3D printing the pterygopalatine fossa: a negative space model of a complex structure

Clinically relevant morphometric analysis of pterygopalatine fossa and its volumetric relationship with adjacent paranasal sinuses: a CT-based study

OBJECTIVES

This study aimed to perform morphometric measurements of the pterygopalatine fossa (PPF), the transition zone to critical neurovascular structures. The second aim was to investigate the relationship between the volumes of the PPF and the paranasal sinuses and the effect of nasal septum deviation (NSD) types on all these measurements.

METHODS

We performed PPF's morphometry and all volume measurements on the CT images of 260 patients (130 male and 130 female, age range 18-79).

RESULTS

All volumetric measurements and the angle between foramen rotundum (FR) and pterygomaxillary fissure (PMF) were significantly higher in males than females. In contrast, the distance between sphenopalatine foramen (SPF) and PMF was considerably higher in females than in males. The PPF volume, the distance between the pterygoid canal (PC) and maxillary sinus, and the angle between FR and PMF were significantly higher on the right side than on the left. In contrast, the angle between PC and SPF and between greater palatine canal and PPF were considerably higher on the left side than on the right. The angle between PC and SPF decreased markedly with age. Only sphenoidal sinus volume was significantly smaller on the same side as the septal deviation. There was no correlation between PPF volume with maxillary and sphenoid sinus volumes from adjacent paranasal sinuses.

CONCLUSIONS

Volumetric and morphometric data obtained from PPF and paranasal sinuses can aid clinicians in diagnosing and treating patients by guiding them in selecting the right surgical approach or tools, especially in endoscopic procedures.

The Integration of 3D Virtual Reality and 3D Printing Technology as Innovative Approaches to Preoperative Planning in Neuro-Oncology

Our study explores the integration of three-dimensional (3D) virtual reality (VR) and 3D printing in neurosurgical preoperative planning. Traditionally, surgeons relied on two-dimensional (2D) imaging for complex neuroanatomy analyses, requiring significant mental visualization. Fortunately, nowadays advanced technology enables the creation of detailed 3D models from patient scans, utilizing different software. Afterwards, these models can be experienced through VR systems, offering comprehensive preoperative rehearsal opportunities. Additionally, 3D models can be 3D printed for hands-on training, therefore enhancing surgical preparedness. This technological integration transforms the paradigm of neurosurgical planning, ensuring safer procedures.

Are 3D-printed anatomical models of the ear effective for teaching anatomy? A comparative pilot study versus cadaveric models

PURPOSE

Despite the combination of chalkboard lectures and cadaveric models, the ear remains a complex anatomical structure that is difficult for medical students to grasp. The aim of this study was to evaluate the contribution of a 3D-printed ear model for educating undergraduate medical students by comparing it with a conventional cadaveric model.

METHODS

Models of the ear comprising the outer ear, tympanic membrane, ossicles and inner ear were modeled and then 3D-printed at 6:1 and 10:1 scales based on cadaveric dissection and CT, cone-beam CT and micro/nano CT scans. Cadaveric models included two partially dissected dry temporal bones and ossicles. Twenty-four 3rd year medical students were given separate access to cadaveric models (n = 12) or 3D-printed models (n = 12). A pre-test and two post-tests were carried out to assess knowledge (n = 24). A satisfaction questionnaire focusing solely on the 3D-printed model, comprising 17 items assessed on a 5-point Likert scale, was completed by all study participants. A 5-point Likert scale questionnaire comprising four items (realism, color, quality and satisfaction with the 3D-printed ear model) was given to three expert anatomy Professors.

RESULTS

The test scores on the first post-test were higher for the students who had used the 3D-printed models (p < 0.05). Overall satisfaction among the students and the experts was very high, averaging 4.7 on a 5-point Likert-type satisfaction scale.

CONCLUSION

This study highlights the overall pedagogical value of a 3D-printed model for learning ear anatomy.

