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

BACKGROUND: Medical three-dimensional (3D) printing has demonstrated utility and value in anatomic models for vascular conditions. A writing group composed of the Radiological Society of North America (RSNA) Special Interest Group on 3D Printing (3DPSIG) provides appropriateness recommendations for vascular 3D printing indications. METHODS: A structured literature search was conducted to identify all relevant articles using 3D printing technology associated with vascular 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 the following areas: aneurysm, dissection, extremity vascular disease, other arterial diseases, acute venous thromboembolic disease, venous disorders, lymphedema, congenital vascular malformations, vascular trauma, vascular tumors, visceral vasculature for surgical planning, dialysis access, vascular research/development and modeling, and other vasculopathy. Recommendations are provided in accordance with strength of evidence of publications corresponding to each vascular condition combined with expert opinion from members of the 3DPSIG. CONCLUSION: This consensus appropriateness ratings document, created by the members of the 3DPSIG, provides an updated reference for clinical standards of 3D printing for the care of patients with vascular conditions.

Clinical Applications of PRP: Musculoskeletal Applications, Current Practices and Update.

Musculoskeletal tissues are often subjected to deleterious effects stemming from traumatic injuries or degenerative pathologies, which can impede the body's natural repair response. The advent of regenerative medicine has emerged as a promising therapeutic approach in modern patient care. Among the interventions in this cutting-edge field, platelet-rich plasma (PRP) and cell-based therapies, such as mesenchymal stem cells, have garnered significant attention. In this article, we endeavor to provide an overview of the current practices and recent developments in PRP therapy, with a particular emphasis on the clinical applications for musculoskeletal pathologies.

Dual-Energy Computed Tomography and Beyond: Musculoskeletal System.

Traditional monoenergetic computed tomography (CT) scans in musculoskeletal imaging provide excellent detail of bones but are limited in the evaluation of soft tissues. Dual-energy CT (DECT) overcomes many of the traditional limitations of CT and offers anatomical details previously seen only on MR imaging. In addition, DECT has benefits in the evaluation and characterization of arthropathies, bone marrow edema, and collagen applications in the evaluation of tendons, ligaments, and vertebral discs. There is current ongoing research in the application of DECT in arthrography and bone mineral density calculation.

Radiological Society of North America (RSNA) 3D Printing Special Interest Group (SIG) clinical situations for which 3D printing is considered an appropriate representation or extension of data contained in a medical imaging examination: breast conditions.

The use of medical 3D printing has expanded dramatically for breast diseases. A writing group composed of the Radiological Society of North America (RSNA) Special Interest Group on 3D Printing (SIG) provides updated appropriateness criteria for breast 3D printing in various clinical scenarios. Evidence-based appropriateness criteria are provided for the following clinical scenarios: benign breast lesions and high-risk breast lesions, breast cancer, breast reconstruction, and breast radiation (treatment planning and radiation delivery).

Evaluation of a deep learning method for the automated detection of supraspinatus tears on MRI.

OBJECTIVE: To evaluate if deep learning is a feasible approach for automated detection of supraspinatus tears on MRI. MATERIALS AND METHODS: A total of 200 shoulder MRI studies performed between 2015 and 2019 were retrospectively obtained from our institutional database using a balanced random sampling of studies containing a full-thickness tear, partial-thickness tear, or intact supraspinatus tendon. A 3-stage pipeline was developed comprised of a slice selection network based on a pre-trained residual neural network (ResNet); a segmentation network based on an encoder-decoder network (U-Net); and a custom multi-input convolutional neural network (CNN) classifier. Binary reference labels were created following review of radiologist reports and images by a radiology fellow and consensus validation by two musculoskeletal radiologists. Twenty percent of the data was reserved as a holdout test set with the remaining 80% used for training and optimization under a fivefold cross-validation strategy. Classification and segmentation accuracy were evaluated using area under the receiver operating characteristic curve (AUROC) and Dice similarity coefficient, respectively. Baseline characteristics in correctly versus incorrectly classified cases were compared using independent sample t-test and chi-squared. RESULTS: Test sensitivity and specificity of the classifier at the optimal Youden's index were 85.0% (95% CI: 62.1-96.8%) and 85.0% (95% CI: 62.1-96.8%), respectively. AUROC was 0.943 (95% CI: 0.820-0.991). Dice segmentation accuracy was 0.814 (95% CI: 0.805-0.826). There was no significant difference in AUROC between 1.5 T and 3.0 T studies. Sub-analysis showed superior sensitivity on full-thickness (100%) versus partial-thickness (72.5%) subgroups. DATA CONCLUSION: Deep learning is a feasible approach to detect supraspinatus tears on MRI.

