Clinical situations for which 3D printing is considered an appropriate representation or extension of data contained in a medical imaging examination: pediatric congenital heart disease conditions.

BACKGROUND: The use of medical 3D printing (focusing on anatomical modeling) has continued to grow since the Radiological Society of North America's (RSNA) 3D Printing Special Interest Group (3DPSIG) released its initial guideline and appropriateness rating document in 2018. The 3DPSIG formed a focused writing group to provide updated appropriateness ratings for 3D printing anatomical models across a variety of congenital heart disease. Evidence-based- (where available) and expert-consensus-driven appropriateness ratings are provided for twenty-eight congenital heart lesion categories. METHODS: A structured literature search was conducted to identify all relevant articles using 3D printing technology associated with pediatric congenital heart disease indications. Each study was vetted by the authors and strength of evidence was assessed according to published appropriateness ratings. RESULTS: Evidence-based recommendations for when 3D printing is appropriate are provided for pediatric congenital heart lesions. Recommendations are provided in accordance with strength of evidence of publications corresponding to each cardiac clinical scenario combined with expert opinion from members of the 3DPSIG. CONCLUSIONS: This consensus appropriateness ratings document, created by the members of the RSNA 3DPSIG, provides a reference for clinical standards of 3D printing for pediatric congenital heart disease clinical scenarios.

Predicting chronological age based on age-related osteophyte development in the superior and inferior vertebral centrum margins of T12-L5.

The purpose of this study was to determine the relationship between vertebral margins at individual vertebral levels between T12-L5 vertebra and chronological age and develop predictive models. Three hundred and nineteen CT scans from a medical imaging database in North America were randomly selected. Three superior and inferior vertebral margin sites were scored based on observable age-related changes. All individual vertebral margin site scores significantly correlated with age at death with Pearson r values ranging from 0.47 to 0.77. Totaling the individual vertebral margin site scores for L1-L5 improved Pearson r to 0.92. All resulting predictive models were significant, and the best models predicted age at death within 10 years 70%-76% of the time for males, females, and combined male and females. In conclusion, this study produced accurate and reliable models to predict age at death using age-related changes in the spine for a North American population.

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

BACKGROUND: Medical three dimensional (3D) printing is performed for neurosurgical and otolaryngologic conditions, but without evidence-based guidance on clinical appropriateness. A writing group composed of the Radiological Society of North America (RSNA) Special Interest Group on 3D Printing (SIG) provides appropriateness recommendations for neurologic 3D printing conditions. METHODS: A structured literature search was conducted to identify all relevant articles using 3D printing technology associated with neurologic and otolaryngologic conditions. Each study was vetted by the authors and strength of evidence was assessed according to published guidelines. RESULTS: Evidence-based recommendations for when 3D printing is appropriate are provided for diseases of the calvaria and skull base, brain tumors and cerebrovascular disease. Recommendations are provided in accordance with strength of evidence of publications corresponding to each neurologic condition combined with expert opinion from members of the 3D printing SIG. CONCLUSIONS: This consensus guidance document, created by the members of the 3D printing SIG, provides a reference for clinical standards of 3D printing for neurologic conditions.

Institutional Strategies to Maintain and Grow Imaging Research During the COVID-19 Pandemic.

Understanding imaging research experiences, challenges, and strategies for academic radiology departments during and after COVID-19 is critical to prepare for future disruptive events. We summarize key insights and programmatic initiatives at major academic hospitals across the world, based on literature review and meetings of the Radiological Society of North America Vice Chairs of Research (RSNA VCR) group. Through expert discussion and case studies, we provide suggested guidelines to maintain and grow radiology research in the postpandemic era.

Design and Validation of a 3D Printed Cranio-Facial Simulator: A Novel Tool for Surgical Education.

