Cerebrovascular biomodelling: a technical note

3-D Printed Fracture Models Improve Resident Performance and Clinical Outcomes in Operative Fracture Management

OBJECTIVE

To determine if preoperative examination of patient additive manufactured (AM) fracture models can be used to improve resident operative competency and patient outcomes.

DESIGN

Prospective cohort study. Seventeen matched pairs of fracture fixation surgeries (for a total of 34 surgeries) were performed. Residents first performed a set of baseline surgeries (n = 17) without AM fracture models. The residents then performed a second set of surgeries randomly assigned to include an AM model (n = 11) or to omit it (n = 6). Following each surgery, the attending surgeon evaluated the resident using an Ottawa Surgical Competency Operating Room Evaluation (O-Score). The authors also recorded clinical outcomes including operative time, blood loss, fluoroscopy duration, and patient reported outcome measurement information system (PROMIS) scores of pain and function at 6 months.

SETTING

Single-center academic level one trauma center.

PARTICIPANTS

Twelve orthopaedic residents, between postgraduate year (PGY) 2 and 5, participated in this study.

RESULTS

Residents significantly improved their O-Scores between the first and second surgery when they trained with AM models for the second surgery (p = 0.004, 2.43 ± 0.79 versus 3.73 ± 0.64). Similar improvements were not observed in the control group (p = 0.916, 2.69 ± 0.69 versus 2.77 ± 0.36). AM model training also significantly improved clinical outcomes, including surgery time (p = 0.006), fluoroscopy exposure time (p = 0.002), and patient reported functional outcomes (p = 0.0006).

CONCLUSIONS

Conclusions: Training with AM fracture models improves the performance of orthopaedic surgery residents during fracture surgery.

A Review of the Benefits 3D Printing Brings to Patients with Neurological Diseases

This interdisciplinary review focuses on how flexible three-dimensional printing (3DP) technology can aid patients with neurological diseases. It covers a wide variety of current and possible applications ranging from neurosurgery to customizable polypill along with a brief description of the various 3DP techniques. The article goes into detail about how 3DP technology can aid delicate neurosurgical planning and its consequent outcome for patients. It also covers areas such as how the 3DP model can be utilized in patient counseling along with designing specific implants involved in cranioplasty and customization of a specialized instrument such as 3DP optogenetic probes. Furthermore, the review includes how a 3DP nasal cast can contribute to the development of nose-to-brain drug delivery along with looking into how bioprinting could be used for regenerating nerves and how 3D-printed drugs could offer practical benefits to patients suffering from neurological diseases via polypill.

Investigation of the Use of Hollow Elastic Biomodels Produced by Additive Manufacturing for Clip Choice and Surgical Simulation in Microsurgery for Intracranial Aneurysms

BACKGROUND

Intracranial aneurysms (IAs) are dilatations of the cerebral arteries, whose treatment is commonly based on the implant of a metallic clip on the aneurysm neck. Despite the dissection and understanding of the surgical anatomy of the IA when often only parts of it are visible, the choice of the ideal clip to be used is one of the surgical difficulties. Although current imaging tests guarantee IA visualization, currently there is no planning method that allows for a real three-dimensional (3D) visualization for optimal choice of clip prior to surgery. The aim of this study is to evaluate whether IA biomodels generated by additive manufacturing methods are useful for surgical clip selection in microsurgeries for IA.

METHODS

Three-dimensional (3D) IA biomodels of 10 patients with IA were evaluated using computerized tomography, surgical microscope, and 3D printer. The research was divided into 4 phases as follows: development of the 3D biomodels, evaluation of the biomodel dimensional characteristics, surgical planning evaluation with the biomodel and its clipping effectiveness, and evaluation of the actual surgical simulation process within the models.

RESULTS

Ten 3D biomodels were obtained, made of a malleable and hollow part, formed by the IA and related arteries, and another rigid part, mimicking the skull and other arteries of the skull base. Based on these 3D models, 10 clips were chosen during the surgical planning, and all exactly matched the clip characteristics used during the actual surgeries. The surgical simulation with the biomodels performed by 2 neurosurgeons still in training obtained 100% accuracy in the identification of the clips that were eventually used during the actual surgeries.

CONCLUSIONS

3D biomodels generated by additive manufacturing methods were effective for surgical clip selection in microsurgeries for IA, reducing surgical time, increasing cerebral angioarchitecture understanding, and providing more safety in this type of surgery.

Handmade models for aneurysm surgery: A useful tool for training

Background

Aneurysm surgery is considered difficult by young and trainee neurosurgeons. This is due to difficulty in understanding orientation of aneurysm complex (proximal and distal vessels, aneurysm neck, and fundus) in relation to the surrounding structures (skull, brain, vessels, and nerves) after head is rotated, extended, and fixed on the head frame. Virtual three-dimensional (3D) imaging studies and 3D-printed models help young neurosurgeons but are not accessible to most of the centers due to need for resources (human and equipment). Authors used handmade 3D models of aneurysm complex to train young neurosurgeons before and during surgery to make them understand steps to treat it.

Methods

RadiAnt DICOM viewer software (2022.1.1, 64-bit, Medixant, Poznan, Poland) was used for acquiring 3D Volume Rendering Technique images to make aneurysm models preoperatively. Twisted 20 Gauze galvanized iron wires were used for making proximal and distal branches and Epoxy Putty (M-seal, Pidilite ^® industries, Mumbai, India) was used to make smooth surfaces of the vessels, aneurysm necks, and fundi. Models were used in operating room (OR) before and during surgery to help surgeons and trainees get oriented to the aneurysm complexes.

Results

Handmade models, oriented as per patients' head position, were useful to make surgeons and trainees to understand projection of various components of the aneurysm complex in relation to adjacent structures, especially skull base, during both preoperative planning and in OR even before completion of the dissection.

