Development of a 3D-printed external ventricular drain placement simulator: technical note

Clinical situations for which 3D printing is considered an appropriate representation or extension of data contained in a medical imaging examination: neurosurgical and otolaryngologic conditions

BACKGROUND

Medical three dimensional (3D) printing is performed for neurosurgical and otolaryngologic conditions, but without evidence-based guidance on clinical appropriateness. A writing group composed of the Radiological Society of North America (RSNA) Special Interest Group on 3D Printing (SIG) provides appropriateness recommendations for neurologic 3D printing conditions.

METHODS

A structured literature search was conducted to identify all relevant articles using 3D printing technology associated with neurologic and otolaryngologic conditions. Each study was vetted by the authors and strength of evidence was assessed according to published guidelines.

RESULTS

Evidence-based recommendations for when 3D printing is appropriate are provided for diseases of the calvaria and skull base, brain tumors and cerebrovascular disease. Recommendations are provided in accordance with strength of evidence of publications corresponding to each neurologic condition combined with expert opinion from members of the 3D printing SIG.

CONCLUSIONS

This consensus guidance document, created by the members of the 3D printing SIG, provides a reference for clinical standards of 3D printing for neurologic conditions.

Physiological Responses and Training Satisfaction During National Rollout of a Neurosurgical Intraoperative Catastrophe Simulator for Resident Training

BACKGROUND

Systematic use of neurosurgical training simulators across institutions is significantly hindered by logistical and financial constraints.

OBJECTIVE

To evaluate feasibility of large-scale implementation of an intraoperative catastrophe simulation, we introduced a highly portable and low-cost immersive neurosurgical simulator into a nationwide curriculum for neurosurgery residents, during years 2016 to 2019.

METHODS

The simulator was deployed at 9 Society of Neurological Surgeons junior resident courses and a Congress of Neurological Surgeons education course for a cohort of 526 residents. Heart rate was tracked to monitor physiological responses to simulated stress. Experiential survey data were collected to evaluate simulator fidelity and resident attitudes toward simulation.

RESULTS

Residents rated the simulator positively with a statistically significant increase in satisfaction over time accompanying refinements in the simulator model and clinical scenario. The simulated complications induced stress-related tachycardia in most participants (n = 249); however, a cohort of participants was identified that experienced significant bradycardia (n = 24) in response to simulated stress.

CONCLUSION

Incorporation of immersive neurosurgical simulation into the US national curriculum is logistically feasible and cost-effective for neurosurgical learners. Participant surveys and physiological data suggest that the simulation model recreates the situational physiological stress experienced during practice in the live clinical environment. Simulation may provide an opportunity to identify trainees with maladaptive responses to operative stress who could benefit from additional simulated exposure to mitigate stress impacts on performance.

Overcoming Barriers in Neurosurgical Education: A Novel Approach to Practical Ventriculostomy Simulation

BACKGROUND

In the high-risk, high-stakes specialty of neurosurgery, traditional teaching methods often fail to provide young residents with the proficiency needed to perform complex procedures in stressful situations, with direct effects on patient outcomes. Physical simulators provide the freedom of focused, hands-on training in a more controlled environment. However, the adoption of simulators in neurosurgical training remains a challenge because of high acquisition costs, complex production processes, and lack of realism.

OBJECTIVE

To introduce an easily reproducible, cost-effective simulator for external ventricular drain placements through various ventriculostomy approaches with life-like tactile brain characteristics based on real patients' data.

METHODS

Whole brain and skull reconstruction from patient's computed tomography and MRI data were achieved using freeware and a desktop 3-dimensional printer. Subsequently, a negative brain silicone mold was created. Based on neurosurgical expertise and rheological measurements of brain tissue, gelatin in various concentrations was tested to cast tactilely realistic brain simulants. A sample group of 16 neurosurgeons and medical students tested and evaluated the simulator in respect to realism, haptics, and general usage, scored on a 5-point Likert scale.

RESULTS

We saw a rapid and significant improvement of accuracy among novice medical students. All participants deemed the simulator as highly realistic, effective, and superior to conventional training methods.

CONCLUSION

We were able to demonstrate that building and implementing a high-fidelity simulator for one of the most important neurosurgical procedures as an effective educational and training tool is achievable in a timely manner and without extensive investments.

3D-Printed Disease Models for Neurosurgical Planning, Simulation, and Training

Spatial insight into intracranial pathology and structure is important for neurosurgeons to perform safe and successful surgeries. Three-dimensional (3D) printing technology in the medical field has made it possible to produce intuitive models that can help with spatial perception. Recent advances in 3D-printed disease models have removed barriers to entering the clinical field and medical market, such as precision and texture reality, speed of production, and cost. The 3D-printed disease model is now ready to be actively applied to daily clinical practice in neurosurgical planning, simulation, and training. In this review, the development of 3D-printed neurosurgical disease models and their application are summarized and discussed.

Role of Three-dimensional Printing in Neurosurgery: An Institutional Experience

Background:

Recent advancements in three-dimensional (3D) printing technology in the field of neurosurgery have given a newer modality of management for patients. In this article, we intend to share our institutional experience regarding the use of 3D printing in three modalities, namely, cranioplasty using customized 3D-printed molds of polymethylmethacrylate, 3D-printed model-assisted management of craniovertebral (CV) junction abnormalities, and 3D model-assisted management of brain tumors.

Materials and Methods:

A total of 55 patients were included in our study between March 2017 and December 2019 at S. M. S Medical College, Jaipur, India. 3D-printed models were prepared for cranioplasty in 30 cases, CV junction anomalies in 18 cases, and brain tumors in 7 cases. Preoperative and postoperative data were analyzed as per the diagnosis.

Results:

In cranioplasty, cranial contour and approximation of the margins were excellent and esthetic appearance improved in all patients. In CV junction anomalies, neck pain and myelopathy were improved in all patients, as analyzed using the visual analog scale and the Japanese Orthopedic Association Scale score, respectively. Our questionnaire survey revealed that 3D models for brain tumors were useful in understanding space interval and depth intraoperatively with added advantage of patient education.

Conclusion:

Rapid prototyping 3D-printing technologies provide a practical and anatomically accurate means to produce patient-specific and disease-specific models. These models allow for surgical planning, training, simulation, and devices for the assessment and treatment of neurosurgical disease. Expansion of this technology in neurosurgery will serve practitioners, trainees, and patients.

