and posterior tympanotomy as well as full electrode insertion.

The effect of self-directed virtual reality simulation on dissection training performance in mastoidectomy

OBJECTIVES/HYPOTHESIS

To establish the effect of self-directed virtual reality (VR) simulation training on cadaveric dissection training performance in mastoidectomy and the transferability of skills acquired in VR simulation training to the cadaveric dissection training setting.

STUDY DESIGN

Prospective study.

METHODS

Two cohorts of 20 novice otorhinolaryngology residents received either self-directed VR simulation training before cadaveric dissection training or vice versa. Cadaveric and VR simulation performances were assessed using final-product analysis with three blinded expert raters.

RESULTS

The group receiving VR simulation training before cadaveric dissection had a mean final-product score of 14.9 (95 % confidence interval [CI] [12.9-16.9]) compared with 9.8 (95% CI [8.4-11.1]) in the group not receiving VR simulation training before cadaveric dissection. This 52% increase in performance was statistically significantly (P < 0.0001). A single dissection mastoidectomy did not increase VR simulation performance (P = 0.22).

CONCLUSIONS

Two hours of self-directed VR simulation training was effective in increasing cadaveric dissection mastoidectomy performance and suggests that mastoidectomy skills are transferable from VR simulation to the traditional dissection setting. Virtual reality simulation training can therefore be employed to optimize training, and can spare the use of donated material and instructional resources for more advanced training after basic competencies have been acquired in the VR simulation environment.

LEVEL OF EVIDENCE

NA. Laryngoscope, 126:1883-1888, 2016.

Peak and ceiling effects in final-product analysis of mastoidectomy performance

BACKGROUND

Virtual reality surgical simulation of mastoidectomy is a promising training tool for novices. Final-product analysis for assessing novice mastoidectomy performance could be limited by a peak or ceiling effect. These may be countered by simulator-integrated tutoring.

METHODS

Twenty-two participants completed a single session of self-directed practice of the mastoidectomy procedure in a virtual reality simulator. Participants were randomised for additional simulator-integrated tutoring. Performances were assessed at 10-minute intervals using final-product analysis.

RESULTS

In all, 45.5 per cent of participants peaked before the 60-minute time limit. None of the participants achieved the maximum score, suggesting a ceiling effect. The tutored group performed better than the non-tutored group but tutoring did not eliminate the peak or ceiling effects.

CONCLUSION

Timing and adequate instruction is important when using final-product analysis to assess novice mastoidectomy performance. Improved real-time feedback and tutoring could address the limitations of final product based assessment.

Notes From the Field: Secondary Task Precision for Cognitive Load Estimation During Virtual Reality Surgical Simulation Training

Cognitive load (CL) theory suggests that working memory can be overloaded in complex learning tasks such as surgical technical skills training, which can impair learning. Valid and feasible methods for estimating the CL in specific learning contexts are necessary before the efficacy of CL-lowering instructional interventions can be established. This study aims to explore secondary task precision for the estimation of CL in virtual reality (VR) surgical simulation and also investigate the effects of CL-modifying factors such as simulator-integrated tutoring and repeated practice. Twenty-four participants were randomized for visual assistance by a simulator-integrated tutor function during the first 5 of 12 repeated mastoidectomy procedures on a VR temporal bone simulator. Secondary task precision was found to be significantly lower during simulation compared with nonsimulation baseline, p < .001. Contrary to expectations, simulator-integrated tutoring and repeated practice did not have an impact on secondary task precision. This finding suggests that even though considerable changes in CL are reflected in secondary task precision, it lacks sensitivity. In contrast, secondary task reaction time could be more sensitive, but requires substantial postprocessing of data. Therefore, future studies on the effect of CL modifying interventions should weigh the pros and cons of the various secondary task measurements.

Cognitive load in distributed and massed practice in virtual reality mastoidectomy simulation

OBJECTIVES/HYPOTHESIS

Cognitive load theory states that working memory is limited. This has implications for learning and suggests that reducing cognitive load (CL) could promote learning and skills acquisition. This study aims to explore the effect of repeated practice and simulator-integrated tutoring on CL in virtual reality (VR) mastoidectomy simulation.