Conclusion

Handmade models of aneurysms are inexpensive tool and can help trainee neurosurgeons to plan and execute surgical management of aneurysms.

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.

Advanced Manufacturing in the Fabrication of a Lifelike Brain Glioblastoma Simulator for the Training of Neurosurgeons

Neurosurgeons require considerable expertise and practical experience to deal with the critical situations commonly encountered in complex surgical operations such as cerebral cancer; however, trainees in neurosurgery seldom have the opportunity to develop these skills in the operating room. Physical simulators can give trainees the experience they require. In this study, we adopted advanced molding and replication techniques in the fabrication of a physical simulator for use in practicing the removal of cerebral tumors. Our combination of additive manufacturing and molding technology with elastic material casting made it possible to create a simulator that realistically mimics the skull, brain stem, soft brain lobes, and cerebral cancer with cerebral tumors located precisely where they are likely to appear. Multiple and systematic experiments were conducted to prove that the elastic material used herein was appropriated for building professional medical physical simulator. One neurosurgical trainee reported that under the guidance of a senior neurosurgeon, the physical simulator helped to elucidate the overall process of cerebral cancer removal and provided a realistic impression of the tactile feelings involved in craniotomy. The trainee also learned how to make decisions when facing the infiltration of a cerebral tumor into normal brain lobes. Our results demonstrate the efficacy of the proposed physical simulator in preparing trainees for the rigors involved in performing highly delicate surgical operations.

Additive Manufacturing for Neurosurgery: Digital Light Processing of Individualized Patient-Specific Cerebral Aneurysms

This study aims at demonstrating the feasibility of reproducing individualized patient-specific three-dimensional models of cerebral aneurysms by using the direct light processing (DLP) 3D printing technique in a low-time and inexpensive way. Such models were used to help neurosurgeons understand the anatomy of the aneurysms together with the surrounding vessels and their relationships, providing, therefore, a tangible supporting tool with which to train and plan surgical operations. The starting 3D models were obtained by processing the computed tomography angiographies and the digital subtraction angiographies of three patients. Then, a 3D DLP printer was used to print the models, and, if acceptable, on the basis of the neurosurgeon’s opinion, they were used for the planning of the neurosurgery operation and patient information. All the models were printed within three hours, providing a comprehensive representation of the cerebral aneurysms and the surrounding structures and improving the understanding of their anatomy and simplifying the planning of the surgical operation.

3D Printing of Physical Organ Models: Recent Developments and Challenges

Physical organ models are the objects that replicate the patient-specific anatomy and have played important roles in modern medical diagnosis and disease treatment. 3D printing, as a powerful multi-function manufacturing technology, breaks the limitations of traditional methods and provides a great potential for manufacturing organ models. However, the clinical application of organ model is still in small scale, facing the challenges including high cost, poor mimicking performance and insufficient accuracy. In this review, the mainstream 3D printing technologies are introduced, and the existing manufacturing methods are divided into "directly printing" and "indirectly printing", with an emphasis on choosing suitable techniques and materials. This review also summarizes the ideas to address these challenges and focuses on three points: 1) what are the characteristics and requirements of organ models in different application scenarios, 2) how to choose the suitable 3D printing methods and materials according to different application categories, and 3) how to reduce the cost of organ models and make the process simple and convenient. Moreover, the state-of-the-art in organ models are summarized and the contribution of 3D printed organ models to various surgical procedures is highlighted. Finally, current limitations, evaluation criteria and future perspectives for this emerging area are discussed.

Three-Dimensional Modeling in Training, Simulation, and Surgical Planning in Open Vascular and Endovascular Neurosurgery: A Systematic Review of the Literature

BACKGROUND

The expanding use of three-dimensional (3D) printing in open vascular and endovascular neurosurgery presents a promising new tool in resident learning as well as operative planning. Recent studies have investigated the accuracy, efficacy, and practicality of 3D-printed models of patient-specific disease.

OBJECTIVE

To review the literature exploring 3D modeling in neurovascular and endovascular surgery for training, simulation, and surgical preparation.

METHODS

A systematic search of the PubMed database was conducted using keywords relating to 3D printing and neurovascular or endovascular surgery. Articles were manually screened to include those that focused on resident training, surgical simulation, or preoperative planning. Information on fabrication method, materials, cost, and validation measures was collected.

RESULTS

A total of 27 articles were identified that met inclusion criteria. Twenty-one studies used 3D printing to produce aneurysm models, 5 produced arteriovenous malformation models, and 1 produced aneurysm and arteriovenous malformation models. Stereolithography was the most common fabrication method used, with acrylonitrile butadiene styrene and VeroClearTangoPlus (Stratasys) being the most frequently used materials. The mean manufacturing cost per model was U.S. $624.83. Outcomes included model measurement accuracy, concordance of intraoperative devices with those selected preoperatively, and qualitative feedback.

CONCLUSIONS

Models generated by 3D printing are anatomically accurate and aid in resident learning as well as operative planning in open vascular and endovascular neurosurgery. As advancements in printing methods are made and manufacturing costs decrease, this tool may supplement training on a wider scale in a field in which direct exposure to cases is limited.

