Use of ultra-high-resolution data for temporal bone dissection simulation

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Micro-anatomy of the ear of the southern white rhinoceros (Ceratotherium simum simum)

The white rhinoceros is the largest of the five extant rhinoceros species. The population is declining rapidly because of intense poaching. However, normal anatomical descriptions in this species are lacking. The purpose of this study is to describe the osseous anatomy of the middle and inner ear of the southern white rhinoceros using micro-focus X-ray computed tomography imaging. Four temporal bones obtained from two 1-day old southern white rhinoceros preserved in 10% formalin were scanned. Tri-dimensional reconstructions were obtained and volumes of the middle ear ossicles and inner ear structures were calculated. Excellent high spatial resolution 3D images were obtained for all samples and virtual models of the auditory ossicles and bony labyrinth were generated. Visualization of the tympanic membrane, middle ear and inner ear structures was possible in all samples. Whereas the stapes and incus had a shape similar to their human or equine counterparts, the malleus showed a unique appearance with a long rostral branch projecting latero-distally to the manubrium. The cochlea described 2 turns rostro-laterally around its axis, with a medial direction of rotation. However, identification of the soft tissue structures of the middle ear was sometimes difficult and visualization of the small structures of the membranous labyrinth was not possible using this formalin fixation and alternative techniques should be investigated. Further investigations are needed in order to provide a complete virtual model including both soft and bone tissues of this difficultly accessible region.

Feasibility Study of a Mechanical Real-Time Feedback System for Optimizing the Sound Transfer in the Reconstructed Middle Ear

OBJECTIVE

To evaluate electromechanical excitation as an alternative excitation mode for middle ear transfer function (METF) measurements as well as real-time feedback in prosthetic ossicular reconstruction.

METHOD

In eight human cadaveric temporal bones, the ossicular chain was excited using acoustic and mechanical (floating mass transducer, FMT) stimulation to determine the METF. After disconnecting the ossicular chain and reconstruction with partial or total prosthesis the METFs were measured again. Continuous FMT stimulation was then applied to improve the prosthesis' position using real-time feedback of the METF.

RESULTS

Mechanical stimulation of ossicular vibration showed characteristic differences to acoustic excitation resulting from the force characteristics of the FMT. Furthermore, the interspecimen METF variability was greater with electromechanical than acoustic stimulation because of interspecimen variability in the FMT coupling conditions. When the METF with FMT excitation was used as a real-time feedback tool, a measurable improvement in the quality of ossicular reconstruction could be achieved.

CONCLUSIONS

Mechanical excitation is an effective and suitable alternative stimulation method in experimental METF measurements. The system provides real-time feedback for ossicular reconstruction in the experimental setting. Some influencing factors still need to be distinguished for reliable measurements. However, the method does not yet meet the requirements for clinical application as an intraoperative, real-time monitoring tool. However, the system could be an excellent model for high-end cadaveric temporal bone training in ossiculoplasty.

Virtual or Augmented Reality to Enhance Surgical Education and Surgical Planning

Virtual reality and augmented reality technologies have evolved with a growing presence in both clinical care and surgical training.

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.

Finite element analysis of auditory characteristics in patients with middle ear diseases

CONCLUSION

This study validates that a finite element model of the human ossicular chain and tympanic membrane can be used as an effective surgical assessment tool in clinics.

OBJECTIVE

The present study was performed to investigate the application of a finite element model of ossicular chain and tympanic membrane for fabrication of individualized artificial ossicles.

METHODS

Twenty patients (20 ears) who underwent surgery for middle ear disease (n = 20) and 10 healthy controls (10 ears) were enrolled in the hospital. Computed tomography (CT) and pure tone audiometry were performed before and after surgery. A finite element model was developed using CT scans, and correlation analysis was conducted between stapes displacement and surgical methods. An audiometric test was also performed for 14 patients before and after surgery.

RESULTS

Stapes displacement in the healthy group (average = 3.31 × 10^-5 mm) was significantly greater than that in the impaired group (average = 1.41 × 10^-6 mm) prior to surgery. After surgery, the average displacement in the impaired group was 2.55 × 10^-6 mm, which represented a significant improvement. For the patients who underwent the audiometric test, 10 improved hearing after surgery, and stapes displacement increased in nine of these 10 patients.

