Mirror-Imaged Rapid Prototype Skull Model and Pre-Molded Synthetic Scaffold to Achieve Optimal Orbital Cavity Reconstruction

Modeling Methods in Craniofacial Virtual Surgical Planning

Despite the widespread use of virtual surgical planning (VSP), few papers describe the modeling methods used to generate the digital simulations that underpin VSP. This paper aims to review the modeling methods that are currently available for use in VSP and the implications of their use in clinical practice. A literature review was undertaken of the two broad categories of modeling techniques; contour-based planning-namely mirroring from the contralateral side, templating from a normative database, and extrapolation from surrounding landmarks-and occlusal-based planning (OBP). The indications for each modeling method were discussed, including mandibular/maxillary reconstruction, pediatric craniofacial surgery, and orthognathic, as well as the limitations to the accuracy of modeling types. Unilateral defects of the upper/midface, wherein contour accuracy is paramount, are best reconstructed using mirroring methods, whereas bilateral defects-or cases with asymmetry due to craniofacial dysmorphology-are most suited to normative-data-based methods. Cases involving resection of the alveolar margin, in which functional occlusion is the primary outcome are best managed with OBP. Similarly, orthognathic surgery typically uses OBP, although complex cases involving asymmetry, such as clefts, may benefit from a combination of OBP and normative data methods. The choice of modeling methods is, therefore, largely driven by the defect type and the goals of reconstruction.

Technical considerations of computer-aided planning in severe orbital trauma: A retrospective study

The aim of this study was to evaluate the clinical outcomes of linear and orbital volume measurements in severe orbital trauma. Patients with severe orbital trauma that involved more than two walls and entailed a marked degree of comminution were included in this retrospective analysis. However, patients with incomplete clinical records and a simple blowout or zygmatico-orbital fractures were excluded. All the cases underwent surgical correction guided by virtual surgical planning and 3D-printed templates. The measurement protocol depended on assessing orbital dimensions, orbital volumetry, and the zygomatic bone's position in the three-dimensional planes. All patients' preoperative 3D CT scans were obtained, and DICOM files were imported into a three-dimensional image processing software. Data were then converted for 3D reconstruction in the axial, coronal, and sagittal views. A total of 18 patients with a mean age was 39.28 ± 6.28 were included in this study. The results revealed a significant difference between the pre and postoperative differences in distances in relation to the FHP (Frankfurt Horizontal Plane) (P = 0.0014) and sagittal planes (P < 0.0001). The orbital width and height of the traumatized orbit were significantly decreased from 45.26 ± 6.72 mm and 45.30 ± 2.89 mm to 39.74 ± 3.91 mm (P = 0.0022), and 40.34 ± 0.86 mm (P < 0.0001), respectively. Clinically, there was a satisfactory degree of symmetry regarding the zygomatic bones' position and orbital dimensions postoperatively. Moreover, the mean orbital volume on the traumatized side decreased significantly from 23.16 ± 1.91 cm³ preoperatively to 20.7 ± 1.96 cm³ postoperatively (P < 0.0001). These findings were associated with a low incidence of complications. Within the limitations of the study it seems that the described methodology is a relevant addition to clinical treatment options. It incorporates all the latest technology to plan virtual reconstruction surgery in the treatment of complex orbital trauma and should be adapted accordingly in cases of severe displacement and comminution.

Patient-specific Implants for Orbital Fractures: A Systematic Review

PURPOSE

Orbital fractures are common facial fractures that can be challenging to repair and require careful attention to avoid unacceptable ophthalmic complications. Customized implants that are unique to an individual patient, or patient-specific implants (PSIs), have been increasingly used to repair orbital wall fractures. This systematic review summarizes the current evidence regarding custom-made orbital wall implants.

METHODS

A keyword search of published literature from January 2010 to September 2021 was performed using Ovid MEDLINE, PubMed, and the Cochrane Library databases. Original articles that included more than 3 human subjects with an orbital fracture repaired with a PSI were included. The search results were reviewed, duplicates were removed and relevant articles were included for analysis.

RESULTS

Fifteen articles meeting the inclusion criteria. The articles were categorized into 3 separate groups based on the method of PSI fabrication: manual molding of a PSI on a 3D-printed orbital model (53%), directly from a 3D printer (27%), or via a template fabricated from a 3D printer (20%). Three primary postoperative outcomes were assessed: rates of diplopia, enophthalmos, and orbital volume. Postoperative rates of diplopia and enophthalmos improved regardless of the PSI technique, and postoperative orbital volumes were reduced compared with their preoperative state. When PSIs were compared to conventional implants, patient outcomes were comparable.

CONCLUSIONS

This review of existing PSI orbital implant literature highlights that while PSI can accurately and safely repair orbital fractures, patient outcomes are largely comparable to orbital fractures repaired by conventional methods, and PSI do not offer a definitive benefit over conventional implants.

Controversies and Contemporary Management of Orbital Floor Fractures

Substantial controversy exists regarding the timing of intervention and management of patients with orbital floor fractures. Recent advances in computer-aided technology, including the use of 3-dimensional printing, intraoperative navigational imaging, and the use of novel implants, have allowed for improvement in prospective management modalities. As such, this article aims to review the indications and timing of repair, surgical approaches, materials used for repair, and contemporary adjuncts to repair. Indications for orbital floor fracture repair remain controversial as many of these fractures heal without intervention or adverse sequelae. Intraoperative navigation and imaging, as well as endoscopic guidance, can improve visualization of defects mitigating implant positioning errors, thereby reducing the need for secondary corrective procedures. Patient-specific implants may be constructed to fit the individual patient's anatomy using the preoperative CT dataset and mirroring the contralateral unaffected side and have been shown to improve pre-operative efficiency and minimize postoperative complications. With increased data, we can hope to form evidence-based indications for using particular biomaterials and the criteria for orbital defect characteristics, which may be best addressed by a specific surgical approach.

Accuracy of the Application of 3-Dimensional Printing Models in Orbital Blowout Fractures-A Preliminary Study

BACKGROUND

Application of 3-dimensional (3D) printing technology has grown in the medical field over the past 2 decades. In managing orbital blowout fractures, 3D printed models can be used as intraoperative navigators and could shorten the operational time by facilitating prebending or shaping of the mesh preoperatively. However, a comparison of the accuracy of computed tomography (CT) images and printed 3D models is lacking.