Patient-specific implants for craniomaxillofacial surgery: A manufacturer's experience

Additive manufacturing technologies have enabled the development of customised implants for craniomaxillofacial applications using biomaterials such as polymethylmethacrylate (PMMA), porous high-density polyethylene (pHDPE), and titanium mesh. This study aims to report an Australian manufacturer's experience in developing, designing and supplying patient-specific craniomaxillofacial implants over 23 years and summarise feedback received from clinicians. The authors conducted a retrospective review of the manufacturer's implant database of orders placed for custom craniomaxillofacial implants between 1996 and 2019. The variables collected included material, country of order, gender, patient age, and reported complications, which included a measure of custom implant "fit" and adverse events. The development of critical checkpoints in the custom manufacturing process that minimise clinical or logistical non-conformities is highlighted and discussed. A total of 4120 patient-specific implants were supplied, of which 2689 were manufactured from PMMA, 885 from titanium mesh, and 546 from pHDPE. The majority of the implants were used in Australia (2260), United Kingdom (412), Germany (377), and New Zealand (338). PMMA was the preferred material for cranial implants whereas pHDPE was preferred for maxillofacial applications. Age or gender did not influence the material choice. Implant "fit" and adverse outcomes were used as a metric of implant performance. Between 2007 and 2019 there were 37 infections (0.98%) and 164 non-conformities recorded of which 75 (1.8%) were related to implant 'fit'. Our experience demonstrates a safe, reliable, and clinically streamlined manufacturing process which supports surgeons that require bespoke craniomaxillofacial solutions for reconstruction surgery.

Clinical application of 3D virtual and printed models for cerebrovascular diseases

OBJECTIVE

Three-dimensional (3D) printing techniques are rapidly advancing in the medical industry and in clinical practice. We aimed to evaluate the usefulness of 3D virtual and printed models of 6 representative cerebrovascular diseases using the software we developed.

METHODS

Six cases consisted of 4 intracranial aneurysms (IAs) including complex ones with intrasaccular thrombosis, large size and a skull base location; 1 cavernous malformation in the pons; and 1 arteriovenous malformation in the parietal lobe. The 3D modeling process was performed retrospectively in 3 cases and prospectively in 1 IA. Segmentation of raw data and rendering and modification for 3D virtual models were processed mostly automatically.

RESULTS

Most intracranial structures were satisfactorily made, including the skull, brain, vessels, thrombus, tentorium and major cranial nerves. Based on 3D modeling, surgical plan was changed in 1 prospective IA case. However, it was still difficult to discriminate small vessels and cranial nerves, to feel a realistic tactile sense and to directly perform presurgical simulations, such as dissection, removal, clipping and microanastomosis.

CONCLUSIONS

The 3D modeling was thought to be very helpful in experiencing the operative views from various directions in advance, in selecting an appropriate surgical approach, and in educating physicians and patients. With advancements in radiological resolution, processing techniques and material properties, 3D modeling is expected to simulate real brain tissues more closely.

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.

Engineering Additive Manufacturing and Molding Techniques to Create Lifelike Willis' Circle Simulators with Aneurysms for Training Neurosurgeons

Neurosurgeons require considerable expertise and practical experience in dealing with the critical situations commonly encountered during difficult surgeries; however, neurosurgical trainees seldom have the opportunity to develop these skills in the operating room. Therefore, physical simulators are used to give trainees the experience they require. In this study, we created a physical simulator to assist in training neurosurgeons in aneurysm clipping and the handling of emergency situations during surgery. Our combination of additive manufacturing with molding technology, elastic material casting, and ultrasonication-assisted dissolution made it possible to create a simulator that realistically mimics the brain stem, soft brain lobes, cerebral arteries, and a hollow transparent Circle of Willis, in which the thickness of vascular walls can be controlled and aneurysms can be fabricated in locations where they are likely to appear. The proposed fabrication process also made it possible to limit the error in overall vascular wall thickness to just 2–5%, while achieving a Young’s Modulus closely matching the characteristics of blood vessels (~5%). One neurosurgical trainee reported that the physical simulator helped to elucidate the overall process of aneurysm clipping and provided a realistic impression of the tactile feelings involved in this delicate operation. The trainee also experienced shock and dismay at the appearance of leakage, which could not immediately be arrested using the clip. Overall, these results demonstrate the efficacy of the proposed physical simulator in preparing trainees for the rigors involved in performing highly delicate neurological surgical operations.

Measuring the performance of patient-specific solutions for minimally invasive transforaminal lumbar interbody fusion surgery

Pre-surgical planning using 3D-printed BioModels enables the preparation of a "patient-specific" kit to assist instrumented spinal fusion surgery. This approach has the potential to decrease operating time while also offering logistical benefits and cost savings for healthcare. We report our experience with this method in 129 consecutive patients undergoing minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) over 27 months at a single centre and performed by a single surgeon. Patient imaging and surgical planning software were used to manufacture a 3D-printed patient-specific MIS TLIF kit for each patient consisting of a 1:1 scale spine BioModel, stereotactic K-wire guide, osteotomy guide, and retractors. Pre-selected pedicle screws, rods, and cages were sourced and supplied with the patient-specific kit. Additional implants were available on-shelf to address a size discrepancy between the kit implant and intraoperative measurements. Each BioModel was used pre-operatively for surgical planning, patient consent and education. The BioModel was sterilised for intraoperative reference and navigation purposes. Efficiency measures included operating time (153 ± 44 min), sterile tray usage (14 ± 3), fluoroscopy screening time (57.2 ± 23.7 s), operative waste (19 ± 8 L contaminated, 116 ± 30 L uncontaminated), and median hospital stay (4 days). The pre-selected kit implants exactly matched intraoperative measurements for 597/639 pedicle screws, 249/258 rods, and 46/148 cages. Pedicle screw placement accuracy was 97.8% (625/639) on postoperative CT. Complications included one intraoperative dural tear, no blood products administered, and six reoperations. Our experience demonstrates a viable application of patient-specific 3D-printed solutions and provides a benchmark for studies of efficiency in spinal fusion surgery.