Contemporary imaging of auditory implants

There have been significant advances in the diversity and effectiveness of hearing technologies in recent years. Implanted auditory devices may be divided into those that stimulate the cochlear hair cells (bone conduction devices and middle ear implants), and those that stimulate the neural structures (cochlear implants and central auditory implants). Contemporary preoperative and postoperative imaging may be used to help individualise implant selection, optimise surgical technique and predict auditory outcome. This review will introduce the concepts behind auditory implants, and explains how imaging is increasingly used to aid insertion and evaluation of these devices.

Preoperative preparation for otologic surgery: temporal bone simulation

PURPOSE OF REVIEW

The field of temporal bone simulation (TBS) has largely focused on the development and validation of simulators as training and assessment tools. As technology has progressed over the years, researchers have, however, envisioned new clinical applications for simulators extending to preoperative surgical planning and case rehearsal. The purpose of this article was to review the current state of the art in TBS and to highlight recent advancements in the field. Because of space limitations, we will limit our discussion to computer-based virtual reality simulators.

RECENT FINDINGS

A review of the recent literature on TBS revealed very limited application of virtual reality simulators for preoperative preparation. Current evidence suggests limitations in fidelity preclude successful patient-specific case rehearsal using virtual reality simulation. Further investigation and clinical evaluation are required to validate its use outside of training and skill assessment.

SUMMARY

This article provides an overview of the current use of virtual reality simulators with emphasis on preoperative planning. We evaluate the limitations of the technology, and discuss potential areas of improvement for the future. More studies are necessary to assess the value of virtual reality simulation for preoperative preparation.

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.

NUMERICAL ANALYSIS OF TYMPANOSCLEROSIS AND TREATMENT EFFECT

Tympanosclerosis is a typical middle ear disease, which is one of the main causes of conduction deafness. We investigate the effects of tympanosclerosis and lesion excision on sound transmission of the human ear by using finite element technique. Based on CT scan images from Zhongshan Hospital of Fudan University on the normal human middle ear, numerical values of the CT scans were obtained by further processing of the images using a self-compiled program. The CT data of the right ear from a healthy volunteer were digitalized and imported into PATRAN software to reconstruct the finite element model of the ear by a self-compiling program. A frequency response analysis was made for the model, and comparative analysis was made between the calculated results and experimental data, which validated the model in this paper. The results show that the sclerosis of the ligaments and tensor muscle in the middle ear caused by force on the ossicles is larger than the normal ear and the amplitude of the stapes footplate is larger than the normal ear. This leads to a decrease of the final conductive hearing function. Furthermore, the excision of the stapes ligament and tensor tympani is good for the restoration of normal hearing. This paper provides new research perspective for clinical treatment.

Evaluation of a temporal bone prototype by experts in otology

BACKGROUND

Inexperienced otologists require training on the temporal bone drilling process, prior to any surgical activity. The shortage of cadaveric temporal bones exerts pressure to create realistic physical prototypes. This paper describes the evaluation by otology experts of a specially developed temporal bone resin model.

METHODS

Computed tomography images were transformed into digital files, and anatomically identical right temporal bone models were created using stereolithography. These hand-painted resin prototypes were sent to 25 otologists, accompanied by a 20-item questionnaire.

RESULTS

Satisfaction rate was 92 per cent. The overall prototype score was 48.87 out of 60. Average scores were: 12.63 out of 15 for anatomy-morphology, 6.98 out of 9 for quality of drilling, 16.74 out of 21 for identification of anatomical elements and 7.41 out of 9 for stages of drilling. Limitations of the model included an excessively vivid facial nerve colour and difficulty in identifying the posterior semicircular canal. Disadvantages related to the thickness of the resin and its residues were identified.

CONCLUSION

The prototype appears to provide an attractive solution to the shortage of cadaveric temporal bones. However, interest in the model for drilling technique training for inexperienced otologists has not yet been assessed.

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.