MATERIAL AND METHODS

This is a single-center retrospective study. Patients with unilateral orbital blowout fracture and signed up for customized 3D printing model were included. Reference points for the 2D distance were defined (intersupraorbital notch distance, transverse horizontal, sagittal vertical, and anteroposterior axes for orbital cavity) and measured directly on 3D printing models and on corresponding CT images. The difference and correlation analysis were conducted.

RESULTS

In total, 9 patients were reviewed from June 2017 to December 2020. The mean difference in the intersupraorbital notch measurement between the 2 modules was -0.14 mm (P = 0.67). The mean difference in the distance measured from the modules in the horizontal, vertical, and anteroposterior axes of the traumatic orbits was 0.06 mm (P = 0.85), -0.23 mm (P = 0.47), and 0.51 mm (P = 0.32), whereas that of the unaffected orbits was 0.16 mm (P = 0.44), 0.34 mm (P = 0.24), and 0.1 mm (P = 0.88), respectively. Although 2D parameter differences (<1 mm) between 3D printing models and CT images were discovered, they were not statistically significant.

CONCLUSIONS

Three-dimensional printing models showed high identity and correlation to CT image. Therefore, personalized models might be a reliable tool of virtual surgery or as a guide in realistic surgical scenarios for orbital blowout fractures.

Is the Mirroring Technology Reliable in the Use of Computer-Aided Design for Orbital Reconstruction? Three-Dimensional Analysis of Asymmetry in the Orbits

BACKGROUND

Reconstruction of the orbital area remains a challenge in many cases. The recently introduced mirroring technology provides surgeons with patient-specific information for accurate orbital reconstruction; its premise is that the three-dimensional anatomy of craniofacial bone is symmetric. The purpose of this study was to verify this premise of the mirroring technology by assessing three-dimensional asymmetry.

METHODS

Facial computed tomographic data of 104 patients were imported into iPlan software. Four reference points (i.e., zygomaticofrontal suture, frontomaxillary suture, infraorbital foramen, and optic canal) were set, and the three-dimensional distances from these points to the anterior nasal spine on the mirroring plane were calculated. In addition, the orbital cavity volume and the three-dimensional distances from point optic canal to the other reference points were calculated for the assessment of the orbit anatomy. Three plastic surgeons performed these processes independently.

RESULTS

No statistically significant difference was found in the three-dimensional distances between anterior nasal spine and the four reference points bilaterally. Also, no statistically significant difference in the three-dimensional distances between the point representing the optic canal and other reference points was detected bilaterally. Orbital cavity volume showed a mild asymmetry, but the discrepancy was acceptable for computer-aided design applications. For all reference points, the maximum value of the 95 percent CI was less than 1.4 mm.

CONCLUSIONS

The three-dimensional location of the orbits and the three-dimensional anatomy of the orbit were symmetric. Thus, the mirroring technology could be a reliable first step in computer-aided design, computer-assisted surgery, and navigation-assisted surgery.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Clinical acceptance of advanced visualization methods: a comparison study of 3D-print, virtual reality glasses, and 3D-display

BACKGROUND

To compare different methods of three-dimensional representations, namely 3D-Print, Virtual Reality (VR)-Glasses and 3D-Display regarding the understanding of the pathology, accuracy of details, quality of the anatomical representation and technical operability and assessment of possible change in treatment in different disciplines and levels of professional experience.

METHODS

Interviews were conducted with twenty physicians from the disciplines of cardiology, oral and maxillofacial surgery, orthopedic surgery, and radiology between 2018 and 2020 at the University Hospital of Basel. They were all presented with three different three-dimensional clinical cases derived from CT data from their area of expertise, one case for each method. During this, the physicians were asked for their feedback written down on a pencil and paper questionnaire.

RESULTS

Concerning the understanding of the pathology and quality of the anatomical representation, VR-Glasses were rated best in three out of four disciplines and two out of three levels of professional experience. Regarding the accuracy of details, 3D-Display was rated best in three out of four disciplines and all levels of professional experience. As to operability, 3D-Display was consistently rated best in all levels of professional experience and all disciplines. Possible change in treatment was reported using 3D-Print in 33%, VR-Glasses in 44%, and 3D-Display in 33% of participants. Physicians with a professional experience of more than ten years reported no change in treatment using any method.

CONCLUSIONS

3D-Print, VR-Glasses, and 3D-Displays are very well accepted, and a relevant percentage of participants with less than ten years of professional work experience could imagine a possible change in treatment using any of these three-dimensional methods. Our findings challenge scientists, technicians, and physicians to further develop these methods to improve the three-dimensional understanding of pathologies and to add value to the education of young and inexperienced physicians.

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.

Endoscopic repair of combined orbital floor and medial wall fractures involving the inferomedial strut

OBJECTIVES

To evaluate the safety, efficacy, and feasibility of an endoscopic transconjunctival inferior fornix and precaruncular approach for repair of combined orbital medial wall and floor fractures involving the inferomedial strut.

METHODS

A retrospective study was performed in 84 patients with combined orbital medial wall and floor fractures involving the inferomedial strut. All patients underwent surgery by endoscopic transconjunctival inferior fornix and precaruncular approach. A large polyester mesh plate was implanted to cover the fracture defect. The enophthalmos, diplopia, and surgical complications were evaluated pre- and postoperatively. Patients were followed for at least 6 months.

RESULTS

A total of 84 patients (55 men and 29 women) with a mean age of 36.88 ± 12.95 years were included in this study. Preoperatively, all 84 patients had an enophthalmos >2 mm, and the mean exophthalmometry measurement was 11.6 ± 2.14 mm. Diplopia was presented in 33 patients. Postoperatively, good symmetry was acquired in 81 of 84 patients, with a mean improvement of 3.02 ± 0.99 mm in the enophthalmos (P < 0.05). Recovery from diplopia occurred in 32 of 33 patients. A new onset of diplopia occurred postoperatively in 13 of the remaining 51 patients, only to recover spontaneously after 1 month. One patient suffered retrobulbar hemorrhage after surgery and was cured by conservative therapy. No other serious complications occurred.

CONCLUSIONS

The endoscopic transconjunctival inferior fornix and precaruncular approach is a promising management technique for combined orbital medial wall and floor fractures involving the inferomedial strut.

