Cardiothoracic Applications of 3-dimensional Printing. J Thorac Imaging. 2016;31:253-272. [PMID: 27149367 DOI: 10.1097/rti.0000000000000217]

Treatment of complex limb fractures with 3D printing technology combined with personalized plates: a retrospective study of case series and literature review

Background

In recent years, 3D printing technology has made significant strides in the medical field. With the advancement of orthopedics, there is an increasing pursuit of high surgical quality and optimal functional recovery. 3D printing enables the creation of precise physical models of fractures, and customized personalized steel plates can better realign and more comprehensively and securely fix fractures. These technologies improve preoperative diagnosis, simulation, and planning for complex limb fractures, providing patients with better treatment options.

Patients and methods

Five typical cases were selected from a pool of numerous patients treated with 3D printing technology combined with personalized custom steel plates at our hospital. These cases were chosen to demonstrate the entire process of printing 3D models and customizing individualized steel plates, including details of the patients' surgeries and treatment procedures. Literature reviews were conducted, with a focus on highlighting the application of 3D printing technology combined with personalized custom steel plates in the treatment of complex limb fractures.

Results

3D printing technology can produce accurate physical models of fractures, and personalized custom plates can achieve better fracture realignment and more comprehensive and robust fixation. These technologies provide patients with better treatment options.

Conclusion

The use of 3D printing models and personalized custom steel plates can improve preoperative diagnosis, simulation, and planning for complex limb fractures, realizing personalized medicine. This approach helps reduce surgical time, minimize trauma, enhance treatment outcomes, and improve patient functional recovery.

Advancing Surgical Arrhythmia Ablation: Novel Insights on 3D Printing Applications and Two Biocompatible Materials

To date, studies assessing the safety profile of 3D printing materials for application in cardiac ablation are sparse. Our aim is to evaluate the safety and feasibility of two biocompatible 3D printing materials, investigating their potential use for intra-procedural guides to navigate surgical cardiac arrhythmia ablation. Herein, we 3D printed various prototypes in varying thicknesses (0.8 mm-3 mm) using a resin (MED625FLX) and a thermoplastic polyurethane elastomer (TPU95A). Geometrical testing was performed to assess the material properties pre- and post-sterilization. Furthermore, we investigated the thermal propagation behavior beneath the 3D printing materials during cryo-energy and radiofrequency ablation using an in vitro wet-lab setup. Moreover, electron microscopy and Raman spectroscopy were performed on biological tissue that had been exposed to the 3D printing materials to assess microparticle release. Post-sterilization assessments revealed that MED625FLX at thicknesses of 1 mm, 2.5 mm, and 3 mm, along with TPU95A at 1 mm and 2.5 mm, maintained geometrical integrity. Thermal analysis revealed that material type, energy source, and their factorial combination with distance from the energy source significantly influenced the temperatures beneath the 3D-printed material. Electron microscopy revealed traces of nitrogen and sulfur underneath the MED625FLX prints (1 mm, 2.5 mm) after cryo-ablation exposure. The other samples were uncontaminated. While Raman spectroscopy did not detect material release, further research is warranted to better understand these findings for application in clinical settings.

Cardiovascular Computed Tomography in the Diagnosis of Cardiovascular Disease: Beyond Lumen Assessment

Cardiovascular CT is being widely used in the diagnosis of cardiovascular disease due to the rapid technological advancements in CT scanning techniques. These advancements include the development of multi-slice CT, from early generation to the latest models, which has the capability of acquiring images with high spatial and temporal resolution. The recent emergence of photon-counting CT has further enhanced CT performance in clinical applications, providing improved spatial and contrast resolution. CT-derived fractional flow reserve is superior to standard CT-based anatomical assessment for the detection of lesion-specific myocardial ischemia. CT-derived 3D-printed patient-specific models are also superior to standard CT, offering advantages in terms of educational value, surgical planning, and the simulation of cardiovascular disease treatment, as well as enhancing doctor-patient communication. Three-dimensional visualization tools including virtual reality, augmented reality, and mixed reality are further advancing the clinical value of cardiovascular CT in cardiovascular disease. With the widespread use of artificial intelligence, machine learning, and deep learning in cardiovascular disease, the diagnostic performance of cardiovascular CT has significantly improved, with promising results being presented in terms of both disease diagnosis and prediction. This review article provides an overview of the applications of cardiovascular CT, covering its performance from the perspective of its diagnostic value based on traditional lumen assessment to the identification of vulnerable lesions for the prediction of disease outcomes with the use of these advanced technologies. The limitations and future prospects of these technologies are also discussed.

3D Printing for Cardiovascular Surgery and Intervention: A Review Article

3D printing technology can be applied to practically every aspect of modern life, fulfilling the needs of people from various backgrounds. The utilization of 3D printing in the context of adult heart disease can be succinctly categorized into 3 primary domains: preoperative strategizing or simulation, medical instruction, and clinical consultations. 3D-printed model utilization improves surgical planning and intraoperative decision-making and minimizes surgical risks, and it has demonstrated its efficacy as an innovative educational tool for aspiring surgeons with limited practical exposure. Despite all the applications of 3D printing, it has not yet been shown to improve long-term outcomes, including safety. There are no data on the outcomes of controlled trials available. To appropriately diagnose heart disease, 3D-printed models of the heart can provide a better understanding of the intracardiac anatomy and provide all the information needed for operative planning. Experientially, 3D printing provides a wide range of perceptions for understanding lower extremity arteries' spatial geometry and anatomical features of pathology. Practicing cardiac surgery processes using objects printed using 3D imaging data can become the norm rather than the exception, leading to improved accuracy and quality of treatment. This study aimed to review the various applications of 3D printing technology in cardiac surgery and intervention.