Monolithic 3D printing of embeddable and highly stretchable strain sensors using conductive ionogels

Medical training simulations that utilize 3D-printed, patient-specific tissue models improve practitioner and patient understanding of individualized procedures and capacitate pre-operative, patient-specific rehearsals. The impact of these novel constructs in medical training and pre-procedure rehearsals has been limited, however, by the lack of effectively embedded sensors that detect the location, direction, and amplitude of strains applied by the practitioner on the simulated structures. The monolithic fabrication of strain sensors embedded into lifelike tissue models with customizable orientation and placement could address this limitation. The demonstration of 3D printing of an ionogel as a stretchable, piezoresistive strain sensor embedded in an elastomer is presented as a proof-of-concept of this integrated fabrication for the first time. The significant hysteresis and drift inherent to solid-phase piezoresistive composites and the dimensional instability of low-hysteresis piezoresistive liquids inspired the adoption of a 3D-printable piezoresistive ionogel composed of reduced graphene oxide and an ionic liquid. The shear-thinning rheology of the ionogel obviates the need to fabricate additional structures that define or contain the geometry of the sensing channel. Sensors are printed on and subsequently encapsulated in polydimethylsiloxane (PDMS), a thermoset elastomer commonly used for analog tissue models, to demonstrate seamless fabrication. Strain sensors demonstrate geometry- and strain-dependent gauge factors of 0.54-2.41, a high dynamic strain range of 350% that surpasses the failure strain of most dermal and viscus tissue, low hysteresis (<3.5% degree of hysteresis up to 300% strain) and baseline drift, a single-value response, and excellent fatigue stability (5000 stretching cycles). In addition, we fabricate sensors with stencil-printed silver/PDMS electrodes in place of wires to highlight the potential of seamless integration with printed electrodes. The compositional tunability of ionic liquid/graphene-based composites and the shear-thinning rheology of this class of conductive gels endows an expansive combination of customized sensor geometry and performance that can be tailored to patient-specific, high-fidelity, monolithically fabricated tissue models.

In vivo cerebral aneurysm models

Cerebral aneurysm rupture is a devastating event resulting in subarachnoid hemorrhage and is associated with significant morbidity and death. Up to 50% of individuals do not survive aneurysm rupture, with the majority of survivors suffering some degree of neurological deficit. Therefore, prior to aneurysm rupture, a large number of diagnosed patients are treated either microsurgically via clipping or endovascularly to prevent aneurysm filling. With the advancement of endovascular surgical techniques and devices, endovascular treatment of cerebral aneurysms is becoming the first-line therapy at many hospitals. Despite this fact, a large number of endovascularly treated patients will have aneurysm recanalization and progression and will require retreatment. The lack of approved pharmacological interventions for cerebral aneurysms and the need for retreatment have led to a growing interest in understanding the molecular, cellular, and physiological determinants of cerebral aneurysm pathogenesis, maturation, and rupture. To this end, the use of animal cerebral aneurysm models has contributed significantly to our current understanding of cerebral aneurysm biology and to the development of and training in endovascular devices. This review summarizes the small and large animal models of cerebral aneurysm that are being used to explore the pathophysiology of cerebral aneurysms, as well as the development of novel endovascular devices for aneurysm treatment.

Surgical Training for the Management of Intraoperative Aneurysm Rupture Using a Three-Dimensional Artificial Model

Background

Intraoperative aneurysm rupture (IAR) is one of the most dreaded complications of microsurgical cerebral aneurysm clipping. The surgical result is directly affected by whether an operator can control IAR. However, the development of endovascular treatment has decreased the probability of exposure to this situation for neurosurgical residents. Therefore, neurovascular surgeons must develop the skills and mental attitude to deal with IAR through off-the-job training, without conducting actual operations.

Materials and Methods

We have developed a tabletop training system using three-dimensional artificial modeling that can be used for daily clinical practice.

Results and Conclusions

Our model is useful for training because of its low cost, reusability, and ease of preparation and practice.

Virtual, 3-Dimensional Temporal Bone Model and Its Educational Value for Neurosurgical Trainees

OBJECTIVE

Learning complex neuroanatomy is an arduous yet important task for every neurosurgical trainee. As technology has advanced, various modalities have been created to aid our understanding of anatomy. This study sought to assess the educational value of a virtual, 3-dimensional (3D) temporal bone model.

METHODS

The 3D temporal bone model was created with assistance of computer graphic designers and published online. Its educational value as a teaching was tool was assessed by querying 73 neurosurgery residents at 4 institutions and was compared with that of a standard, 2-dimensional (2D) temporal bone resource. Data were collected via a survey, and significance among responses was analyzed via a univariate chi-square test.

RESULTS

The survey response rate was 37%. Greater than 90% of residents preferred to study with the 3D model compared with the 2D resource and felt that the 3D model allowed them understand the anatomy more realistically (P = 0.001). Moreover, >90% of residents believed that reviewing the 3D model before an actual surgery could lead to improved operative efficiency and safety (P = 0.001).

CONCLUSIONS

This study demonstrates the utility of a novel, 3D temporal bone model as a teaching tool for neurosurgery residents. The model contains accurate anatomic structures and allows user interaction via a virtual, immersive environment.

Three-dimensional intracranial middle cerebral artery aneurysm models for aneurysm surgery and training

To develop a realistic model of middle cerebral artery (MCA) aneurysms using three-dimensional (3D) printing for surgical planning, research, and training of neurosurgical residents. This study included eight MCA aneurysm cases. The aneurysm together with the adjacent arteries and skull base were printed based on raw computed tomography angiography (CTA) data using a 3D printer with acrylonitrile-butadiene-styrene as the model material. The aneurysm models were used for surgical planning, and craniotomy and clipping practice by neurosurgical residents. Feedback was obtained using a survey. 3D aneurysm models were created for all seven MCA aneurysm patients. There was good agreement in the model aneurysm diameter, width, and neck and the CTA data, with no significant difference (p > 0.05) among the groups. The simulator was useful for choosing the clips to use before surgery. The average response to each of the survey questions was greater than 3.85 (range 3.0-5.0) on a five-point scale. The 3D printed MCA aneurysm models were accurate. Simulation and practice using the 3D models was useful for understanding the aneurysm structure and choosing the clips to use before surgery, especially for junior neurosurgeons.