Evaluation of a haptics-based virtual reality temporal bone simulator for anatomy and surgery training

INTRODUCTION

Virtual reality simulation training may improve knowledge of anatomy and surgical skills. We evaluated a 3-dimensional, haptic, virtual reality temporal bone simulator for dissection training.

METHODS

The subjects were 7 otolaryngology residents (3 training sessions each) and 7 medical students (1 training session each). The virtual reality temporal bone simulation station included a computer with software that was linked to a force-feedback hand stylus, and the system recorded performance and collisions with vital anatomic structures. Subjects performed virtual reality dissections and completed questionnaires after the training sessions.

RESULTS

Residents and students had favorable responses to most questions of the technology acceptance model (TAM) questionnaire. The average TAM scores were above neutral for residents and medical students in all domains, and the average TAM score for residents was significantly higher for the usefulness domain and lower for the playful domain than students. The average satisfaction questionnaire for residents showed that residents had greater overall satisfaction with cadaver temporal bone dissection training than training with the virtual reality simulator or plastic temporal bone. For medical students, the average comprehension score was significantly increased from before to after training for all anatomic structures. Medical students had significantly more collisions with the dura than residents. The residents had similar mean performance scores after the first and third training sessions for all dissection procedures.

DISCUSSION

The virtual reality temporal bone simulator provided satisfactory training for otolaryngology residents and medical students.

Translating the simulation of procedural drilling techniques for interactive neurosurgical training

BACKGROUND

Through previous efforts we have developed a fully virtual environment to provide procedural training of otologic surgical technique. The virtual environment is based on high-resolution volumetric data of the regional anatomy. These volumetric data help drive an interactive multisensory, ie, visual (stereo), aural (stereo), and tactile, simulation environment. Subsequently, we have extended our efforts to support the training of neurosurgical procedural technique as part of the Congress of Neurological Surgeons simulation initiative.

OBJECTIVE

To deliberately study the integration of simulation technologies into the neurosurgical curriculum and to determine their efficacy in teaching minimally invasive cranial and skull base approaches.

METHODS

We discuss issues of biofidelity and our methods to provide objective, quantitative and automated assessment for the residents.

RESULTS

We conclude with a discussion of our experiences by reporting preliminary formative pilot studies and proposed approaches to take the simulation to the next level through additional validation studies.

CONCLUSION

We have presented our efforts to translate an otologic simulation environment for use in the neurosurgical curriculum. We have demonstrated the initial proof of principles and define the steps to integrate and validate the system as an adjuvant to the neurosurgical curriculum.

Translating the Simulation of Procedural Drilling Techniques for Interactive Neurosurgical Training

BACKGROUND:

Through previous efforts we have developed a fully virtual environment to provide procedural training of otologic surgical technique. The virtual environment is based on high-resolution volumetric data of the regional anatomy. These volumetric data help drive an interactive multisensory, ie, visual (stereo), aural (stereo), and tactile, simulation environment. Subsequently, we have extended our efforts to support the training of neurosurgical procedural technique as part of the Congress of Neurological Surgeons simulation initiative.

OBJECTIVE:

To deliberately study the integration of simulation technologies into the neurosurgical curriculum and to determine their efficacy in teaching minimally invasive cranial and skull base approaches.

METHODS:

We discuss issues of biofidelity and our methods to provide objective, quantitative and automated assessment for the residents.

RESULTS:

We conclude with a discussion of our experiences by reporting preliminary formative pilot studies and proposed approaches to take the simulation to the next level through additional validation studies.

CONCLUSION:

We have presented our efforts to translate an otologic simulation environment for use in the neurosurgical curriculum. We have demonstrated the initial proof of principles and define the steps to integrate and validate the system as an adjuvant to the neurosurgical curriculum.