A review of additive manufacturing applications in ophthalmology

Additive Manufacturing (AM) capabilities in terms of product customization, manufacture of complex shape, minimal time, and low volume production those are very well suited for medical implants and biological models. AM technology permits the fabrication of physical object based on the 3D CAD model through layer by layer manufacturing method. AM use Magnetic Resonance Image (MRI), Computed Tomography (CT), and 3D scanning images and these data are converted into surface tessellation language (STL) file for fabrication. The applications of AM in ophthalmology includes diagnosis and treatment planning, customized prosthesis, implants, surgical practice/simulation, pre-operative surgical planning, fabrication of assistive tools, surgical tools, and instruments. In this article, development of AM technology in ophthalmology and its potential applications is reviewed. The aim of this study is nurturing an awareness of the engineers and ophthalmologists to enhance the ophthalmic devices and instruments. Here some of the 3D printed case examples of functional prototype and concept prototypes are carried out to understand the capabilities of this technology. This research paper explores the possibility of AM technology that can be successfully executed in the ophthalmology field for developing innovative products. This novel technique is used toward improving the quality of treatment and surgical skills by customization and pre-operative treatment planning which are more promising factors.

Patient-Specific Implants in Oculofacial Plastic Surgery

PURPOSE

To investigate how patient-specific implants (PSIs) are being utilized for periocular facial skeletal reconstruction. Specifically, to characterize indications for custom implants, areas of reconstruction, intraoperative variables impacting implant placement, as well as to report on postoperative outcomes.

MATERIALS AND METHODS

A retrospective chart review was performed for patients who received a PSI for periocular skeletal reconstruction between 2015 and 2019. Three independent academic centers were included in this study, which encompassed 4 different primary surgeons. Medical records, radiographic imaging, and operative reports were reviewed.

RESULTS

Eleven patients, 8 females and 3 males, ages ranging from 15 to 63 years old received PSIs. The average duration of follow up was 16 months ± 6.6 months (range: 9-30 months). The most common underlying etiology for reconstruction was prior trauma (54.5%) followed by benign tumor resection (18.2%). The most frequent area of reconstruction involved the inferior orbital rim and adjacent maxilla (63.6%). Implant materials included porous polyethylene, polyetheretherketone, and titanium. Six implants required intraoperative modification, most commonly accommodate critical neurovascular structures (66.6%) or improve contour (33.3%). Two postoperative complications were noted, both in the form of infection with 1 implant requiring removal.

CONCLUSIONS

Reconstruction of complex facial skeletal defects can be achieved by utilizing computer-assisted design software and 3D printing techniques to create PSIs. These implants represent the most customizable option for symmetric restoration of the facial skeleton by not only addressing structural deficits but also volumetric loss. This was particularly apparent in reconstruction of the orbital rim and midface. PSIs were found to be of most benefit in patients with prior trauma or complex skeletal defects after tumor resection.

The use of a 3D-printed individualized navigation template to assist in the anatomical reconstruction surgery of the anterior cruciate ligament

Background

To explore the location accuracy and early clinical outcomes of using a 3D-printed individualized navigation template to assist in the reconstruction of the anterior cruciate ligament (ACL).

Methods

A single center randomized control study was conducted. Patients with ACL injury were treated with a conventional operation or an operation assisted by a 3D-printed individualized navigation template (the 3D group). The primary endpoint was the accuracy of the actual reconstruction compared with the planned position.

Results

There were 20 and 23 participants in the conventional group and the 3D group, respectively. There were no differences in the bone tunnel position between the actual postoperative position and the preoperative design in the 3D group (P>0.05). Compared with the 3D group, the positioning of the femoral tunnel was more inferior and shallower in the conventional group (P<0.05). The position of the tibia tunnel was closer to the anterior and medial edge of the tibial platform in the conventional group compared to the 3D group (P<0.05). The intraoperative positioning time was shorter in the 3D group than in the conventional group (3.3±1.0 vs. 5.9±1.8 minutes, P<0.001). The Lysholm and International Knee Documentation Committee scores did not differ between the two groups (P>0.05 for both), and all patients improved after surgery (P<0.001).

Conclusions

The 3D-printed individualized navigation template showed good location accuracy and resulted in reduced intraoperative positioning time compared to the traditional method for ACL reconstruction.

Aging of the Adult Bony Orbit

BACKGROUND

Accurate quantitative data of the adult bony orbital volume and dimension are needed for treatment optimization. In the present study, the authors aim to evaluate adult orbital volume and corresponding linear dimensions according to age, volume, and individual symmetry.

METHODS

Seventy computerized tomography facial scans of adults were randomly chosen from an institutional database and 3-dimensionally reconstructed. Studies were excluded for orbital pathology or incomplete radiographic data. Anatomic landmarks were marked. Interval linear distances and orbital volumes were calculated. Data were analyzed using paired T-tests, independent T-tests, linear regression analysis, and 1-way analysis of variance.

RESULTS

A total of 140 orbits from 70 patients were analyzed (female = 35, male = 35), ranging from 20 to 88 years of age. Orbital volume was similar between an individual's left and right side; however, a difference was observed in vertical orbital height, orbital width, inferior orbital rim position, orbital roof length, orbital width, and medial orbital wall length (0.45, 0.64, 0.4, 0.77, 0.97, and 5.1 mm, respectively; P < 0.05). In comparison to females, males averaged larger orbital volume by 3.07 cm (29.58 cm versus 26.51 cm, P = 0.0002), medial wall length by 2.66 mm (P < 0.05), and orbital width by 2.66 mm (P < 0.05). Orbital volume did not correlate with patient age, while lateral wall length was correlative.

CONCLUSION

This accurate normative data of the adult bony orbit impacts key aspects of patient diagnosis and treatment and also suggest clinical signs of periorbital aging are not due to bony orbital changes.

Theoretical model of pediatric orbital trapdoor fractures and provisional personalized 3D printing-assisted surgical solution

Pediatric orbital trapdoor fractures are common in children and adolescents and usually require emergency surgical intervention. Herein, a personalized 3D printing-assisted approach to surgical treatment is proposed, serving to accurately and effectively repair pediatric orbital trapdoor fractures. We first investigated stress distribution in external force-induced orbital blowout fractures via numerical simulation, determining that maximum stresses on inferior and medial walls exceed those on superior and lateral walls and thus confer higher probability of fracture. We also examined 36 pediatric patients treated for orbital trapdoor fractures between 2014 and 2019 to verify our theoretical construct. Using 3D printing technique, we then created orbital models based on computed tomography (CT) studies of these patients. Absorbable implants were tailor-made, replicating those of 3D-printed models during surgical repairs of fractured orbital bones. As follow-up, we compared CT images and clinical parameters (extraocular movements, diplopia, enophthalmos) before and 12 months after operative procedures. There were only two patients with diplopia and six with enophthalmos >2 mm at 12 months, attesting to the efficacy of our novel 3D printing-assisted strategy.

