Utility of multimaterial 3D printers in creating models with pathological entities to enhance the training experience of neurosurgeons

Development of Three-Dimensional Printed Craniocerebral Models for Simulated Neurosurgery

OBJECTIVE

To use three-dimensional (3D) printed craniocerebral models to guide neurosurgery and design the best operative route preoperatively.

METHODS

Computed tomography, magnetic resonance imaging, computed tomography angiography, and functional magnetic resonance images of the patients were collected as needed, reconstructed to form multicolor 3D craniocerebral images, and printed to form solid 3D models. The hollow aneurysm model was printed with rubberlike material; craniocerebral models were printed with resin or gypsum.

RESULTS

The 3D printed hollow aneurysm model was highly representative of what was observed during the surgery. The model had realistic texture and elasticity and was used for preoperative simulation of aneurysm clipping for clip selection, which was the same as was used during the surgery. The craniocerebral aneurysm model clearly showed the spatial relation between the aneurysm and surrounding tissues, which can be used to select the best surgical approach in the preoperative simulation, to evaluate the necessity of drilling the anterior clinoid process, and to determine the feasibility of using a contralateral approach. The craniocerebral tumor and anatomic model showed the spatial relation between tumor and intracranial vasculatures, tractus pyramidalis, and functional areas, which was helpful 1) when selecting the optimal surgical approach to avoid damage to brain function, 2) for learning the functional anatomy of the craniocerebral structure, and 3) for preoperative selection of surgical spaces in the sellar region.

CONCLUSIONS

3D printing provides neurosurgeons with solid craniocerebral models that can be observed and operated on directly and effectively, which further improves the accuracy of neurosurgeries.

Three-dimensional Printing of Models of Cleft Lip and Palate

Supplemental Digital Content is available in the text.

The utility of a multimaterial 3D printed model for surgical planning of complex deformity of the skull base and craniovertebral junction

Utilizing advanced 3D printing techniques, a multimaterial model was created for the surgical planning of a complex deformity of the skull base and craniovertebral junction. The model contained bone anatomy as well as vasculature and the previously placed occipital cervical instrumentation. Careful evaluation allowed for a unique preoperative perspective of the craniovertebral deformity and instrumentation options. This patient-specific model was invaluable in choosing the most effective approach and correction strategy, which was not readily apparent from standard 2D imaging. Advanced 3D multimaterial printing provides a cost-effective method of presurgical planning, which can also be used for both patient and resident education.

Three-Dimensional Printing: Basic Principles and Applications in Medicine and Radiology

The advent of three-dimensional printing (3DP) technology has enabled the creation of a tangible and complex 3D object that goes beyond a simple 3D-shaded visualization on a flat monitor. Since the early 2000s, 3DP machines have been used only in hard tissue applications. Recently developed multi-materials for 3DP have been used extensively for a variety of medical applications, such as personalized surgical planning and guidance, customized implants, biomedical research, and preclinical education. In this review article, we discuss the 3D reconstruction process, touching on medical imaging, and various 3DP systems applicable to medicine. In addition, the 3DP medical applications using multi-materials are introduced, as well as our recent results.

Using 3D Printing to Create Personalized Brain Models for Neurosurgical Training and Preoperative Planning

BACKGROUND

Three-dimensional (3D) printing holds promise for a wide variety of biomedical applications, from surgical planning, practicing, and teaching to creating implantable devices. The growth of this cheap and easy additive manufacturing technology in orthopedic, plastic, and vascular surgery has been explosive; however, its potential in the field of neurosurgery remains underexplored. A major limitation is that current technologies are unable to directly print ultrasoft materials like human brain tissue.

OBJECTIVE

In this technical note, the authors present a new technology to create deformable, personalized models of the human brain.

METHODS

The method combines 3D printing, molding, and casting to create a physiologically, anatomically, and tactilely realistic model based on magnetic resonance images. Created from soft gelatin, the model is easy to produce, cost-efficient, durable, and orders of magnitude softer than conventionally printed 3D models. The personalized brain model cost $50, and its fabrication took 24 hours.

RESULTS

In mechanical tests, the model stiffness (E = 25.29 ± 2.68 kPa) was 5 orders of magnitude softer than common 3D printed materials, and less than an order of magnitude stiffer than mammalian brain tissue (E = 2.64 ± 0.40 kPa). In a multicenter surgical survey, model size (100.00%), visual appearance (83.33%), and surgical anatomy (81.25%) were perceived as very realistic. The model was perceived as very useful for patient illustration (85.00%), teaching (94.44%), learning (100.00%), surgical training (95.00%), and preoperative planning (95.00%).