Three-dimensional brain arteriovenous malformation models for clinical use and resident training

BACKGROUND

To fabricate three-dimensional (3D) models of brain arteriovenous malformation (bAVM) and report our experience with customized 3D printed models of patients with bAVM as an educational and clinical tool for patients, doctors, and surgical residents.

METHODS

Using computerized tomography angiography (CTA) or digital subtraction angiography (DSA) images, the rapid prototyping process was completed with specialized software and "in-house" 3D printing service. Intraoperative validation of model fidelity was performed by comparing to DSA images of the same patient during the endovascular treatment process. 3D bAVM models were used for preoperative patient education and consultation, surgical planning, and resident training.

RESULTS

3D printed bAVM models were successful made. By neurosurgeons' evaluation, the printed models precisely replicated the actual bAVM structure of the same patients (n = 7, 97% concordance, range 95%-99% with average of < 2 mm variation). The use of 3D models was associated shorter time for preoperative patient education and consultation, higher acceptable of the procedure for patients and relatives, shorter time between obtaining intraoperative DSA data and the start of endovascular treatment. Thirty surgical residents from residency programs tested the bAVM models and provided feedback on their resemblance to real bAVM structures and the usefulness of printed solid model as an educational tool.

CONCLUSIONS

Patient-specific 3D printed models of bAVM can be constructed with high fidelity. 3D printed bAVM models were proven to be helpful in preoperative patient consultation, surgical planning, and resident training.

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: technologies, applications, and limitations in neurosurgery

Three-dimensional (3D) printers are a developing technology penetrating a variety of markets, including the medical sector. Since its introduction to the medical field in the late 1980s, 3D printers have constructed a range of devices, such as dentures, hearing aids, and prosthetics. With the ultimate goals of decreasing healthcare costs and improving patient care and outcomes, neurosurgeons are utilizing this dynamic technology, as well. Digital Imaging and Communication in Medicine (DICOM) can be translated into Stereolithography (STL) files, which are then read and methodically built by 3D Printers. Vessels, tumors, and skulls are just a few of the anatomical structures created in a variety of materials, which enable surgeons to conduct research, educate surgeons in training, and improve pre-operative planning without risk to patients. Due to the infancy of the field and a wide range of technologies with varying advantages and disadvantages, there is currently no standard 3D printing process for patient care and medical research. In an effort to enable clinicians to optimize the use of additive manufacturing (AM) technologies, we outline the most suitable 3D printing models and computer-aided design (CAD) software for 3D printing in neurosurgery, their applications, and the limitations that need to be overcome if 3D printers are to become common practice in the neurosurgical field.

Fabrication of cerebral aneurysm simulator with a desktop 3D printer

Now, more and more patients are suffering cerebral aneurysm. However, long training time limits the rapid growth of cerebrovascular neurosurgeons. Here we developed a novel cerebral aneurysm simulator which can be better represented the dynamic bulging process of cerebral aneurysm The proposed simulator features the integration of a hollow elastic vascular model, a skull model and a brain model, which can be affordably fabricated at the clinic (Fab@Clinic), under $25.00 each with the help of a low-cost desktop 3D printer. Moreover, the clinical blood flow and pulsation pressure similar to the human can be well simulated, which can be used to train the neurosurgical residents how to clip aneurysms more effectively.

A systematic review of 3-D printing in cardiovascular and cerebrovascular diseases

Objective:

The application of 3-D printing has been increasingly used in medicine, with research showing many applications in cardiovascular disease. This systematic review analyzes those studies published about the applications of 3-D printed, patient-specific models in cardiovascular and cerebrovascular diseases.

Methods:

A search of PubMed/Medline and Scopus databases was performed to identify studies investigating the 3-D printing in cardiovascular and cerebrovascular diseases. Only studies based on patient’s medical images were eligible for review, while reports on in vitro phantom or review articles were excluded.

Results:

A total of 48 studies met selection criteria for inclusion in the review. A range of patient-specific 3-D printed models of different cardiovascular and cerebrovascular diseases were generated in these studies with most of them being developed using cardiac CT and MRI data, less commonly with 3-D invasive angiographic or echocardiographic images. The review of these studies showed high accuracy of 3-D printed, patient-specific models to represent complex anatomy of the cardiovascular and cerebrovascular system and depict various abnormalities, especially congenital heart diseases and valvular pathologies. Further, 3-D printing can serve as a useful education tool for both parents and clinicians, and a valuable tool for pre-surgical planning and simulation.

Conclusion:

This systematic review shows that 3-D printed models based on medical imaging modalities can accurately replicate complex anatomical structures and pathologies of the cardiovascular and cerebrovascular system. 3-D printing is a useful tool for both education and surgical planning in these diseases.

3D-printing techniques in a medical setting: a systematic literature review

BACKGROUND

Three-dimensional (3D) printing has numerous applications and has gained much interest in the medical world. The constantly improving quality of 3D-printing applications has contributed to their increased use on patients. This paper summarizes the literature on surgical 3D-printing applications used on patients, with a focus on reported clinical and economic outcomes.

METHODS

Three major literature databases were screened for case series (more than three cases described in the same study) and trials of surgical applications of 3D printing in humans.

RESULTS

227 surgical papers were analyzed and summarized using an evidence table. The papers described the use of 3D printing for surgical guides, anatomical models, and custom implants. 3D printing is used in multiple surgical domains, such as orthopedics, maxillofacial surgery, cranial surgery, and spinal surgery. In general, the advantages of 3D-printed parts are said to include reduced surgical time, improved medical outcome, and decreased radiation exposure. The costs of printing and additional scans generally increase the overall cost of the procedure.

