Preoperative three-dimensional model creation of magnetic resonance brain images as a tool to assist neurosurgical planning

Navigating complexity: a comprehensive review of microcatheter shaping techniques in endovascular aneurysm embolization

The endovascular intervention technique has gained prominence in the treatment of intracranial aneurysms due to its minimal invasiveness and shorter recovery time. A critical step of the intervention is the shaping of the microcatheter, which ensures its accurate placement and stability within the aneurysm sac. This is vital for enhancing coil placement and minimizing the risk of catheter kickback during the coiling process. Currently, microcatheter shaping is primarily reliant on the operator's experience, who shapes them based on the curvature of the target vessel and aneurysm location, utilizing 3D rotational angiography or CT angiography. Some researchers have documented their experiences with conventional shaping methods. Additionally, some scholars have explored auxiliary techniques such as 3D printing and computer simulations to facilitate microcatheter shaping. However, the shaping of microcatheters can still pose challenges, especially in cases with complex anatomical structures or very small aneurysms, and even experienced operators may encounter difficulties, and there has been a lack of a holistic summary of microcatheter shaping techniques in the literature. In this article, we present a review of the literature from 1994 to 2023 on microcatheter shaping techniques in endovascular aneurysm embolization. Our review aims to present a thorough overview of the various experiences and techniques shared by researchers over the last 3 decades, provides an analysis of shaping methods, and serves as an invaluable resource for both novice and experienced practitioners, highlighting the significance of understanding and mastering this technique for successful endovascular intervention in intracranial aneurysms.

Application of microcatheter shaping based on computational fluid dynamics simulation of cerebral blood flow in the intervention of posterior communicating aneurysm of the internal carotid artery

Introduction

The present study aimed to investigate the application of the aneurysm embolization microcatheter plasticity method based on computational fluid dynamics (CFD) to simulate cerebral blood flow in the interventional treatment of posterior communicating aneurysms in the internal carotid artery and to evaluate its practicality and safety.

Methods

A total of 20 patients with posterior internal carotid artery communicating aneurysms who used CFD to simulate cerebral flow lines from January 2020 to December 2022 in our hospital were analyzed. Microcatheter shaping and interventional embolization were performed according to the main cerebral flow lines, and the success rate, stability, and effect of the microcatheter being in place were analyzed.

Results

Among the 20 patients, the microcatheters were all smoothly placed and the catheters were stable during the in vitro model test. In addition, the microcatheters were all smoothly placed during the operation, with a success rate of 100%. The catheter tips were stable and well-supported intraoperatively, and no catheter prolapse was registered. The aneurysm was completely embolized in 19 cases immediately after surgery, and a small amount of the aneurysm neck remained in one case. There were no intraoperative complications related to the embolization catheter operation.

Conclusion

Microcatheter shaping based on CFD simulation of cerebral blood flow, with precise catheter shaping, leads to a high success rate in catheter placing, stability, and good support, and greatly reduces the difficulty of catheter shaping. This catheter-shaping method is worthy of further study and exploration.

Advanced 3D Visualization and 3D Printing in Radiology

Since the discovery of X-rays in 1895, medical imaging systems have played a crucial role in medicine by permitting the visualization of internal structures and understanding the function of organ systems. Traditional imaging modalities including Computed Tomography (CT), Magnetic Resonance Imaging (MRI) and Ultrasound (US) present fixed two-dimensional (2D) images which are difficult to conceptualize complex anatomy. Advanced volumetric medical imaging allows for three-dimensional (3D) image post-processing and image segmentation to be performed, enabling the creation of 3D volume renderings and enhanced visualization of pertinent anatomic structures in 3D. Furthermore, 3D imaging is used to generate 3D printed models and extended reality (augmented reality and virtual reality) models. A 3D image translates medical imaging information into a visual story rendering complex data and abstract ideas into an easily understood and tangible concept. Clinicians use 3D models to comprehend complex anatomical structures and to plan and guide surgical interventions more precisely. This chapter will review the volumetric radiological techniques that are commonly utilized for advanced 3D visualization. It will also provide examples of 3D printing and extended reality technology applications in radiology and describe the positive impact of advanced radiological image visualization on patient care.

Multiple Meningioma Resection by Bilateral Extended Rostrotentorial Craniotomy with a 3D-Print Guide in a Cat

Simple Summary

Meningioma is the most common intracranial neoplasia in cats. Treatments for meningiomas—including complete surgical resection, debulking, irradiation, or palliative therapy—have been reported in veterinary medicine. However, multiple meningiomas (two or more meningiomas in the same patient, separated by anatomical location) have been reported to affect the complication rate and prognosis. Moreover, the characteristics of neurosurgery—such as accurate localization and awareness of the anatomical structures of the lesions—make the surgery especially difficult for inexperienced surgeons. Surgical navigation systems have been developed, but recently, patient-specific three-dimensional(3D)-printed models and guides have also been used in orthopedics and neurosurgeries for treating many disorders with good results. A 13-year-old castrated male domestic shorthair cat was referred with multiple meningiomas located within the right frontal and occipital lobes. The cat suffered from generalized tonic–clonic seizures and mild proprioceptive ataxia. After removing both of the tumors, the cat showed a favorable clinical outcome and no neurological abnormalities throughout long-term follow-up. With a patient-specific 3D guide technology, a craniotomy for multiple meningiomas can be performed safely and accurately.