CONCLUSIONS

With minor refinements, personalized, deformable brain models created via 3D printing will improve surgical training and preoperative planning with the ultimate goal to provide accurate, customized, high-precision treatment.

Advantages and disadvantages of 3-dimensional printing in surgery: A systematic review

BACKGROUND

Three-dimensional (3D) printing is becoming increasingly important in medicine and especially in surgery. The aim of the present work was to identify the advantages and disadvantages of 3D printing applied in surgery.

METHODS

We conducted a systematic review of articles on 3D printing applications in surgery published between 2005 and 2015 and identified using a PubMed and EMBASE search. Studies dealing with bioprinting, dentistry, and limb prosthesis or those not conducted in a hospital setting were excluded.

RESULTS

A total of 158 studies met the inclusion criteria. Three-dimensional printing was used to produce anatomic models (n = 113, 71.5%), surgical guides and templates (n = 40, 25.3%), implants (n = 15, 9.5%) and molds (n = 10, 6.3%), and primarily in maxillofacial (n = 79, 50.0%) and orthopedic (n = 39, 24.7%) operations. The main advantages reported were the possibilities for preoperative planning (n = 77, 48.7%), the accuracy of the process used (n = 53, 33.5%), and the time saved in the operating room (n = 52, 32.9%); 34 studies (21.5%) stressed that the accuracy was not satisfactory. The time needed to prepare the object (n = 31, 19.6%) and the additional costs (n = 30, 19.0%) were also seen as important limitations for routine use of 3D printing.

CONCLUSION

The additional cost and the time needed to produce devices by current 3D technology still limit its widespread use in hospitals. The development of guidelines to improve the reporting of experience with 3D printing in surgery is highly desirable.

Salt as a new colored solid model for simulation surgery

BACKGROUND

Simulated craniomaxillofacial surgery is critical for planning the procedure, shortening operative time, and practicing the procedure. However, typical models are expensive, given their solid materials, and the surgical sensations do not accurately reflect the procedure performed using human bone. To solve these problems, a new solid salt model has been developed.

METHOD

Stereolithography data was generated using computed tomography data, and a salt model was created using a 3D inkjet printer. By extracting specific data for elements such as the teeth and mandibular canal, these elements were highlighted in the solid model using different colored material. Also, we compared the maximum load and plastic deformation of the salt model, a stereolithographic resin model, and a pig limb.

RESULT

The salt model had similar tenacity to bone, and the risk of damage to the teeth and inferior alveolar nerve was easily confirmed.

CONCLUSION

The material cost of the salt model is extremely low, and the salt model may provide a more accurate sensation of cutting human bone. Thus, this model is useful for both simulated operation and practice for inexperienced surgeons.

Neurosurgical endoscopic training via a realistic 3-dimensional model with pathology

INTRODUCTION

Training in intraventricular endoscopy is particularly challenging because the volume of cases is relatively small and the techniques involved are unlike those usually used in conventional neurosurgery. Present training models are inadequate for various reasons. Using 3-dimensional (3D) printing techniques, models with pathology can be created using actual patient's imaging data. This technical article introduces a new training model based on a patient with hydrocephalus secondary to a pineal tumour, enabling the models to be used to simulate third ventriculostomies and pineal biopsies.

METHODS

Multiple models of the head of a patient with hydrocephalus were created using 3D rapid prototyping technique. These models were modified to allow for a fluid-filled ventricular system under appropriate tension. The models were qualitatively assessed in the various steps involved in an endoscopic third ventriculostomy and intraventricular biopsy procedure, initially by 3 independent neurosurgeons and subsequently by 12 participants of an intraventricular endoscopy workshop.

RESULTS

All 3 surgeons agreed on the ease and usefulness of these models in the teaching of endoscopic third ventriculostomy, performing endoscopic biopsies, and the integration of navigation to ventriculoscopy. Their overall score for the ventricular model realism was above average. The 12 participants of the intraventricular endoscopy workshop averaged between a score of 4.0 to 4.6 of 5 for every individual step of the procedure.

DISCUSSION

Neurosurgical endoscopic training currently is a long process of stepwise training. These 3D printed models provide a realistic simulation environment for a neuroendoscopy procedure that allows safe and effective teaching of navigation and endoscopy in a standardized and repetitive fashion.

Individualized Surgical Approach Planning for Petroclival Tumors Using a 3D Printer

Objectives To determine the utility of three-dimensional (3D) printed models in individualized petroclival tumor resection planning by measuring the fidelity of printed anatomical structures and comparing tumor exposure afforded by different approaches. Design Case series and review of the literature. Setting Tertiary care center. Participants Three patients with petroclival lesions. Main Outcome Measures Subjective opinion of access by neuro-otologists and neurosurgeons as well as surface area of tumor exposure. Results Surgeons found the 3D models of each patient's skull and tumor useful for preoperative planning. Limitations of individual surgical approaches not identified through preoperative imaging were apparent after 3D models were evaluated. Significant variability in exposure was noted between models for similar or identical approaches. A notable drawback is that our printing process did not replicate mastoid air cells. Conclusions We found that 3D modeling is useful for individualized preoperative planning for approaching petroclival tumors. Our printing techniques did produce authentic replicas of the tumors in relation to bony structures.