Preventing and Mitigating Radiology System Failures: A Guide to Disaster Planning.

Disaster planning is a core facet of modern health care practice. Owing to complex infrastructure requirements, radiology departments are vulnerable to system failures that may occur in isolation or during a disaster event when the urgency for and volume of imaging examinations increases. Planning for systems failures helps ensure continuity of service provision and patient care during an adverse event. Hazards to which a radiology department is vulnerable can be identified by applying a systematic approach with recognized tools such as the Hazard, Risk, and Vulnerability Analysis. Potential critical weaknesses within the department are highlighted by the Failure Mode and Effects Analysis tool. Recognizing the potential latent conditions and active failures that may impact systems allows implementation of strategies to prevent failure or to build resilience and mitigate the effects if they happen. Inherent system resilience to an adverse event can be estimated, and the ability of a department to operate during a disaster and the subsequent recovery can be predicted. The main systems at risk in a radiology department are staff, structure, stuff (supplies and/or equipment), and software, although individual issues and solutions within these are department specific. When medical imaging or examination interpretation needs cannot be met in the radiology department, the use of portable imaging modalities and teleradiology can augment the disaster response. All phases of disaster response planning should consider both sustaining operations and the transition back to normal function. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article. Work of the U.S. Government published under an exclusive license with the RSNA.

A review and guide to creating patient specific 3D printed anatomical models from MRI for benign gynecologic surgery.

BACKGROUND: Patient specific three-dimensional (3D) models can be derived from two-dimensional medical images, such as magnetic resonance (MR) images. 3D models have been shown to improve anatomical comprehension by providing more accurate assessments of anatomical volumes and better perspectives of structural orientations relative to adjacent structures. The clinical benefit of using patient specific 3D printed models have been highlighted in the fields of orthopaedics, cardiothoracics, and neurosurgery for the purpose of pre-surgical planning. However, reports on the clinical use of 3D printed models in the field of gynecology are limited. MAIN TEXT: This article aims to provide a brief overview of the principles of 3D printing and the steps required to derive patient-specific, anatomically accurate 3D printed models of gynecologic anatomy from MR images. Examples of 3D printed models for uterine fibroids and endometriosis are presented as well as a discussion on the barriers to clinical uptake and the future directions for 3D printing in the field of gynecological surgery. CONCLUSION: Successful gynecologic surgery requires a thorough understanding of the patient's anatomy and burden of disease. Future use of patient specific 3D printed models is encouraged so the clinical benefit can be better understood and evidence to support their use in standard of care can be provided.

Emergency Radiology During the COVID-19 Pandemic: The Canadian Association of Radiologists Recommendations for Practice.

Coronavirus Disease 2019 (COVID-19) is the disease caused by the novel coronavirus officially named the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), declared as a pandemic by the World Health Organization on March 11, 2020. The COVID-19 pandemic presents an unprecedented challenge to emergency radiology practice. The continuity of an effective emergency imaging service for both COVID-19 and non-COVID-19 patients is essential, while adhering to best infection control practices. Under the direction of the Board of the Canadian Association of Radiologists, this general guidance document has been synthesized by collaborative consensus of a group of emergency radiologists. These recommendations aim to assist radiologists involved in emergency diagnostic imaging to help mitigate the spread of COVID-19 and continue to add value to patient care in the emergency setting.

Multidetector Computed Tomography in Traumatic and Nontraumatic Aortic Emergencies: Emphasis on Acute Aortic Syndromes.

Aortic emergencies comprise of a list of conditions which are uncommon but are potentially fatal. Prognosis is usually determined by emergent diagnosis and treatment and hence radiology plays a key role in patient management. In this article, we aim to review the various causes of aortic emergencies and the relevant imaging findings placing special emphasis on acute aortic syndromes.

Encapsulating Peritoneal Sclerosis: The Abdominal Cocoon.