STUDY DESIGN

Prospective trial.

METHODS

Forty novice medical students performed 12 repeated virtual mastoidectomy procedures in the Visible Ear Simulator: 21 completed distributed practice with practice blocks spaced in time and 19 participants completed massed practice (all practices performed in 1 day). Participants were randomized for tutoring with the simulator-integrated tutor function. Cognitive load was estimated by measuring reaction time in a secondary task. Data were analyzed using linear mixed models for repeated measurements.

RESULTS

The mean reaction time increased by 37% during the procedure compared with baseline, demonstrating that the procedure placed substantial cognitive demands. Repeated practice significantly lowered CL in the distributed practice group but not in massed practice group. In addition, CL was found to be further increased by 10.3% in the later and more complex stages of the procedure. The simulator-integrated tutor function did not have an impact on CL.

CONCLUSION

Distributed practice decreased CL in repeated VR mastoidectomy training more consistently than was seen in massed practice. This suggests a possible effect of skills and memory consolidation occurring over time. To optimize technical skills learning, training should be organized as time-distributed practice rather than as a massed block of practice, which is common in skills-training courses.

LEVEL OF EVIDENCE

N/A.

End User Comparison of Anatomically Matched 3-Dimensional Printed and Virtual Haptic Temporal Bone Simulation: A Pilot Study

OBJECTIVE

Simulation has assumed a prominent role in education. It is important to explore the effectiveness of different modalities. In this article, we directly compare surgical resident impression of 2 distinct temporal bone simulations (physical and haptic).

STUDY DESIGN

Research Ethics Board-approved prospective cohort study.

SETTING

A haptic voxel-based virtual model (VM) and a physical 3-dimensional printed temporal bone model (PBM) were developed. Participants rated each construct on a number of parameters and performed a direct comparison of the simulations using a survey instrument that employed a 7-point Likert scale and rank lists.

SUBJECTS AND METHODS

Ten otolaryngology residents dissected anatomically identical, matched physical and virtual models. Data for both simulations originated from 10 unique cadaveric micro-computed tomography images.

RESULTS

Subjects rated the PBM drill quality as being more similar to cadaveric temporal bone than the VM (cortical bone mean: 5.5 vs 3.2, P = .011; trabecular bone mean: 5.2 vs 2.8, P = .004) and with better air cell system representation (mean: 5.4 vs 4.5, P = .003). Subjects strongly agreed that both simulations are effective educational tools, but they rated the PBM higher (mean: 6.7 vs 5.4, P = .019). Notably, subjects agreed that both modalities should be integrated into training, but they were more favorably inclined toward the PBM (mean: 7.0 vs 5.5, P = .002). In direct comparison, the PBM was the preferred simulation in 7 of 9 educational domains.

CONCLUSIONS

Appraisal of a PBM and a VM found both to have perceived educational benefit. However, the PBM was considered to have more realistic physical properties and was considered the preferred training instrument.

The realism and usefulness of the Voxel-Man TempoSurg and the Visible Ear simulator

Comparing two different temporal bone simulators, at a point when EWTD limits mean simulation can save vital time during training.

Comparison of cadaveric and isomorphic virtual haptic simulation in temporal bone training

Background

Virtual surgery may improve learning and provides an opportunity for pre-operative surgical rehearsal. We describe a novel haptic temporal bone simulator specifically developed for multicore processing and improved visual realism. A position locking algorithm for enhanced drill-bone interaction and haptic fidelity is further employed. The simulation construct is evaluated against cadaveric education.

Methods

A voxel-based simulator was designed for multicore architecture employing Marching Cubes and Laplacian smoothing to perform real-time haptic and graphic rendering of virtual bone.

Ten Otolaryngology trainees dissected a cadaveric temporal bone (CTB) followed by a virtual isomorphic haptic model (VM) based on derivative microCT data. Participants rated 1) physical characteristics, 2) specific anatomic constructs, 3) usefulness in skill development and 4) perceived educational value. The survey instrument employed a Likert scale (1-7).