3D printing as a pedagogical tool for teaching normal human anatomy: a systematic review

BACKGROUND

Three-dimensional-printed anatomical models (3DPAMs) appear to be a relevant tool due to their educational value and their feasibility. The objectives of this review were to describe and analyse the methods utilised for creating 3DPAMs used in teaching human anatomy and for evaluating its pedagogical contribution.

METHODS

An electronic search was conducted on PubMed using the following terms: education, school, learning, teaching, learn, teach, educational, three-dimensional, 3D, 3-dimensional, printing, printed, print, anatomy, anatomical, anatomically, and anatomic. Data retrieved included study characteristics, model design, morphological evaluation, educational performance, advantages, and disadvantages.

RESULTS

Of the 68 articles selected, the cephalic region was the most studied (33 articles); 51 articles mentioned bone printing. In 47 articles, the 3DPAM was designed from CT scans. Five printing processes were listed. Plastic and its derivatives were used in 48 studies. The cost per design ranged from 1.25 USD to 2800 USD. Thirty-seven studies compared 3DPAM to a reference model. Thirty-three articles investigated educational performance. The main advantages were visual and haptic qualities, effectiveness for teaching, reproducibility, customizability and manipulability, time savings, integration of functional anatomy, better mental rotation ability, knowledge retention, and educator/student satisfaction. The main disadvantages were related to the design: consistency, lack of detail or transparency, overly bright colours, long printing time, and high cost.

CONCLUSION

This systematic review demonstrates that 3DPAMs are feasible at a low cost and effective for teaching anatomy. More realistic models require access to more expensive 3D printing technologies and substantially longer design time, which would greatly increase the overall cost. Choosing an appropriate image acquisition modality is key. From a pedagogical viewpoint, 3DPAMs are effective tools for teaching anatomy, positively impacting the learning outcomes and satisfaction level. The pedagogical effectiveness of 3DPAMs seems to be best when they reproduce complex anatomical areas, and they are used by students early in their medical studies.

Effects of the individual three-dimensional printed craniofacial bones with a quick response code on the skull spatial knowledge of undergraduate medical students

Understanding the three-dimensional (3D) structure of the human skull is imperative for medical courses. However, medical students are overwhelmed by the spatial complexity of the skull. Separated polyvinyl chloride (PVC) bone models have advantages as learning tools, but they are fragile and expensive. This study aimed to reconstruct 3D-printed skull bone models (3D-PSBs) using polylactic acid (PLA) with anatomical characteristics for spatial recognition of the skull. Student responses to 3D-PSB application were investigated through a questionnaire and tests to understand the requirement of these models as a learning tool. The students were randomly divided into 3D-PSB (n = 63) and skull (n = 67) groups to analyze pre- and post-test scores. Their knowledge was improved, with the gain scores of the 3D-PSB group (50.0 ± 3.0) higher than that of the skull group (37.3 ± 5.2). Most students agreed that using 3D-PSBs with quick response codes could improve immediate feedback on teaching (88%; 4.41 ± 0.75), while 85.9% of the students agreed that individual 3D-PSBs clarified the structures hidden within the skull (4.41 ± 0.75). The ball drop test revealed that the mechanical strength of the cement/PLA model was significantly greater than that of the cement or PLA model. The prices of the PVC, cement, and cement/PLA models were 234, 1.9, and 10 times higher than that of the 3D-PSB model, respectively. These findings imply that low-cost 3D-PSB models could revolutionize skull anatomical education by incorporating digital technologies like the QR system into the anatomical teaching repertoire.