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Numerical simulation is used to theoretically investigate the mechanism of external force-induced orbital blowout fractures.

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3D printing--assisted surgical treatment is proposed to effectively repair pediatric orbital trapdoor fractures.

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Clinical studies are performed by repairing fractured orbital bones via 3D printed customized absorbable implants.

An Exploration of Multidisciplinary Team Care With Digital Technology for Complicated Cranio-Maxillofacial Bone Defects and Fractures

OBJECTIVE

Early treatment of fractures of the cranio-maxillofacial complex (CMFC) is challenging and likely to result in craniofacial deformity. Multidisciplinary team (MDT) care has developed very rapidly and has recently been accepted in cancer treatment. Therefore, the authors explored the application of MDT care with digital technology in CMFC fractures.

STUDY DESIGN

A 29-year-old man presented for treatment of CMFC fractures and bone defects. An MDT of oral surgeons, ophthalmic surgeons, neurological surgeons, and other experts was convened. After CT scan and three-dimensional reconstruction, the authors performed personalized surgery that included 9 specialists over an 8-hour period.

RESULTS

The operation was successful and all fractures achieved clinical stability. At 1-month follow-up, appropriate appearance and functional recovery had been achieved.

CONCLUSION

In this study, MDT care with digital technology was very effective and had low associated costs. The involvement of more disciplines in MDT care may result in fewer complications.

Three-Dimensional Diagnosis in Orbital Reconstructive Surgery

Introduction

Orbital floor fractures are common among mid-face fractures. The general aim of treatment is to restore orbital volume and anatomy with grafts or reconstructive materials. Malpositioning of the implants and inadequate volume restorations are common complications of these procedures. The aim of our study is to present the surgical outcomes of orbital reconstruction aided by our algorithm of patient-specific virtual planning.

Materials and Methods

The current study was performed on 77 patients with orbital wall fractures who were categorized into two groups: Group A - 42 patients (virtual planning) and Group B - 35 patients (traditional approach). Criteria of analysis included the presence of diplopia postoperatively and duration of surgical procedures.

Results

Diplopia was recorded right after surgery in 16 cases (38.1%) of Group A and in 12 cases (34.3%) of Group B. However, 6 months postreconstruction, residual diplopia was recorded in 4 cases (9.5%) of Group A and in 12 cases (34.3%) of Group B. Mean operation time in Group A for the patients with isolated zygoma fracture was 2.23 h; for isolated orbital wall fracture was 1.98 h; and for combined zygoma, orbital wall, and facial bone fracture was 3.07 h. In Group B, these indexes were 3.47, 2.05, and 3.31 h, respectively.

Conclusions

Application of virtual planning could significantly improve postoperative outcomes in orbital reconstruction. However, application of this technology could be limited by complicated defects of the orbital walls, which would require complex shape of the implant that might be difficult to be prevent virtually.

Analysis of Orbital Morphology and its Relationship With Eyelid Morphology

Correct anatomical reconstruction of the orbital wall for function and cosmesis is important; however, this is difficult because of the structure's complexity. The authors aimed to analyze and classify orbital morphology from computed tomography (CT) images and examine the relationship between orbital morphology and eyelid morphology in the Japanese population. CT images of 60 men (right side, 29; left side, 31) and 44 women (each side, 22) were included. The lengths of the orbital medial wall and floor in the coronal plane at the anterior, middle, and posterior planes of the orbit; angle between them; simotic index; and the thickness of upper eyelid were measured. Additionally, the presence or absence of double eyelids was evaluated. Non-paired Student's t test and Pearson correlation coefficient test were used for analysis. Orbital morphology was symmetrical on both sides, and men had a larger orbit than women. Orbital morphology was classified into 2 groups according to the posterior angle, and there was a difference between the groups in the simotic index. The difference between groups may represent a genetic difference between the Jomon and Yayoi people and not only provide a new classification for the orbit of the population but also be useful in orbital reconstruction.

Cost Analysis for In-house versus Industry-printed Skull Models for Acute Midfacial Fractures

Industry-printed (IP) 3-dimensional (3D) models are commonly used for secondary midfacial reconstructive cases but not for acute cases due to their high cost and long turnaround time. We have begun using in-house (IH) printed models for complex unilateral midface trauma. We hypothesized that IH models would decrease cost and turnaround time, compared with IP models.

Three-Dimensional Analysis of Isolated Orbital Floor Fractures Pre- and Post-Reconstruction with Standard Titanium Meshes and "Hybrid" Patient-Specific Implants

The aim of this study was to compare the efficacy of the intraoperative bending of titanium mesh with the efficacy of pre-contoured “hybrid” patient-specific titanium mesh for the surgical repair of isolated orbital floor fractures. In-house 3D-printed anatomical models were used as bending guides. The main outcome measures were preoperative and postoperative orbital volume and surgery time. We performed a retrospective cohort study including 22 patients who had undergone surgery between May 2016 and November 2018. The first twelve patients underwent conventional reconstruction with intraoperative free-hand bending of an orbital floor mesh plate. The subsequent ten patients received pre-contoured plates based on 3D-printed orbital models that were produced by mirroring the non-fractured orbit of the patient using a medical imaging software. We compared the preoperative and postoperative absolute volume difference (unfractured orbit, fractured orbit), the fracture area, the fracture collapse, and the effective surgery time between the two groups. In comparison to the intraoperative bending of titanium mesh, the application of preformed plates based on a 3D-printed orbital model resulted in a non-significant absolute volume difference in the intervention group (p = 0.276) and statistically significant volume difference in the conventional group (p = 0.002). Further, there was a significant reduction of the surgery time (57.3 ± 23.4 min versus 99.8 ± 28.9 min, p = 0.001). The results of this study suggest that the use of 3D-printed orbital models leads to a more accurate reconstruction and a time reduction during surgery.