Three-dimensional analysis of reconstructed skulls using three different open-source software versus commercial software

This study aimed to compare the 3D skull models reconstructed from computed tomography (CT) images using three different open-source software with a commercial software as a reference. The commercial Mimics v17.0 software was used to reconstruct the 3D skull models from 58 subjects. Next, two open-source software, MITK Workbench 2016.11, 3D Slicer 4.8.1 and InVesalius 3.1 were used to reconstruct the 3D skull models from the same subjects. All four software went through similar steps in 3D reconstruction process. The 3D skull models from the commercial and open-source software were exported in standard tessellation language (STL) format into CloudCompare v2.8 software and superimposed for geometric analyses. Hausdorff distance (HD) analysis demonstrated the average points distance of Mimics versus MITK was 0.25 mm. Meanwhile, for Mimics versus 3D Slicer and Mimics versus InVesalius, there was almost no differences between the two superimposed 3D skull models with average points distance of 0.01 mm. Based on Dice similarity coefficient (DSC) analysis, the similarity between Mimics versus MITK, Mimics versus 3D Slicer and Mimics versus InVesalius were 94.1, 98.8 and 98.3%, respectively. In conclusion, this study confirmed that the alternative open-source software, MITK, 3D Slicer and InVesalius gave comparable results in 3D reconstruction of skull models compared to the commercial gold standard Mimics software. This open-source software could possibly be used for pre-operative planning in cranio-maxillofacial cases and for patient management in the hospitals or institutions with limited budget.

The Quantitative Impact of Using 3D Printed Anatomical Models for Surgical Planning Optimization: Literature Review

3D printing has entered the medical field as a visualization tool that allows the manufacture of three-dimensional (3D) models that physically represent the anatomy of a patient in need of analysis to improve surgical results. This article analyzes the literature around reported study cases that make use of anatomical models for their surgical processes' planning, focusing on obtaining the quantitative results of each one of them. A search of case studies was carried out in the main medical databases such as PubMed, ScienceDirect, SpringerLink, among others; to obtain the most relevant results of the 56 selected articles, the information of each study was analyzed and categorized. These articles presented figures and data about the benefits that are considered more representative to measure the positive impact of this technology. These benefits are summarized in variables such as the decrease in surgical time, greater accuracy in the diagnosis of pathology, blood loss reduction, and decreasing operating room costs; owed to an improvement in the surgery planning. It was found that in all the cases analyzed there was an improvement in the surgical results related to these variables, which were summarized in macro figures that combine this improvement quantitatively. In the analyzed studies, it was evident that there is great potential in the use of 3D printing for presurgical planning, being as the results of these analyzed interventions were better when using this technology. In addition, it was found that the results obtained initially, before applying the inclusion and exclusion criteria, were mostly of a qualitative nature; expressing the perception of researchers regarding the positive use of this tool in the field and evidencing an opportunity for this research to focus on concrete and technical information to show in numerical terms the effectiveness of this tool, to demonstrate the cost-benefit that it has for the field.

Trends and Challenges in the Development of 3D-Printed Heart Valves and Other Cardiac Implants: A Review of Current Advances

This article provides a comprehensive review of the current trends and challenges in the development of 3D-printed heart valves and other cardiac implants. By providing personalized solutions and pushing the limits of regenerative medicine, 3D printing technology has revolutionized the field of cardiac healthcare. The use of several organic and synthetic polymers in 3D printing heart valves is explored in this article, with emphasis on both their benefits and drawbacks. In cardiac tissue engineering, stem cells are essential, and their potential to lessen immunological rejection and thrombogenic consequences is highlighted. In the clinical applications section, the article emphasizes the importance of 3D printing in preoperative planning. Surgery results are enhanced when surgeons can visualize and assess the size and placement of implants using patient-specific anatomical models. Customized implants that are designed to match the anatomy of a particular patient reduce the likelihood of complications and enhance postoperative results. The development of physiologically active cardiac implants, made possible by 3D bioprinting, shows promise by eliminating the need for artificial valves. In conclusion, this paper highlights cutting-edge research and the promise of 3D-printed cardiac implants to improve patient outcomes and revolutionize cardiac treatment.

Three-Dimensional Bioprinting in Cardiovascular Disease: Current Status and Future Directions

Three-dimensional (3D) printing plays an important role in cardiovascular disease through the use of personalised models that replicate the normal anatomy and its pathology with high accuracy and reliability. While 3D printed heart and vascular models have been shown to improve medical education, preoperative planning and simulation of cardiac procedures, as well as to enhance communication with patients, 3D bioprinting represents a potential advancement of 3D printing technology by allowing the printing of cellular or biological components, functional tissues and organs that can be used in a variety of applications in cardiovascular disease. Recent advances in bioprinting technology have shown the ability to support vascularisation of large-scale constructs with enhanced biocompatibility and structural stability, thus creating opportunities to replace damaged tissues or organs. In this review, we provide an overview of the use of 3D bioprinting in cardiovascular disease with a focus on technologies and applications in cardiac tissues, vascular constructs and grafts, heart valves and myocardium. Limitations and future research directions are highlighted.

Medical 3D Printing Using Desktop Inverted Vat Photopolymerization: Background, Clinical Applications, and Challenges

Medical 3D printing is a complex, highly interdisciplinary, and revolutionary technology that is positively transforming the care of patients. The technology is being increasingly adopted at the Point of Care (PoC) as a consequence of the strong value offered to medical practitioners. One of the key technologies within the medical 3D printing portfolio enabling this transition is desktop inverted Vat Photopolymerization (VP) owing to its accessibility, high quality, and versatility of materials. Several reports in the peer-reviewed literature have detailed the medical impact of 3D printing technologies as a whole. This review focuses on the multitude of clinical applications of desktop inverted VP 3D printing which have grown substantially in the last decade. The principles, advantages, and challenges of this technology are reviewed from a medical standpoint. This review serves as a primer for the continually growing exciting applications of desktop-inverted VP 3D printing in healthcare.

Patient-Specific 3D-Printed Low-Cost Models in Medical Education and Clinical Practice

3D printing has been increasingly used for medical applications with studies reporting its value, ranging from medical education to pre-surgical planning and simulation, assisting doctor-patient communication or communication with clinicians, and the development of optimal computed tomography (CT) imaging protocols. This article presents our experience of utilising a 3D-printing facility to print a range of patient-specific low-cost models for medical applications. These models include personalized models in cardiovascular disease (from congenital heart disease to aortic aneurysm, aortic dissection and coronary artery disease) and tumours (lung cancer, pancreatic cancer and biliary disease) based on CT data. Furthermore, we designed and developed novel 3D-printed models, including a 3D-printed breast model for the simulation of breast cancer magnetic resonance imaging (MRI), and calcified coronary plaques for the simulation of extensive calcifications in the coronary arteries. Most of these 3D-printed models were scanned with CT (except for the breast model which was scanned using MRI) for investigation of their educational and clinical value, with promising results achieved. The models were confirmed to be highly accurate in replicating both anatomy and pathology in different body regions with affordable costs. Our experience of producing low-cost and affordable 3D-printed models highlights the feasibility of utilizing 3D-printing technology in medical education and clinical practice.

