Comparison of cadaveric and isomorphic three-dimensional printed models in temporal bone education.

OBJECTIVES/HYPOTHESIS: Current three-dimensional (3D) printed simulations are complicated by insufficient void spaces and inconsistent density. We describe a novel simulation with focus on internal anatomic fidelity and evaluate against template/identical cadaveric education. STUDY DESIGN: Research ethics board-approved prospective cohort study. METHODS: Generation of a 3D printed temporal bone was performed using a proprietary algorithm that deconstructs the digital model into slices prior to printing. This supplemental process facilitates removal of residual material from air-containing spaces and permits requisite infiltrative access to the all regions of the model. Ten otolaryngology trainees dissected a cadaveric temporal bone (CTB) followed by a matched/isomorphic 3D printed bone model (PBM), based on derivative micro-computed tomography 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 seven-point Likert scale. RESULTS: Trainees felt physical characteristics of the PBM were quite similar to CTB, with highly ranked cortical (5.5 ± 1.5) and trabecular (5.2 ± 1.3) bone drill quality. The overall model was considered comparable to CTB (5.9 ± 0.74), with respectable air cell reproduction (6.1 ± 1.1). Internal constructs were rated as satisfactory (range, 4.9-6.2). The simulation was considered a beneficial training tool for all types of mastoidectomy (range, 5.9-6.6), posterior tympanotomy (6.5 ± 0.71), and skull base approaches (range, 6-6.5). Participants believed the model to be an effective training instrument (6.7 ± 0.68), which should be incorporated into the temporal bone lab (7.0 ± 0.0). The PBM was thought to improve confidence (6.7 ± 0.68) and operative performance (6.7 ± 0.48). CONCLUSIONS: Study participants found the PBM to be an effective platform that compared favorably to CTB. The model was considered a valuable adjunctive training tool with both realistic mechanical and visual character. LEVEL OF EVIDENCE: NA

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.

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. 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.

Gesture-controlled interactive three dimensional anatomy: a novel teaching tool in head and neck surgery.

BACKGROUND: There is a need for innovative anatomic teaching tools. This paper describes a three dimensional (3D) tool employing the Microsoft Kinect™. Using this instrument, 3D temporal bone anatomy can be manipulated with the use of hand gestures, in the absence of mouse or keyboard. METHODS: CT Temporal bone data is imported into an image processing program and segmented. This information is then exported in polygonal mesh format to an in-house designed 3D graphics engine with an integrated Microsoft Kinect™. Motion in the virtual environment is controlled by tracking hand position relative to the user's left shoulder. RESULTS: The tool successfully tracked scene depth and user joint locations. This permitted gesture-based control over the entire 3D environment. Stereoscopy was deemed appropriate with significant object projection, while still maintaining the operator's ability to resolve image details. Specific anatomical structures can be selected from within the larger virtual environment. These structures can be extracted and rotated at the discretion of the user. Voice command employing the Kinect's™ intrinsic speech library was also implemented, but is easily confounded by environmental noise. CONCLUSION: There is a need for the development of virtual anatomy models to complement traditional education. Initial development is time intensive. Nonetheless, our novel gesture-controlled interactive 3D model of the temporal bone represents a promising interactive teaching tool utilizing a novel interface.

Design and Validation of 3D Printed Complex Bone Models with Internal Anatomic Fidelity for Surgical Training and Rehearsal.

Physical models of complex bony structures can be used for surgical skills training. Current models focus on surface rendering but suffer from a lack of internal accuracy due to limitations in the manufacturing process. We describe a technique for generating internally accurate rapid-prototyped anatomical models with solid and hollow structures from clinical and microCT data using a 3D printer. In a face validation experiment, otolaryngology residents drilled a cadaveric bone and its corresponding printed model. The printed bone models were deemed highly realistic representations across all measured parameters and the educational value of the models was strongly appreciated.

Generation of a 3D printed temporal bone model with internal fidelity and validation of the mechanical construct.

OBJECTIVE: To generate a rapid-prototyped temporal bone model from computed tomography (CT) data with a specific focus on internal anatomic fidelity. STUDY DESIGN: Research ethics board-approved prospective cohort study. SETTING: Current iterations of a rapid-prototyped temporal bone model are complicated by absent void spaces and inconsistent bone density due to limited infiltrant exposure. The creation of a high-fidelity model allows surgical trainees to practice in a standardized and reproducible training environment. This learning paradigm will significantly augment resident understanding of surgical approaches and techniques to prevent adverse outcomes. SUBJECTS AND METHODS: We describe a technique for generating internally accurate rapid-prototyped anatomical models with solid and hollow structures, including void spaces. The novel slicing algorithm digitally deconstructs a model into segments and permits removal of extraneous print material and allows infiltrant penetration of the entire bone structure. Precise reassembly is facilitated by digitally generated fiducials. Infiltrant of choice was determined by expert assessment and subjected to objective mechanical property assessment with comparison to cadaveric sheep bone. RESULTS: The printed bone models are highly realistic. Void space representation was excellent with 88% concordance between cadaveric bone and the resultant rapid-prototyped temporal bone model. Ultimately, cyanoacrylate with hydroquinone was determined to be the most appropriate infiltrant for both cortical and trabecular simulation. The mechanical properties of all tested infiltrants were similar to real bone. CONCLUSION: This model serves as an excellent replica of a human temporal bone for training and preoperative surgical rehearsal and can be dissected in a true-to-life fashion.

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.