Utility of image-guided external ventriculostomy: analysis of contemporary practice in the United Kingdom and Ireland

OBJECTIVE

Freehand external ventricular drain (EVD) insertion is associated with a high rate of catheter misplacement. Image-guided EVD placement with neuronavigation or ultrasound has been proposed as a safer, more accurate alternative with potential to facilitate proper placement and reduce catheter malfunction risk. This study aimed to determine the impact of image-guided EVD placement on catheter tip position and drain functionality.

METHODS

This study is a secondary analysis of a data set from a prospective, multicenter study. Data were collated for EVD placements undertaken in the United Kingdom and Ireland from November 2014 to April 2015. In total, 21 large tertiary care academic medical centers were included.

RESULTS

Over the study period, 632 EVDs were inserted and 65.9% had tips lying free-floating in the CSF. Only 19.6% of insertions took place under image guidance. The use of image guidance did not significantly improve the position of the catheter tip on postoperative imaging, even when stratified by ventricular size. There was also no association between navigation use and drain blockage.

CONCLUSIONS

Image-guided EVD placement was not associated with an increased likelihood of achieving optimal catheter position or with a lower rate of catheter blockage. Educational efforts should aim to enhance surgeons' ability to apply the technique correctly in cases of disturbed cerebral anatomy or small ventricles to reduce procedural risks and facilitate effective catheter positioning.

3D printed rodent skin-skull-brain model: A novel animal-free approach for neurosurgical training

In neuroscience, stereotactic brain surgery is a standard yet challenging technique for which laboratory and veterinary personnel must be sufficiently and properly trained. There is currently no animal-free training option for neurosurgeries; stereotactic techniques are learned and practiced on dead animals. Here we have used three-dimensional (3D) printing technologies to create rat and mouse skin-skull-brain models, specifically conceived for rodent stereotaxic surgery training. We used 3D models obtained from microCT pictures and printed them using materials that would provide the most accurate haptic feedback for each model—PC-ABS material for the rat and Durable resin for the mouse. We filled the skulls with Polyurethane expanding foam to mimic the brain. In order to simulate rodent skin, we added a rectangular 1mm thick clear silicone sheet on the skull. Ten qualified rodent neurosurgeons then performed a variety of stereotaxic surgeries on these rat and mouse 3D printed models. Participants evaluated models fidelity compared to cadaveric skulls and their appropriateness for educational use. The 3D printed rat and mouse skin-skull-brain models received an overwhelmingly positive response. They were perceived as very realistic, and considered an excellent alternative to cadaveric skulls for training purposes. They can be made rapidly and at low cost. Our real-size 3D printed replicas could enable cost- and time-efficient, animal-free neurosurgery training. They can be absolute replacements for stereotaxic surgery techniques practice including but not limited to craniotomies, screw placement, brain injections, implantations and cement applications. This project is a significant step forward in implementing the replacement, reduction, and refinement (3Rs) principles to animal experimentation. These 3D printed models could lead the way to the complete replacement of live animals for stereotaxic surgery training in laboratories and veterinary studies.

A simple and cost-effective model for ventricular catheter placement training: technical note

OBJECTIVE

External ventricular drain (EVD) placement is one of first cranial procedures neurosurgery residents are expected to perform independently. While proper training improves patient outcomes, there are few options for practicing EVD placement prior to placing the EVD in patients in a clinical setting. Proposed solutions to this include using cadaveric models and virtual simulations, but barriers exist with these as well in regard to authenticity. EVD simulators using virtual reality technologies are a promising new technique for training, but the cost of these devices poses a barrier to general/widespread accessibility among smaller programs or underserved hospitals. The authors desribe a novel, yet simple, and cost-effective technique (less than $5 per mold) for developing a brain model constructed of homemade ballistics gelatin that can be used for teaching and practicing the placement of EVD.

METHODS

A brain model is made with ballistics gelatin using an anatomically correct skull model as a mold. A 3D-printed ventricular system model is used to create a mold of an anatomically correct ventricular system in the brain model. A group of medical students (n = 10) were given a basic presentation about EVD placement, including standard landmarks and placement techniques, and were also shown a demonstration of EVD placement on the brain model. They were then allowed to perform an EVD placement using the brain model. The students were surveyed on their experience with using the brain model, including usability and practicality of the model. Accuracy of EVD placement by each student was also assessed, with adequate position of catheter tip being in the ipsilateral frontal horn.

RESULTS

The final product is fairly inexpensive and easy to make. It is soft enough to pass a catheter through, but it is also firm enough to maintain its shape, including a cavity representing the lateral ventricles. The dense gelatin holds the catheter in its final resting position, while the two halves are separated and inspected. All participants in the test group of medical students reported that the brain model was easy to use, helped them understand the steps and technique of EVD placement, and provided good feedback on the ideal position of ventricular catheters. All of the participants in the group had adequate positioning of their ventricular catheters after one attempt.

CONCLUSIONS

The presented brain model is easy to replicate, inexpensive, anatomically accurate, and provides a medium for neurosurgeons to teach and practice ventricular catheter placement in a risk-free environment.

Crisis Management Simulation: Review of Current Experience

Crisis management simulation is important in training the next generation of surgeons. In this review, we highlight our experiences with the cavernous carotid injury model. We then delve into other crisis simulation models available for the neurosurgical specialty. The discussion focuses upon how these trainings can continue to evolve. Much work is yet to be done in this exciting arena and we present several avenues for future discovery. Simulation continues to be an important training tool for the surgical learner.

Development of patient specific, realistic, and reusable video assisted thoracoscopic surgery simulator using 3D printing and pediatric computed tomography images

Herein, realistic and reusable phantoms for simulation of pediatric lung video-assisted thoracoscopic surgery (VATS) were proposed and evaluated. 3D-printed phantoms for VATS were designed based on chest computed tomography (CT) data of a pediatric patient with esophageal atresia and tracheoesophageal fistula. Models reflecting the patient-specific structure were fabricated based on the CT images. Appropriate reusable design, realistic mechanical properties with various material types, and 3D printers (fused deposition modeling (FDM) and PolyJet printers) were used to represent the realistic anatomical structures. As a result, the phantom printed by PolyJet reflected closer mechanical properties than those of the FDM phantom. Accuracies (mean difference ± 95 confidence interval) of phantoms by FDM and PolyJet were 0.53 ± 0.46 and 0.98 ± 0.55 mm, respectively. Phantoms were used by surgeons for VATS training, which is considered more reflective of the clinical situation than the conventional simulation phantom. In conclusion, the patient-specific, realistic, and reusable VATS phantom provides a better understanding the complex anatomical structure of a patient and could be used as an educational phantom for esophageal structure replacement in VATS.