Encapsulating peritoneal sclerosis (EPS) is a rare but serious condition that results in (a) encapsulation of bowel within a thickened fibrocollagenous peritoneal membrane and (b) recurrent episodes of bowel obstruction. Although described by various names in the literature, the preferred term is encapsulating peritoneal sclerosis because it best describes the morphologic and histologic changes in this disorder. The etiology of EPS is multifactorial, with a wide variety of implicated predisposing factors that disrupt the normal physiologic function of the peritoneal membrane-prime among these factors being long-term peritoneal dialysis and bacterial peritoneal infections, especially tuberculosis. The clinical features of EPS are usually nonspecific, and knowledge of the radiologic features is necessary to make a specific diagnosis. The findings on radiographs are usually normal. Images from small-bowel follow-through studies show the bowel loops conglomerated in a concertina-like fashion with a serpentine arrangement in a fixed U-shaped configuration. US demonstrates a "cauliflower" appearance of bowel with a narrow base, as well as a "trilaminar" appearance depicted especially with use of high-resolution US probes. CT is the imaging modality of choice and allows identification of the thickened contrast material-enhanced abnormal peritoneal membrane and the encapsulated clumped bowel loops. In addition, CT can potentially help identify the cause of EPS (omental granuloma in tuberculosis), as well as the complications of EPS (bowel obstruction). Conservative medical treatment and surgical therapy early in the course of EPS have been used for management of the condition. The purpose of this article is to review the nomenclature and etiopathogenesis of EPS, describe the multimodality imaging appearances of EPS, including differentiating its features from those of other conditions mimicking EPS, and give an overview of management options. Online DICOM image stacks are available for this article. ©RSNA, 2018.

CT of preoperative and postoperative acetabular fractures revisited.

OBJECTIVE: We compared preoperative and postoperative computed tomography (CT) versus radiographic imaging in the evaluation of acetabular fractures (AFs). METHODS: Fifty-four patients who underwent imaging for AFs were retrospectively evaluated. Postoperative reduction quality was assessed on radiographs and CT scan by 2 observers. Rate of reintervention was noted. Radiation exposure from CT was calculated. RESULTS: After reduction, 24 patients had significant findings on postoperative CT. Five patients required reintervention, all of whom had significant postoperative CT findings and complex fractures. Notably, only 1 of the 5 patients had an indication for reintervention based on radiographs alone.The average dose for preoperative/postoperative CT study was 11.5/12.3 mSv, respectively, with a cumulative average dose of 23.8 mSv. CONCLUSIONS: Although reoperation rate is low after fixation of AFs, CT is required to identify those requiring reintervention. However, postoperative CT should be used judicially, only in patients presenting with complex acetabular fractures.

Uncommon primary pelvic retroperitoneal masses in adults: a pattern-based imaging approach.

There is a broad spectrum of primary pelvic retroperitoneal masses in adults that demonstrate characteristic epidemiologic and histopathologic features and natural histories. These masses may be classified into five distinct subgroups using a pattern-based approach that takes anatomic distribution and certain imaging characteristics into account, allowing greater accuracy in their detection and characterization and helping to optimize patient management. The five groups are cystic (serous and mucinous epithelial neoplasms, pelvic lymphangioma, tailgut cyst, ancient schwannoma), vascular or hypervascular (solitary fibrous tumor, paraganglioma, pelvic arteriovenous malformation, Klippel-Trénaunay-Weber syndrome, extraintestinal GIST [gastrointestinal stromal tumor]), fat-containing (lipoma, liposarcoma, myelolipoma, presacral teratoma), calcified (calcified lymphocele, calcified rejected transplant kidney, rare sarcomas), and myxoid (schwannoma, plexiform neurofibroma, myxoma).Cross-sectional imaging modalities help differentiate the more common gynecologic neoplasms from more unusual masses. In particular, the tissue-specific multiplanar capability of high-resolution magnetic resonance imaging permits better tumor localization and internal characterization, thereby serving as a road map for surgery.

Comparison of MRI alpha angle measurement planes in femoroacetabular impingement.

Insufficient femoral head-neck offset is common in femoroacetabular impingement (FAI) and reflected by the alpha angle, a validated measurement for quantifying this anatomic deformity in patients with FAI. We compared the alpha angle determined on magnetic resonance imaging (MRI) oblique axial plane images with the maximal alpha angle value obtained using radial images. The MRIs of 41 subjects with clinically suspected FAI were reviewed and alpha angle measurements were performed on both oblique axial plane images parallel to the long axis of the femoral neck and radial images obtained using the center of the femoral neck as the axis of rotation. The mean oblique axial plane and mean maximal radial alpha angle values were 53.4 degrees and 70.5 degrees, respectively. In 54% of subjects, the alpha angle was less than 55 degrees on the conventional oblique axial plane image but 55 degrees or greater on the radial plane images. Radial images yielded higher alpha angle values than oblique axial images. Patients with clinically suspected FAI may have a substantial contour abnormality that can be underestimated or missed if only oblique axial plane images are reviewed. Radial plane imaging should be considered in the MRI investigation of FAI.