OBJECTIVE: To assess the ability of current 3D printing technology to generate a craniofacial bony and soft tissue anatomical model for use in simulating the performance of a fronto-orbital advancement (FOA) osteotomy and then to further assess the value of the model as an educational tool. DESIGN: Anatomic models were designed with a process of serial anatomic segmentation/design, 3D printing, dissection, and device refinement. A validation study was conducted with 5 junior and 5 senior plastic surgery residents. The validation study incorporated a multiple-choice Knowledge Assessment test (KA), an Objective Structured Assessment of Technical skills (OSATs), a Global Rating Scale (GRS) and a Michigan Standard Simulation Experience Scale (MiSSES). We compared the scores of both the junior and senior residents and compared junior resident scores, before and after viewing a lecture/demonstration. RESULTS: MiSSES showed high face validity with a score of 85.1/90, signifying high satisfaction with the simulator learning experience. Simulation and the lecture/demonstration improved the junior resident average KA score from 5.6/10 to 9.6/10 (P = .02), OSATs score from 32.4/66 to 64.4/66 (P < .001) and GRS score from 13.9/35 to 27.5/35 (P < .001). The senior residents OSATs score of 56.3/66 was higher than the pre-lecture juniors (32.4/66) (P < .001), but lower than the post-lecture juniors (64.4/66) (P < .001). CONCLUSION: We have successfully fabricated a 3D printed craniofacial simulator capable of being used as an educational tool alongside traditional surgical training. Next steps would be improving soft tissue realism, inclusion of patient and disease specific anatomy and creation of models for other surgical specialties.

Three-dimensional cardiac print assisted percutaneous closure of left ventricular pseudoaneurysm in patient with Behçet's disease.

Spontaneous left ventricular pseudoaneurysms are very rare and can have catastrophic consequences if unrecognized. A case of combined spontaneous left ventricular aneurysm and pseudoaneurysm in Behcet's disease (BD) has been reported. The case emphasizes advanced techniques for percutaneous closure of the defects with the use of an ex-vivo three-dimensional cardiac printed model as a tool to facilitate the procedure.

Morphologic analysis of the sublime tubercle: considerations in the approach to ulnar collateral ligament reconstruction.

Background: Given the increased incidence of ulnar collateral ligament (UCL) injuries and the projected increase in reconstruction procedures, a robust understanding of the morphologic location of the sublime tubercle is paramount to anatomic reconstruction. There is limited research evaluating the morphology of the sublime tubercle of the proximal ulna in an anterior-to-posterior plane. Methods: Twenty-five computed tomography (CT) scans of intact proximal elbow joints for patients were selected using a de-identified database. Cases with history of fracture or surgical intervention to the elbow joint were excluded. These CT scans were then imported into the Mimics Innovation Suite 24.0 software to analyze the sublime tubercle angle from the midpoint of the trochlear notch. All left elbow angle and clock-face values were converted to right elbow values for analysis. Results: The average sublime tubercle angle from the midpoint of the trochlear notch was 282.53 degrees. The angle was converted to a clock face descriptor which located the sublime tubercle at 9.42. Our findings demonstrate that, in the non-throwing population, the morphology of the sublime tubercle can be expected to have a consistent medial location between 9 and 10 o'clock or 2 and 3 o'clock on the contralateral elbow. Conclusions: In relation to the proximal ulnar landmarks, the sublime tubercle, in the non-throwing population, has a consistent relative location.

Volumetric histological characterization of optic nerve degeneration using tissue clearing: literature review and practical study.

Tissue clearing technologies can greatly improve the depth and accuracy with which the three-dimensional structure of tissues, especially those of th*-e nervous system, can be visualized. A review of the present literature suggests that the growing diversity and sophistication of various approaches have contributed to the expansion of this method to a greater variety of tissue types, experimental conditions, and imaging modalities. In the proof-of-concept study presented in this paper, a simplified and modified version of the tissue clearing method CUBIC (clear, unobstructed brain imaging cocktails and computational analysis) was used in conjunction with fluorescent staining and immunohistochemistry to illustrate the three-dimensional structure and molecular characteristics of inflammatory and degenerative activity in the mouse optic nerve. Based on the studies summarized in this mini-review, and our impression from using the mCUBIC method, it appears that tissue clearing could be a viable approach revealing three-dimensional histological features of myelin-rich tissues under normal conditions and after injury.