3D Printing of Rapid, Low-Cost and Patient-Specific Models of Brain Vasculature for Use in Preoperative Planning in Clipping of Intracranial Aneurysms

We developed a practical and cost-effective method of production of a 3D-printed model of the arterial Circle of Willis of patients treated because of an intracranial aneurysm. We present and explain the steps necessary to produce a 3D model from medical image data, and express the significant value such models have in patient-specific pre-operative planning as well as education. A Digital Imaging and Communications in Medicine (DICOM) viewer is used to create 3D visualization from a patient’s Computed Tomography Angiography (CTA) images. After generating the reconstruction, we manually remove the anatomical components that we wish to exclude from the print by utilizing tools provided with the imaging software. We then export this 3D reconstructions file into a Standard Triangulation Language (STL) file which is then run through a “Slicer” software to generate a G-code file for the printer. After the print is complete, the supports created during the printing process are removed manually. The 3D-printed models we created were of good accuracy and scale. The median production time used for the models described in this manuscript was 4.4 h (range: 3.9–4.5 h). Models were evaluated by neurosurgical teams at local hospital for quality and practicality for use in urgent and non-urgent care. We hope we have provided readers adequate insight into the equipment and software they would require to quickly produce their own accurate and cost-effective 3D models from CT angiography images. It has become quite clear to us that the cost-benefit ratio in the production of such a simplified model is worthwhile.

Application of 3D printed model for planning the endoscopic endonasal transsphenoidal surgery

The application of 3D printing in planning endoscopic endonasal transsphenoidal surgery is illustrated based on the analysis of patients with intracranial skull base diseases who received treatment in our department. Cranial computed tomography/magnetic resonance imaging data are attained preoperatively, and three-dimensional reconstruction is performed using MIMICS (Materialise, Leuven, Belgium). Models of intracranial skull base diseases are printed using a 3D printer before surgery. The models clearly demonstrate the morphologies of the intracranial skull base diseases and the spatial relationship with adjacent large vessels and bones. The printing time of each model is 12.52–15.32 h, and the cost ranges from 900 to 1500 RMB. The operative approach was planned in vitro, and patients recovered postoperatively well without severe complications or death. In a questionnaire about the application of 3D printing, experienced neurosurgeons achieved scores of 7.8–8.8 out of 10, while unexperienced neurosurgeons achieved scores of 9.2–9.8. Resection of intracranial skull base lesions is demonstrated to be well assisted by 3D printing technique, which has great potential in disclosing adjacent anatomical relationships and providing the required help to clinical doctors in preoperative planning.

Development and Implementation of an Inexpensive, Easily Producible, Time Efficient External Ventricular Drain Simulator Using 3-Dimensional Printing and Image Registration

BACKGROUND

External ventricular drain (EVD) placement is one of the most commonly performed procedures in neurosurgery, frequently by the junior neurosurgery resident. Simulators for EVD placement are often costly, time-intensive to create, and complicated to set up.

OBJECTIVE

To describe creation of a simulator that is inexpensive, time-efficient, and simple to set up.

METHODS

This simulator involves printing a hollow head using a desktop 3-dimensional (3D) printer. This head is registered to a commercially available image-guidance system. A total of 11 participants volunteered for this simulation module. EVD placement was assessed at baseline, after verbal teaching, and after live 3D view instruction.

RESULTS

Accurate placement of an EVD on the right side at the foramen of Monro or the frontal horn of the lateral ventricle increased from 44% to 98% with training. Similarly, accurate placement on the left increased from 42% to 85% with training.

CONCLUSION

During participation in the simulation, accurate placement of EVDs increased significantly. All participants believed that they had a better understanding of ventricular anatomy and that this module would be useful as a teaching tool for neurosurgery interns.

A Practical 3D-Printed Model for Training of Endoscopic and Exoscopic Intracerebral Hematoma Surgery with a Tubular Retractor

OBJECTIVE

 To present a three-dimensional (3D)-printed model that simulates endoscopic and exoscopic intracerebral hematoma (ICH) surgery with a tubular retractor.

METHODS

 We used 3D printing technology to develop the model that consisted of the skull frame and a replaceable inserted module. Edible gelatin and animal blood were placed into the module to mimic brain tissue and the hematoma. Twenty neurosurgeons were recruited to participate in our training program that required the use of an endoscope and an exoscope to aspirate the hematoma with a tubular retractor. Five postgraduates were asked to complete the entire training with the endoscope five times. Questionnaires were distributed for feedback after the training program.

RESULTS

 The more experienced surgeons obviously performed better than the rather inexperienced surgeons, verifying that our model could reflect the ability of the trainees. As the training progressed, the scores of the postgraduates increased, and the average score of the fifth training was obviously higher than the first score. No significant differences were observed in the trainees' performance with the endoscope and the exoscope. The feedback questionnaires showed the average score for value of the simulator as a training tool was a 3.65 (on a 4-point scale). Our model received better comments regarding the bone texture (mean: 3.20), the brain tissue texture (mean: 3.20), and the experience in aspirating the hematoma (mean: 3.10). The surgical position (mean: 2.95), surgical approach (mean: 2.90), and simulated brain tissue (mean: 2.85) should be improved.

CONCLUSION

 Our model was practical for endoscopic and exoscopic ICH surgery training. The results of our program showed that prior surgical experience benefited the mastery of both the endoscopic and the exoscopic ICH surgery in the 3D-printed model. Our model could make mastering basic skills more efficient.

Design and validation of a 3D-printed simulator for endoscopic third ventriculostomy

BACKGROUND

Simulation-based training has been considered as the most promising curriculum for neurosurgical education to finally improve surgical skills with the greatest efficiency and safety. However, most of the simulators including physical models and virtual reality systems are relatively expensive, which limits their promotion. In this study, the authors tried to develop a realistic, low-cost, and reusable simulator for endoscopic third ventriculostomy (ETV) and evaluate its validity.