3D Printing as a Significant Achievement for Application in Posttraumatic Surgeries - A Literature Review

BACKGROUND

3D printing is increasingly used in many fields of medicine. The broadening of knowledge in this field and the cooperation of doctors and engineers increase the interest in this technology and results in attempts to implement it at every stage of the treatment.

OBJECTIVE

The review aims to summarize the current literature on the use of 3D printing technology in the treatment of post-trauma patients.

METHODS

A review of available scientific publications in PubMed regarding 3D printing and its application in the context of posttraumatic procedures was carried out. Clinical Trials and Reviews from the period 2014-2019 (6-year period) were taken into consideration. The database was searched for "Printing", "ThreeDimensional" [MAJR] [MeSH Term]. Finally, 48 studies have been included in our review article.

RESULTS

3D printing technology has a number of applications in patients who have suffered injuries. 3D printing has found application in the preparation of procedures, accurate visualization of occurring injuries and complications, education of doctors and patients, prototyping, creation of synthetic scaffolding, production and implementation of target implants and rehabilitation.

CONCLUSION

3D printing is increasingly used in providing for posttraumatic patients. It is necessary to conduct further research in this area and to provide development opportunities regarding biopolymers and bioprinting. It is also necessary to improve cooperation between doctors and engineers and to create new centres that can comprehensively use 3D printing - from imaging diagnostics to the production of implants and their surgical use.

Development of 18 Quality Control Gates for Additive Manufacturing of Error Free Patient-Specific Implants

Unlike subtractive manufacturing technologies, additive manufacturing (AM) can fabricate complex shapes from the macro to the micro scale, thereby allowing the design of patient-specific implants following a biomimetic approach for the reconstruction of complex bone configurations. Nevertheless, factors such as high design variability and changeable customer needs are re-shaping current medical standards and quality control strategies in this sector. Such factors necessitate the urgent formulation of comprehensive AM quality control procedures. To address this need, this study explored and reported on a variety of aspects related to the production and the quality control of additively manufactured patient-specific implants in three different AM companies. The research goal was to develop an integrated quality control procedure based on the synthesis and the adaptation of the best quality control practices with the three examined companies and/or reported in literature. The study resulted in the development of an integrated quality control procedure consisting of 18 distinct gates based on the best identified industry practices and reported literature such as the Food and Drug Administration (FDA) guideline for AM medical devices and American Society for Testing and Materials (ASTM) standards, to name a few. This integrated quality control procedure for patient-specific implants seeks to prepare the AM industry for the inevitable future tightening in related medical regulations. Moreover, this study revealed some critical success factors for companies developing additively manufactured patient-specific implants, including ongoing research and development (R&D) investment, investment in advanced technologies for controlling quality, and fostering a quality improvement organizational culture.

Application of Three-Dimensional Printing Technology for Improved Orbital-Maxillary-Zygomatic Reconstruction

The reconstruction of orbital-maxillary-zygomatic complex (OMZC) on patients suffering from trauma and space-occupying lesions is challenging due to the irregularity of craniomaxillofacial bones. To overcome the challenge in precise OMZC reconstruction, individual three-dimensional (3D) disease models and mirror-imaged 3D reconstruction models were printed on the basis of the computer tomography. Preoperative planning by rehearsing surgical procedures was made on the 3D disease models and the scaffolds including titanium and absorbable meshes or plates were anatomically premolded using the mirror-imaged 3D models as guide. Many benefits were achieved including more precise OMZC reconstruction, fluent and smooth procedures of surgeries, shorter operation time, less blood loss, and improved cosmetic outcomes of craniomaxillofacial shapes. There were no complications such as diplopia, infection, foreign body reaction, exophthalmos, enophthalmos, disordered occlusal relationship, and hematoma. And patients were satisfied with the functional and esthetic outcome during the following-up time. Therefore, OMZC reconstruction can be optimized and successful through preoperative planning and premolded scaffolds with 3D printing bone model by computer-aid design and manufacturing.

Clinical Application of a Specific Simulation Software for 3-Dimensional Orbital Volume Modeling for Orbital Wall Reconstruction

In this study, we developed a new 3-dimensional (3D) preoperative planning software and investigated its effectiveness by measuring orbital volume change. Fifty-six patients who underwent unilateral orbital wall reconstruction between December 2015 and February 2018 in our institute were recruited. We developed an orbit-specific automatic 3D modeling software (Osteopore CMF 3D) that can automatically detect orbital fracture site, process mirroring, measure volume, and then produce a customized orbital implant. Using preoperative and postoperative 3D computed tomography, orbital volume was measured and compared between Osteopore CMF 3D and the widely used Mimics. Intraclass correlation coefficient between Osteopore CMF 3D and Mimics showed 90.6% concordance for preoperative injured site orbital volume and 86.7% concordance for postoperative orbital volume, both being statistically significant (preoperative intraclass correlation coefficient, 0.906 [confidence interval {CI}, 0.840-0.945; P < 0.000]; postoperative intraclass correlation coefficient, 0.867 [CI, 0.773-0.922; P < 0.000]). For uninjured sites, the 2 software packages showed 76.6% preoperative concordance and 83.9% postoperative concordance, both being statistically significant (preoperative intraclass correlation coefficient, 0.766 [CI, 0.600-0.863; P < 0.000]; postoperative intraclass correlation coefficient, 0.839 [CI, 0.725-0.905; P < 0.000]). This study introduces our newly developed 3D surgical planning software specialized for orbital wall reconstruction and demonstrates its performance to be comparable with that of a widely used software.

Radiological Society of North America (RSNA) 3D printing Special Interest Group (SIG): guidelines for medical 3D printing and appropriateness for clinical scenarios

Medical three-dimensional (3D) printing has expanded dramatically over the past three decades with growth in both facility adoption and the variety of medical applications. Consideration for each step required to create accurate 3D printed models from medical imaging data impacts patient care and management. In this paper, a writing group representing the Radiological Society of North America Special Interest Group on 3D Printing (SIG) provides recommendations that have been vetted and voted on by the SIG active membership. This body of work includes appropriate clinical use of anatomic models 3D printed for diagnostic use in the care of patients with specific medical conditions. The recommendations provide guidance for approaches and tools in medical 3D printing, from image acquisition, segmentation of the desired anatomy intended for 3D printing, creation of a 3D-printable model, and post-processing of 3D printed anatomic models for patient care.