CONCLUSION

3D printing is well integrated in surgical practice and research. Applications vary from anatomical models mainly intended for surgical planning to surgical guides and implants. Our research suggests that there are several advantages to 3D-printed applications, but that further research is needed to determine whether the increased intervention costs can be balanced with the observable advantages of this new technology. There is a need for a formal cost-effectiveness analysis.

Stereolithographic models in the interdisciplinary planning of treatment for complex intracranial aneurysms

BACKGROUND

Treatment of complex intracranial aneurysms requires strategic pre-interventional or preoperative planning. In addition to modern three-dimensional (3D) rotational angiography, computed tomography angiography (CTA) or magnetic resonance angiogram (MRA), a solid, tangible 3D model may improve anatomical comprehension and treatment planning. A 3D rapid prototyping (RP) technique based on multimodal imaging data was evaluated for use in planning of treatment for complex aneurysmal configurations.

METHODS

Six patients with complex aneurysms were selected for 3D RP based on CTA and 3D rotational angiography data. Images were segmented using image-processing software to create virtual 3D models. Three-dimensional rapid prototyping techniques transformed the imaging data into physical 3D models, which were used and evaluated for interdisciplinary treatment planning.

RESULTS

In all cases, the model provided a comprehensive 3D representation of relevant anatomical structures and improved understanding of related vessels. Based on the 3D model, primary bypass surgery with subsequent reconstruction of the aneurysm was then considered advantageous in all but one patient after simulation of multiple approaches.

CONCLUSIONS

Preoperative prediction of intraoperative anatomy using the 3D model was considered helpful for treatment planning. The use of 3D rapid prototyping may enhance understanding of complex configurations in selected large or giant aneurysms, especially those pretreated with clips or coils.

Cerebral Aneurysm Clipping Surgery Simulation Using Patient-Specific 3D Printing and Silicone Casting

BACKGROUND

Neurosurgery simulator development is growing as practitioners recognize the need for improved instructional and rehearsal platforms to improve procedural skills and patient care. In addition, changes in practice patterns have decreased the volume of specific cases, such as aneurysm clippings, which reduces the opportunity for operating room experience.

OBJECTIVE

The authors developed a hands-on, dimensionally accurate model for aneurysm clipping using patient-derived anatomic data and three-dimensional (3D) printing. Design of the model focused on reproducibility as well as adaptability to new patient geometry.

METHODS

A modular, reproducible, and patient-derived medical simulacrum was developed for medical learners to practice aneurysmal clipping procedures. Various forms of 3D printing were used to develop a geometrically accurate cranium and vascular tree featuring 9 patient-derived aneurysms. 3D printing in conjunction with elastomeric casting was leveraged to achieve a patient-derived brain model with tactile properties not yet available from commercial 3D printing technology. An educational pilot study was performed to gauge simulation efficacy.

RESULTS

Through the novel manufacturing process, a patient-derived simulacrum was developed for neurovascular surgical simulation. A follow-up qualitative study suggests potential to enhance current educational programs; assessments support the efficacy of the simulacrum.

CONCLUSIONS

The proposed aneurysm clipping simulator has the potential to improve learning experiences in surgical environment. 3D printing and elastomeric casting can produce patient-derived models for a dynamic learning environment that add value to surgical training and preparation.

Review of 3-Dimensional Printing on Cranial Neurosurgery Simulation Training

OBJECTIVE

Shorter working times, reduced operative exposure to complex procedures, and increased subspecialization have resulted in training constraints within most surgical fields. Simulation has been suggested as a possible means of acquiring new surgical skills without exposing patients to the surgeon's operative "learning curve." Here we review the potential impact of 3-dimensional printing on simulation and training within cranial neurosurgery and its implications for the future.

METHODS

In accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, a comprehensive search of PubMed, OVID MEDLINE, Embase, and the Cochrane Database of Systematic Reviews was performed.

RESULTS

In total, 31 studies relating to the use of 3-dimensional (3D) printing within neurosurgery, of which 16 were specifically related to simulation and training, were identified. The main impact of 3D printing on neurosurgical simulation training was within vascular surgery, where patient-specific replication of vascular anatomy and pathologies can aid surgeons in operative planning and clip placement for reconstruction of vascular anatomy. Models containing replicas of brain tumors have also been reconstructed and used for training purposes, with some providing realistic representations of skin, subcutaneous tissue, bone, dura, normal brain, and tumor tissue.

CONCLUSION

3D printing provides a unique means of directly replicating patient-specific pathologies. It can identify anatomic variation and provide a medium in which training models can be generated rapidly, allowing the trainee and experienced neurosurgeon to practice parts of operations preoperatively. Future studies are required to validate this technology in comparison with current simulators and show improved patient outcomes.

Implantation of 3D-Printed Patient-Specific Aneurysm Models into Cadaveric Specimens: A New Training Paradigm to Allow for Improvements in Cerebrovascular Surgery and Research

Aim. To evaluate the feasibility of implanting 3D-printed brain aneurysm model in human cadavers and to assess their utility in neurosurgical research, complex case management/planning, and operative training. Methods. Two 3D-printed aneurysm models, basilar apex and middle cerebral artery, were generated and implanted in four cadaveric specimens. The aneurysms were implanted at the same anatomical region as the modeled patient. Pterional and orbitozygomatic approaches were done on each specimen. The aneurysm implant, manipulation capabilities, and surgical clipping were evaluated. Results. The 3D aneurysm models were successfully implanted to the cadaveric specimens' arterial circulation in all cases. The features of the neck in terms of flexibility and its relationship with other arterial branches allowed for the practice of surgical maneuvering characteristic to aneurysm clipping. Furthermore, the relationship of the aneurysm dome with the surrounding structures allowed for better understanding of the aneurysmal local mass effect. Noticeably, all of these observations were done in a realistic environment provided by our customized embalming model for neurosurgical simulation. Conclusion. 3D aneurysms models implanted in cadaveric specimens may represent an untapped training method for replicating clip technique; for practicing certain approaches to aneurysms specific to a particular patient; and for improving neurosurgical research.