Results

Residents were equivocal about the physical properties of the VM, as cortical (3.2 ± 2.0) and trabecular (2.8 ± 1.6) bone drilling character was appraised as dissimilar to CTB. Overall similarity to cadaveric training was moderate (3.5 ± 1.8). Residents generally felt the VM was beneficial in skill development, rating it highest for translabyrinthine skull-base approaches (5.2 ± 1.3). The VM was considered an effective (5.4 ± 1.5) and accurate (5.7 ± 1.4) training tool which should be integrated into resident education (5.5 ± 1.4). The VM was thought to improve performance (5.3 ± 1.8) and confidence (5.3 ± 1.9) and was highly rated for anatomic learning (6.1 ± 1.9).

Conclusion

Study participants found the VM to be a beneficial and effective platform for learning temporal bone anatomy and surgical techniques. They identify some concern with limited physical realism likely owing to the haptic device interface. This study is the first to compare isomorphic simulation in education. This significantly removes possible confounding features as the haptic simulation was based on derivative imaging.

Mixed reality temporal bone surgical dissector: mechanical design

Objective

The Development of a Novel Mixed Reality (MR) Simulation.

An evolving training environment emphasizes the importance of simulation. Current haptic temporal bone simulators have difficulty representing realistic contact forces and while 3D printed models convincingly represent vibrational properties of bone, they cannot reproduce soft tissue. This paper introduces a mixed reality model, where the effective elements of both simulations are combined; haptic rendering of soft tissue directly interacts with a printed bone model.

This paper addresses one aspect in a series of challenges, specifically the mechanical merger of a haptic device with an otic drill. This further necessitates gravity cancelation of the work assembly gripper mechanism. In this system, the haptic end-effector is replaced by a high-speed drill and the virtual contact forces need to be repositioned to the drill tip from the mid wand.

Previous publications detail generation of both the requisite printed and haptic simulations.

Method

Custom software was developed to reposition the haptic interaction point to the drill tip. A custom fitting, to hold the otic drill, was developed and its weight was offset using the haptic device. The robustness of the system to disturbances and its stable performance during drilling were tested. The experiments were performed on a mixed reality model consisting of two drillable rapid-prototyped layers separated by a free-space. Within the free-space, a linear virtual force model is applied to simulate drill contact with soft tissue.

Results

Testing illustrated the effectiveness of gravity cancellation. Additionally, the system exhibited excellent performance given random inputs and during the drill’s passage between real and virtual components of the model. No issues with registration at model boundaries were encountered.

Conclusion

These tests provide a proof of concept for the initial stages in the development of a novel mixed-reality temporal bone simulator.

Three-dimensional temporal bone reconstruction from histological sections

OBJECTIVE

To produce a high-resolution, three-dimensional temporal bone model from serial sections, using a personal computer.

METHOD

Digital images were acquired from histological sections of the temporal bone. Image registration, segmentation and three-dimensional volumetric reconstruction were performed using a personal computer. The model was assessed for anatomical accuracy and interactivity by otologists.

RESULTS

An accurate, high-resolution, three-dimensional model of the temporal bone was produced, containing structures relevant to otological surgery. The facial nerve, labyrinth, internal carotid artery, jugular bulb and all of the ossicles were seen (including the stapes footplate), together with the internal and external auditory meati. Some projections also showed the chorda tympani nerve.

CONCLUSION

A high-resolution, three-dimensional computer model of the complete temporal bone was produced using a personal computer. Because of the increasing difficulty in procuring cadaveric bones, this model could be a useful adjunct for training.

Virtual reality simulator for vitreoretinal surgery using integrated OCT data

Operative practice using surgical simulators has become a part of training in many surgical specialties, including ophthalmology. We introduce a virtual reality retina surgery simulator capable of integrating optical coherence tomography (OCT) scans from real patients for practicing vitreoretinal surgery using different pathologic scenarios.