Patient-Specific 3D-Printed Models in Pediatric Congenital Heart Disease

Three-dimensional (3D) printing technology has become increasingly used in the medical field, with reports demonstrating its superior advantages in both educational and clinical value when compared with standard image visualizations or current diagnostic approaches. Patient-specific or personalized 3D printed models serve as a valuable tool in cardiovascular disease because of the difficulty associated with comprehending cardiovascular anatomy and pathology on 2D flat screens. Additionally, the added value of using 3D-printed models is especially apparent in congenital heart disease (CHD), due to its wide spectrum of anomalies and its complexity. This review provides an overview of 3D-printed models in pediatric CHD, with a focus on educational value for medical students or graduates, clinical applications such as pre-operative planning and simulation of congenital heart surgical procedures, and communication between physicians and patients/parents of patients and between colleagues in the diagnosis and treatment of CHD. Limitations and perspectives on future research directions for the application of 3D printing technology into pediatric cardiology practice are highlighted.

Quality assurance in 3D-printing: A dimensional accuracy study of patient-specific 3D-printed vascular anatomical models

3D printing enables the rapid manufacture of patient-specific anatomical models that substantially improve patient consultation and offer unprecedented opportunities for surgical planning and training. However, the multistep preparation process may inadvertently lead to inaccurate anatomical representations which may impact clinical decision making detrimentally. Here, we investigated the dimensional accuracy of patient-specific vascular anatomical models manufactured via digital anatomical segmentation and Fused-Deposition Modelling (FDM), Stereolithography (SLA), Selective Laser Sintering (SLS), and PolyJet 3D printing, respectively. All printing modalities reliably produced hand-held patient-specific models of high quality. Quantitative assessment revealed an overall dimensional error of 0.20 ± 3.23%, 0.53 ± 3.16%, -0.11 ± 2.81% and -0.72 ± 2.72% for FDM, SLA, PolyJet and SLS printed models, respectively, compared to unmodified Computed Tomography Angiograms (CTAs) data. Comparison of digital 3D models to CTA data revealed an average relative dimensional error of -0.83 ± 2.13% resulting from digital anatomical segmentation and processing. Therefore, dimensional error resulting from the print modality alone were 0.76 ± 2.88%, + 0.90 ± 2.26%, + 1.62 ± 2.20% and +0.88 ± 1.97%, for FDM, SLA, PolyJet and SLS printed models, respectively. Impact on absolute measurements of feature size were minimal and assessment of relative error showed a propensity for models to be marginally underestimated. This study revealed a high level of dimensional accuracy of 3D-printed patient-specific vascular anatomical models, suggesting they meet the requirements to be used as medical devices for clinical applications.

Accuracy of anatomic 3-dimensionally printed canine humeral models

OBJECTIVE

To evaluate the accuracy of various three-dimensional print (3DP) technologies using morphometric measurements.

STUDY DESIGN

Experimental.

SAMPLE POPULATION

Cadaveric canine humeri and size-matched 3DP models.

METHODS

Fiduciary radiopaque markers were affixed to canine humeri of three different sizes (4, 13, 29 kg) at predetermined anatomical landmarks. 3DP models were created using one of three printers; desktop printers Form 3L and Ultimaker 5S, and industrial printer Objet Connex (n = 5/group/printer). Marker based morphometric dimensions between cadavers and 3DP models were statistically compared using 2-factor repeated measures ANOVA followed by Tukey's post-hoc test (p < .05).

RESULTS

Bone size and printer type both significantly affected 3DP accuracy, with size having the larger effect (p < .0001 and p < .02, respectively). Regardless of printing technology, model size was smaller than native bone in most cases. At the humeral condylar level, the best accuracy was seen in the medium-sized humerus with the Ultimaker printer ([0.09 mm], p < .03). Accuracy was reduced in the proximal humerus in all groups.

CONCLUSION

Desktop printers were overall more accurate than the industrial printer. Although significant differences were identified between models of different sizes, the submillimetric magnitude of these differences is unlikely to be clinically relevant.

CLINICAL SIGNIFICANCE

While preoperative planning using 3DP models is becoming mainstream, accurate representation of the actual bone is critical. This study demonstrates that common desktop printers are suitable for this purpose.

Cardiac computed tomographic imaging in cardio-oncology: An expert consensus document of the Society of Cardiovascular Computed Tomography (SCCT). Endorsed by the International Cardio-Oncology Society (ICOS)

Cardio-Oncology is a rapidly growing sub-specialty of medicine, however, there is very limited guidance on the use of cardiac CT (CCT) in the care of Cardio-Oncology patients. In order to fill in the existing gaps, this Expert Consensus statement comprised of a multidisciplinary collaboration of experts in Cardiology, Radiology, Cardiovascular Multimodality Imaging, Cardio-Oncology, Oncology and Radiation Oncology aims to summarize current evidence for CCT applications in Cardio-Oncology and provide practice recommendations for clinicians.

Application of three-dimensional printing technology in renal diseases

Three-dimensional (3D) printing technology involves the application of digital models to create 3D objects. It is used in construction and manufacturing and has gradually spread to medical applications, such as implants, drug development, medical devices, prosthetic limbs, and in vitro models. The application of 3D printing has great prospects for development in orthopedics, maxillofacial plastic surgery, cardiovascular conditions, liver disease, and other fields. With in-depth research on 3D printing technology and the continuous update of printing materials, this technology also shows broad development prospects in renal medicine. In this paper, the author mainly summarizes the basic theory of 3D printing technology, its research progress, application status, and development prospect in renal diseases.