Use of 3-D printing technologies in craniomaxillofacial surgery: a review

Three-dimensional (3-D) printing is a method of manufacturing in which materials like plastic or metal are deposited onto one another in layers to produce a 3-D object. Because of the complex anatomy of craniomaxillofacial structures, full recovery of craniomaxillofacial tissues from trauma, surgeries, or congenital malformations is extremely challenging. 3-D printing of scaffolds, tissue analogs, and organs has been proposed as an exciting alternative to address some of these key challenges in craniomaxillofacial surgery. There are four broad types of 3-D printing surgical applications that can be used in craniomaxillofacial surgery: contour models (positive-space models to allow preapplication of hardware before surgery), guides (negative-space models of actual patient data to guide cutting and drilling), splints (negative-space models of virtual postoperative positions to guide final alignment), and implants (negative-space 3-D printed implantable materials or 3-D printed molds into which nonprintable materials are poured). 3-D printing technology is being successfully used for surgeries for head and neck malignancies, mandibular reconstruction, orthognathic surgeries, for mandibulectomies after osteoradionecrosis, orbital floor fracture surgeries, nasal reconstruction, and cranioplasties. The excitement behind 3-D printing continues to increase and hopefully will drive improvements in the technology and its surgical applications, especially in craniomaxillofacial region. This present review sets out to explore use of 3-D printing technologies in craniomaxillofacial surgery.

Generation of customized orbital implant templates using 3-dimensional printing for orbital wall reconstruction

OBJECTIVES

To describe and evaluate a novel surgical approach to orbital wall reconstruction that uses three-dimensionally (3D) printed templates to mold a customized orbital implant.

METHODS

A review was conducted of 11 consecutive patients who underwent orbital wall reconstruction using 3D-printed customized orbital implant templates. In these procedures, the orbital implant was 3D pressed during surgery and inserted into the fracture site. The outcomes of this approach were analyzed quantitatively by measuring the orbital tissue volumes within the bony orbit using computed tomography.

RESULTS

All 11 orbital wall reconstructions (6 orbital floor and 5 medial wall fractures) were successful with no post operative ophthalmic complications. Statistically significant differences were found between the preoperative and post operative orbital tissue volumes for the affected orbit (24.00 ± 1.74 vs 22.31 ± 1.90 cm³; P = 0.003). There was no statistically significant difference found between the tissue volume of the contralateral unaffected orbit and the affected orbit after reconstruction (22.01 ± 1.60 cm³ vs 22.31 ± 1.90 cm³; P = 0.182).

CONCLUSION

3D-printed customized orbital implant templates can be used to press and trim conventional implantable materials with patient-specific contours and sizes for optimal orbital wall reconstruction. It is difficult to design an orbital implant that exactly matches the shape and surface of a blowout fracture site due to the unique 3D structure of the orbit. The traditional surgical method is to visually inspect the fracture site and use eye measurements to cut a two-dimensional orbital implant that corresponds to the anatomical structure of the fracture site. However, implants that do not fit the anatomical structure of a fracture site well can cause complications such as enophthalmos, diplopia and displacement of the implant.

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.

DESIGN OF A MAXILLOFACIAL PROSTHESIS BASED ON TOPOLOGY OPTIMIZATION

The use of custom implants has recently gained increasing importance in craniofacial surgery in order to optimize preoperative planning and reduce operative time. The design of patient-specific implants plays an important role to restore craniofacial bone. Nevertheless, the design method has become the bottleneck. In this study, a new design method of a maxillofacial prosthesis based on the topology optimization was proposed to realize lightweight custom implants. At first, parametric predesign of the optimized model was carried out to ensure that the optimized model conformed to the main physiological anatomical structure and recover basic function structure. Then, the design region is defined under given load and boundary conditions. The material interpolation technique of SIMP with the penalization factor is adopted to get the final optimized 3D model. Finally, the experimental results verify that the method of topology optimization for the maxillofacial prosthesis proposed is efficient.

Applications of Computer Technology in Complex Craniofacial Reconstruction

Background:

To demonstrate our use of advanced 3-dimensional (3D) computer technology in the analysis, virtual surgical planning (VSP), 3D modeling (3DM), and treatment of complex congenital and acquired craniofacial deformities.

Methods:

We present a series of craniofacial defects treated at a tertiary craniofacial referral center utilizing state-of-the-art 3D computer technology. All patients treated at our center using computer-assisted VSP, prefabricated custom-designed 3DMs, and/or 3D printed custom implants (3DPCI) in the reconstruction of craniofacial defects were included in this analysis.

Results:

We describe the use of 3D computer technology to precisely analyze, plan, and reconstruct 31 craniofacial deformities/syndromes caused by: Pierre-Robin (7), Treacher Collins (5), Apert’s (2), Pfeiffer (2), Crouzon (1) Syndromes, craniosynostosis (6), hemifacial microsomia (2), micrognathia (2), multiple facial clefts (1), and trauma (3). In select cases where the available bone was insufficient for skeletal reconstruction, 3DPCIs were fabricated using 3D printing. We used VSP in 30, 3DMs in all 31, distraction osteogenesis in 16, and 3DPCIs in 13 cases. Utilizing these technologies, the above complex craniofacial defects were corrected without significant complications and with excellent aesthetic results.

Conclusion:

Modern 3D technology allows the surgeon to better analyze complex craniofacial deformities, precisely plan surgical correction with computer simulation of results, customize osteotomies, plan distractions, and print 3DPCI, as needed. The use of advanced 3D computer technology can be applied safely and potentially improve aesthetic and functional outcomes after complex craniofacial reconstruction. These techniques warrant further study and may be reproducible in various centers of care.