METHODS

A 3D-printed rigid skull with the ventricular system originated from a de-identified patient with obstructive hydrocephalus was constructed. The third ventricular floor was designed as a replaceable module. Thirty-nine neurosurgeons tested the simulator and a rating system was established to assess their performance. All participants filled out questionnaires to evaluate the simulator after training. Five neurosurgical students were recruited to finish the whole training for ten times in order to explore the learning curve of ETV.

RESULTS

We found that (1) the more experienced surgeons performed obviously better than the rather inexperienced surgeons which verified that our model could reflect the ability of the trainees; (2) as the training progressed, the scores of the post-graduates increased and the fifth training average score was obviously higher than their first training average score. The feedback questionnaires showed the average scores for value of the simulator as a training tool and global rating were 3.15 and 3.54 (on a 4-point scale).

CONCLUSION

Our model was practical for ETV training. The results of our program showed that our model could precisely reflect the operators' ability to perform ETV and could make it more efficient to master basic skills.

Current Practice in Preoperative Virtual and Physical Simulation in Neurosurgery

In brain tumor surgery, an appropriate and careful surgical planning process is crucial for surgeons and can determine the success or failure of the surgery. A deep comprehension of spatial relationships between tumor borders and surrounding healthy tissues enables accurate surgical planning that leads to the identification of the optimal and patient-specific surgical strategy. A physical replica of the region of interest is a valuable aid for preoperative planning and simulation, allowing the physician to directly handle the patient’s anatomy and easily study the volumes involved in the surgery. In the literature, different anatomical models, produced with 3D technologies, are reported and several methodologies were proposed. Many of them share the idea that the employment of 3D printing technologies to produce anatomical models can be introduced into standard clinical practice since 3D printing is now considered to be a mature technology. Therefore, the main aim of the paper is to take into account the literature best practices and to describe the current workflow and methodology used to standardize the pre-operative virtual and physical simulation in neurosurgery. The main aim is also to introduce these practices and standards to neurosurgeons and clinical engineers interested in learning and implementing cost-effective in-house preoperative surgical planning processes. To assess the validity of the proposed scheme, four clinical cases of preoperative planning of brain cancer surgery are reported and discussed. Our preliminary results showed that the proposed methodology can be applied effectively in the neurosurgical clinical practice both in terms of affordability and in terms of simulation realism and efficacy.

Patient-specific 3-dimensionally printed models for neurosurgical planning and education

OBJECTIVE

Advances in 3-dimensional (3D) printing technology permit the rapid creation of detailed anatomical models. Integration of this technology into neurosurgical practice is still in its nascence, however. One potential application is to create models depicting neurosurgical pathology. The goal of this study was to assess the clinical value of patient-specific 3D printed models for neurosurgical planning and education.

METHODS

The authors created life-sized, patient-specific models for 4 preoperative cases. Three of the cases involved adults (2 patients with petroclival meningioma and 1 with trigeminal neuralgia) and the remaining case involved a pediatric patient with craniopharyngioma. Models were derived from routine clinical imaging sequences and manufactured using commercially available software and hardware.

RESULTS

Life-sized, 3D printed models depicting bony, vascular, and neural pathology relevant to each case were successfully manufactured. A variety of commercially available software and hardware were used to create and print each model from radiological sequences. The models for the adult cases were printed in separate pieces, which had to be painted by hand, and could be disassembled for detailed study, while the model for the pediatric case was printed as a single piece in separate-colored resins and could not be disassembled for study. Two of the models were used for patient education, and all were used for presurgical planning by the surgeon.

CONCLUSIONS

Patient-specific 3D printed models are useful to neurosurgical practice. They may be used as a visualization aid for surgeons and patients, or for education of trainees.

Developing a 3D composite training model for cranial remodeling

OBJECTIVE

Craniosynostosis correction, including cranial vault remodeling, fronto-orbital advancement (FOA), and endoscopic suturectomy, requires practical experience with complex anatomy and tools. The infrequent exposure to complex neurosurgical procedures such as these during residency limits extraoperative training. Lack of cadaveric teaching tools given the pediatric nature of synostosis compounds this challenge. The authors sought to create lifelike 3D printed models based on actual cases of craniosynostosis in infants and incorporate them into a practical course for endoscopic and open correction. The authors hypothesized that this training tool would increase extraoperative facility and familiarity with cranial vault reconstruction to better prepare surgeons for in vivo procedures.

METHODS

The authors utilized representative craniosynostosis patient scans to create 3D printed models of the calvaria, soft tissues, and cranial contents. Two annual courses implementing these models were held, and surveys were completed by participants (n = 18, 5 attending physicians, 4 fellows, 9 residents) on the day of the course. These participants were surveyed during the course and 1 year later to assess the impact of this training tool. A comparable cohort of trainees who did not participate in the course (n = 11) was also surveyed at the time of the 1-year follow-up to assess their preparation and confidence with performing craniosynostosis surgeries.

RESULTS

An iterative process using multiple materials and the various printing parameters was used to create representative models. Participants performed all major surgical steps, and we quantified the fidelity and utility of the model through surveys. All attendees reported that the model was a valuable training tool for open reconstruction (n = 18/18 [100%]) and endoscopic suturectomy (n = 17/18 [94%]). In the first year, 83% of course participants (n = 14/17) agreed or strongly agreed that the skin and bone materials were realistic and appropriately detailed; the second year, 100% (n = 16/16) agreed or strongly agreed that the skin material was realistic and appropriately detailed, and 88% (n = 14/16) agreed or strongly agreed that the bone material was realistic and appropriately detailed. All participants responded that they would use the models for their own personal training and the training of residents and fellows in their programs.

CONCLUSIONS

The authors have developed realistic 3D printed models of craniosynostosis including soft tissues that allow for surgical practice simulation. The use of these models in surgical simulation provides a level of preparedness that exceeds what currently exists through traditional resident training experience. Employing practical modules using such models as part of a standardized resident curriculum is a logical evolution in neurosurgical education and training.