3D Printed Models in Cardiovascular Disease: An Exciting Future to Deliver Personalized Medicine

3D printing has shown great promise in medical applications with increased reports in the literature. Patient-specific 3D printed heart and vascular models replicate normal anatomy and pathology with high accuracy and demonstrate superior advantages over the standard image visualizations for improving understanding of complex cardiovascular structures, providing guidance for surgical planning and simulation of interventional procedures, as well as enhancing doctor-to-patient communication. 3D printed models can also be used to optimize CT scanning protocols for radiation dose reduction. This review article provides an overview of the current status of using 3D printing technology in cardiovascular disease. Limitations and barriers to applying 3D printing in clinical practice are emphasized while future directions are highlighted.

Radiopaque Recreations of Lung Pathologies From Clinical Computed Tomography Images Using Potassium Iodide Inkjet 3-dimensional Printing: Proof of Concept

PURPOSE

The purpose of this study was to develop a 3-dimensional (3D) printing method to create computed tomography (CT) realistic phantoms of lung cancer nodules and lung parenchymal disease from clinical CT images.

MATERIALS AND METHODS

Low-density paper was used as substrate material for inkjet printing with potassium iodide solution to reproduce phantoms that mimic the CT attenuation of lung parenchyma. The relationship between grayscale values and the corresponding CT numbers of prints was first established through the derivation of exponential fitted equation from scanning data. Next, chest CTs from patients with early-stage lung cancer and coronavirus disease 2019 (COVID-19) pneumonia were chosen for 3D printing. CT images of original lung nodule and the 3D-printed nodule phantom were compared based on pixel-to-pixel correlation and radiomic features.

RESULTS

CT images of part-solid lung cancer and 3D-printed nodule phantom showed both high visual similarity and quantitative correlation. R2 values from linear regressions of pixel-to-pixel correlations between 5 sets of patient and 3D-printed image pairs were 0.92, 0.94, 0.86, 0.85, and 0.83, respectively. Comparison of radiomic measures between clinical CT and printed models demonstrated 6.1% median difference, with 25th and 75th percentile range at 2.4% and 15.2% absolute difference, respectively. The densities and parenchymal morphologies from COVID-19 pneumonia CT images were well reproduced in the 3D-printed phantom scans.

CONCLUSION

The 3D printing method presented in this work facilitates creation of CT-realistic reproductions of lung cancer and parenchymal disease from individual patient scans with microbiological and pathology confirmation.

3D Printed Surgical Guide for Coronary Artery Bypass Graft: Workflow from Computed Tomography to Prototype

Patient-specific three-dimensional (3D) printed models have been increasingly used in many medical fields, including cardiac surgery for which they are used as planning and communication tools. To locate and plan the correct region of interest for the bypass placement during coronary artery bypass graft (CABG) surgery, cardiac surgeons can pre-operatively rely on different medical images. This article aims to present a workflow for the production of a patient-specific 3D-printed surgical guide, from data acquisition and image segmentation to final prototyping. The aim of this surgical guide is to help visualize the region of interest for bypass placement during the operation, through the use of dedicated surgical holes. The results showed the feasibility of this surgical guide in terms of design and fitting to the phantom. Further studies are needed to assess material biocompatibility and technical properties.

Anatomical Engineering and 3D Printing for Surgery and Medical Devices: International Review and Future Exponential Innovations

Three-dimensional printing (3DP) has recently gained importance in the medical industry, especially in surgical specialties. It uses different techniques and materials based on patients' needs, which allows bioprofessionals to design and develop unique pieces using medical imaging provided by computed tomography (CT) and magnetic resonance imaging (MRI). Therefore, the Department of Biology and Medicine and the Department of Physics and Engineering, at the Bioastronautics and Space Mechatronics Research Group, have managed and supervised an international cooperation study, in order to present a general review of the innovative surgical applications, focused on anatomical systems, such as the nervous and craniofacial system, cardiovascular system, digestive system, genitourinary system, and musculoskeletal system. Finally, the integration with augmented, mixed, virtual reality is analyzed to show the advantages of personalized treatments, taking into account the improvements for preoperative, intraoperative planning, and medical training. Also, this article explores the creation of devices and tools for space surgery to get better outcomes under changing gravity conditions.

Three-dimensional printing in paediatric orthopaedic surgery

Three-dimensional (3D) printing is a rapidly evolving and promising field to improve outcomes of orthopaedic surgery. The use of patient-specific 3D-printed models is specifically interesting in paediatric orthopaedic surgery, as limb deformity corrections often require an individual 3D treatment. In this editorial, various operative applications of 3D printing in paediatric orthopaedic surgery are discussed. The technical aspects and the imaging acquisition with computed tomography and magnetic resonance imaging are outlined. Next, there is a focus on the intraoperative applications of 3D printing during paediatric orthopaedic surgical procedures. An overview of various upper and lower limb deformities in paediatrics is given, in which 3D printing is already implemented, including post-traumatic forearm corrections and proximal femoral osteotomies. The use of patient-specific instrumentation (PSI) or guiding templates during the surgical procedure shows to be promising in reducing operation time, intraoperative haemorrhage and radiation exposure. Moreover, 3D-printed models for the use of PSI or patient-specific navigation templates are promising in improving the accuracy of complex limb deformity surgery in children. Lastly, the future of 3D printing in paediatric orthopaedics extends beyond the intraoperative applications; various other medical applications include 3D casting and prosthetic limb replacement. In conclusion, 3D printing opportunities are numerous, and the fast developments are exciting, but more evidence is required to prove its superiority over conventional paediatric orthopaedic surgery.

Use of rotational angiography in congenital cardiac catheterisations to generate three-dimensional-printed models

BACKGROUND

Three-dimensional printing is increasingly utilised for congenital heart defect procedural planning. CT or MR datasets are typically used for printing, but similar datasets can be obtained from three-dimensional rotational angiography. We sought to assess the feasibility and accuracy of printing three-dimensional models of CHD from rotational angiography datasets.

METHODS

Retrospective review of CHD catheterisations using rotational angiography was performed, and patient and procedural details were collected. Imaging data from rotational angiography were segmented, cleaned, and printed with polylactic acid on a Dremel® 3D Idea Builder (Dremel, Mount Prospect, IL, USA). Printing time and materials' costs were captured. CT scans of printed models were compared objectively to the original virtual models. Two independent, non-interventional paediatric cardiologists provided subjective ratings of the quality and accuracy of the printed models.