Correction of a Posttraumatic Orbital Deformity Using Three-Dimensional Modeling, Virtual Surgical Planning with Computer-Assisted Design, and Three-Dimensional Printing of Custom Implants

We describe a case of complex, posttraumatic skull and orbital deformities that were evaluated and treated with advanced computer technology, including virtual surgical planning, three-dimensional (3D) modeling, and printed patient custom implants (PCI) fabricated by 3D printing. A 50-year-old man presented to our craniofacial referral center 1 year after failed reduction of complex left orbital, zygomatic, and frontal bone fractures due to a motorcycle collision. The patient's chief complaint was debilitating diplopia in all fields of gaze. On examination, he had left enophthalmos, left canthal displacement, lower eyelid ectropion, vertical orbital dystopia, and a laterally and inferiorly displaced, comminuted zygoma with orbital rim and frontal bone defects. The normal orbit was mirrored to precisely guide repositioning of the globe, orbital reconstruction, and cranioplasty. Preinjury appearance with normal globe position was restored with complete resolution of diplopia. Modern 3D technology allows the surgeon to better analyze complex orbital deformities and precisely plan surgical correction with the option of printing a PCI. These techniques were successfully applied to resolve a case of debilitating diplopia and aesthetic deficits after facial trauma. Further application of advanced 3D computer technology can potentially improve the results of severe orbital and craniofacial trauma reconstruction.

Recent advances in the reconstruction of cranio-maxillofacial defects using computer-aided design/computer-aided manufacturing

With the development of computer-aided design/computer-aided manufacturing (CAD/CAM) technology, it has been possible to reconstruct the cranio-maxillofacial defect with more accurate preoperative planning, precise patient-specific implants (PSIs), and shorter operation times. The manufacturing processes include subtractive manufacturing and additive manufacturing and should be selected in consideration of the material type, available technology, post-processing, accuracy, lead time, properties, and surface quality. Materials such as titanium, polyethylene, polyetheretherketone (PEEK), hydroxyapatite (HA), poly-DL-lactic acid (PDLLA), polylactide-co-glycolide acid (PLGA), and calcium phosphate are used. Design methods for the reconstruction of cranio-maxillofacial defects include the use of a pre-operative model printed with pre-operative data, printing a cutting guide or template after virtual surgery, a model after virtual surgery printed with reconstructed data using a mirror image, and manufacturing PSIs by directly obtaining PSI data after reconstruction using a mirror image. By selecting the appropriate design method, manufacturing process, and implant material according to the case, it is possible to obtain a more accurate surgical procedure, reduced operation time, the prevention of various complications that can occur using the traditional method, and predictive results compared to the traditional method.

Patient-specific puzzle implant preformed with 3D-printed rapid prototype model for combined orbital floor and medial wall fracture

BACKGROUND

The management of combined orbital floor and medial wall fractures involving the inferomedial strut is challenging due to absence of stable cornerstone. In this article, we proposed surgical strategies using customized 3D puzzle implant preformed with Rapid Prototype (RP) skull model.

METHODS

Retrospective review was done in 28 patients diagnosed with combined orbital floor and medial wall fracture. Using preoperative CT scans, original and mirror-imaged RP skull models for each patient were prepared and sterilized. In all patients, porous polyethylene-coated titanium mesh was premolded onto RP skull model in two ways; Customized 3D jigsaw puzzle technique was used in 15 patients with comminuted inferomedial strut, whereas individual 3D implant technique was used in each fracture for 13 patients with intact inferomedial strut. Outcomes including enophthalmos, visual acuity, and presence of diplopia were assessed and orbital volume was measured using OsiriX software preoperatively and postoperatively.

RESULTS

Satisfactory results were achieved in both groups in terms of clinical improvements. Of 10 patients with preoperative diplopia, 9 improved in 6 months, except one with persistent symptom who underwent extraocular muscle rupture. 18 patients who had moderate to severe enophthalmos preoperatively improved, and one remained with mild degree. Orbital volume ratio, defined as volumetric ratio between affected and control orbit, decreased from 127.6% to 99.79% (p < 0.05) in comminuted group, and that in intact group decreased from 117.03% to 101.3% (p < 0.05).

CONCLUSION

Our surgical strategies using the jigsaw puzzle and individual reconstruction technique provide accurate restoration of combined orbital floor and medial wall fractures.

Clinical effects of 3-D printing-assisted personalized reconstructive surgery for blowout orbital fractures

PURPOSE

One of the key challenges during orbital fracture reconstructive surgery, due to the complex anatomy of the orbit, is shaping and trimming the precise contour of the implants. The objectives of this study were to describe and evaluate the use of a three-dimensional (3-D) printing technique for personalized reconstructive surgery for repairing orbital fractures.

METHODS

A total of 29 cases which had 3-D technique-assisted surgical reconstruction, and 27 cases which had traditional surgery, were retrospectively analyzed. Preoperative and postoperative CT images were measured using MIMICS software, and the contour of the fracture zone and the Medpor-titanium implant were analyzed and compared. The surgical duration was also compared between the two groups.

RESULTS

There were statistically significant differences in the maximum width, depth and area between fracture zone and implant between the two groups, with the absolute value in the 3-D group markedly lower as compared to the control group. In addition, the difference in the medial-inferior wall angle between the surgical eye and healthy eye was also statistically significant between the groups. The average surgical duration in the 3-D group was substantially shorter than in the control group. Additionally, the postoperative clinical evaluation in the 3-D group was superior to that of the control group.

CONCLUSION

The 3-D printing technique is of great value for predicting the precise fracture zone before, and during, personalized surgery, and can help surgeons achieve accurate anatomical reconstruction for repairs of blowout orbital fractures. Moreover, the simulated bone template produced by 3-D printing models allows for "true-to-original" orbital reconstruction, which can shorten the surgical duration and improve the accuracy and safety of the operation.

Customized Orbital Wall Reconstruction Using Three-Dimensionally Printed Rapid Prototype Model in Patients With Orbital Wall Fracture

BACKGROUND

It is difficult to restore original orbital contours because of their complex 3-dimensional structure. Moreover, slight implant malpositioning can result in enophthalmos or other complications. The authors describe our experience of using individualized prebent titanium-Medpor mesh implants and stereolithographic modeling in a series of patients who underwent orbital wall reconstruction.

METHODS

A consecutive series of 104 patients with orbital fractures received computer simulation-designed prebent titanium-Medpor mesh implants insertion. Preoperative computed tomography (CT) data were processed for each patient, and a rapid prototyping (RP) model was produced. The uninjured side was concurrently mirrored and superimposed onto the traumatized side to create a mirror image of the RP model. The authors fabricated the titanium-Medpor implants to intraoperatively reconstruct the 3-dimensional orbital structure. The prefabricated titanium-Medpor implants were inserted into the defective orbital wall and fixed. Postoperative CT images were immediately taken to evaluate the reconstructed contours and compare the preoperative and postoperative intraorbital volumes.

