Three-dimensional Printing and 3D Slicer: Powerful Tools in Understanding and Treating Structural Lung Disease

Implementations of 3D printing in ophthalmology

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Treatment of complex airway stenoses using patient-specific 3D-engineered stents: a proof-of-concept study

Anatomically complex airway stenosis (ACAS) represents a challenging situation in which commercially available stents often result in migration or granulation tissue reaction due to poor congruence. This proof-of-concept clinical trial investigated the feasibility and safety of computer-assisted designed (CAD) and manufactured personalised three-dimensional (3D) stents in patients with ACAS from various origins. After CAD of a virtual stent from a CT scan, a mould is manufactured using a 3D computer numerical control machine, from which a medical-grade silicone stent is made. Complication rate, dyspnoea, quality of life and respiratory function were followed after implantation. The congruence of the stent was assessed peroperatively and at 1 week postimplantation (CT scan). The stent could be implanted in all 10 patients. The 3-month complication rate was 40%, including one benign mucus plugging, one stent removal due to intense cough and two stent migrations. 9 of 10 stents showed great congruence within the airways, and 8 of 10 induced significant improvement in dyspnoea, quality of life and respiratory function. These promising outcomes in highly complex situations support further investigation on the subject, including technological improvements.​ TRIAL REGISTRATION NUMBER: NCT02889029.

Angulated Stents-A Novel Stent Improvisation to Manage Difficult Post-tuberculosis Bronchial Stenosis

Post-tuberculosis bronchostenosis (PTBS), a complication of endobronchial tuberculosis is currently treated by bronchial stenting. However, in cases of angulated bronchial stenoses, difficulty is often encountered in stent insertion and maintenance, resulting in stent migration, granulation tissue overgrowth, and restenosis. To accommodate the angulated alignment of the stenosis, we devised an "angulated stent"-a novel improvisation of the conventional stent via splicing and suturing to achieve a resultant angulated shape. A retrospective review was undertaken to evaluate the performance of this stent. Among 283 PTBS patients who underwent interventional bronchoscopy at our center from 2004 to 2014, 21 were treated with at least one angulated stent. Clinical outcomes, including the stenting duration were investigated. After a median follow-up of 26 months, stent removal was successful in 7 (33.3%) out of 21 patients. In patients managed with angulated stents, the median duration to stent change or eventual removal was longer than those treated with straight tube stents (392 days vs. 86 days; p < 0.05). Angulated stents are a feasible treatment option in patients with angulated PTBS by reducing complications and prolonging the stent-changing interval.

The Applications of 3D Printing in Pulmonary Drug Delivery and Treatment of Respiratory Disorders

BACKGROUND

Pulmonary diseases are the third leading cause of morbidity worldwide, however treatment and diagnosis of these diseases continue to be challenging due to the complex anatomical structure as well as physiological processes in the lungs.

METHODS

3D printing is progressively finding new avenues in the medical field and this technology is constantly being used for diseases where diagnosis and treatment heavily rely on the thorough understanding of complex structural-physiology relationships. The structural and functional complexity of the pulmonary system makes it well suited to 3D printing technology.

RESULTS

3D printing can be used to deconstruct the complex anatomy of the lungs and improve our understanding of its physiological mechanisms, cell interactions and pathophysiology of pulmonary diseases. Thus, this technology can be quite helpful in the discovery of novel therapeutic targets, new drugs and devices for the treatment of lung diseases.

CONCLUSION

The intention of this review is to detail our current understanding of the applications of 3D printing in the design and evaluation of inhalable medicines and to provide an overview on its application in the diagnosis and treatment of pulmonary diseases. This review also discusses other technical and regulatory challenges associated with the progression of 3D printing into clinical practice.

Preoperative 3-dimensional computed tomography lung simulation before video-assisted thoracoscopic anatomic segmentectomy for ground glass opacity in lung

Background

Three-dimensional (3D) simulation of pulmonary vessels and the space between the lesion and adjacent tissues may improve the safety and accuracy of video-assisted thoracoscopic surgery (VATS) for lung. The aim of this study was to evaluate the effect of 3D simulation on the outcome of VATS segmentectomy for ground glass opacity (GGO) in lung.

Methods

We retrospectively analyzed 68 cases of small (≤2 cm) GGO, which were diagnosed as cT1aN0M0 lung cancer, from May 1, 2016 to February 28, 2017 in our institute. All the patients underwent VATS segmentectomy. The patients were divided into "3D" group, 3D preoperative reconstruction simulation in 36 patients and "non-3D" group, 32 patients with only computed tomography (CT). Operation plans were firstly made by CT in all patients, then by 3D simulation only in 3D group. The clinical outcomes, including operation time, blood loss, resection margin distance, length of postoperative stay and postoperative complications were compared between the two groups.