RESULTS

Rotational angiography data from 15 catheterisations on vascular structures were printed. Median print time was 3.83 hours, and material costs were $2.84. The CT scans of the printed models highly matched with the original digital models (root mean square for Hausdorff distance 0.013 ± 0.003 mesh units). Independent reviewers correctly described 80 and 87% of the models (p = 0.334) and reported high quality and accuracy (5 versus 5, p = NS; κ = 0.615).

CONCLUSION

Imaging data from rotational angiography can be converted into accurate three-dimensional-printed models of CHD. The cost of printing the models was negligible, but the print time was prohibitive for real-time use. As the speed of three-dimensional printing technology increases, novel future applications may allow for printing patient-specific devices based on rotational angiography datasets.

Assisting Difficult Liver Operations Using 3D Printed Models

Liver cancer is estimated to be the fifth most common in the world, while it is also considered the third leading cause of cancer death. In cases of primary liver cancer, surgery in combination with chemotherapy and radiotherapy can lead to a complete cure or significantly increase the patient’s life expectancy. Since the liver is an organ that performs several critical functions in the human body, the precise estimation of the disease (position and size of tumors and its vicinity to vessels) plays a vital role in a successful operation. In some cases, the removal of the tumor may be successful, but the percentage of the hepatic remnant may not be sufficient to sustain life. Therefore, accurate imaging of the tumor of the liver and proper planning of a difficult surgery to remove tumor(s) from a patient’s liver can be a lifesaver and lead to a complete cure of the disease. The aim of the present study is the initial accurate representation of the liver (parenchyma, tumors, vessels) as a digital three-dimensional (3D) model using advanced image processing and machine learning techniques and its 3D printing in 1:1 scale representing the full size of the liver with the tumor(s). A model of this type has been used at our University surgical department to plan complex hepatobiliary surgeries, provide more accurate information to the patients and their families, as well as improve the training of medical students and resident surgeons and fellows.

3D Printing-A Cutting Edge Technology for Treating Post-Infarction Patients

The increasing complexity of cardiovascular interventions requires advanced peri-procedural imaging and tailored treatment. Three-dimensional printing technology represents one of the most significant advances in the field of cardiac imaging, interventional cardiology or cardiovascular surgery. Patient-specific models may provide substantial information on intervention planning in complex cardiovascular diseases, and volumetric medical imaging from CT or MRI can be translated into patient-specific 3D models using advanced post-processing applications. 3D printing and additive manufacturing have a great variety of clinical applications targeting anatomy, implants and devices, assisting optimal interventional treatment and post-interventional evaluation. Although the 3D printing technology still lacks scientific evidence, its benefits have been shown in structural heart diseases as well as for treatment of complex arrhythmias and corrective surgery interventions. Recent development has enabled transformation of conventional 3D printing into complex 3D functional living tissues contributing to regenerative medicine through engineered bionic materials such hydrogels, cell suspensions or matrix components. This review aims to present the most recent clinical applications of 3D printing in cardiovascular medicine, highlighting also the potential for future development of this revolutionary technology in the medical field.

3D Printing for Cardiovascular Applications: From End-to-End Processes to Emerging Developments

3D printing as a means of fabrication has seen increasing applications in medicine in the last decade, becoming invaluable for cardiovascular applications. This rapidly developing technology has had a significant impact on cardiovascular research, its clinical translation and education. It has expanded our understanding of the cardiovascular system resulting in better devices, tools and consequently improved patient outcomes. This review discusses the latest developments and future directions of generating medical replicas ('phantoms') for use in the cardiovascular field, detailing the end-to-end process from medical imaging to capture structures of interest, to production and use of 3D printed models. We provide comparisons of available imaging modalities and overview of segmentation and post-processing techniques to process images for printing, detailed exploration of latest 3D printing methods and materials, and a comprehensive, up-to-date review of milestone applications and their impact within the cardiovascular domain across research, clinical use and education. We then provide an in-depth exploration of future technologies and innovations around these methods, capturing opportunities and emerging directions across increasingly realistic representations, bioprinting and tissue engineering, and complementary virtual and mixed reality solutions. The next generation of 3D printing techniques allow patient-specific models that are increasingly realistic, replicating properties, anatomy and function.

A calibration CT mini-lung-phantom created by 3-D printing and subtractive manufacturing

We describe the creation and characterization of a calibration CT mini‐lung‐phantom incorporating simulated airways and ground‐glass densities. Ten duplicate mini‐lung‐phantoms with Three‐Dimensional (3‐D) printed tubes simulating airways and gradated density polyurethane foam blocks were designed and built. Dimensional accuracy and CT numbers were measured using micro‐CT and clinical CT scanners. Micro‐CT images of airway tubes demonstrated an average dimensional variation of 0.038 mm from nominal values. The five different densities of incorporated foam blocks, simulating ground‐glass, showed mean CT numbers (±standard deviation) of −897.0 ± 1.5, −844.1 ± 1.5, −774.1 ± 2.6, −695.3 ± 1.6, and −351.0 ± 3.7 HU, respectively. Three‐Dimensional printing and subtractive manufacturing enabled rapid, cost‐effective production of ground‐truth calibration mini‐lung‐phantoms with low inter‐sample variation that can be scanned simultaneously with the patient undergoing lung quantitative CT.

Three-dimensional printing for heart diseases: clinical application review

Heart diseases remain the top threat to human health, and the treatment of heart diseases changes with each passing day. Convincing evidence shows that three-dimensional (3D) printing allows for a more precise understanding of the complex anatomy associated with various heart diseases. In addition, 3D-printed models of cardiac diseases may serve as effective educational tools and for hands-on simulation of surgical interventions. We introduce examples of the clinical applications of different types of 3D printing based on specific cases and clinical application scenarios of 3D printing in treating heart diseases. We also discuss the limitations and clinically unmet needs of 3D printing in this context.

Application of 3D Printing in Preoperative Planning

Preoperative planning is critical for success in the surgical suite. Current techniques for surgical planning are limited; clinicians often rely on prior experience and medical imaging to guide the decision-making process. Furthermore, two-dimensional (2D) presentations of anatomical structures may not accurately portray their three-dimensional (3D) complexity, often leaving physicians ill-equipped for the procedure. Although 3D postprocessed images are an improvement on traditional 2D image sets, they are often inadequate for surgical simulation. Medical 3D printing is a rapidly expanding field and could provide an innovative solution to current constraints of preoperative planning. As 3D printing becomes more prevalent in medical settings, it is important that clinicians develop an understanding of the technologies, as well as its uses. Here, we review the fundamentals of 3D printing and key aspects of its workflow. The many applications of 3D printing for preoperative planning are discussed, along with their challenges.