Individual models for virtual bone drilling in mastoid surgery

Segmented training cases for virtual simulation of bone-drilling interventions in middle ear surgery have proven to be helpful in learning about surgical anatomy of the temporal bone. The anatomy of the mastoid shows a high degree of variability, however, and the aim of this study was to evaluate whether individual virtual models could be created within an affordable timeframe, and to what extend they reflected natural individual anatomy during virtual mastoid surgery. Automatic segmentation schemes were used, and these reduced the time required to create individual models on the basis of DICOM CT scans to less than 5 minutes. Models based on CT data with a slice distance of 0.4 mm or better were found to provide excellent handling, an acceptable depiction of mastoidal organs, and a helpful impression of the individual surgical situation. Although landmarks are still more easily detected in real mastoids, virtual drilling of individual models makes the 3D estimation of specific anatomy more effective than estimations based on interpretation of CT scans alone.

Development of a computer-assisted cranial nerve simulation from the visible human dataset

Advancements in technology and personal computing have allowed for the development of novel teaching modalities such as online web-based modules. These modules are currently being incorporated into medical curricula and, in some paradigms, have been shown to be superior to classroom instruction. We believe that these modules have the potential of significantly enriching anatomy education by helping students better appreciate spatial relationships, especially in areas of the body with greater anatomical complexity. Our objective was to develop an online module designed to teach the anatomy and function of the cranial nerves. A three-dimensional model of the skull, brainstem, and thalamus were reconstructed using data from the Visible Human Project and Amira®. The paths of the cranial nerves were overlaid onto this 3D reconstruction. Videos depicting these paths were then rendered using a "roller coaster-styled" camera approach. Interactive elements adding textual information and user control were inserted into the video using Adobe Creative Suite® 4, and finally, the module was exported as an Adobe Flash movie to be viewable on Internet browsers. Fourteen Flash-based modules were created in total. The primary user interface comprises a website encoded in HTML/CSS and contains links to each of the 14 Flash modules as well as a user tutorial.

Simulation in neurosurgery: a review of computer-based simulation environments and their surgical applications

BACKGROUND

Computer-based surgical simulators create a no-risk virtual environment where surgeons can develop and refine skills through harmless repetition. These applications may be of particular benefit to neurosurgeons, as the vulnerability of nervous tissue limits the margin for error. The rapid progression of computer-processing capabilities in recent years has led to the development of more sophisticated and realistic neurosurgery simulators.

OBJECTIVE

To catalogue the most salient of these advances and characterize our current effort to create a spine surgery simulator.

METHODS

An extensive search of the databases Ovid-MEDLINE, PubMed, and Google Scholar was conducted. Search terms included, but were not limited to: neurosurgery combined with simulation, virtual reality, haptics, and 3-dimensional imaging.

RESULTS

A survey of the literature reveals that surgical simulators are evolving from platforms used for preoperative planning and anatomic education into programs that aim to simulate essential components of key neurosurgical procedures. This evolution is predicated upon the advancement of 3 main components of simulation: graphics/volume rendering, model behavior/tissue deformation, and haptic feedback.

CONCLUSION

The computational burden created by the integration of these complex components often limits the fluidity of real-time interactive simulators. Although haptic interfaces have become increasingly sophisticated, the production of realistic tactile sensory feedback remains a formidable and costly challenge. The rate of future progress may be contingent upon international collaboration between research groups and the establishment of common simulation platforms. Given current limitations, the most potential for growth lies in the innovative design of models that expand the procedural applications of neurosurgery simulation environments.

Improving temporal bone dissection using self-directed virtual reality simulation: results of a randomized blinded control trial

OBJECTIVE

A significant benefit of virtual reality (VR) simulation is the ability to provide self-direct learning for trainees. This study aims to determine whether there are any differences in performance of cadaver temporal bone dissections between novices who received traditional teaching methods and those who received unsupervised self-directed learning in a VR temporal bone simulator.

STUDY DESIGN

Randomized blinded control trial.

SETTING

Royal Victorian Eye and Ear Hospital.

SUBJECTS

Twenty novice trainees.

METHODS

After receiving an hour lecture, participants were randomized into 2 groups to receive an additional 2 hours of training via traditional teaching methods or self-directed learning using a VR simulator with automated guidance. The simulation environment presented participants with structured training tasks, which were accompanied by real-time computer-generated feedback as well as real operative videos and photos. After the training, trainees were asked to perform a cortical mastoidectomy on a cadaveric temporal bone. The dissection was videotaped and assessed by 3 otologists blinded to participants' teaching group.