Results

There were 21 male and 47 female analyzed, aging from 34 to 72 years (median 57). In 3D group, pathological result showed 8 cases of adenocarcinoma, 23 cases of microinvasive adenocarcinoma (MIA), 5 cases of adenocarcinoma in situ (AIS). In non-3D group, 18 cases of MIA, 9 cases of adenocarcinoma and 5 cases of AIS were diagnosed pathologically. The blood loss, postoperative hospital stay and the incidence of the postoperative complications were similar in both of the groups. There was no 30-day postoperative mortality in either group. The median operation time for the 3D group (111 minute) was shorter than non-3D group (139 minute) (P=0.03). Seven cases (19%) in 3D group changed the original operation plan according to the simulation result with the consideration of adequate resection margin distance. All cases in 3D group had adequate resection margin distance. Four cases (13%) in non-3D group got inadequate resection margin distance, and more lung tissues than the original plan were then resected in these patients (P=0.04).

Conclusions

3D preoperative simulation may be more precise in operation plan than CT scan and can significantly shorten the operation time in VATS segmentectomy for GGO in lung.

A Preliminary Investigation into the Accuracy of 3D Modeling and 3D Printing in Forensic Anthropology Evidence Reconstruction

There is currently no published empirical evidence‐base demonstrating 3D printing to be an accurate and reliable tool in forensic anthropology, despite 3D printed replicas being exhibited as demonstrative evidence in court. In this study, human bones (n = 3) scanned using computed tomography were reconstructed as virtual 3D models (n = 6), and 3D printed using six commercially available printers, with osteometric data recorded at each stage. Virtual models and 3D prints were on average accurate to the source bones, with mean differences from −0.4 to 1.2 mm (−0.4% to 12.0%). Interobserver differences ranged from −5.1 to 0.7 mm (−5.3% to 0.7%). Reconstruction and modeling parameters influenced accuracy, and prints produced using selective laser sintering (SLS) were most consistently accurate. This preliminary investigation into virtual modeling and 3D printer capability provides a novel insight into the accuracy of 3D printing osteological samples and begins to establish an evidence‐base for validating 3D printed bones as demonstrative evidence.

The utility of 3D-printed airway stents to improve treatment strategies for central airway obstructions

Airway stents are commonly used in the management of patients suffering from central airway obstruction (CAO). CAO may occur directly from airway strictures, obstructing airway cancers, airway fistulas or tracheobronchomalacia, resulting from the weakening and dynamic collapse of the airway wall. Current airway stents are constructed from biocompatible medical-grade silicone or from a nickel-titanium (nitinol) alloy with fixed geometry. The stents are inserted via the mouth during a bronchoscopic procedure. Existing stents have many shortcomings including the development of obstructing granulation tissue in the weeks and months following placement, mucous build up within the stent, and cough. Furthermore, airway stents are expensive and, if improperly sized for a given airway, may be easily dislodged (stent migration). Currently, in Australia, it is estimated that approximately 12,000 patients will develop CAO annually, many of whom will require airway stenting intervention. Of all stenting procedures, the rate of failure is currently reported to be at 22%. With a growing incidence of lung cancer prevalence globally, the need for updating airway stent technology is now greater than ever and personalizing stents using 3D-printing technology may offer the best chance of addressing many of the current limitations in stent design. This review article will assess what represents the gold standard in stent manufacture with regards to treatment of tracheobronchial CAO, the challenges of current airway stents, and outlines the necessity and challenges of incorporating 3D-printing technology into personalizing airway stents today.

Airway stents

Stents and tubes to maintain the patency of the airways are commonly used for malignant obstruction and are occasionally employed in benign disease. Malignant airway obstruction usually results from direct involvement of bronchogenic carcinoma, or by extension of carcinomas occurring in the esophagus or the thyroid. External compression from lymph nodes or metastatic disease from other organs can also cause central airway obstruction. Most malignant airway lesions are surgically inoperable due to advanced disease stage and require multimodality palliation, including stent placement. As with any other medical device, stents have significantly evolved over the last 50 years and deserve an in-depth understanding of their true capabilities and complications. Not every silicone stent is created equal and the same holds for metallic stents. Herein, we present an overview of the topic as well as some of the more practical and controversial issues surrounding airway stents. We also try to dispel the myths surrounding stent removal and their supposed use only in central airways. At the end, we come to the long-held conclusion that stents should not be used as first line treatment of choice, but after ruling out the possibility of curative surgical resection or repair.