The effect of three-dimensional (3D) printing on quantitative and qualitative outcomes in paediatric orthopaedic osteotomies: a systematic review

Three-dimensional (3D) printing technology is increasingly being utilized in various surgical specialities. In paediatric orthopaedics it has been applied in the pre-operative and intra-operative stages, allowing complex deformities to be replicated and patient-specific instrumentation to be used. This systematic review analyses the literature on the effect of 3D printing on paediatric orthopaedic osteotomy outcomes.A systematic review of several databases was conducted according to PRISMA guidelines. Studies evaluating the use of 3D printing technology in orthopaedic osteotomy procedures in children (aged ≤ 16 years) were included. Spinal and bone tumour surgery were excluded. Data extracted included demographics, disease pathology, target bone, type of technology, imaging modality used, qualitative/quantitative outcomes and follow-up. Articles were further categorized as either 'pre-operative' or 'intra-operative' applications of the technology.Twenty-two articles fitting the inclusion criteria were included. The reported studies included 212 patients. There were five articles of level of evidence 3 and 17 level 4.A large variety of outcomes were reported with the most commonly used being operating time, fluoroscopic exposure and intra-operative blood loss.A significant difference in operative time, fluoroscopic exposure, blood loss and angular correction was found in the 'intra-operative' application group. No significant difference was found in the 'pre-operative' category.Despite a relatively low evidence base pool of studies, our aggregate data demonstrate a benefit of 3D printing technology in various deformity correction applications, especially when used in the 'intra-operative' setting. Further research including paediatric-specific core outcomes is required to determine the potential benefit of this novel addition. Cite this article: EFORT Open Rev 2021;6:130-138. DOI: 10.1302/2058-5241.6.200092.

A Radiopaque Nanoparticle-Based Ink Using PolyJet 3D Printing for Medical Applications

The aim of this study was to develop a 3D printable radiopaque ink and successfully print a finished artifact. Radiopaque 3D printing would be hugely beneficial to improve the visibility of medical devices and implants, as well as allowing more realistic phantoms and calibration aids to be produced. Most 3D printing technologies are polymer based. Polymers are naturally radiolucent, allowing X-rays to pass through, showing up as faint dark gray regions on X-ray detectors, as for soft tissues. During this study, a 3D printable ultraviolet (UV) curable resin containing zirconium oxide (ZrO₂) nanoparticles was developed. 5 wt.% ZrO₂ was dispersed in a base resin using a high-shear mixer. Particles remained in suspension for 6-8 h at room temperature, allowing time for 3D printing. A model of a hand including radiopaque bones and a test block demonstrating a range of internal radiopaque features were successfully 3D printed. Radiopacity was demonstrated in the 3D-printed models, and there was good dispersion of ZrO₂ within the resin matrix. The impregnated resin remained UV curable and viscosity was not compromised. In this study, 3D-printed radiopaque features demonstrated clear radiopacity under X-ray and microcomputed tomography imaging.

Clinical Applications of Patient-Specific 3D Printed Models in Cardiovascular Disease: Current Status and Future Directions

Three-dimensional (3D) printing has been increasingly used in medicine with applications in many different fields ranging from orthopaedics and tumours to cardiovascular disease. Realistic 3D models can be printed with different materials to replicate anatomical structures and pathologies with high accuracy. 3D printed models generated from medical imaging data acquired with computed tomography, magnetic resonance imaging or ultrasound augment the understanding of complex anatomy and pathology, assist preoperative planning and simulate surgical or interventional procedures to achieve precision medicine for improvement of treatment outcomes, train young or junior doctors to gain their confidence in patient management and provide medical education to medical students or healthcare professionals as an effective training tool. This article provides an overview of patient-specific 3D printed models with a focus on the applications in cardiovascular disease including: 3D printed models in congenital heart disease, coronary artery disease, pulmonary embolism, aortic aneurysm and aortic dissection, and aortic valvular disease. Clinical value of the patient-specific 3D printed models in these areas is presented based on the current literature, while limitations and future research in 3D printing including bioprinting of cardiovascular disease are highlighted.

Clinical situations for which 3D printing is considered an appropriate representation or extension of data contained in a medical imaging examination: adult cardiac conditions

BACKGROUND

Medical 3D printing as a component of care for adults with cardiovascular diseases has expanded dramatically. A writing group composed of the Radiological Society of North America (RSNA) Special Interest Group on 3D Printing (SIG) provides appropriateness criteria for adult cardiac 3D printing indications.

METHODS

A structured literature search was conducted to identify all relevant articles using 3D printing technology associated with a number of adult cardiac indications, physiologic, and pathologic processes. Each study was vetted by the authors and graded according to published guidelines.

RESULTS

Evidence-based appropriateness guidelines are provided for the following areas in adult cardiac care; cardiac fundamentals, perioperative and intraoperative care, coronary disease and ischemic heart disease, complications of myocardial infarction, valve disease, cardiac arrhythmias, cardiac neoplasm, cardiac transplant and mechanical circulatory support, heart failure, preventative cardiology, cardiac and pericardial disease and cardiac trauma.

CONCLUSIONS

Adoption of common clinical standards regarding appropriate use, information and material management, and quality control are needed to ensure the greatest possible clinical benefit from 3D printing. This consensus guideline document, created by the members of the RSNA 3D printing Special Interest Group, will provide a reference for clinical standards of 3D printing for adult cardiac indications.

Adipose-derived mesenchymal stem cell seeded Atelocollagen scaffolds for cardiac tissue engineering

ADMSCs were isolated from subcutaneous adipose tissue, characterized and cultured in vitro. GFP-labeled ADMSCs can grow and proliferate well on the Atelocollagen scaffolds, and induced by 5-aza the cells can differentiate into cardio-like cells. 3D cultured ADMSCs on Atelocollagen scaffolds were transplanted into mice ischemia myocardium, and have good biocompatibility with host cardio tissue.