Three-dimensional printing in ophthalmology and eye care: current applications and future developments

Three-dimensional (3D) printing uses a process of adding material in a layer-by-layer fashion to form the end product. This technology is advancing rapidly and is being increasingly utilized in the medical field as it becomes more accessible and cost-effective. It has an increasingly important role in ophthalmology and eyecare as its current and potential applications are extensive and slowly evolving. Three-dimensional printing represents an important method of manufacturing customized products such as orbital implants, ocular prostheses, ophthalmic models, surgical instruments, spectacles and other gadgets. Surgical planning, simulation, training and teaching have all benefitted from this technology. Advances in bioprinting seem to be the future direction of 3D printing with possibilities of printing out viable ocular tissues such as corneas and retinas in the future. It is expected that more ophthalmologists and other clinicians will use this technology in the near future.

Characterisation of Selected Materials in Medical Applications

Tissue engineering is an interdisciplinary field of science that has developed very intensively in recent years. The first part of this review describes materials with medical and dental applications from the following groups: metals, polymers, ceramics, and composites. Both positive and negative sides of their application are presented from the point of view of medical application and mechanical properties. A variety of techniques for the manufacture of biomedical components are presented in this review. The main focus of this work is on additive manufacturing and 3D printing, as these modern techniques have been evaluated to be the best methods for the manufacture of medical and dental devices. The second part presents devices for skull bone reconstruction. The materials from which they are made and the possibilities offered by 3D printing in this field are also described. The last part concerns dental transitional implants (scaffolds) for guided bone regeneration, focusing on polylactide–hydroxyapatite nanocomposite due to its unique properties. This section summarises the current knowledge of scaffolds, focusing on the material, mechanical and biological requirements, the effects of these devices on the human body, and their great potential for applications.

3D Printing in Eye Care

Three-dimensional printing enables precise modeling of anatomical structures and has been employed in a broad range of applications across medicine. Its earliest use in eye care included orbital models for training and surgical planning, which have subsequently enabled the design of custom-fit prostheses in oculoplastic surgery. It has evolved to include the production of surgical instruments, diagnostic tools, spectacles, and devices for delivery of drug and radiation therapy. During the COVID-19 pandemic, increased demand for personal protective equipment and supply chain shortages inspired many institutions to 3D-print their own eye protection. Cataract surgery, the most common procedure performed worldwide, may someday make use of custom-printed intraocular lenses. Perhaps its most alluring potential resides in the possibility of printing tissues at a cellular level to address unmet needs in the world of corneal and retinal diseases. Early models toward this end have shown promise for engineering tissues which, while not quite ready for transplantation, can serve as a useful model for in vitro disease and therapeutic research. As more institutions incorporate in-house or outsourced 3D printing for research models and clinical care, ethical and regulatory concerns will become a greater consideration. This report highlights the uses of 3D printing in eye care by subspecialty and clinical modality, with an aim to provide a useful entry point for anyone seeking to engage with the technology in their area of interest.

From CT to 3D Printed Models, Serious Gaming, and Virtual Reality: Framework for Educational 3D Visualization of Complex Anatomical Spaces From Within-the Pterygopalatine Fossa

We describe the framework for capturing the internal view of complex anatomical spaces via multiple media and haptic platforms, exemplified by realistic and conceptual representations of the pterygopalatine fossa (PPF). A realistic three-dimensional (3D) mesh of the PPF was developed by segmenting the osseous anatomy on computed tomography (CT) using Materialize InPrint. Subsequently in Autodesk 3D Studio Max, the realistic mesh was enhanced with graphically designed neurovascular anatomy and additionally a conceptual representation of the PPF with its connections and contents was created. An interactive web-compatible Adobe Flash tutorial using ActionScript was developed, allowing users to advance through a series of educational slides that contained interactive rotatable interior camera views and scrollable CT cross-sectional content, incorporating both the realistic and conceptual models. Both models were also 3D printed using polyamide material. In the realistic model, the neurovasculature was colored with water-based acrylic paint. A 3-piece modular design with embedded magnets allows for internal visualization and seamless assembly. A serious gaming environment of the conceptual PPF was also developed using Truevision3D application programming interface, where users can freely move around rooms and hallways that represent various spaces. Lastly, the realistic model was incorporated into a headset-based virtual reality environment, Surgical Theater, allowing visualization and fly-through inside and outside the model. Multiple 3D techniques for visualization of complex 3D anatomical spaces from within were described, with the necessary software and skills detailed. A rough estimate of the time and cost needed to develop these tools as well as multiple supplementary source and end result files are also made available. Educators could utilize multiple advanced delivery methods to incorporate custom digital 3D models of complex anatomical spaces understood from inside.