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

In this paper, the authors present a physical model developed to simulate accurate external ventricular drain (EVD) placement with realistic haptic and visual feedbacks to serve as a platform for complete procedural training. Insertion of an EVD via ventriculostomy is a common neurosurgical procedure used to monitor intracranial pressures and/or drain CSF. Currently, realistic training tools are scarce and mainly limited to virtual reality simulation systems. The use of 3D printing technology enables the development of realistic anatomical structures and customized design for physical simulators. In this study, the authors used the advantages of 3D printing to directly build the model geometry from stealth head CT scans and build a phantom brain mold based on 3D scans of a plastinated human brain. The resultant simulator provides realistic haptic feedback during a procedure, with visualization of catheter trajectory and fluid drainage. A multiinstitutional survey was also used to prove content validity of the simulator. With minor refinement, this simulator is expected to be a cost-effective tool for training neurosurgical residents in EVD placement.

Three-dimensional printing in surgery: a review of current surgical applications

BACKGROUND

Three-dimensional printing (3DP) is gaining increasing recognition as a technique that will transform the landscape of surgical practice. It allows for the rapid conversion of anatomic images into physical objects, which are being used across a variety of surgical specialties. It has been unclear which groups are leading the way in coming up with novel ways of using the technology and what specifically the technology is being used for. The aim of this article was to review the current applications of 3DP in modern surgical practice.

MATERIALS AND METHODS

An electronic search was carried out in MEDLINE, EMBASE, and PsycINFO for terms related to 3DP. These were then screened for relevance and practical applications of the technology in surgery.

RESULTS

Four hundred eighty-eight articles were initially found, and these were eventually narrowed down to 93 full-text articles. It was determined that there were three main areas in which the technology is being used to print: (1) anatomic models, (2) surgical instruments, and (3) implants and prostheses.

CONCLUSIONS

Different specialties are at different stages in the use of the technology. The costs involved with implementing the technology and time taken for printing are important factors to consider before widespread use. For the foreseeable future, this is an exciting and interesting technology with the capacity to radically change health care and revolutionize modern surgery.

Emerging Applications of Bedside 3D Printing in Plastic Surgery

Modern imaging techniques are an essential component of preoperative planning in plastic and reconstructive surgery. However, conventional modalities, including three-dimensional (3D) reconstructions, are limited by their representation on 2D workstations. 3D printing, also known as rapid prototyping or additive manufacturing, was once the province of industry to fabricate models from a computer-aided design (CAD) in a layer-by-layer manner. The early adopters in clinical practice have embraced the medical imaging-guided 3D-printed biomodels for their ability to provide tactile feedback and a superior appreciation of visuospatial relationship between anatomical structures. With increasing accessibility, investigators are able to convert standard imaging data into a CAD file using various 3D reconstruction softwares and ultimately fabricate 3D models using 3D printing techniques, such as stereolithography, multijet modeling, selective laser sintering, binder jet technique, and fused deposition modeling. However, many clinicians have questioned whether the cost-to-benefit ratio justifies its ongoing use. The cost and size of 3D printers have rapidly decreased over the past decade in parallel with the expiration of key 3D printing patents. Significant improvements in clinical imaging and user-friendly 3D software have permitted computer-aided 3D modeling of anatomical structures and implants without outsourcing in many cases. These developments offer immense potential for the application of 3D printing at the bedside for a variety of clinical applications. In this review, existing uses of 3D printing in plastic surgery practice spanning the spectrum from templates for facial transplantation surgery through to the formation of bespoke craniofacial implants to optimize post-operative esthetics are described. Furthermore, we discuss the potential of 3D printing to become an essential office-based tool in plastic surgery to assist in preoperative planning, developing intraoperative guidance tools, teaching patients and surgical trainees, and producing patient-specific prosthetics in everyday surgical practice.

Training in Brain Retraction Using a Self-Made Three-Dimensional Model

A hollow brain model was created using soft urethane. A tube passing through the hollow was attached for use as a water inlet and manometer. Water sufficient in quantity to realize the intended initial pressure was infused through the tube. The brain model was retracted with a brain spatula and the surgical corridor was opened. By measuring local force with a sensor set on the brain spatula, the model could be used for training in brain retraction. At the same time, the water column of the manometer was measured and the relationship with the force of the brain spatula was investigated. A positive correlation between the water column and local force was confirmed. This indicated that it was possible to use this model without a force sensor for the same training using water column measurements.