Abstract

A 13-year-old castrated male domestic shorthair cat was referred for the surgical removal of multiple meningiomas. The cat experienced generalized tonic–clonic seizures, altered mentation, mild proprioceptive ataxia, and circling. Magnetic resonance imaging (MRI) revealed two round, solitary, well-delineated, space-occupying lesions suggestive of multiple meningiomas in the right frontal and occipital lobes. Before surgery, patient-specific three-dimensional (3D) printed models and guides were produced using a 3D program based on MRI and computed tomography (CT), and a rehearsal surgery was performed. With a 3D guide to find the location of the craniotomy lines, bilateral extended rostrotentorial craniotomy allowed en bloc resection of multiple meningiomas. The bone fragment was replaced and secured to the skull with a craniofacial plate and screws with an artificial dura. All of the surgical steps were performed without complications. The preoperative presenting signs were resolved by the time of follow-up examinations 2 weeks after surgery. Twelve months after the removal of the multiple meningiomas, the cat survived without further neurological progression. For the resection of multiple meningiomas, surgery can result in large bone defects and risk of massive hemorrhage. For this challenging surgery, patient-specific 3D models and guides can be effective for accurate and safe craniotomies.

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.

Three-Dimensional Printing for Cancer Applications: Research Landscape and Technologies

As a variety of novel technologies, 3D printing has been considerably applied in the field of health care, including cancer treatment. With its fast prototyping nature, 3D printing could transform basic oncology discoveries to clinical use quickly, speed up and even revolutionise the whole drug discovery and development process. This literature review provides insight into the up-to-date applications of 3D printing on cancer research and treatment, from fundamental research and drug discovery to drug development and clinical applications. These include 3D printing of anticancer pharmaceutics, 3D-bioprinted cancer cell models and customised nonbiological medical devices. Finally, the challenges of 3D printing for cancer applications are elaborated, and the future of 3D-printed medical applications is envisioned.

Three-Dimensional Printed Anatomic Models Derived From Magnetic Resonance Imaging Data: Current State and Image Acquisition Recommendations for Appropriate Clinical Scenarios

Three-dimensional (3D) printing technologies have been increasingly utilized in medicine over the past several years and can greatly facilitate surgical planning thereby improving patient outcomes. Although still much less utilized compared to computed tomography (CT), magnetic resonance imaging (MRI) is gaining traction in medical 3D printing. The purpose of this study was two-fold: 1) to determine the prevalence in the existing literature of using MRI to create 3D printed anatomic models for surgical planning and 2) to provide image acquisition recommendations for appropriate clinical scenarios where MRI is the most suitable imaging modality. The workflow for creating 3D printed anatomic models from medical imaging data is complex and involves image segmentation of the regions of interest and conversion of that data into 3D surface meshes, which are compatible with printing technologies. CT is most commonly used to create 3D printed anatomic models due to the high image quality and relative ease of performing image segmentation from CT data. As compared to CT datasets, 3D printing using MRI data offers advantages since it provides exquisite soft tissue contrast needed for accurate organ segmentation and it does not expose patients to unnecessary ionizing radiation. MRI, however, often requires complicated imaging techniques and time-consuming postprocessing procedures to generate high-resolution 3D anatomic models needed for 3D printing. Despite these challenges, 3D modeling and printing from MRI data holds great clinical promises thanks to emerging innovations in both advanced MRI imaging and postprocessing techniques. EVIDENCE LEVEL: 2 TECHNICAL EFFICATCY: 5.

Clinical application of patient-specific 3D printing brain tumor model production system for neurosurgery

The usefulness of 3-dimensional (3D)-printed disease models has been recognized in various medical fields. This study aims to introduce a production platform for patient-specific 3D-printed brain tumor model in clinical practice and evaluate its effectiveness. A full-cycle platform was created for the clinical application of a 3D-printed brain tumor model (3D-printed model) production system. Essential elements included automated segmentation software, cloud-based interactive communication tools, customized brain models with exquisite expression of brain anatomy in transparent material, adjunctive devices for surgical simulation, and swift process cycles to meet practical needs. A simulated clinical usefulness validation was conducted in which neurosurgeons assessed the usefulness of the 3D-printed models in 10 cases. We successfully produced clinically applicable patient-specific models within 4 days using the established platform. The simulated clinical usefulness validation results revealed the significant superiority of the 3D-printed models in surgical planning regarding surgical posture (p = 0.0147) and craniotomy design (p = 0.0072) compared to conventional magnetic resonance images. The benefit was more noticeable for neurosurgeons with less experience. We established a 3D-printed brain tumor model production system that is ready to use in daily clinical practice for neurosurgery.

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.