Hybrid computed tomography and magnetic resonance imaging 3D printed models for neurosurgery planning

In the last decade, the clinical applications of three-dimensional (3D) printed models, in the neurosurgery field among others, have expanded widely based on several technical improvements in 3D printers, an increased variety of materials, but especially in postprocessing software. More commonly, physical models are obtained from a unique imaging technique with potential utilization in presurgical planning, generation/creation of patient-specific surgical material and personalized prosthesis or implants. Using specific software solutions, it is possible to obtain a more accurate segmentation of different anatomical and pathological structures and a more precise registration between different medical image sources allowing generating hybrid computed tomography (CT) and magnetic resonance imaging (MRI) 3D printed models. The need of neurosurgeons for a better understanding of the complex anatomy of central nervous system (CNS) and spine is pushing the use of these hybrid models, which are able to combine morphological information from CT and MRI, and also able to add physiological data from advanced MRI sequences, such as diffusion-weighted imaging (DWI), diffusion tensor imaging (DTI), perfusion weighted imaging (PWI) and functional MRI (fMRI). The inclusion of physiopathological data from advanced MRI sequences enables neurosurgeons to identify those areas with increased biological aggressiveness within a certain lesion prior to surgery or biopsy procedures. Preliminary data support the use of this more accurate presurgical perspective, to select the better surgical approach, reduce the global length of surgery and minimize the rate of intraoperative complications, morbidities or patient recovery times after surgery. The use of 3D printed models in neurosurgery has also demonstrated to be a valid tool for surgeons training and to improve communication between specialists and patients. Further studies are needed to test the feasibility of this novel approach in common clinical practice and determine the degree of improvement the neurosurgeons receive and the potential impact on patient outcome.

Simulation-based Education for Endoscopic Third Ventriculostomy: A Comparison Between Virtual and Physical Training Models

BACKGROUND

The relative educational benefits of virtual reality (VR) and physical simulation models for endoscopic third ventriculostomy (ETV) have not been evaluated "head to head."

OBJECTIVE

To compare and identify the relative utility of a physical and VR ETV simulation model for use in neurosurgical training.

METHODS

Twenty-three neurosurgical residents and 3 fellows performed an ETV on both a physical and VR simulation model. Trainees rated the models using 5-point Likert scales evaluating the domains of anatomy, instrument handling, procedural content, and the overall fidelity of the simulation. Paired t tests were performed for each domain's mean overall score and individual items.

RESULTS

The VR model has relative benefits compared with the physical model with respect to realistic representation of intraventricular anatomy at the foramen of Monro (4.5, standard deviation [SD] = 0.7 vs 4.1, SD = 0.6; P = .04) and the third ventricle floor (4.4, SD = 0.6 vs 4.0, SD = 0.9; P = .03), although the overall anatomy score was similar (4.2, SD = 0.6 vs 4.0, SD = 0.6; P = .11). For overall instrument handling and procedural content, the physical simulator outperformed the VR model (3.7, SD = 0.8 vs 4.5; SD = 0.5, P < .001 and 3.9; SD = 0.8 vs 4.2, SD = 0.6; P = .02, respectively). Overall task fidelity across the 2 simulators was not perceived as significantly different.

CONCLUSION

Simulation model selection should be based on educational objectives. Training focused on learning anatomy or decision-making for anatomic cues may be aided with the VR simulation model. A focus on developing manual dexterity and technical skills using endoscopic equipment in the operating room may be better learned on the physical simulation model.

A novel, low-cost, reusable, high-fidelity neurosurgical training simulator for cerebrovascular bypass surgery

OBJECTIVE

Cerebrovascular bypass surgery is a challenging yet important neurosurgical procedure that is performed to restore circulation in the treatment of carotid occlusive diseases, giant/complex aneurysms, and skull base tumors. It requires advanced microsurgical skills and dedicated training in microsurgical techniques. Most available training tools, however, either lack the realism of the actual bypass surgery (e.g., artificial vessel, chicken wing models) or require special facilities and regulations (e.g., cadaver, live animal, placenta models). The aim of the present study was to design a readily accessible, realistic, easy-to-build, reusable, and high-fidelity simulator to train neurosurgeons or trainees on vascular anastomosis techniques even in the operating room.

METHODS

The authors used an anatomical skull and brain model, artificial vessels, and a water pump to simulate both extracranial and intracranial circulations. They demonstrated the step-by-step preparation of the bypass simulator using readily available and affordable equipment and consumables.

RESULTS

All necessary steps of a superficial temporal artery-middle cerebral artery bypass surgery (from skin opening to skin closure) were performed on the simulator under a surgical microscope. The simulator was used by both experienced neurosurgeons and trainees. Feedback survey results from the participants of the microsurgery course suggested that the model is superior to existing microanastomosis training kits in simulating real surgery conditions (e.g., depth, blood flow, anatomical constraints) and holds promise for widespread use in neurosurgical training.

CONCLUSIONS

With no requirement for specialized laboratory facilities and regulations, this novel, low-cost, reusable, high-fidelity simulator can be readily constructed and used for neurosurgical training with various scenarios and modifications.

A prototype assembled 3D-printed phantom of the glenohumeral joint for fluoroscopic-guided shoulder arthrography

PURPOSE

To describe the methodology of constructing a three-dimensional (3D) printed model of the glenohumeral joint, to serve as an interventional phantom for fluoroscopy-guided shoulder arthrography training.

MATERIALS AND METHODS

The osseous structures, intra-articular space and skin surface of the shoulder were digitally extracted as separate 3D meshes from a normal CT arthrogram of the shoulder, using commercially available software. The osseous structures were 3D-printed in gypsum, a fluoroscopically radiopaque mineral, using binder jet technology. The joint capsule was 3D printed with rubber-like TangoPlus material, using PolyJet technology. The capsule was secured to the humeral head and glenoid to create a sealed intra-articular space. A polyamide mold of the skin was printed using selective laser sintering. The joint was stabilized inside the mold, and the surrounding soft tissues were cast in silicone of varying densities. Fluoroscopically-guided shoulder arthrography was performed using anterior, posterior, and rotator interval approaches. CT arthrographic imaging of the phantom was also performed.