Next-generation transcatheter aortic valve implantation

Objective

Transcatheter aortic valve implantation (TAVI) procedures are increasing rapidly, but the durability of tissue valve and periprocedural complications are not satisfactory. Immune reaction to the galactose-α-1,3 galactose β-1,4-N-acetylglucosamine (α-Gal) and conventional processing protocols of cardiac xenografts lead to calcification. Next-generation TAVI needs to be made with α-Gal–free xenografts by multiple anticalcification therapies to avoid immune rejection and enhance durability, and three-dimensional (3D) printing technology to improve the procedural safety.

Methods

Porcine pericardia were decellularized and immunologically modified with α-galactosidase. The pericardia were treated by space filler, crosslinked with glutaraldehyde in organic solvent, and detoxified. The sheep-specific nitinol (nickel–titanium memory alloy) wire backbone was made from a 3D-printed model for ovine aortic root. After it passed the fitting test, we manufactured a self-expandable stented valve with the porcine pericardia mounted on the customized nitinol wire–based stent. After in vitro circulation using customized silicone aortic root, we performed TAVI in 9 sheep and obtained hemodynamic, radiological, immunohistopathological, and biochemical results.

Results

The valve functioned well, with excellent stent fitting and good coronary flow under in vitro circulation. Sheep were sequentially scheduled to be humanely killed until 238 days after TAVI. Echocardiography and cardiac catheterization demonstrated good hemodynamic status and function of the aortic valve. The xenografts were well preserved without α-Gal immune reaction or calcification based on the immunological, radiographic, microscopic, and biochemical examinations.

Conclusions

We proved preclinical safety and efficacy for next-generation α-Gal–free TAVI with multiple anticalcification therapies and 3D-printing technology. A future clinical study is warranted based on these promising preclinical results.

Cardiac computed tomography angiography in the paediatric population: Expert consensus from the Filiale de cardiologie pédiatrique et congénitale (FCPC) and the Société française d'imagerie cardiaque et vasculaire diagnostique et interventionnelle (SFICV)

This paper aims to provide a paediatric cardiac computed tomography angiography expert panel consensus based on the opinions of experts from the Société française d'imagerie cardiaque et vasculaire diagnostique et interventionnelle (SFICV) and the Filiale de cardiologie pédiatrique congénitale (FCPC). This expert panel consensus includes recommendations for indications, patient preparation, computed tomography angiography radiation dose reduction techniques and postprocessing techniques. We think that to realize its full potential and to avoid pitfalls, cardiac computed tomography angiography in children with congenital heart disease requires training and experience. Moreover, paediatric cardiac computed tomography angiography protocols should be standardized to acquire optimal images in this population with the lowest radiation dose possible, to prevent unnecessary radiation exposure. We also provide a suggested structured report and a list of acquisition protocols and technical parameters in relation to specific vendors.

Pediatric cardiac computed tomography angiography: Expert consensus from the Filiale de Cardiologie Pédiatrique et Congénitale (FCPC) and the Société Française d'Imagerie Cardiaque et Vasculaire diagnostique et interventionnelle (SFICV)

This article was designed to provide a pediatric cardiac computed tomography angiography (CCTA) expert panel consensus based on opinions of experts of the Société Française d'Imagerie Cardiaque et Vasculaire diagnostique et interventionnelle (SFICV) and of the Filiale de Cardiologie Pédiatrique Congénitale (FCPC). This expert panel consensus includes recommendations for indications, patient preparation, CTA radiation dose reduction techniques, and post-processing techniques. The consensus was based on data from available literature (original papers, reviews and guidelines) and on opinions of a group of specialists with extensive experience in the use of CT imaging in congenital heart disease. In order to reach high potential and avoid pitfalls, CCTA in children with congenital heart disease requires training and experience. Moreover, pediatric cardiac CCTA protocols should be standardized to acquire optimal images in this population with the lowest radiation dose possible to prevent unnecessary radiation exposure. We also provided a suggested structured report and a list of acquisition protocols and technical parameters in relation to specific vendors.

3D printing in adult cardiovascular surgery and interventions: a systematic review

3D printing in adult cardiac and vascular surgery has been evaluated over the last 10 years, and all of the available literature reports benefits from the use of 3D models. In the present study, we analyzed the current applications of 3D printing for adult cardiovascular disease treated with surgical or catheter-based interventions, including the clinical medical simulation of physiological or pathology conducted with 3D printing in this field. A search of PubMed and MEDLINE databases were supplemented by searching through bibliographies of key articles. Thereafter, data on demographic, clinical scenarios and application, imaging modality, purposes of using with 3D printing, outcomes and follow-up were extracted. A total of 43 articles were deemed eligible and included. 296 patients (mean age: 65.4±14.2 years; male, 58.2%) received 3D printing for cardiac and vascular surgery or conditions [percutaneous left atrial appendage occlusion (LAAO), TAVR, mitral valve disease, aortic valve replacement, coronary artery abnormality, HOCM, aortic aneurysm and aortic dissection, Kommerell's diverticulum, primary cardiac tumor and ventricular aneurysm]. Eight papers reported the utility of 3D printing in the medical simulator and training fields. Most studies were conducted starting in 2014. Twenty-six was case report. The major scenario used with 3D printing technology was LAAO (50.3%) and followed by TAVR (17.6%). CT and echocardiography were two main imaging techniques that were used to generate 3D-printed heart models. All studies showed that 3D-printed models were helpful for preoperative planning, orientation, and medical teaching. The important finding is that 3D printing provides a unique patient-specific method to assess complex anatomy and is helpful for intraoperative orientation, decision-making, creating functional models, and teaching adult cardiac and vascular surgery, including catheter-based heart surgery.

The role of 3D printing in pediatric airway obstruction: A systematic review

BACKGROUND

Tracheomalacia and tracheal stenosis are complicated, patient-specific diseases that require a multidisciplinary approach to diagnose and treat. Surgical interventions such as aortopexy, slide tracheoplasty, and stents potentially have high rates of morbidity. Given the emergence of three-dimensional (3D) printing as a versatile adjunct in managing complex pathology, there is a growing body of evidence that there is a strong role for 3D printing in both surgical planning and implant creation for pediatric airway obstruction.