3D Printing of Diffuse Low-Grade Gliomas Involving Eloquent Cortical Areas and Subcortical Functional Pathways: Technical Note

BACKGROUND

Surgical resection of diffuse low-grade gliomas (DLGGs) involving cortical eloquent areas and subcortical functional pathways represents a challenge in neurosurgery. Patient-specific, 3-dimensional (3D)-printed models of head and brain structures have emerged in recent years as an educational and clinical tool for patients, doctors, and surgical residents.

METHODS

Using multimodal high-definition magnetic resonance imaging data, which incorporates information from specific task-based functional neuroimaging and diffusion tensor imaging tractography and rapid prototyping technologies with specialized software and "in-house" 3D printing, we were able to generate 3D-printed head models that were used for preoperative patient education and consultation, surgical planning, and resident training in 2 complicated DLGG surgeries.

RESULTS

This 3D-printed model is rapid prototyped and shows a means to model individualized, diffuse, low-level glioma in 3D space with respect to cortical eloquent areas and subcortical pathways. Survey results from 8 surgeons with different levels of expertise strongly support the use of this model for surgical planning, intraoperative surgical guidance, doctor-patient communication, and surgical training (>95% acceptance).

CONCLUSIONS

Spatial proximity of DLGG to cortical eloquent areas and subcortical tracts can be readily assessed in patient-specific 3D printed models with high fidelity. 3D-printed multimodal models could be helpful in preoperative patient consultation, surgical planning, and resident 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.

3D printing with MRI in pediatric applications

3D printing (3DP) applications for clinical evaluation, preoperative planning, patient and trainee education, and simulation has increased in the past decade. Most of the applications are found in cardiovascular, head and neck, orthopedic, neurological, urological, and oncological surgical cases. This review has three parts. The first part discusses the technical pathway to realizing a physical model, 3DP considerations in pediatric MRI image acquisition, data and resolution requirements, and related structural segmentation and postprocessing steps needed to generalize both virtual and physical models. Standard practices and processing software used in these processes will be assessed. The second part discusses complementary examples in pediatric applications, including cases from cardiology, neuroradiology, neurology, and neurosurgery, head and neck, orthopedics, pelvic and urological applications, oncological applications, and fetal imaging. The third part explores other 3D printing applications and considerations such as using 3DP to develop tissue-specific phantoms and devices for testing in the MR environment, to educate patients and their families, to train clinicians and students, and facility requirements for building a 3DP program. Level of Evidence: 5 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2020;51:1641-1658.

Three-Dimensional Printed Patient Models for Complex Pediatric Spinal Surgery

Background: Pediatric spinal deformity surgeries are challenging operations that require considerable expertise and resources. The unique anatomy and rarity of these cases present challenges in surgical training and preparation. We present a case series illustrating how 3-dimensional (3-D) printed models were used in preoperative planning for 3 cases of pediatric spinal deformity surgery. Case Series: Patient 1 was a 6-year-old male with scoliosis secondary to an L3 hemivertebra and severe congenital heart disease who underwent excision of the L3 hemivertebra and L2-L4 spinal fusion. Patient 2 was an 11-year-old male with an L2 hemivertebra and lumbar kyphosis who underwent excision of the L2 hemivertebra and T12-L4 spinal fusion. Patient 3 was a 6-year-old female with Down syndrome who presented with atlantoaxial instability and acute lymphoblastic leukemia. She underwent occipital-cervical spinal fusion and decompression. Prior to surgery, 3-D printed models of the patients' spines were created based on computed tomography (CT) imaging. Conclusion: The anatomic complexity and risk of devastating neurologic consequences in spine surgery call for careful preparations. 3-D models enable more efficient and precise surgical planning compared to the use of 2-dimensional CT/magnetic resonance images. The 3-D models also make it easier to visualize patient anatomy, allowing patients and their families who lack medical training to interpret and understand cross-sectional anatomy, which in our experience, enhanced the consultations.

A small 3D-printing model of macroadenomas for endoscopic endonasal surgery

PURPOSE

This paper examines the application of 3D printing technology in the endoscopic endonasal approach for the treatment of macroadenomas.

METHODS

We have retrospectively analysed 20 patients who diagnosed with macroadenoma underwent endoscopic transsphenoidal surgery in Wuhan Union hospital from January 2017 to May 2017. Among the 20 patients, 10 patients received the service of 3D printing technology preoperatively. The data of 3D processing and clinical result were recorded for further evaluation.

RESULTS

The 10 patients who received the service had a successful 3D printed model of their tumors, it shows the anatomy of sphenoid sinus, tumor location which were in good agreement with our intraoperative observations. The 10 patients who received the service had a less operation time (127.0 ± 15.53 vs. 143.40 ± 17.89), blood loss (159.90 ± 12.31 vs. 170.00 ± 29.06) and less postoperative complication rate (20% vs. 40%). the design time of the 3D images varies 2 h 10 min to 4 h 32 min. the printing time of the 3D models varies 10 h 12 min to 22 h 34 min.

CONCLUSIONS

The use of 3D printing technology has unquestionable potential applications to endoscopic endonasal approach for macroadenomas, in particular reflecting the complicated anatomy of sphenoid sinus and tumor location. Owing to the advantages of 3D printing technology, it may help the patients get a good prognosis.