RESULTS

A life-size phantom of the glenohumeral joint was constructed. The radiopaque osseous structures replicated in-vivo osseous corticomedullary differentiation, with dense cortical bone and less dense medullary cancellous bone. The glenoid labrum was successfully integrated into the printed capsule, and visualized on CT arthrography. The phantom was repeatedly used to perform shoulder arthrography using all three conventional approaches, and simulated the in vivo challenges of needle guidance.

CONCLUSIONS

3D printing of a complex capsule, such as the glenohumeral joint, is possible with this technique. Such a model can serve as a valuable training tool.

Three-Dimensional Printing of Archived Human Fetal Material for Teaching Purposes

The practical aspect of human developmental biology education is often limited to the observation and use of animal models to illustrate developmental anatomy. This is due in part to the difficulty of accessing human embryonic and fetal specimens, and the sensitivity inherent to presenting these specimens as teaching materials. This report presents a new approach using three-dimensional (3D) printed replicas of actual human materials in practical classes, thus allowing for the inclusion of accurate examples of human developmental anatomy in the educational context. A series of 3D prints have been produced from digital data collected by computed tomography (CT) imaging of an archived series of preserved human embryonic and fetal specimens. The final versions of 3D prints have been generated in a range of single or multiple materials to illustrate the progression of human development, including the development of internal anatomy. Furthermore, multiple copies of each replica have been printed for large group teaching. In addition to the educational benefit of examining accurate 3D replicas, this approach lessens the potential for adverse student reaction (due to cultural background or personal experience) to observing actual human embryonic/fetal anatomical specimens, and reduces the potential of damage or loss of original specimens. This approach, in combination with ongoing improvements in the management and analysis of digital data and advances in scanning technology, has enormous potential to allow embryology students access to both local and international collections of human gestational material. Anat Sci Educ 00: 000-000. © 2018 American Association of Anatomists.

Design and fabrication of a personalized anthropomorphic phantom using 3D printing and tissue equivalent materials

To fabricate an individualized anthropomorphic lung phantom with tissue-equivalent radiation attenuation properties using a cost-effective three-dimensional (3D) printing technique. Based on anonymized human chest CT images, the phantom contained a 3D-printed skin shell, filled with tissue equivalent materials with similar radiation attenuation characteristics. The filling materials were a mixture of CaCO₃, MgO, agarose, NaCl, pearl powder and silica gel. The dose calculation accuracy of different treatment planning system (TPS) algorithms was validated and compared with the ion chamber measurements in the phantom, including tumor and surrounding normal tissues. The chest phantom was shown to represent a human's chest in terms of radiation attenuation property and human anatomy. The Hounsfield unit ranges were -60 to -100, 20 to 60, and 120 to 300 for fat, muscle, and bone, respectively. The actual measured values of the ionization chamber were 213.7 cGy for the tumor, 53.85 cGy for normal lung tissue, and 4.1 cGy for the spinal cord, compared to 214.1, 55.2, and 4.5 cGy, respectively, with use of the Monte Carlo algorithm in TPS. The application of 3D printing in anthropomorphic phantoms can improve personalized medical need and efficiency with reduce costs thus, can be used for radiation dose verification.

3D Printed lattice microstructures to mimic soft biological materials

OBJECTIVE

Our group has developed a method for 3D printing mechanically-realistic soft tissue, as a building block towards developing anatomically realistic 3D-printed biomechanical testbed models.

METHODS

A Polyjet 3D printer was used to print lattice microstructures, which were tested in compression to evaluate the elastic profile. Lattice properties including element diameter, element spacing (ES), element cross-sectional geometry, element arrangement, and lattice rotation were varied to determine their effect on the stress-strain curve. As a case study, a single 3D printed sample was tuned such that its elastic profile matched plantar fat.

RESULTS

Element diameter and ES had the largest effect on the stress-strain profile, and rotating the lattice microstructure tends to linearize the curves. A simple cubic lattice microstructure of cylindrical elements, with 0.5 mm diameter columns and 1.2 mm spacing had a stress-strain curve the was closest to plantar fat. The elastic modulus at 10, 30, and 50% strain was 7.55, 9.50, and 252 kPa respectively. Physiologic plantar fat at the same strain values has moduli values of 1.08, 7.13, and 188 kPa.

SIGNIFICANCE

We demonstrated that lattice microstructures can decrease the young's modulus of soft 3D printed materials by three orders of magnitude. By creating a method for fine-tuning the elastic profile of 3D-printed materials to behave like human soft tissue, we provide an attractive alternative to more exotic and time-consuming techniques such as molding and casting.

Development of a brain simulator for intracranial targeting: Technical note

Learning and enhancing of manual skills in the field of neurosurgery requires an intensive training which can be maintained by using virtual reality (VR)-based or physical model (PM)-based simulators. However, both simulator types are limited to one specific intracranial procedure, e.g. the application of an external ventricular drainage (EVD), and they do not provide any accuracy verification. We present a brain simulator which consists of a 3D human skull model having five electroconductive balls in its interior. The installed balls represent intracranial target points providing various accuracy problems in neuronavigation. They are electrically contacted to lamps getting an optical signal by touching them with a current-carrying target tool. The simulator fulfills two requirements: First, it can prove the accuracy of navigation systems and algorithms. Second, it allows becoming familiar with a navigation system's application in an ex vivo setting. It could be a helpful device in neurosurgical skills labs.

A 3-Dimensional-Printed Spine Localizer: Introducing the Concept of Online Dissemination of Novel Surgical Instruments

Background/Aims

To date, applications of 3-dimensional (3D) printing in neurosurgery have been limited to the creation of anatomical models for training and simulation, fabrication of customized implants, and production of patient-specific surgical tool guides. We aim to demonstrate a new application of this technology for the online dissemination of novel surgical instrument designs across the world.

Methods

A link to a 3D printing file and instructions for assembly of a spine localizer are included in this article. This device was used to determine the optimal location of skin incision in lumbar microsurgery in 43 consecutive patients. Data regarding the accuracy of the surgeon's initial estimate of the target site based on palpation of anatomical landmarks and the accuracy of the localizer device in locating the target spine segment were prospectively collected.

Results

In 35 cases (81%), the surgeon’s initial estimate of the target site was correct. In the remaining 8 cases (19%), the initial estimate was off by 1 motion segment. Inaccuracy of the surgeon’s estimate was found to be associated with a higher body mass index and the presence of transitional lumbosacral anatomy, but not with age, sex, or location of the target segment. In all patients, the location of the incision guided by the localizer was found to overlie the target segment, yielding a device accuracy of 100%. There was no need to extend the incision or modify the surgical trajectory.