RESULTS

The overall performance scores of the simulator-based training group were significantly higher than those of the traditional training group (67% vs 29%; P < .001), with an intraclass correlation coefficient of 0.93, indicating excellent interrater reliability. Using other assessments of performance, such as injury size, the VR simulator-based training group also performed better than the traditional group.

CONCLUSIONS

This study indicates that self-directed learning on VR simulators can be used to improve performance on cadaver dissection in novice trainees compared with traditional teaching methods alone.

Assessing mental representation of mastoidectomy by a computer-based drawing tool

CONCLUSIONS

This simple computer-based drawing tool provides valid information on mental representation of mastoidectomy at its initial phase.

OBJECTIVE

The aim of this study was to elaborate a simple computer-based drawing tool to assess the mental representation of mastoidectomy.

METHODS

Twelve trainees in otology (five beginners, seven mid-level) and four otology experts participated in this prospective study. The image of a mastoid was displayed on a screen. All subjects reproduced the movements of mastoidectomy with a pen on a graphic tablet. Movements appeared as gray lines on the image. Surgeons were evaluated before and after a dissection course. The surface of mastoidectomy, perimeter, circularity, and the angle between traces and cavity edges were measured by Image J software.

RESULTS

The total surface of mastoidectomy was higher in experts than in mid-level and beginner trainees (respectively 99 ± 6.5%, vs 57 ± 1.5%, and 22 ± 5.6%, p < 0.01 for experts vs beginners and p < 0.05 for experts vs mid-level, ANOVA and Bonferroni). Circularity was also higher in experts than in trainees. After training, total surface and circularity increased. The angle between traces and cavity edges was lower in experts than in trainees and was reduced after training.

Radiographic anatomy of the infracochlear approach to the petrous apex for computer-assisted surgery

OBJECTIVE

1) To define the surgical anatomy and dimensions of the infracochlear approach to the petrous apex through the use of high-resolution computed tomography and 2) use of digitized images of cadaveric temporal bones for computer simulation of infracochlear access using the Ohio Supercomputer Center/Ohio State University temporal bone simulator.

BACKGROUND

The petrous apex is a surgically challenging area to access. Many routes have been described and used successfully in clinical practice. However, these routes have not been defined with the aim of application in computer-assisted surgery. The infracochlear approach, due to its access via a transcanal route, affords the opportunity for its potential application in minimally invasive computer-assisted surgery.

METHODS

High-resolution computed tomographic scans were performed on 102 cadaveric skulls (204 temporal bones). Standard measurements were taken using an open-source picture archiving and communication system software of the maximum height, width, and depth of the infracochlear approach. In addition, the maximum diameter of a circular fenestration that could be created in the infracochlear space without breaching the basal turn of the cochlea, internal carotid artery, or the jugular bulb was used to simulate a drill path. In addition, 5 temporal bone specimens (3 left, 2 right) underwent high-resolution computed tomography, with the digitized images being used to create simulated temporal bones for infracochlear surgical access; the transcanal infracochlear approach was then performed by the same surgeon on the cadaveric bone.

RESULTS

The mean height, width, and depth of the infracochlear space in temporal bones with nonpneumatized petrous apices were 7.2 +/- 0.4, 9.4 +/- 0.8, and 17.5 +/- 1.0 mm, respectively. Corresponding dimensions in pneumatized petrous apices were 7.6 +/- 0.4, 10.1 +/- 1.1, and 18.6 +/- 0.8 mm, respectively. The mean diameter of the circular fenestra in the nonpneumatized petrous apices was 5.1 +/- 0.4 compared with 5.7 +/- 0.6 mm in pneumatized petrous pieces. This was statistically significant (unpaired t test; p value = 0.04). The time to perform a simulated infracochlear approach to the petrous apex ranged from 3.1 to 12.6 minutes (mean, 6.1 minutes). The time to perform the same approach on the cadaveric bone ranged from 4.32 to 14.1 minutes (mean, 9.3 minutes).