3D printing of patient-specific anatomy: A tool to improve patient consent and enhance imaging interpretation by trainees

We report the use of three-dimensional or 3D printed, patient-specific anatomy as a tool to improve informed patient consent and patient understanding in a case of posterior lumbar fixation. Next, we discuss its utility as an educational tool to enhance imaging interpretation by neurosurgery trainees.

Simulation and resident education in spinal neurosurgery

BACKGROUND

A host of factors have contributed to the increasing use of simulation in neurosurgical resident education. Although the number of simulation-related publications has increased exponentially over the past two decades, no studies have specifically examined the role of simulation in resident education in spinal neurosurgery.

METHODS

We performed a structured search of several databases to identify articles detailing the use of simulation in spinal neurosurgery education in an attempt to catalogue potential applications for its use.

RESULTS

A brief history of simulation in medicine is given, followed by current trends of spinal simulation utilization in residency programs. General themes from the literature are identified that are integral for implementing simulation into neurosurgical residency curriculum. Finally, various applications are reported.

CONCLUSION

The use of simulation in spinal neurosurgery education is not as ubiquitous in comparison to other neurosurgical subspecialties, but many promising methods of simulation are available for augmenting resident education.

Novel ex vivo model for hands-on teaching of and training in EUS-guided biliary drainage: creation of "Mumbai EUS" stereolithography/3D printing bile duct prototype (with videos)

BACKGROUND

EUS-guided biliary drainage (EUS-BD) has emerged as an alternative rescue method in patients with failed ERCP. Opportunities for teaching and training are limited because of a low case volume at most centers.

OBJECTIVE

To evaluate a stereolithography/3-dimensional (3D) printing bile duct prototype for teaching and training in EUS-BD.

DESIGN

Prospective observational feasibility study.

SETTING

Tertiary referral center.

SUBJECTS

Twenty endosonographers attending an interventional EUS workshop.

INTERVENTION

A prototype of a dilated biliary system was prepared by computer-aided design and 3D printing. The study participants performed guidewire manipulation and EUS-BD procedures (antegrade procedure and/or choledochoduodenostomy) on the prototype. Participants were scored with the device on a scale of 1 to 5 via a questionnaire. Participants' success rate for various steps of the EUS-BD procedure was noted.

MAIN OUTCOME MEASUREMENTS

Subjective and objective evaluation of the prototype regarding its overall applicability, quality of radiographic and EUS images, and 4 steps of EUS-BD procedure (needle puncture, guidewire manipulation, tract dilation, stent placement).

RESULTS

Fifteen participants returned the questionnaire, and 10 completed all 4 steps of EUS-BD. The median score for overall utility was 4, whereas that for EUS and US views was 5. Participants with experience in performing more than 20 EUS-BD procedures scored the prototype significantly lower for stent placement (P = .013) and equivalent for needle puncture, tract dilation, and wire manipulation. The success rate of various steps was 100% for needle puncture and tract dilation, 82.35% for wire manipulation, and 80% for stent placement. The mean overall procedure time was 18 minutes.

LIMITATIONS

Small number of participants.

CONCLUSION

The 3D printing bile duct prototype appears suitable for teaching of and training in the various steps of EUS-BD. Further studies are required to elucidate its role.

Endoscopic skull base training using 3D printed models with pre-existing pathology

Endoscopic base of skull surgery has been growing in acceptance in the recent past due to improvements in visualisation and micro instrumentation as well as the surgical maturing of early endoscopic skull base practitioners. Unfortunately, these demanding procedures have a steep learning curve. A physical simulation that is able to reproduce the complex anatomy of the anterior skull base provides very useful means of learning the necessary skills in a safe and effective environment. This paper aims to assess the ease of learning endoscopic skull base exposure and drilling techniques using an anatomically accurate physical model with a pre-existing pathology (i.e., basilar invagination) created from actual patient data. Five models of a patient with platy-basia and basilar invagination were created from the original MRI and CT imaging data of a patient. The models were used as part of a training workshop for ENT surgeons with varying degrees of experience in endoscopic base of skull surgery, from trainees to experienced consultants. The surgeons were given a list of key steps to achieve in exposing and drilling the skull base using the simulation model. They were then asked to list the level of difficulty of learning these steps using the model. The participants found the models suitable for learning registration, navigation and skull base drilling techniques. All participants also found the deep structures to be accurately represented spatially as confirmed by the navigation system. These models allow structured simulation to be conducted in a workshop environment where surgeons and trainees can practice to perform complex procedures in a controlled fashion under the supervision of experts.