A review of visualization techniques of post-mortem computed tomography data for forensic death investigations.

Postmortem computed tomography (PMCT) is a standard image modality used in forensic death investigations. Case- and audience-specific visualizations are vital for identifying relevant findings and communicating them appropriately. Different data types and visualization methods exist in 2D and 3D, and all of these types have specific applications. 2D visualizations are more suited for the radiological assessment of PMCT data because they allow the depiction of subtle details. 3D visualizations are better suited for creating visualizations for medical laypersons, such as state attorneys, because they maintain the anatomical context. Visualizations can be refined by using additional techniques, such as annotation or layering. Specialized methods such as 3D printing and virtual and augmented reality often require data conversion. The resulting data can also be used to combine PMCT data with other 3D data such as crime scene laser scans to create crime scene reconstructions. Knowledge of these techniques is essential for the successful handling of PMCT data in a forensic setting. In this review, we present an overview of current visualization techniques for PMCT.

Changing Enhancement Pattern and Tumor Volume of Vestibular Schwannomas After Subtotal Resection.

BACKGROUND: Surgical strategy in vestibular schwannomas may require subtotal resection to preserve neurologic function. Residual tumor growth pattern and contrast enhancement in the immediate postresection period remain uncertain. We sought to evaluate changes in the enhancement pattern and volume of vestibular schwannomas after subtotal resection in the immediate postoperative period. METHODS: Volumetric analysis of tumor size and enhancement patterns of vestibular schwannomas were measured on magnetic resonance imaging (MRI) scans obtained within 3 days of surgery, 3 months after surgery, and 1 year after surgery. RESULTS: Nineteen patients were eligible for inclusion in the study (9 male and 10 female) with an average age of 47 years. Contrast enhancement was absent in 6 of 19 (32%) of cases on the immediate postresection MRI with return of expected enhancement on subsequent studies. Volumetric analysis identified that tumors decreased in size by an average of 35% in the first 3 months (P = 0.025) after resection and 46% in the first year after resection (P < 0.01). CONCLUSIONS: Vestibular schwannomas that undergo subtotal resection tend to decrease in size over the first 3 months after resection. Residual tumor volume may fail to enhance on the immediate postresection MRI. Both of these findings could lead surgeons to misinterpret degree of resection after surgery and have implications for clinical decision making and research reporting in the scientific literature for vestibular schwannomas after subtotal resection.

Implementation of 3D Printing in Medical Care for Preoperative Planning of Complex Ventricular Septal Defect.

Three-dimensional (3D) modeling and printing in medicine have emerged to encompass every aspect of medical applications. This ranges from education, illustration, and treatment, as well as patient care whether for purposes of diagnosis or treatment and surgical planning. In the past few decades, these novel tools have shown promising utility to help radiologists and the medical team to improve quality of patient care and outcomes via 3D printing application and utilization. This workflow will be illustrated through a ventricular septal defect (VSD) case at which 3D analysis was critical in the assessment and treatment planning of the patient's underlying medical condition.