CONCLUSION

Temporal bones with pneumatized petrous apices have an overall larger infracochlear space. The mean diameter of a circular infracochlear path that would avoid damage to vital structures was sufficiently large in both pneumatized and nonpneumatized petrous apices to have a potential application as a safe approach in computer-assisted surgery. Such an application is feasible with mating of a robotic system with computed tomographic- or magnetic resonance imaging-guided imagery, which is the next phase of this study.

Three-dimensional modeling of the temporal bone for surgical training

INTRODUCTION

The anatomy of the temporal bone (TB) can only be mastered by repeated surgical and anatomic dissections, and surgical teaching initiative had a major effect on outcomes. The aim of this study was to investigate the validity of an artificial TB model devoted to surgical training and education.

MATERIALS AND METHODS

A helical computed tomographic (CT) scan was used to acquire high-resolution data of cadaveric TB. Digital imaging and communications in medicine (DICOM) data were converted into.stl files after data processing. Cadaveric TBs were prototyped using stereolithography. The validation of the prototype needed several steps. First of all, we have studied on CT scan the positional relationship between the facial nerve and other structures of the cadaveric TBs and prototyped bones. Otoendoscopy of the middle ear and the internal acoustic canal and visualization of anatomic landmarks during TB drilling of the cadaveric TBs and prototyped bones were also performed.

RESULTS

Seven normal CT scans of cadaveric TB were selected to make prototyped bone using stereolithography. Measurements of volume and distance showed no significant difference between prototypes and cadaver TBs. Classic mastoid surgical procedures were performed in the Anatomy Department: exposing sigmoid sinus, facial nerve, labyrinth, dura mater, jugular bulb, and internal carotid artery. Two simulations of implantable middle ear prosthesis were made successfully.

CONCLUSION

These prototypes made using stereolithography seem to be a good anatomic model for surgical training. This model could also be interesting for surgical planning in congenital ear anomalies before middle ear prosthesis implantation.

Enhancement of temporal bone anatomy learning with computer 3D rendered imaging software

AIM

To determine whether the use of 3D anatomical models is helpful to students and enhances their anatomical knowledge.

METHODS

First year undergraduate students on the speech therapy or hearing aid practitioner courses attended either a lecture alone or a lecture followed by a 3D anatomy based tutorial, the latter which was also attended by ENT residents. Participants who received the tutorial were free to use the 3D model on the university computers or on their home computer and were then asked to answer a satisfaction questionnaire. At the end of the first year examinations, the grades of the undergraduate students were compared between the lecture alone group and lecture plus tutorial group.

RESULTS

Generally, all participants found this new tool interesting and user-friendly for the learning of temporal bone anatomy. However, most also considered the help of a teacher indispensable to guide them through the virtual dissection. First year undergraduate students who received the 3D anatomy tutorial performed significantly better during their end of year examination compared to those receiving a lecture alone, particularly concerning the more difficult questions.

CONCLUSION

The 3D anatomical software, used in parallel with traditional teaching methods, such as lectures and cadaver dissection, appears to be a promising tool to improve student learning of temporal bone anatomy.

Review of temporal bone dissection teaching: how it was, is and will be

Objective:

We aimed to review the history of anatomical dissection, and to examine how modern educational techniques will change the way temporal bone dissection is taught to otolaryngology trainees.

Method:

Review of the literature using Medline, Embase and PubMed database searches.

Results:

Temporal bone anatomy has traditionally been taught using cadaveric specimens. However, resources such as three-dimensional reconstructed models and ‘virtual reality’ temporal bone simulators have a place in educating the otolaryngology trainee.

Conclusion:

We should encourage the use of fresh frozen cadaveric temporal bone specimens for future otologists. Artificial three-dimensional models and virtual reality temporal bone simulators can be used to educate junior trainees, thus conserving the scarce resource of cadaveric bones.

Training otologic surgical skills through simulation-moving toward validation: a pilot study and lessons learned

INTRODUCTION

Methods for surgical education and training have changed little over the years. Recent calls to improve surgical efficiency and safety impose additional pressures that have an impact on surgical education and training. USE OF SIMULATION: Integration of data from advanced imaging technologies and computer technologies are creating simulation environments of unprecedented realism. Surgical education and training are poised to exploit low-cost simulation technologies to mitigate these pressures that are having an adverse impact on curricula. To become effective, simulation needs to undergo rigorous validation studies.