Using Three-Dimensional Printing to Create Individualized Cranial Nerve Models for Skull Base Tumor Surgery

OBJECTIVE

Using three-dimensional (3D) printing to create individualized patient models of the skull base, the optic chiasm and facial nerve can be previsualized to help identify and protect these structures during tumor removal surgery.

METHODS

Preoperative imaging data for 2 cases of sellar tumor and 1 case of acoustic neuroma were obtained. Based on these data, the cranial nerves were visualized using 3D T1-weighted turbo field echo sequence and diffusion tensor imaging-based fiber tracking. Mimics software was used to create 3D reconstructions of the skull base regions surrounding the tumors, and 3D solid models were printed for use in simulation of the basic surgical steps.

RESULTS

The 3D printed personalized skull base tumor solid models contained information regarding the skull, brain tissue, blood vessels, cranial nerves, tumors, and other associated structures. The sphenoid sinus anatomy, saddle area, and cerebellopontine angle region could be visually displayed, and the spatial relationship between the tumor and the cranial nerves and important blood vessels was clearly defined. The models allowed for simulation of the operation, prediction of operative details, and verification of accuracy of cranial nerve reconstruction during the operation. Questionnaire assessment showed that neurosurgeons highly valued the accuracy and usefulness of these skull base tumor models.

CONCLUSIONS

3D printed models of skull base tumors and nearby cranial nerves, by allowing for the surgical procedure to be simulated beforehand, facilitate preoperative planning and help prevent cranial nerve injury.

3D printing for preoperative planning and surgical training: a review

Surgeons typically rely on their past training and experiences as well as visual aids from medical imaging techniques such as magnetic resonance imaging (MRI) or computed tomography (CT) for the planning of surgical processes. Often, due to the anatomical complexity of the surgery site, two dimensional or virtual images are not sufficient to successfully convey the structural details. For such scenarios, a 3D printed model of the patient's anatomy enables personalized preoperative planning. This paper reviews critical aspects of 3D printing for preoperative planning and surgical training, starting with an overview of the process-flow and 3D printing techniques, followed by their applications spanning across multiple organ systems in the human body. State of the art in these technologies are described along with a discussion of current limitations and future opportunities.

Three dimensional scapular prints for evaluating glenoid morphology: An exploratory study

BACKGROUND

Computerised Tomography (CT) scans are conventionally employed to assess the glenoid morphology prior to total shoulder arthroplasty (TSA). This study explores the role of three-dimensional (3D) models for assessing glenoid morphology.

METHODS

CT scans of 32 patients scheduled for TSA were reconstructed to scapular models using customised software and a desktop 3D printer. The size and aspect ratios were maintained. Glenoid version, glenoid maximum height and width, and the maximum acromion antero-posterior (AP) length were compared between the models and CT scans.

RESULTS

The models were an accurate qualitative reflection of scapular anatomy. The average retroversion in 3D models was 8.19°±30.8° compared to 10.26°±42.5° in scan images. The mean difference was 2.07°±24.6° (p=0.408). However, the mean absolute error was 5.02°±12.3°. The mean difference of the glenoid maximum width and the acromion maximum AP length was 0.22±3.33mm (p=0.862) and 0.32±14.12mm (p=0.213) respectively. However, the mean difference was significant for the glenoid maximum height measuring 3.67±12.04mm with p=0.004. The correlation between the examiners was high for all parameters, with intraclass correlation ranging between 0.94 and 0.99.

CONCLUSION

3D printing technology promises to be a useful tool for preoperative planning with accurate reproduction of transverse plane anatomy. 3D prints represent superior definition of reconstructed anatomical measures such as glenoid height as compared to conventional CT Scans.

Development and validation of 3D printed virtual models for robot-assisted radical prostatectomy and partial nephrectomy: urologists' and patients' perception

PURPOSE

To test the face and content validity of 3D virtual-rendered printed models used before robot-assisted prostate cancer and nephron-sparing surgery.

METHODS

Patients who underwent live surgery during an international urological meeting organized in January 2017 were enrolled. Those with organ-confined prostate cancer underwent robot-assisted radical prostatectomy. Patients with a single renal tumor underwent minimally invasive nephron-sparing surgery. High-resolution (HR) imaging was obtained for all patients. Those with kidney tumors received contrast-enhanced CT scan with angiography; those with prostate cancer underwent mp-MRI. Images in DICOM format were processed by dedicated software. The first step was the rendering of a 3D virtual model. The models were then printed. They were presented during the live surgery of the urological meeting. All the participants and the operated patients were asked to fill a questionnaire about their opinion expressed in Likert scale (1-10) about the use and application of the 3D printed models.

RESULTS

18 patients were enrolled, including 8 undergoing robot-assisted radical prostatectomy and 10 undergoing minimally invasive partial nephrectomy. For each patient, a virtual 3D printed model was created. The attendants rated the utility of printed models in surgical planning, anatomical representation and the role of technology in surgical training as 8/10, 10/10 and 9/10, respectively. All patients reported favorable feedbacks (from 9 to 10/10) about the use of the technology during the case discussion with the surgeon.