Conclusion

This 3D-printable localizer serves as an example of a device that can be disseminated online and printed at the point of use, thus promoting online tool-sharing by neurosurgeons.

Systematic Review of the Use of 3-Dimensional Printing in Surgical Teaching and Assessment

OBJECTIVE

The use of 3-dimensional (3D) printing in medicine has rapidly expanded in recent years as the technology has developed. The potential uses of 3D printing are manifold. This article provides a systematic review of the uses of 3D printing within surgical training and assessment.

METHODS

A structured literature search of the major literature databases was performed in adherence to PRISMA guidelines. Articles that met predefined inclusion and exclusion criteria were appraised with respect to the key objectives of the review and sources of bias were analysed.

RESULTS

Overall, 49 studies were identified for inclusion in the qualitative analysis. Heterogeneity in study design and outcome measures used prohibited meaningful meta-analysis. 3D printing has been used in surgical training across a broad range of specialities but most commonly in neurosurgery and otorhinolaryngology. Both objective and subjective outcome measures have been studied, demonstrating the usage of 3D printed models in training and education. 3D printing has also been used in anatomical education and preoperative planning, demonstrating improved outcomes when compared to traditional educational methods and improved patient outcomes, respectively.

CONCLUSIONS

3D printing technology has a broad range of potential applications within surgical education and training. Although the field is still in its relative infancy, several studies have already demonstrated its usage both instead of and in addition to traditional educational methods.

Operative simulation of anterior clinoidectomy using a rapid prototyping model molded by a three-dimensional printer

BACKGROUND

As the anatomical three-dimensional (3D) positional relationship around the anterior clinoid process (ACP) is complex, experience of many surgeries is necessary to understand anterior clinoidectomy (AC). We prepared a 3D synthetic image from computed tomographic angiography (CTA) and magnetic resonance imaging (MRI) data and a rapid prototyping (RP) model from the imaging data using a 3D printer. The objective of this study was to evaluate anatomical reproduction of the 3D synthetic image and intraosseous region after AC in the RP model. In addition, the usefulness of the RP model for operative simulation was investigated.

METHODS

The subjects were 51 patients who were examined by CTA and MRI before surgery. The size of the ACP, thickness and length of the optic nerve and artery, and intraosseous length after AC were measured in the 3D synthetic image and RP model, and reproducibility in the RP model was evaluated. In addition, 10 neurosurgeons performed AC in the completed RP models to investigate their usefulness for operative simulation.

RESULTS

The RP model reproduced the region in the vicinity of the ACP in the 3D synthetic image, including the intraosseous region, at a high accuracy. In addition, drilling of the RP model was a useful operative simulation method of AC.

CONCLUSIONS

The RP model of the vicinity of ACP, prepared using a 3D printer, showed favorable anatomical reproducibility, including reproduction of the intraosseous region. In addition, it was concluded that this RP model is useful as a surgical education tool for drilling.

Training in Cerebral Aneurysm Clipping Using Self-Made 3-Dimensional Models

INTRODUCTION

Recently, there have been increasingly fewer opportunities for junior surgeons to receive on-the-job training. Therefore, we created custom-built three-dimensional (3D) surgical simulators for training in connection with cerebral aneurysm clipping.

METHODS

Three patient-specific models were composed of a trimmed skull, retractable brain, and a hollow elastic aneurysm with its parent artery. The brain models were created using 3D printers via a casting technique. The artery models were made by 3D printing and a lost-wax technique. Four residents and 2 junior neurosurgeons attended the training courses. The trainees retracted the brain, observed the parent arteries and aneurysmal neck, selected the clip(s), and clipped the neck of an aneurysm. The duration of simulation was recorded. A senior neurosurgeon then assessed the trainee's technical skill and explained how to improve his/her performance for the procedure using a video of the actual surgery. Subsequently, the trainee attempted the clipping simulation again, using the same model. After the course, the senior neurosurgeon assessed each trainee's technical skill. The trainee critiqued the usefulness of the model and the effectiveness of the training course.

RESULTS

Trainees succeeded in performing the simulation in line with an actual surgery. Their skills tended to improve upon completion of the training.

CONCLUSION

These simulation models are easy to create, and we believe that they are very useful for training junior neurosurgeons in the surgical techniques needed for cerebral aneurysm clipping.

Three-dimensional printing of a sinus pericranii model: technical note

BACKGROUND

Sinus pericranii (SP) is a rare venous malformation consisting of a single or multiple abnormal emissary veins communicating between intracranial sinuses and dilated epicranial veins. There is no consensus concerning diagnosis, management, and treatment of SP.

TECHNICAL NOTE

We report the case of a 4-month-old infant with a SP for whom we used a three-dimensional printed model in order to define the angioarchitecture, improve management, and help parents' understanding of this uncommon condition.

Three-Dimensional Printing of a Hemorrhagic Cervical Cancer Model for Postgraduate Gynecological Training

INTRODUCTION

A realistic hemorrhagic cervical cancer model was three-dimensionally (3D) printed and used in a postgraduate medical simulation training session.

MATERIALS AND METHODS

Computer-assisted design (CAD) software was the platform of choice to create and refine the cervical model. Once the prototype was finalized, another software allowed for the addition of a neoplastic mass, which included openings for bleeding from the neoplasm and cervical os. 3D printing was done using two desktop printers and three different materials. An emergency medicine simulation case was presented to obstetrics and gynecology residents who were at varying stages of their training. The scenario included history taking and physical examination of a standardized patient. This was a hybrid simulation; a synthetic pelvic task trainer that allowed the placement of the cervical model was connected to the standardized patient. The task trainer was placed under a drape and appeared to extend from the standardized patient's body. At various points in the simulation, the standardized patient controlled the cervical bleeding through a peripheral venous line. Feedback forms were completed, and the models were discussed and evaluated with staff.

RESULTS

A final cervical model was created and successfully printed. Overall, the models were reported to be similar to a real cervix. The models bled well. Most models were not sutured during the scenarios, but overall, the value of the printed cervical models was reported to be high.