The Role of Three-Dimensional Printing Technology as an Additional Tool in Unilateral Condylar Hyperplasia Surgical Planning

The purpose of this study is to evaluate whether additive manufactory technology through the use of 3D mandible and skull cast models can provide additional support to the virtual surgical planning for patients affected by unilateral condylar hyperplasia (UCH). This study describes 2 patients affected by active UCH. Cone beam computed tomography (CBCT) scans were converted in STL files and then sent to a 3D printer that provided 3D cast models of patient's mandible and skull. Surgical planning was conducted performing linear measurement both on 3D virtual images and on 3D cast models. Proportional condylectomy was then simulated with the virtual software and on the 3D cast models as well. After 18 months, new CBCT scans of the patients were acquired and new 3D cast models were printed. Measurements performed on the 3D cast models were close and reliable if compared to measurements obtained on 3D virtual images. None of the patients underwent further surgeries obtaining stable results in terms of symmetry. 3D printing technologies have a relevant support for a more accurate planning and surgical treatment in UCH.

A Three-Dimensional Print Model of the Pterygopalatine Fossa Significantly Enhances the Learning Experience

The pterygopalatine fossa (PPF) is a bilateral space deep within the skull that serves as a major neurovascular junction. However, its small volume and poor accessibility make it a difficult space to comprehend using two-dimensional illustrations and cadaveric dissections. A three-dimensional (3D) printed model of the PPF was developed as a visual and kinesthetic learning tool for completely visualizing the fossa, its boundaries, its communicating channels, and its neurovascular structures. The model was evaluated by analyzing student performance on pre- and post-quizzes and a student satisfaction survey based on the five-point Likert scale. The first cohort comprised of 88 students who had never before studied the PPF. The second cohort consisted of 30 students who were previously taught the PPF. Each cohort was randomly divided into a control group who were provided with a half skull and an intervention group that were provided with the 3D printed model. The intervention group performed significantly better on the post-quiz as compared to the control group in cohort I (P = 0.001); while not significant, it also improved learning in cohort II students (P = 0.124). Satisfaction surveys indicated that the intervention group found the 3D printed model to be significantly more useful (P < 0.05) as compared to the half skull used by the control group. Importantly, the effect sizes for cohorts I and II (0.504 and 0.581, respectively) validated the statistical results. Together, this study highlights the importance of 3D printed models as teaching tools in anatomy education.

Evaluating phone camera and cloud service-based 3D imaging and printing of human bones for anatomical education

OBJECTIVE

To evaluate the feasibility of a phone camera and cloud service-based workflow to image bone specimens and print their three-dimensional (3D) models for anatomical education.

DESIGN

The images of four typical human bone specimens, photographed by a phone camera, were aligned and converted into digital images for incorporation into a digital model through the Get3D website and submitted to an online 3D printing platform to obtain the 3D printed models. The fidelity of the 3D digital, printed models relative to the original specimens, was evaluated through anatomical annotations and 3D scanning.

SETTING

The Morphologic Science Experimental Center, Central South University, China.

PARTICIPANTS

Specimens of four typical bones-the femur, rib, cervical vertebra and skull-were used to evaluate the feasibility of the workflow.

OUTCOME MEASURES

The gross fidelity of anatomical features within the digital models and 3D printed models was evaluated first using anatomical annotations in reference to Netter's Atlas of Human Anatomy. The measurements of the deviation were quantised and visualised for analysis in Geomagic Control 2015.