Clinical Applications of 3D Printing: Primer for Radiologists

Three-dimensional (3D) printing refers to a number of manufacturing technologies that create physical models from digital information. Radiology is poised to advance the application of 3D printing in health care because our specialty has an established history of acquiring and managing the digital information needed to create such models. The 3D Printing Task Force of the Radiology Research Alliance presents a review of the clinical applications of this burgeoning technology, with a focus on the opportunities for radiology. Topics include uses for treatment planning, medical education, and procedural simulation, as well as patient education. Challenges for creating custom implantable devices including financial and regulatory processes for clinical application are reviewed. Precedent procedures that may translate to this new technology are discussed. The task force identifies research opportunities needed to document the value of 3D printing as it relates to patient care.

Radiologic Factors Predicting Deterioration of Mental Status in Patients with Acute Traumatic Subdural Hematoma

OBJECTIVE

To evaluate whether subdural hematoma (SDH) volume and other radiologic factors predict deterioration of mental status in patients with acute traumatic SDH.

METHODS

SDH volumes were measured with a semiautomated tool. The area under the receiver operating characteristic curve was used to determine optimal cutoff values for mental deterioration, including the variables midline shift, SDH volume, hematoma thickness, and Sylvian fissure ratio. Multivariate logistic regression was used to calculate the odds ratio for mental deterioration based on several predictive factors.

RESULTS

We enrolled 103 consecutive patients admitted to our hospital with acute traumatic SDH over an 8-year period. We observed an increase in SDH volume of approximately 7.2 mL as SDH thickness increased by 1 mm. A steeper slope for midline shift was observed in patients with SDH volumes of approximately 75 mL in the younger age group compared with patients in the older age group. When comparing cutoff values used to predict poor mental status at time of admission between the 2 age groups, we observed smaller midline shifts in the older patients.

CONCLUSIONS

Among younger patients, an overall tendency for more rapid midline shift progression was observed in patients with relatively low SDH volumes compared with older patients. Older patients seem to tolerate larger hematoma volumes owing to brain atrophy compared with younger patients. When there is a midline shift, older patients seem to be more vulnerable to mental deterioration than younger patients.

Measuring and Establishing the Accuracy and Reproducibility of 3D Printed Medical Models

Despite the rapid growth of three-dimensional (3D) printing applications in medicine, the accuracy and reproducibility of 3D printed medical models have not been thoroughly investigated. Although current technologies enable 3D models to be created with accuracy within the limits of clinical imaging spatial resolutions, this is not always achieved in practice. Inaccuracies are due to errors that occur during the imaging, segmentation, postprocessing, and 3D printing steps. Radiologists' understanding of the factors that influence 3D printed model accuracy and the metrics used to measure this accuracy is key in directing appropriate practices and establishing reference standards and validation procedures. The authors review the various factors in each step of the 3D model printing process that contribute to model inaccuracy, including the intrinsic limitations of each printing technology. In addition, common sources of model inaccuracy are illustrated. Metrics involving comparisons of model dimensions and morphology that have been developed to quantify differences between 3D models also are described and illustrated. These metrics can be used to define the accuracy of a model, as compared with the reference standard, and to measure the variability of models created by different observers or using different workflows. The accuracies reported for specific indications of 3D printing are summarized, and potential guidelines for quality assurance and workflow assessment are discussed. Online supplemental material is available for this article. ©RSNA, 2017.

Factors Predicting Ventricle Volume Increase After Aneurysmal Clipping in Patients with Subarachnoid Hemorrhage

OBJECTIVE

Although many studies have evaluated risk factors associated with hydrocephalus after aneurysmal subarachnoid hemorrhage, specific ventricle volume changes after subarachnoid hemorrhage have not been evaluated. We sought to evaluate factors predicting ventricle volume enlargement in patients with aneurysmal subarachnoid hemorrhage by measuring ventricle volume with a validated, semiautomated tool.

METHODS

Uni- and multivariable linear regression analyses were conducted with the follow-up ventricle volume as the dependent variable and the duration between subarachnoid hemorrhage occurrence and follow-up imaging as the independent variable, classified by the use of various predictive factors. A logistic regression model was used to calculate the odds ratio for the greater ventricle volume group compared with the lower ventricle volume group based on predictive factors.

RESULTS

We included 173 participants with a mean age of 55.5 years. Overall, an approximate increase in ventricle volume of 1.1 mL was observed daily within 60 days of clipping due to subarachnoid hemorrhage. In the multivariate logistic regression analysis, patients in the first and second tertile groups for body mass index showed approximately a 5.9- and 4.1-fold increased risk of greater follow-up ventricle volume, respectively, compared with the third tertile group for body mass index within 60 days of subarachnoid hemorrhage.

CONCLUSIONS

We found that greater body mass index independently predicted suppression of ventricle volume growth, owing to maintenance of subarachnoid trabeculae structures after subarachnoid hemorrhage. Further studies are needed to confirm our findings.