DISCUSSION

The models were well received, but it was suggested that more colors be integrated into the cervix in order to better emphasize the intended pathology. The model design requires further improvement, such as the addition of a locking mechanism, in order to ensure that the cervix stays inside the task trainer throughout the simulation. Adjustments to the simulated blood product would allow the bleeding to flow more vigorously. Additionally, a different simulation scenario might be more suitable to explore the residents' ability to suture the cervical models, as cervical suturing of a neoplasm is not a common emergency department procedure.

CONCLUSION

3D-printed cervical models are an economical and anatomically accurate option for simulation training and other educational purposes.

3D printing in neurosurgery: A systematic review

BACKGROUND

The recent expansion of three-dimensional (3D) printing technology into the field of neurosurgery has prompted a widespread investigation of its utility. In this article, we review the current body of literature describing rapid prototyping techniques with applications to the practice of neurosurgery.

METHODS

An extensive and systematic search of the Compendex, Scopus, and PubMed medical databases was conducted using keywords relating to 3D printing and neurosurgery. Results were manually screened for relevance to applications within the field.

RESULTS

Of the search results, 36 articles were identified and included in this review. The articles spanned the various subspecialties of the field including cerebrovascular, neuro-oncologic, spinal, functional, and endoscopic neurosurgery.

CONCLUSIONS

We conclude that 3D printing techniques are practical and anatomically accurate methods of producing patient-specific models for surgical planning, simulation and training, tissue-engineered implants, and secondary devices. Expansion of this technology may, therefore, contribute to advancing the neurosurgical field from several standpoints.

Current Applications and Future Perspectives of the Use of 3D Printing in Anatomical Training and Neurosurgery

3D printing is a form of rapid prototyping technology, which has led to innovative new applications in biomedicine. It facilitates the production of highly accurate three dimensional objects from substrate materials. The inherent accuracy and other properties of 3D printing have allowed it to have exciting applications in anatomy education and surgery, with the specialty of neurosurgery having benefited particularly well. This article presents the findings of a literature review of the Pubmed and Web of Science databases investigating the applications of 3D printing in anatomy and surgical education, and neurosurgery. A number of applications within these fields were found, with many significantly improving the quality of anatomy and surgical education, and the practice of neurosurgery. They also offered advantages over existing approaches and practices. It is envisaged that the number of useful applications will rise in the coming years, particularly as the costs of this technology decrease and its uptake rises.

A neurosurgical simulation of skull base tumors using a 3D printed rapid prototyping model containing mesh structures

BACKGROUND

Deep regions are not visible in three-dimensional (3D) printed rapid prototyping (RP) models prepared from opaque materials, which is not the case with translucent images. The objectives of this study were to develop an RP model in which a skull base tumor was simulated using mesh, and to investigate its usefulness for surgical simulations by evaluating the visibility of its deep regions.

METHODS

A 3D printer that employs binder jetting and is mainly used to prepare plaster models was used. RP models containing a solid tumor, no tumor, and a mesh tumor were prepared based on computed tomography, magnetic resonance imaging, and angiographic data for four cases of petroclival tumor. Twelve neurosurgeons graded the three types of RP model into the following four categories: 'clearly visible,' 'visible,' 'difficult to see,' and 'invisible,' based on the visibility of the internal carotid artery, basilar artery, and brain stem through a craniotomy performed via the combined transpetrosal approach. In addition, the 3D positional relationships between these structures and the tumor were assessed.

RESULTS

The internal carotid artery, basilar artery, and brain stem and the positional relationships of these structures with the tumor were significantly more visible in the RP models with mesh tumors than in the RP models with solid or no tumors.

CONCLUSIONS

The deep regions of PR models containing mesh skull base tumors were easy to visualize. This 3D printing-based method might be applicable to various surgical simulations.

Simulator and 2 tools: Validation of performance measures from a novel neurosurgery simulation model using the current Standards framework

BACKGROUND

Ventriculostomy is a common neurosurgical procedure with a relatively steep learning curve. A low-cost, high-fidelity simulator paired with procedure-specific performance measures would provide a safe environment to teach ventriculostomy procedural skills. The same validated simulation model could also allow for assessment of trainees' proficiencies with measures that align with Accreditation Council for Graduate Medical Education milestones. This study extends previous work to evaluate validity evidence from the simulator, its newly developed performance assessment, the Ventricolostomy Procedural Assessment Tool, and the Objective Structured Assessment for Technical Skills.

METHODS

After Institutional Review Board exemption, performance data were collected from 11 novice and 3 expert neurosurgeons (n = 14). Participants self-reported their ability to perform tasks on the simulator using the Ventricolostomy Procedural Assessment Tool, an 11-item, step-wise instrument with 5-point rating scales ranging from 1 (unable to perform) to 5 (performs easily and smoothly). De-identified operative performances were videotaped and independently rated by 3 neurosurgeons, using the Ventricolostomy Procedural Assessment Tool and Objective Structured Assessment for Technical Skills. We evaluated multiple sources of validity evidence (2014 Standards) to examine psychometric quality of the measures and to test our assumption that the tools could discriminate between novice and expert performances adequately. We used a multifacet Rasch model and traditional indices, such as Cronbach alpha, intraclass correlation, and Wilcoxon signed-rank test estimates.

RESULTS

Validity evidence relevant to test content and response processes was supported adequately. Evidence of internal structure was supported by high interitem consistency (n = 0.95) and inter-rater agreement for most Ventricolostomy Procedural Assessment Tool items (Intraclass correlation coefficient = [0.00, 0.91]) and all Objective Structured Assessment for Technical Skills items (Intraclass correlation coefficient = [0.80, 0.93]). Overall, novices performed at a lower level than experts on both scales (P < .05), supporting evidence relevant to relationships to other variables. Deeper analysis of novice/expert ratings indicated novices attained lower performances ratings for all Ventricolostomy Procedural Assessment Tool and Objective Structured Assessment for Technical Skills items, but statistical significance was only achieved for the Objective Structured Assessment for Technical Skills items (P < .01). Rater bias estimates were favorable, supporting evidence relevant to consequences of testing.

CONCLUSION

Despite a small sample, favorable evidence using current Standards supports the use of the novel simulator and both tools combined for skills training and performance assessment, but challenges (potential threats to validity) should be considered prior to implementation.