INTERVENTION

With funding from that National Institute on Deafness and Other Communicative Disorders, we have embarked on a research design project to develop, disseminate, and validate a surgical system for use in otologic resident training and assessment and present key steps from this process.

DISCUSSION

We discuss limiting factors related to technology and conducting multi-institutional studies, along with current developments to integrate curricula, as well as training and assessment capabilities in surgical education using simulation.

Construction of a three-dimensional interactive model of the skull base and cranial nerves

OBJECTIVE

The goal was to develop an interactive three-dimensional (3-D) computerized anatomic model of the skull base for teaching microneurosurgical anatomy and for operative planning.

METHODS

The 3-D model was constructed using commercially available software (Maya 6.0 Unlimited; Alias Systems Corp., Delaware, MD), a personal computer, four cranial specimens, and six dry bones. Photographs from at least two angles of the superior and lateral views were imported to the 3-D software. Many photographs were needed to produce the model in anatomically complex areas. Careful dissection was needed to expose important structures in the two views. Landmarks, including foramen, bone, and dura mater, were used as reference points.

RESULTS

The 3-D model of the skull base and related structures was constructed using more than 300,000 remodeled polygons. The model can be viewed from any angle. It can be rotated 360 degrees in any plane using any structure as the focal point of rotation. The model can be reduced or enlarged using the zoom function. Variable transparencies could be assigned to any structures so that the structures at any level can be seen. Anatomic labels can be attached to the structures in the 3-D model for educational purposes.

CONCLUSION

This computer-generated 3-D model can be observed and studied repeatedly without the time limitations and stresses imposed by surgery. This model may offer the potential to create interactive surgical exercises useful in evaluating multiple surgical routes to specific target areas in the skull base.

The role of virtual reality in surgical training in otorhinolaryngology

PURPOSE OF REVIEW

This article reviews the rationale, current status and future directions for the development and implementation of virtual reality surgical simulators as training tools.

RECENT FINDINGS

The complexity of modern surgical techniques, which utilize advanced technology, presents a dilemma for surgical training. Hands-on patient experience - the traditional apprenticeship method for teaching operations - may not apply because of the learning curve for skill acquisition and patient safety expectation. The paranasal sinuses and temporal bone have intricate anatomy with a significant amount of vital structures either within the surgical field or in close proximity. The current standard of surgical care in these areas involves the use of endoscopes, cameras and microscopes, requiring additional hand-eye coordination, an accurate command of fine motor skills, and a thorough knowledge of the anatomy under magnified vision. A surgeon's disorientation or loss of perspective can lead to complications, often catastrophic and occasionally lethal. These considerations define the ideal environment for surgical simulation; not surprisingly, significant research and validation of simulators in these areas have occurred.

SUMMARY

Virtual reality simulators are demonstrating validity as training and skills assessment tools. Future prototypes will find application for routine use in teaching, surgical planning and the development of new instruments and computer-assisted devices.

A downloadable three-dimensional virtual model of the visible ear

PURPOSE

To develop a three-dimensional (3-D) virtual model of a human temporal bone and surrounding structures.

METHODS

A fresh-frozen human temporal bone was serially sectioned and digital images of the surface of the tissue block were recorded (the 'Visible Ear'). The image stack was resampled at a final resolution of 50 x 50 x 50/100 micro m/voxel, registered in custom software and segmented in PhotoShop 7.0. The segmented image layers were imported into Amira 3.1 to generate smooth polygonal surface models.

RESULTS

The 3-D virtual model presents the structures of the middle, inner and outer ears in their surgically relevant surroundings. It is packaged within a cross-platform freeware, which allows for full rotation, visibility and transparency control, as well as the ability to slice the 3-D model open at any section. The appropriate raw image can be superimposed on the cleavage plane. The model can be downloaded at: (https://research.meei.harvard.edu/Otopathology/3dmodels/).