Virtual reality cerebral aneurysm clipping simulation with real-time haptic feedback

BACKGROUND

With the decrease in the number of cerebral aneurysms treated surgically and the increase of complexity of those treated surgically, there is a need for simulation-based tools to teach future neurosurgeons the operative techniques of aneurysm clipping.

OBJECTIVE

To develop and evaluate the usefulness of a new haptic-based virtual reality simulator in the training of neurosurgical residents.

METHODS

A real-time sensory haptic feedback virtual reality aneurysm clipping simulator was developed using the ImmersiveTouch platform. A prototype middle cerebral artery aneurysm simulation was created from a computed tomographic angiogram. Aneurysm and vessel volume deformation and haptic feedback are provided in a 3-dimensional immersive virtual reality environment. Intraoperative aneurysm rupture was also simulated. Seventeen neurosurgery residents from 3 residency programs tested the simulator and provided feedback on its usefulness and resemblance to real aneurysm clipping surgery.

RESULTS

Residents thought that the simulation would be useful in preparing for real-life surgery. About two-thirds of the residents thought that the 3-dimensional immersive anatomic details provided a close resemblance to real operative anatomy and accurate guidance for deciding surgical approaches. They thought the simulation was useful for preoperative surgical rehearsal and neurosurgical training. A third of the residents thought that the technology in its current form provided realistic haptic feedback for aneurysm surgery.

CONCLUSION

Neurosurgical residents thought that the novel immersive VR simulator is helpful in their training, especially because they do not get a chance to perform aneurysm clippings until late in their residency programs.

Three-dimensional printing of anatomically accurate, patient specific intracranial aneurysm models

OBJECTIVE

To develop and validate a method for creating realistic, patient specific replicas of cerebral aneurysms by means of fused deposition modeling.

METHODS

The luminal boundaries of 10 cerebral aneurysms, together with adjacent proximal and distal sections of the parent artery, were segmented based on DSA images, and corresponding virtual three-dimensional (3D) surface reconstructions were created. From these, polylactic acid and MakerBot Flexible Filament replicas of each aneurysm were created by means of fused deposition modeling. The accuracy of the replicas was assessed by quantifying statistical significance in the variations of their inner dimensions relative to 3D DSA images. Feasibility for using these replicas as flow phantoms in combination with phase contrast MRI was demonstrated.

RESULTS

3D printed aneurysm models were created for all 10 subjects. Good agreement was seen between the models and the source anatomy. Aneurysm diameter measurements of the printed models and source images correlated well (r=0.999; p<0.001), with no statistically significant group difference (p=0.4) or observed bias. The SDs of the measurements were 0.5 mm and 0.2 mm for source images and 3D models, respectively. 3D printed models could be imaged with flow via MRI.

CONCLUSIONS

The 3D printed aneurysm models presented were accurate and were able to be produced inhouse. These models can be used for previously cited applications, but their anatomical accuracy also enables their use as MRI flow phantoms for comparison with ongoing studies of computational fluid dynamics. Proof of principle imaging experiments confirm MRI flow phantom utility.

Rapid prototyping of three-dimensional biomodels as an adjuvant in the surgical planning for intracranial aneurysms

PURPOSE

To fabricate a three-dimensional biomodels of intracranial aneurysms, using rapid prototyping technology, to facilitate optimal anatomical visualization of aneurysms prior to and during surgery.

METHODS

Four intracranial aneurysms cases were selected for this study. Using CT angiography images, the rapid prototyping process was completed using a PolyJet technology machine. The size and morphology of the prototypes were compared to brain digital subtraction arteriography of the same patients.

RESULTS

The biomodels reproduced the exact location and morphology of the intracranial aneurysms, particularly the necks, in life-size dimensions and exactly the same as measured by digital subtraction arteriography. The arterial segments adjacent to the aneurysm and arteries anatomically known by the surgeon were also shown, which could guide the surgeon to the aneurysmal segment. The models showed an average unit cost of US$ 130 and each one took an average of 20 hours to be fabricated.

CONCLUSIONS

It is possible to fabricate 3D physical biomodels of intracranial aneurysms from CT angiography images. These prototypes may be useful in the surgical planning for intracranial aneurysms to clarify the anatomy, define surgical techniques and facilitate the choice of suitable materials, such as clips and clip appliers.

Prototyping of cerebral vasculature physical models

Background:

Prototyping of cerebral vasculature models through stereolithographic methods have the ability to accurately depict the 3D structures of complicated aneurysms with high accuracy. We describe the method to manufacture such a model and review some of its uses in the context of treatment planning, research, and surgical training.

Methods:

We prospectively used the data from the rotational angiography of a 40-year-old female who presented with an unruptured right paraclinoid aneurysm. The 3D virtual model was then converted to a physical life-sized model.

Results:

The model constructed was shown to be a very accurate depiction of the aneurysm and its associated vasculature. It was found to be useful, among other things, for surgical training and as a patient education tool.

Conclusion:

With improving and more widespread printing options, these models have the potential to become an important part of research and training modalities.

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

The advent of multimaterial 3D printers allows the creation of neurosurgical models of a more realistic nature, mimicking real tissues. The authors used the latest generation of 3D printer to create a model, with an inbuilt pathological entity, of varying consistency and density. Using this model the authors were able to take trainees through the basic steps, from navigation and planning of skin flap to performing initial steps in a craniotomy and simple tumor excision. As the technology advances, models of this nature may be able to supplement the training of neurosurgeons in a simulated operating theater environment, thus improving the training experience.