CONCLUSIONS

In our experience, 3D printing technology has been perceived as a useful tool for the purpose of surgical planning, physician education/training and patient counseling. Further researches are expected to increase the level of evidence.

3D printing materials and their use in medical education: a review of current technology and trends for the future

3D printing is a new technology in constant evolution. It has rapidly expanded and is now being used in health education. Patient-specific models with anatomical fidelity created from imaging dataset have the potential to significantly improve the knowledge and skills of a new generation of surgeons. This review outlines five technical steps required to complete a printed model: They include (1) selecting the anatomical area of interest, (2) the creation of the 3D geometry, (3) the optimisation of the file for the printing and the appropriate selection of (4) the 3D printer and (5) materials. All of these steps require time, expertise and money. A thorough understanding of educational needs is therefore essential in order to optimise educational value. At present, most of the available printing materials are rigid and therefore not optimum for flexibility and elasticity unlike biological tissue. We believe that the manipuation and tuning of material properties through the creation of composites and/or blending materials will eventually allow for the creation of patient-specific models which have both anatomical and tissue fidelity.

Three-Dimensional Bioprinting and Its Potential in the Field of Articular Cartilage Regeneration

Three-dimensional (3D) bioprinting techniques can be used for the fabrication of personalized, regenerative constructs for tissue repair. The current article provides insight into the potential and opportunities of 3D bioprinting for the fabrication of cartilage regenerative constructs. Although 3D printing is already used in the orthopedic clinic, the shift toward 3D bioprinting has not yet occurred. We believe that this shift will provide an important step forward in the field of cartilage regeneration. Three-dimensional bioprinting techniques allow incorporation of cells and biological cues during the manufacturing process, to generate biologically active implants. The outer shape of the construct can be personalized based on clinical images of the patient's defect. Additionally, by printing with multiple bio-inks, osteochondral or zonally organized constructs can be generated. Relevant mechanical properties can be obtained by hybrid printing with thermoplastic polymers and hydrogels, as well as by the incorporation of electrospun meshes in hydrogels. Finally, bioprinting techniques contribute to the automation of the implant production process, reducing the infection risk. To prompt the shift from nonliving implants toward living 3D bioprinted cartilage constructs in the clinic, some challenges need to be addressed. The bio-inks and required cartilage construct architecture need to be further optimized. The bio-ink and printing process need to meet the sterility requirements for implantation. Finally, standards are essential to ensure a reproducible quality of the 3D printed constructs. Once these challenges are addressed, 3D bioprinted living articular cartilage implants may find their way into daily clinical practice.

Three-Dimensional Printing Role in Neurologic Disease

Three-dimensional printing has evolved dramatically in recent years and is now available for clinical use. Technical operations of 2 of the most common rapid prototyping processes (stereolithography and fused deposition modeling) and the steps involved in the creation of a prototype are discussed. Current applications in human neurosurgery including presurgical planning and educational opportunities are reviewed before focusing on the current applications in veterinary neurology.

Three-Dimensional Printing Model as a Tool to Assist in Surgery for Large Mandibular Tumour: a Case Report

Objectives

Recently, three-dimensional printing models based on preoperative computed tomography and magnetic resonance imaging images have been widely used in medical fields. This study presents an effective use of the three-dimensional printing model in exploring complex spatial relationship between the tumour and surrounding tissue and in simulation surgery based planning of the operative procedure.

Material and Methods

The patient was a 7-year-old boy with ameloblastic fibro-odontoma. Prior to surgery, a hybrid three-dimensional printing model consisting of the jaw bone, the tumour and the inferior alveolar nerve was fabricated. After the simulation surgery based on this model, enucleation of the tumour, leaving tooth 46 intact (Universal Numbering System by ADA) safe, was planned.

Results

Enucleation of the tumour was successfully carried out. One year later, healing was found to be satisfactory both clinically and radiographically.

Conclusions

The study presented an effective application of a novel hybrid three-dimensional printing model composed of hard and soft tissues. Such innovations can bring significant benefits, especially to the field of oncological surgery.

Current and emerging applications of 3D printing in medicine

Three-dimensional (3D) printing enables the production of anatomically matched and patient-specific devices and constructs with high tunability and complexity. It also allows on-demand fabrication with high productivity in a cost-effective manner. As a result, 3D printing has become a leading manufacturing technique in healthcare and medicine for a wide range of applications including dentistry, tissue engineering and regenerative medicine, engineered tissue models, medical devices, anatomical models and drug formulation. Today, 3D printing is widely adopted by the healthcare industry and academia. It provides commercially available medical products and a platform for emerging research areas including tissue and organ printing. In this review, our goal is to discuss the current and emerging applications of 3D printing in medicine. A brief summary on additive manufacturing technologies and available printable materials is also given. The technological and regulatory barriers that are slowing down the full implementation of 3D printing in the medical field are also discussed.