RESULTS

All reconstructions were successful without postoperative complications. The implants were correctly positioned in the sagittal, axial, and coronal planes relative to the original orbital contours. The mean preoperative intraorbital volumes of the uninjured and traumatized sides were 21.39 ± 1.93 and 23.17 ± 2.00 cm, respectively, and the postoperative mean intraorbital volume was 20.74 ± 2.07 cm.

CONCLUSIONS

Orbital reconstruction can be optimized using individually manufactured rapid prototype skull model and premolded synthetic scaffold by computer-aid of mirroring-reconstruction of 3-dimensional images and 3-dimensional printing techniques.

Surgical applications of three-dimensional printing: a review of the current literature & how to get started

Three dimensional (3D) printing involves a number of additive manufacturing techniques that are used to build structures from the ground up. This technology has been adapted to a wide range of surgical applications at an impressive rate. It has been used to print patient-specific anatomic models, implants, prosthetics, external fixators, splints, surgical instrumentation, and surgical cutting guides. The profound utility of this technology in surgery explains the exponential growth. It is important to learn how 3D printing has been used in surgery and how to potentially apply this technology. PubMed was searched for studies that addressed the clinical application of 3D printing in all surgical fields, yielding 442 results. Data was manually extracted from the 168 included studies. We found an exponential increase in studies addressing surgical applications for 3D printing since 2011, with the largest growth in craniofacial, oromaxillofacial, and cardiothoracic specialties. The pertinent considerations for getting started with 3D printing were identified and are discussed, including, software, printing techniques, printing materials, sterilization of printing materials, and cost and time requirements. Also, the diverse and increasing applications of 3D printing were recorded and are discussed. There is large array of potential applications for 3D printing. Decreasing cost and increasing ease of use are making this technology more available. Incorporating 3D printing into a surgical practice can be a rewarding process that yields impressive results.

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.

Application of Rapid Prototyping Technique and Intraoperative Navigation System for the Repair and Reconstruction of Orbital Wall Fractures

BACKGROUND

Restoring the orbital cavity in large blow out fractures is a challenge for surgeons due to the anatomical complexity. This study evaluated the clinical outcomes and orbital volume after orbital wall fracture repair using a rapid prototyping (RP) technique and intraoperative navigation system.

METHODS

This prospective study was conducted on the medical records and radiology records of 12 patients who had undergone a unilateral blow out fracture reconstruction using a RP technique and an intraoperative navigation system from November 2014 to March 2015. The surgical results were assessed by an ophthalmic examination and a comparison of the preoperative and postoperative orbital volume ratio (OVR) values.

RESULTS

All patients had a successful treatment outcome without complications. Volumetric analysis revealed a significant decrease in the mean OVR from 1.0952±0.0662 (ranging from 0.9917 to 1.2509) preoperatively to 0.9942±0.0427 (ranging from 0.9394 to 1.0680) postoperatively.

CONCLUSION

The application of a RP technique for the repair of orbital wall fractures is a useful tool that may help improve the clinical outcomes by understanding the individual anatomy, determining the operability, and restoring the orbital cavity volume through optimal implant positioning along with an intraoperative navigation system.

The residual STL volume as a metric to evaluate accuracy and reproducibility of anatomic models for 3D printing: application in the validation of 3D-printable models of maxillofacial bone from reduced radiation dose CT images

Background

The effects of reduced radiation dose CT for the generation of maxillofacial bone STL models for 3D printing is currently unknown. Images of two full-face transplantation patients scanned with non-contrast 320-detector row CT were reconstructed at fractions of the acquisition radiation dose using noise simulation software and both filtered back-projection (FBP) and Adaptive Iterative Dose Reduction 3D (AIDR3D). The maxillofacial bone STL model segmented with thresholding from AIDR3D images at 100 % dose was considered the reference. For all other dose/reconstruction method combinations, a “residual STL volume” was calculated as the topologic subtraction of the STL model derived from that dataset from the reference and correlated to radiation dose.

Results

The residual volume decreased with increasing radiation dose and was lower for AIDR3D compared to FBP reconstructions at all doses. As a fraction of the reference STL volume, the residual volume decreased from 2.9 % (20 % dose) to 1.4 % (50 % dose) in patient 1, and from 4.1 % to 1.9 %, respectively in patient 2 for AIDR3D reconstructions. For FBP reconstructions it decreased from 3.3 % (20 % dose) to 1.0 % (100 % dose) in patient 1, and from 5.5 % to 1.6 %, respectively in patient 2. Its morphology resembled a thin shell on the osseous surface with average thickness <0.1 mm.

Conclusion

The residual volume, a topological difference metric of STL models of tissue depicted in DICOM images supports that reduction of CT dose by up to 80 % of the clinical acquisition in conjunction with iterative reconstruction yields maxillofacial bone models accurate for 3D printing.

Streamlined, Inexpensive 3D Printing of the Brain and Skull

Neuroimaging technologies such as Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) collect three-dimensional data (3D) that is typically viewed on two-dimensional (2D) screens. Actual 3D models, however, allow interaction with real objects such as implantable electrode grids, potentially improving patient specific neurosurgical planning and personalized clinical education. Desktop 3D printers can now produce relatively inexpensive, good quality prints. We describe our process for reliably generating life-sized 3D brain prints from MRIs and 3D skull prints from CTs. We have integrated a standardized, primarily open-source process for 3D printing brains and skulls. We describe how to convert clinical neuroimaging Digital Imaging and Communications in Medicine (DICOM) images to stereolithography (STL) files, a common 3D object file format that can be sent to 3D printing services. We additionally share how to convert these STL files to machine instruction gcode files, for reliable in-house printing on desktop, open-source 3D printers. We have successfully printed over 19 patient brain hemispheres from 7 patients on two different open-source desktop 3D printers. Each brain hemisphere costs approximately $3–4 in consumable plastic filament as described, and the total process takes 14–17 hours, almost all of which is unsupervised (preprocessing = 4–6 hr; printing = 9–11 hr, post-processing = <30 min). Printing a matching portion of a skull costs $1–5 in consumable plastic filament and takes less than 14 hr, in total. We have developed a streamlined, cost-effective process for 3D printing brain and skull models. We surveyed healthcare providers and patients who confirmed that rapid-prototype patient specific 3D models may help interdisciplinary surgical planning and patient education. The methods we describe can be applied for other clinical, research, and educational purposes.