Development of three-dimensional hollow elastic model for cerebral aneurysm clipping simulation enabling rapid and low cost prototyping

OBJECTIVE

We developed a method for fabricating a three-dimensional hollow and elastic aneurysm model useful for surgical simulation and surgical training. In this article, we explain the hollow elastic model prototyping method and report on the effects of applying it to presurgical simulation and surgical training.

METHODS

A three-dimensional printer using acrylonitrile-butadiene-styrene as a modeling material was used to produce a vessel model. The prototype was then coated with liquid silicone. After the silicone had hardened, the acrylonitrile-butadiene-styrene was melted with xylene and removed, leaving an outer layer as a hollow elastic model.

RESULTS

Simulations using the hollow elastic model were performed in 12 patients. In all patients, the clipping proceeded as scheduled. The surgeon's postoperative assessment was favorable in all cases. This method enables easy fabrication at low cost.

CONCLUSION

Simulation using the hollow elastic model is thought to be useful for understanding of three-dimensional aneurysm structure.

Fabrication and Design of Customized Maxillofacial Biomodel for Implant Using Computer Aided Design and Rapid Prototyping Technique

The purpose of this research is to fabricate bio-model that based on Rapid Prototyping technology which is by using Fused Deposition Modeling (FDM) and designing an implant by using a Computer Aided Design technology. A case study from Hospital Kuala Lumpur which is the maxillofacial will be fabricated by using FDM technique. The completed 3D prototype or biomodel will be analyzed to makes the result more truthful in terms of the dimensional accuracy, operational error and cost analysis. Computer aided design technology is used to design the customized implant in order to replace the fractured maxilla part.

Cerebrovascular biomodeling for aneurysm surgery: simulation-based training by means of rapid prototyping technologies

OBJECTIVE

Opportunities for developing procedural skills are progressively rare. Therefore, sophisticated educational tools are highly warranted.

METHODS

This study compared stereolithography and 3-dimensional printing for simulating cerebral aneurysm surgery. The latter jets multiple materials simultaneously and thus has the ability to print assemblies of multiple materials with different features. The authors created the solid skull and the cerebral vessels in different materials to simulate the real aneurysm when clipped.

RESULTS

Precise plastic replicas of complex anatomical data provide intuitive tactile views that can be scrutinized from any perspective. Hollowed out vessel sections allow serial clipping efforts, evaluation of different clips, and clip positions. The models can be used for accurate prediction of vascular anatomy, for optimization of teaching surgical skills, for advanced procedural competency training, and for patient counseling.

CONCLUSION

Simultaneous 3-dimensional printing is the most promising rapid prototyping technique to produce biomodels that meet the high demands of neurovascular surgery.

Simulation of and training for cerebral aneurysm clipping with 3-dimensional models

OBJECTIVE

With improvements in endovascular techniques, fewer aneurysms are treated by surgical clipping, and those aneurysms targeted for open surgery are often complex and difficult to treat. We devised a hollow, 3-dimensional (3D) model of individual cerebral aneurysms for preoperative simulation and surgical training. The methods and initial experience with this model system are presented.

METHODS

The 3D hollow aneurysm models of 3 retrospective and 8 prospective cases were made with a prototyping technique according to data from 3D computed tomographic angiograms of each patient. Commercially available titanium clips used in our routine surgery were applied, and the internal lumen was observed with an endoscope to confirm the patency of parent vessels. The actual surgery was performed later.

RESULTS

In the 8 prospective cases, the clips were applied during surgery in the same direction and configuration as in the preoperative simulation. Fine adjustments were necessary in each case, and 2 patients needed additional clips to occlude the atherosclerotic aneurysmal wall. With these 3D models, it was easy for neurosurgical trainees to grasp the vascular configuration and the concept of neck occlusion. Practicing surgery with these models also improved their handling of the instruments used during aneurysm surgery, such as clips and appliers.

CONCLUSION

Using the hollow 3D models to simulate clipping preoperatively, we could treat the aneurysms confidently during live surgery. These models allow easy and concrete recognition of the 3D configuration of aneurysms and parent vessels.

Rapid Prototyping

As the appreciation of structural heart disease in children and adults has increased and as catheter-based closure procedures are now being performed in clinical practice, cardiovascular physicians have multiple compelling new reasons to better understand cardiac anatomic and spatial relationships. Current 2-dimensional imaging techniques remain limited both in their ability to represent the complex 3-dimensional relationships present in structural heart disease and in their capacity to adequately facilitate often complex corrective procedures. This review discusses the cardiovascular applications of rapid prototyping, a new technology that may not only play a significant role in the planning of catheter-based interventions but also may serve as a valuable educational tool to enhance the medical community’s understanding of the many forms of structural heart disease.

The Cleveland Clinic PediPump: anatomic modeling and virtual fitting studies in a lamb model

Implantation of ventricular assist devices (VADs) is challenging in small patients with limited space in the chest. We created three-dimensional models of lambs to facilitate fitting of the PediPump, a pediatric VAD currently under development. Serial computed tomography (CT) scans were acquired at multiple time points (n = 8) for three lambs. Digital models were created using these CT datasets and three-dimensional image processing software (Mimics, Materialise). Pixels representing the heart and chest wall were rendered as three-dimensional models. Using three-dimensional model manipulation software (Magics RP, Materialise), on-screen models of extravascular and intravascular VADs were placed in right, left and biventricular support configurations to determine optimal placement. A cannulation strategy was established and in some cases three-dimensional models of the inflow and outflow grafts were created. After the final CT study, an open-chest fitting study was performed using rapid prototype models of the pediatric VAD and cannulas. The pump location and orientation predictions from the virtual fitting studies matched those determined at the time of the open-chest fitting studies. Using three-dimensional modeling, we have established a fitting protocol that facilitates animal implantations; the same modeling techniques may be useful for device fitting in humans.