"Black Bone" MRI: a novel imaging technique for 3D printing

OBJECTIVES

Three-dimensionally printed anatomical models are rapidly becoming an integral part of pre-operative planning of complex surgical cases. We have previously reported the "Black Bone" MRI technique as a non-ionizing alternative to CT. Segmentation of bone becomes possible by minimizing soft tissue contrast to enhance the bone-soft tissue boundary. The objectives of this study were to ascertain the potential of utilizing this technique to produce three-dimensional (3D) printed models.

METHODS

"Black Bone" MRI acquired from adult volunteers and infants with craniosynostosis were 3D rendered and 3D printed. A custom phantom provided a surrogate marker of accuracy permitting comparison between direct measurements and 3D printed models created by segmenting both CT and "Black Bone" MRI data sets using two different software packages.

RESULTS

"Black Bone" MRI was successfully utilized to produce 3D models of the craniofacial skeleton in both adults and an infant. Measurements of the cube phantom and 3D printed models demonstrated submillimetre discrepancy.

CONCLUSIONS

In this novel preliminary study exploring the potential of 3D printing from "Black Bone" MRI data, the feasibility of producing anatomical 3D models has been demonstrated, thus offering a potential non-ionizing alterative to CT for the craniofacial skeleton.

3D Printing of CT Dataset: Validation of an Open Source and Consumer-Available Workflow

The broad availability of cheap three-dimensional (3D) printing equipment has raised the need for a thorough analysis on its effects on clinical accuracy. Our aim is to determine whether the accuracy of 3D printing process is affected by the use of a low-budget workflow based on open source software and consumer's commercially available 3D printers. A group of test objects was scanned with a 64-slice computed tomography (CT) in order to build their 3D copies. CT datasets were elaborated using a software chain based on three free and open source software. Objects were printed out with a commercially available 3D printer. Both the 3D copies and the test objects were measured using a digital professional caliper. Overall, the objects' mean absolute difference between test objects and 3D copies is 0.23 mm and the mean relative difference amounts to 0.55 %. Our results demonstrate that the accuracy of 3D printing process remains high despite the use of a low-budget workflow.

3D printing from MRI Data: Harnessing strengths and minimizing weaknesses

3D printing facilitates the creation of accurate physical models of patient-specific anatomy from medical imaging datasets. While the majority of models to date are created from computed tomography (CT) data, there is increasing interest in creating models from other datasets, such as ultrasound and magnetic resonance imaging (MRI). MRI, in particular, holds great potential for 3D printing, given its excellent tissue characterization and lack of ionizing radiation. There are, however, challenges to 3D printing from MRI data as well. Here we review the basics of 3D printing, explore the current strengths and weaknesses of printing from MRI data as they pertain to model accuracy, and discuss considerations in the design of MRI sequences for 3D printing. Finally, we explore the future of 3D printing and MRI, including creative applications and new materials.

LEVEL OF EVIDENCE

5 J. Magn. Reson. Imaging 2017;45:635-645.

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.

Three-dimensional Physical Modeling: Applications and Experience at Mayo Clinic

Radiologists will be at the center of the rapid technologic expansion of three-dimensional (3D) printing of medical models, as accurate models depend on well-planned, high-quality imaging studies. This article outlines the available technology and the processes necessary to create 3D models from the radiologist's perspective. We review the published medical literature regarding the use of 3D models in various surgical practices and share our experience in creating a hospital-based three-dimensional printing laboratory to aid in the planning of complex surgeries.

3D Printout Models vs. 3D-Rendered Images: Which Is Better for Preoperative Planning?

INTRODUCTION

Correct interpretation of a patient's anatomy and changes that occurs secondary to a disease process are crucial in the preoperative process to ensure optimal surgical treatment. In this study, we presented 3 different pancreatic cancer cases to surgical residents in the form of 3D-rendered images and 3D-printed models to investigate which modality resulted in the most appropriate preoperative plan.

METHODS

We selected 3 cases that would require significantly different preoperative plans based on key features identifiable in the preoperative computed tomography imaging. 3D volume rendering and 3D printing were performed respectively to create 2 different training ways. A total of 30, year 1 surgical residents were randomly divided into 2 groups. Besides traditional 2D computed tomography images, residents in group A (n = 15) reviewed 3D computer models, whereas in group B, residents (n = 15) reviewed 3D-printed models. Both groups subsequently completed an examination, designed in-house, to assess the appropriateness of their preoperative plan and provide a numerical score of the quality of the surgical plan.

RESULTS

Residents in group B showed significantly higher quality of the surgical plan scores compared with residents in group A (76.4 ± 10.5 vs. 66.5 ± 11.2, p = 0.018). This difference was due in large part to a significant difference in knowledge of key surgical steps (22.1 ± 2.9 vs. 17.4 ± 4.2, p = 0.004) between each group. All participants reported a high level of satisfaction with the exercise.

CONCLUSION

Results from this study support our hypothesis that 3D-printed models improve the quality of surgical trainee's preoperative plans.