METHODS

A structured PubMed.gov literature search was utilized, and a two-researcher systematic review was performed following the PRISMA criteria. The following search query was utilized: (((((3D printing) OR three-dimensional printing) OR 3D printed) OR three-dimensional printed) AND trachea) OR airway.

RESULTS

Over 23,000 publications were screened. Eight literature reviews and thirty-seven original papers met inclusion criteria. Of the thirty-seven original papers, eleven discussed 3D printing for surgical planning and twenty-six discussed 3D printing implants for interventions.

CONCLUSION

The reported application of 3D printing for management of pediatric airway obstruction is emerging with positive and broad applications. 3D printing for surgical planning not only improves pre-operative assessment of surgical approach and stent customization, but also helps facilitate patient/family education. 3D printing for custom implantable interventions is focused on bioresorbable external airway splints and biological grafts, with both animal studies and human case reports showing good results in improving symptoms.

Identifying a commercially-available 3D printing process that minimizes model distortion after annealing and autoclaving and the effect of steam sterilization on mechanical strength

Background

Fused deposition modeling 3D printing is used in medicine for diverse purposes such as creating patient-specific anatomical models and surgical instruments. For use in the sterile surgical field, it is necessary to understand the mechanical behavior of these prints across 3D printing materials and after autoclaving. It has been previously understood that steam sterilization weakens polylactic acid, however, annealing heat treatment of polylactic acid increases its crystallinity and mechanical strength. We aim to identify an optimal and commercially available 3D printing process that minimizes distortion after annealing and autoclaving and to quantify mechanical strength after these interventions.

Methods

Thirty millimeters cubes with four different infill geometries were 3D printed and subjected to hot water-bath annealing then immediate autoclaving. Seven commercially available 3D printing materials were tested to understand their mechanical behavior after intervention. The dimensions in the X, Y, and Z axes were measured before and after annealing, and again after subsequent autoclaving. Standard and strength-optimized Army-Navy retractor designs were printed using the 3D printing material and infill geometry that deformed the least. These retractors were subjected to annealing and autoclaving interventions and tested for differences in mechanical strength.

Results

For both the annealing and subsequent autoclaving intervention, the material and infill geometry that deformed the least, respectively, was Essentium PLA Gray and “grid”. Standard retractors without intervention failed at 95 N +/− 2.4 N. Annealed retractors failed at 127.3 N +/− 10 N. Autoclave only retractors failed at 15.7 N +/− 1.4 N. Annealed then autoclaved retractors failed at 19.8 N +/− 3.1 N. Strength-optimized retractors, after the annealing then autoclaving intervention, failed at 164.8 N +/− 12.5 N.

Conclusion

For 30 mm cubes, the 3D printing material and infill geometry that deformed the least, respectively, was Essentium PLA and “grid”. Hot water-bath annealing results in increased 3D printed model strength, however autoclaving 3D prints markedly diminishes strength. Strength-optimized 3D printed PLA Army-Navy retractors overcome the strength limitation due to autoclaving.

Use of Three-dimensional Printing in the Development of Optimal Cardiac CT Scanning Protocols

Three-dimensional (3D) printing is increasingly used in medical applications with most of the studies focusing on its applications in medical education and training, pre-surgical planning and simulation, and doctor-patient communication. An emerging area of utilising 3D printed models lies in the development of cardiac computed tomography (CT) protocols for visualisation and detection of cardiovascular disease. Specifically, 3D printed heart and cardiovascular models have shown potential value in the evaluation of coronary plaques and coronary stents, aortic diseases and detection of pulmonary embolism. This review article provides an overview of the clinical value of 3D printed models in these areas with regard to the development of optimal CT scanning protocols for both diagnostic evaluation of cardiovascular disease and reduction of radiation dose. The expected outcomes are to encourage further research towards this direction.

3D Printing Applications for Transcatheter Aortic Valve Replacement

PURPOSE OF REVIEW

A combination of evolving 3D printing technologies, new 3D printable materials, and multi-disciplinary collaborations have made 3D printing applications for transcatheter aortic valve replacement (TAVR) a promising tool to promote innovation, increase procedural success, and provide a compelling educational tool. This review synthesizes the knowledge via publications and our group's experience in this area that exemplify uses of 3D printing for TAVR.

RECENT FINDINGS

Patient-specific 3D-printed models have been used for TAVR pre-procedural device sizing, benchtop prediction of procedural complications, planning for valve-in-valve and bicuspid aortic valve procedures, and more. Recent publications also demonstrate how 3D printing can be used to test assumptions about why certain complications occur during THV implantation. Finally, new materials and combinations of existing materials are starting to bridge the large divide between current 3D material and cardiac tissue properties. Several studies have demonstrated the utility of 3D printing in understanding challenges of TAVR. Innovative approaches to benchtop testing and multi-material printing have brought us closer to being able to predict how a THV will interact with a specific patient's aortic anatomy. This work to date is likely to open the door for advancements in other areas of structural heart disease, such as interventions involving the mitral valve, tricuspid valve, and left atrial appendage.

3D printed CT-based abdominal structure mannequin for enabling research

An anthropomorphic phantom is a radiologically accurate, tissue realistic model of the human body that can be used for research into innovative imaging and interventional techniques, education simulation and calibration of medical imaging equipment. Currently available CT phantoms are appropriate tools for calibration of medical imaging equipment but have major disadvantages for research and educational simulation. They are expensive, lacking the realistic appearance and characteristics of anatomical organs when visualized during X-ray based image scanning. In addition, CT phantoms are not modular hence users are not able to remove specific organs from inside the phantom for research or training purposes. 3D printing technology has evolved and can be used to print anatomically accurate abdominal organs for a modular anthropomorphic mannequin to address limitations of existing phantoms. In this study, CT images from a clinical patient were used to 3D print the following organ shells: liver, kidneys, spleen, and large and small intestines. In addition, fatty tissue was made using modelling beeswax and musculature was modeled using liquid urethane rubber to match the radiological density of real tissue in CT Hounsfield Units at 120kVp. Similarly, all 3D printed organ shells were filled with an agar-based solution to mimic the radiological density of real tissue in CT Hounsfield Units at 120kVp. The mannequin has scope for applications in various aspects of medical imaging and education, allowing us to address key areas of clinical importance without the need for scanning patients.