3-Dimensional Printed Alternative to the Standard Synthetic Flocked Nasopharyngeal Swabs Used for Coronavirus Disease 2019 Testing.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19), can be detected in respiratory samples by real-time reverse transcriptase polymerase chain reaction (RT-PCR) or other molecular methods. Accessibility of diagnostic testing for COVID-19 has been limited by intermittent shortages of supplies required for testing, including flocked nasopharyngeal (FLNP) swabs. METHODS: We developed a 3-dimensional printed nasopharyngeal (3DP) swab as a replacement of the FLNP swab. The performance of 3DP and FLNP swabs were compared in a clinical trial of symptomatic patients at 3 clinical sites (n = 291) using 3 SARS-CoV-2 emergency use authorization tests: a modified version of the Centers for Disease Control and Prevention (CDC) RT-PCR Diagnostic Panel and 2 commercial automated formats, Roche Cobas and NeuMoDx. RESULTS: The cycle threshold-C(t)-values from the gene targets and the RNase P gene control in the CDC assay showed no significant differences between swabs for both gene targets (P = .152 and P = .092), with the RNase P target performing significantly better in the 3DP swabs (P < .001). The C(t) values showed no significant differences between swabs for both viral gene targets in the Roche cobas assay (P = .05 and P = .05) as well as the NeuMoDx assay (P = .401 and P = .484). The overall clinical correlation of COVID-19 diagnosis between all methods was 95.88% (Kappa 0.901). CONCLUSIONS: The 3DP swabs were equivalent to standard FLNP in 3 testing platforms for SARS-CoV-2. Given the need for widespread testing, 3DP swabs printed onsite are an alternate to FLNP that can rapidly scale in response to acute needs when supply chain disruptions affect availability of collection kits.

Potential use of deep learning techniques for postmortem imaging.

The use of postmortem computed tomography in forensic medicine, in addition to conventional autopsy, is now a standard procedure in several countries. However, the large number of cases, the large amount of data, and the lack of postmortem radiology experts have pushed researchers to develop solutions that are able to automate diagnosis by applying deep learning techniques to postmortem computed tomography images. While deep learning techniques require a good understanding of image analysis and mathematical optimization, the goal of this review was to provide to the community of postmortem radiology experts the key concepts needed to assess the potential of such techniques and how they could impact their work.

Radiographic Comparison of Superior and Inferior Gluteal Vessels in Jackknife versus Prone Position: A Prospective, Self-Controlled Trial.

Mortality after gluteal augmentation with fat transfer techniques is extremely high. Placement of fat subcutaneously versus in the gluteal musculature, or both, is considerably debated. The purpose of this study was to radiographically show the anatomical difference in live subjects in different procedural positions: the flexed or "jackknife" versus prone position. A total of 10 women underwent computed tomographic scanning of the pelvis with venous phase run-off in both the jackknife and prone positions. A computed tomography-specialized radiologist then reviewed images and measured distances from the inferior and superior gluteal veins to the skin and muscle. Three-dimensional imaging and analysis were also performed. Measurements were significantly shorter with respect to distance from skin to muscle, skin to vessel, and vessel to muscle observed from inferior and superior gluteal veins in the jackknife versus the prone position. Three-dimensional modeling showed a significant reduction in the volume and inferior and superior gluteal vein diameters when in the jackknife position. When placed in the jackknife position for gluteal augmentation with fat transfer, extreme caution should be taken with the injecting cannula, as the underlying muscle is only 2 to 3 cm deep. Three-dimensional analysis showed narrowed and reduced volume of gluteal vasculature when in the jackknife position; this is a possible indication of torsion or stretch on the vessel around the pelvic rim that could cause vein avulsion injury from the pressurized fat within the piriform space.

A 3D-printed nasopharyngeal swab for COVID-19 diagnostic testing.

The nasopharyngeal swab is a critical component of the COVID-19 testing kit. Supply chain remains greatly impacted by the pandemic. Teams from USF Health Radiology and Northwell Health System developed a 3D-printed stopgap alternative. This descriptive study details the workflow and provides guidance for hospital-based 3D printing labs to leverage the design to make a positive impact on the pandemic. Swab use is also outlined, and the early information regarding clinical use is described, including an ongoing multicenter trial methodology.

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.

An Analysis of Hounsfield Unit Values and Volumetrics from Computerized Tomography of the Proximal Femur for Sex and Age Estimation.