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: review of application in medicine and hepatic surgery

Three-dimensional (3D) printing (3DP) is a rapid prototyping technology that has gained increasing recognition in many different fields. Inherent accuracy and low-cost property enable applicability of 3DP in many areas, such as manufacturing, aerospace, medical, and industrial design. Recently, 3DP has gained considerable attention in the medical field. The image data can be quickly turned into physical objects by using 3DP technology. These objects are being used across a variety of surgical specialties. The shortage of cadaver specimens is a major problem in medical education. However, this concern has been solved with the emergence of 3DP model. Custom-made items can be produced by using 3DP technology. This innovation allows 3DP use in preoperative planning and surgical training. Learning is difficult among medical students because of the complex anatomical structures of the liver. Thus, 3D visualization is a useful tool in anatomy teaching and hepatic surgical training. However, conventional models do not capture haptic qualities. 3DP can produce highly accurate and complex physical models. Many types of human or animal differentiated cells can be printed successfully with the development of 3D bio-printing technology. This progress represents a valuable breakthrough that exhibits many potential uses, such as research on drug metabolism or liver disease mechanism. This technology can also be used to solve shortage of organs for transplant in the future.

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.

Preoperative surgical simulation of laparoscopic adrenalectomy for neuroblastoma using a three-dimensional printed model based on preoperative CT images

BACKGROUND

Three-dimensional (3D) printed models based on computed tomography (CT) images facilitate the visualization of complex structures and are useful for understanding the surgical anatomy preoperatively. We developed a preoperative surgical simulation method using a 3D printed model based on CT images obtained prior to laparoscopic adrenalectomy for adrenal neuroblastomas (NBs).

MATERIALS AND METHODS

The multi-detector CT images were transferred to a 3D workstation, and 3D volume data were obtained by reconstructing the sections. A model was made with a 3D printer using acrylic ultraviolet curable resin. The adrenal tumor, kidney, renal vein and artery, inferior vena cava, aorta, and outer body were fabricated. The pneumoperitoneum, insertion of trocars, and laparoscopic view were all attainable in this model. We used this model for three cases with adrenal NB.

RESULTS

We used this model to discuss the port layout before the operation and to simulate the laparoscopic view and range of forceps movement. All three cases with NB were completely resected without any surgical complications.

CONCLUSIONS

The surgical simulation using 3D printed models based on preoperative CT images for adrenal NB was very useful for understanding the patient's surgical anatomy and for planning the surgical procedures, especially for determining the optimal port layout.

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.

Applications of three-dimensional printing technology in urological practice

A rapid expansion in the medical applications of three-dimensional (3D)-printing technology has been seen in recent years. This technology is capable of manufacturing low-cost and customisable surgical devices, 3D models for use in preoperative planning and surgical education, and fabricated biomaterials. While several studies have suggested 3D printers may be a useful and cost-effective tool in urological practice, few studies are available that clearly demonstrate the clinical benefit of 3D-printed materials. Nevertheless, 3D-printing technology continues to advance rapidly and promises to play an increasingly larger role in the field of urology. Herein, we review the current urological applications of 3D printing and discuss the potential impact of 3D-printing technology on the future of urological practice.

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.

Three-dimensional liver model based on preoperative CT images as a tool to assist in surgical planning for hepatoblastoma in a child

The patient is a 3-year-old female diagnosed with PRETEXT IV hepatoblastoma (HB). Although the tumor was decreased after the neoadjuvant chemotherapy, HB still located at the porta hepatis. The patient underwent extended left lobectomy successfully after surgical simulation using three-dimensional (3D) printing liver model based on preoperative CT.

Evaluation of three-dimensional printing for laparoscopic partial nephrectomy of renal tumors: a preliminary report

OBJECTIVES

To investigate the impact of three-dimensional (3D) printing on the surgical planning, potential of training and patients' comprehension of minimally invasive surgery for renal tumors.

METHODS

Patients of a T1N0M0 single renal tumor and indicated for laparoscopic partial nephrectomy were selected. CT data were sent for post-processing and output to the 3D printer to create kidney models with tumor. By presenting to experienced laparoscopic urologists and patients, respectively, the models' realism, effectiveness for surgical planning and training, and patients' comprehension of disease and procedure were evaluated with plotted questionnaires (10-point rating scales, 1-not at all useful/not at all realistic/poor, 10-very useful/very realistic/excellent). The size of resected tumors was compared with that on the models.

RESULTS

Ten kidney models of such patients were fabricated successfully. The overall effectiveness in surgical planning and training (7.8 ± 0.7-8.0 ± 1.1), and realism (6.0 ± 0.6-7.8 ± 1.0) were reached by four invited urologists. Intraoperative correlation was advocated by the two performing urologists. Patients were fascinated with the demonstration of a tactile "diseased organ" (average ≥ 9.0). The size deviation was 3.4 ± 1.3 mm.

CONCLUSIONS

Generating kidney models of T1N0M0 tumors with 3D printing are feasible with refinements to be performed. Face and content validity was obtained when those models were presented to experienced urologists for making practical planning and training. Understandings of the disease and procedure from patients were well appreciated with this novel technology.