RESULTS

All the specimens were reconstructed in 3D and printed using this workflow. The overall morphology of the digital and 3D printed models displayed a large extent of similarity to the corresponding specimens from a gross anatomical perspective. A high degree of similarity was also noticed in the quantitative analysis, with distance deviations ≤2 mm present among 99% of the random sampling points that were tested.

CONCLUSION

The photogrammetric digitisation workflow adapted in the present study demonstrates fairly high precision with relatively low cost and fewer equipment requirements. This workflow is expected to be used in morphological/anatomical science education, particularly in institutions and schools with limited funds or in certain field research projects involving the fast acquisition of 3D digital data on human/animal bone specimens or on other remains.

Implementations of 3D printing in ophthalmology

PURPOSE

The purpose of this paper is to provide an in-depth understanding of how to best utilize 3D printing in medicine, and more particularly in ophthalmology in order to enhance the clinicians' ability to provide out-of-the-box solutions for unusual challenges that require patient personalization. In this review, we discuss the main applications of 3D printing for diseases of the anterior and posterior segments of the eye and discuss their current status and implementation. We aim to raise awareness among ophthalmologists and report current and future developments.

METHODS

A computerized search from inception up to 2018 of the online electronic database PubMed was performed, using the following search strings: "3D," "printing," "ophthalmology," and "bioprinting." Additional data was extracted from relevant websites. The reference list in each relevant article was analyzed for additional relevant publications.

RESULTS

3D printing first appeared three decades ago. Nevertheless, the implementation and utilization of this technology in healthcare became prominent only in the last 5 years. 3D printing applications in ophthalmology are vast, including organ fabrication, medical devices, production of customized prosthetics, patient-tailored implants, and production of anatomical models for surgical planning and educational purposes.

CONCLUSIONS

The potential applications of 3D printing in ophthalmology are extensive. 3D printing enables cost-effective design and production of instruments that aid in early detection of common ocular conditions, diagnostic and therapeutic devices built specifically for individual patients, 3D-printed contact lenses and intraocular implants, models that assist in surgery planning and improve patient and medical staff education, and more. Advances in bioprinting appears to be the future of 3D printing in healthcare in general, and in ophthalmology in particular, with the emerging possibility of printing viable tissues and ultimately the creation of a functioning cornea, and later retina. It is expected that the various applications of 3D printing in ophthalmology will become part of mainstream medicine.

Cone-beam computed tomography evaluation of the pterygomaxillary fissure and pterygopalatine fossa using 3D rendering programs

PURPOSE

The aim of this study was to investigate the detailed anatomy of the pterygomaxillary fissure (PMF) and pterygopalatine fossa (PPF) and variations therein using three-dimensional (3D) cone-beam computed tomography (CBCT) software.

METHODS

This study was based on a retrospective evaluation of CBCT scans. A total of 825 CBCT images of patients (448 females, 377 males) who met the inclusion criteria were analyzed. PMF shapes were classified, and morphometric measurements (PMF area and PPF volume) were performed according to age, right/left side, and gender using 3D rendering programs. Maxillary and sphenoid sinus pathologies were also classified to reveal possible correlations between morphometric measurements. Analysis of variance was used for comparisons. Multiple comparisons were assessed using the Bonferroni test. Pearson's test was used to assess correlations between parameters. A p value < 0.05 was considered to indicate statistical significance.

RESULTS

Six types of PMF shapes were defined. There were no significant differences in types according to gender, age or sinus pathology. Males had a significantly larger PMF area than females (p < 0.001). Left/right comparison of the PMF area revealed that the mean PMF coronal, axial, and sagittal area dimensions were significantly higher on the right side in all patients. Our results also indicated that the PMF area and PPF volume increased significantly after 40 years of age.

CONCLUSION

Various PMF shapes were defined and classified. PMF and PPF dimensions increased with age. Knowledge of these anatomical variations will allow surgeons to avoid damage to the neurovascular structures passing through the area.