Sex and age are two elements in the establishment of a biological profile for forensic identification. While the pelvic bones are the most ideal structures for sex estimation, the condition of a body is not always ideal due to the nature of death, such as in mass disasters, or postmortem processes. This study utilized CT scans and resultant 3D models of 100 male and 100 female adults of known ages ranging from 18 to 98 years old to collect volumetric and Hounsfield unit measurements of the proximal femur. Equations were created to establish logistic regression models for sex estimation and linear regression models for age estimation. The resultant sex estimation method had an accuracy of 93.5% and utilized the volume of the proximal femur. This study provides three linear regression models for age with an accuracy range of 86%-92% ±12 years. As imaging technologies are increasingly adopted for forensic purposes, the power of 3D data will provide the opportunity for more quantitative and reproducible analyses. The proposed method for sex and age estimation provides a reliable tool that can be utilized in both day-to-day casework and disaster victim identification.

Three-Dimensional Morphological Analysis of Sex, Age, and Symmetry of Proximal Femurs from Computed Tomography: Application to Total Hip Arthroplasty.

The success of a total hip arthroplasty is directly related to the ability of the implant to match original femoral morphology. Given this critical relationship, we characterized normal proximal femoral morphology as it relates to sex, age, and symmetry. Sixty abdominopelvic computed tomography (CT) scans (30 male and 30 female, ages 20-85 years old) from patients without any osseous pathology or implants were utilized. Three-dimensional models were constructed from the CT scans using Mimics v19 (Materialize). Thirteen landmarks were placed on each femur model and yielded eight morphological measurements for each femur. Medullary cavity measurements were taken superior to, at the center of, and inferior to the lesser trochanter. Morphological measurements were analyzed by sex, age group, and left versus right. A significant difference was identified between males and females for femoral head height, inferior neck length, minimum neck diameter, neck shaft angle, mediolateral medullary cavity measurement superior to the lesser trochanter and the anteroposterior at the lesser trochanter (P < 0.05). Age was found to correlate with medullary cavity measurements. As previously identified in the literature, differences with respect to the right and left femur were not of practical significance. The results show that sex is critical in determining prosthesis fit with the examined morphological measurements of the proximal femur while age is more important with respect to the medullary cavity. It is also evident that the current practice of using one femur to approximate the opposite is a viable clinical assumption. Clin. Anat., 33:731-738, 2020. © 2019 Wiley Periodicals, Inc.

Adding Depth to Cephalometric Analysis: Comparing Two- and Three-Dimensional Angular Cephalometric Measurements.

INTRODUCTION: Lateral cephalometric radiographs (LCR) have been the standard tool used for cephalometric analysis in craniofacial surgery. Over the past decade, a three-dimensional (3D) revolution in cephalometric analysis and surgical planning has been underway. To date, research has not validated whether cephalometric measurements taken from two-dimensional (2D) and 3D data sources are equivalent and interchangeable. The authors sought to compare angular cephalometric measurements taken with 2D and 3D modalities. METHODS: Sixty-two head CT scans (36 females, 26 males) with an average age of 63 ±â€Š20 years were studied. Twelve cephalometric angular measurements were taken from 3D reconstructed skulls using the software package Mimics 19.0 (Materialize; Leuven, Belgium). These same facial angles were measured from 2D lateral cephalograms reconstructed from the original CT scans using Dolphin 11.9. Measurements taken with both techniques were compared for agreement using a paired t test. Intra-class correlation coefficient assessment was used to determine inter-rater reliability. Statistical significance was set at P < 0.05. RESULTS: Five of the 12 angular measurements (SNA, SNB, MP-FH, U1-SN, and U1-L1) demonstrated statistically significant differences (P < 0.05) between the 2D and 3D analyses. All of these differences were less than the standard deviations for the respective measure. CONCLUSION: The differences between angular cephalometric values obtained from 2D LCRs and 3D CT reconstructions are small. This supports the practices of using 2D and 3D cephalometric data interchangeably in most applications. Clinicians must be selective in which measures they employ to maximize accuracy and care must be taken when measuring dental inclination with lateral cephalograms.