Microcatheter Shaping for Intracranial Aneurysm Coiling Using the 3-Dimensional Printing Rapid Prototyping Technology: Preliminary Result in the First 10 Consecutive Cases

OBJECTIVE

An optimal microcatheter is necessary for successful coiling of an intracranial aneurysm. The optimal shape may be predetermined before the endovascular surgery via the use of a 3-dimensional (3D) printing rapid prototyping technology. We report a preliminary series of intracranial aneurysms treated with a microcatheter shape determined by the patient's anatomy and configuration of the aneurysm, which was fabricated with a 3D printer aneurysm model.

METHODS

A solid aneurysm model was fabricated with a 3D printer based on the data acquired from the 3D rotational angiogram. A hollow aneurysm model with an identical vessel and aneurysm lumen to the actual anatomy was constructed with use of the solid model as a mold. With use of the solid model, a microcatheter shaping mandrel was formed to identically line the 3D curvature of the parent vessel and the long axis of the aneurysm. With use of the mandrel, a test microcatheter was shaped and validated for the accuracy with the hollow model. All the planning processes were undertaken at least 1 day before treatment. The preshaped mandrel was then applied in the endovascular procedure. Ten consecutive intracranial aneurysms were coiled with the pre-planned shape of the microcatheter and evaluated for the clinical and anatomical outcomes and microcatheter accuracy and stability.

RESULTS

All of pre-planned microcatheters matched the vessel and aneurysm anatomy. Seven required no microguidewire assistance in catheterizing the aneurysm whereas 3 required guiding of a microguidewire. All of the microcatheters accurately aligned the long axis of the aneurysm. The pre-planned microcatheter shapes demonstrated stability in all except in 1 large aneurysm case.

CONCLUSION

When a 3D printing rapid type prototyping technology is used, a patient-specific and optimal microcatheter shape may be determined preoperatively.

Prevention of late postpneumonectomy complications using a 3D printed lung in dog models

OBJECTIVES

Repositioning of the mediastinum with implantation of a prosthesis seems the favoured approach to treat late complications of pneumonectomy caused by mediastinal shift. However, the traditional prostheses are not designed specifically for use in the thoracic cavity, sometimes resulting in failure of treatment for many reasons. The aim of our study was to develop a novel prosthesis to promote prevention or treatment of late postpneumonectomy complications.

METHODS

Using 3D printing technology, we created a novel mimetic lung model replicating the native one and then transplanted it into the thoracic cavity of postpneumonectomy dogs to maintain the original position of the mediastinum. Postoperative morbidity and mortality of late complications were compared between transplanted and non-transplanted groups. The safety and feasibility of implanting a 3D printed prosthesis were also evaluated by chest computed tomography (CT) scan and pathological examination.

RESULTS

At the 1-year follow-up, pneumonectomy dogs with 3D printed lungs showed less morbidity and mortality of late complications. CT images indicated dynamic mediastinal shift in pneumonectomy-only dogs with enlarged contralateral lungs. Nevertheless, there was no obvious change in the position of the mediastinum in 3D printed lung transplanted individuals. Moreover, the 3D printed lungs did not cause any additional side effects and revealed good histocompatibility and tolerance of recipients.

CONCLUSIONS

Our experiences indicated the safety, feasibility and efficacy of transplantation with 3D printed lungs for prevention of late postpneumonectomy complications and provided a practical and possibly unique clinical application of 3D printing technology for surgical therapy.

A three-dimensional mediastinal model created with rapid prototyping in a patient with ectopic thymoma

Preoperative three-dimensional (3D) imaging of a mediastinal tumor using two-dimensional (2D) axial computed tomography is sometimes difficult, and an unexpected appearance of the tumor may be encountered during surgery. In order to evaluate the preoperative feasibility of a 3D mediastinal model that used the rapid prototyping technique, we created a model and report its results. The 2D image showed some of the relationship between the tumor and the pericardium, but the 3D mediastinal model that was created using the rapid prototyping technique showed the 3D lesion in the outer side of the extrapericardium. The patient underwent a thoracoscopic resection of the tumor, and the pathological examination showed a rare middle mediastinal ectopic thymoma. We believe that the construction of mediastinal models is useful for thoracoscopic surgery and other complicated surgeries of the chest diseases.

Novel application of rapid prototyping for simulation of bronchoscopic anatomy

OBJECTIVE

The authors used rapid prototyping (RP) technology to create anatomically congruent models of tracheo-bronchial tree for teaching relevant bronchoscopic anatomy.

DESIGN

Pilot study.

SETTING

A single level tertiary academic medical center.

INTERVENTIONS

Two 3 dimensional (3D) models of tracheo-bronchial tree (one showing normal anatomy and another with an early take off of right apical bronchus) were recreated from Computed Tomographic images using RP technology. These images were then attached to mannequins and examined with a flexible fiberoptic bronchoscope (FFB). These images were then compared with the actual FFB images obtained during lung isolation.

MEASUREMENTS AND MAIN RESULTS

The images obtained through the 3D models were found to be congruent to actual patient anatomy.

CONCLUSIONS

RP can be successfully used to create anatomically accurate models from imaging studies. There is potential for RP to become a valuable educational tool in the future.