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Background and Purpose: Currently, there is neither a standard protocol for vessel wall MR imaging of intracranial atherosclerotic disease (ICAD) nor a gold standard phantom to compare MR sequences. In this study, a plaque phantom is developed and characterized that provides a platform for establishing a uniform imaging approach for ICAD., Materials and Methods: A patient specific injection mold was 3D printed to construct a geometrically accurate ICAD phantom. Polyvinyl alcohol hydrogel was infused into the core shell mold to form the stenotic artery. The ICAD phantom incorporated materials mimicking a stenotic vessel and plaque components, including fibrous cap and lipid core. Two phantoms were scanned using high resolution cone beam CT and compared with four different 3 T MRI systems across eight different sites over a period of 18 months. Inter-phantom variability was assessed by lumen dimensions and contrast to noise ratio (CNR)., Results: Quantitative evaluation of the minimum lumen radius in the stenosis showed that the radius was on average 0.80 mm (95% CI 0.77 to 0.82 mm) in model 1 and 0.77 mm (95% CI 0.74 to 0.81 mm) in model 2. The highest CNRs were observed for comparisons between lipid and vessel wall. To evaluate manufacturing reproducibility, the CNR variability between the two models had an average absolute difference of 4.31 (95% CI 3.82 to 5.78). Variation in CNR between the images from the same scanner separated by 7 months was 2.5-6.2, showing reproducible phantom durability., Conclusions: A plaque phantom composed of a stenotic vessel wall and plaque components was successfully constructed for multicenter high resolution MRI standardization., Competing Interests: Competing interests: MJG: consultant on a fee per hour basis for Codman Neurovascular, InNeuroCo Inc, and Stryker Neurovascular; holds stock in InNeuroCo; and research support from the National Institutes of Health (NIH), Cerevasc LLC, Codman Neurovascular, the Cure Tay Sachs Foundation, Gentuity LLC, InNeuroCo, Medtronic Neurovascular, Microvention/Terumo, Mivi Neuroscience, Neuravi, Neurogami, Neuronal Protection Systems, Rapid Medical, R92M LLC, Philips Healthcare, Stryker Neurovascular, and the Wyss Institute. SA: NIH 1R21HL130969. RHS: The Heart and Stroke Foundation of Canada New Investigator Award, the Canadian Partnership for Stroke Recovery, and the Department of Medicine at Sunnybrook and University of Toronto. TNT: NINDS 5R21-TW010356-02., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.)

Rationale and Objectives: Here we review the current state of multicenter radiology research (MRR), and utilize a survey of experienced researchers to identify common advantages, barriers, and resources to guide future investigators., Materials and Methods: The Association of University Radiologists established a Radiology Research Alliance task force, Multi-center Research Studies in Radiology, composed of 12 society members to review MRR. A REDCap survey was designed to gain more insight from experienced researchers. Recipients were authors identified from a PubMed database search, utilizing search terms "multicenter" or "multisite" and "radiology." The survey included investigator background information, reasons why, barriers to, and resources that investigators found helpful in conducting or participating in MRR., Results: The survey was completed by 23 of 80 recipients (29%), the majority (76%) of whom served as a primary investigator on at least one MRR project. Respondents reported meeting collaborators at national or international (74%) and society (39%) meetings. The most common perceived advantages of MRR were increased sample size (100%) and improved generalizability (91%). External funding was considered the most significant barrier to MRR, reported by 26% of respondents. Institutional funding, setting up a central picture archiving and communication system, and setting up a central database were considered a significant barrier by 30%, 22%, and 22% of respondents, respectively. Resources for overcoming barriers included motivated staff (74%), strong leadership (70%), regular conference calls (57%), and at least one face-to-face meeting (57%)., Conclusions: Barriers to MRR include funding and establishing a central database and a picture archiving and communication system. Upon embarking on an MRR project, forming a motivated team who meets and speaks regularly is essential., (Copyright © 2018 The Association of University Radiologists. All rights reserved.)

Background: There is limited information regarding the effects of spaceflight on the anatomical configuration of the brain and on cerebrospinal fluid (CSF) spaces., Methods: We used magnetic resonance imaging (MRI) to compare images of 18 astronauts' brains before and after missions of long duration, involving stays on the International Space Station, and of 16 astronauts' brains before and after missions of short duration, involving participation in the Space Shuttle Program. Images were interpreted by readers who were unaware of the flight duration. We also generated paired preflight and postflight MRI cine clips derived from high-resolution, three-dimensional imaging of 12 astronauts after long-duration flights and from 6 astronauts after short-duration flights in order to assess the extent of narrowing of CSF spaces and the displacement of brain structures. We also compared preflight ventricular volumes with postflight ventricular volumes by means of an automated analysis of T 1 -weighted MRIs. The main prespecified analyses focused on the change in the volume of the central sulcus, the change in the volume of CSF spaces at the vertex, and vertical displacement of the brain., Results: Narrowing of the central sulcus occurred in 17 of 18 astronauts after long-duration flights (mean flight time, 164.8 days) and in 3 of 16 astronauts after short-duration flights (mean flight time, 13.6 days) (P<0.001). Cine clips from a subgroup of astronauts showed an upward shift of the brain after all long-duration flights (12 astronauts) but not after short-duration flights (6 astronauts) and narrowing of CSF spaces at the vertex after all long-duration flights (12 astronauts) and in 1 of 6 astronauts after short-duration flights. Three astronauts in the long-duration group had optic-disk edema, and all 3 had narrowing of the central sulcus. A cine clip was available for 1 of these 3 astronauts, and the cine clip showed upward shift of the brain., Conclusions: Narrowing of the central sulcus, upward shift of the brain, and narrowing of CSF spaces at the vertex occurred frequently and predominantly in astronauts after long-duration flights. Further investigation, including repeated postflight imaging conducted after some time on Earth, is required to determine the duration and clinical significance of these changes. (Funded by the National Aeronautics and Space Administration.).

Minimal advances have been made in the management of pulmonary contusions (PCs). The purpose of this study was to evaluate the impact of cyclooxygenase inhibition on outcomes following PC in a rat model. PC was induced in anesthetized adult rats. Ibuprofen was given to the treatment group (TG) and water was given to the control group (CG). Lung injury was assessed with pulse oximetry, arterial blood gases, CT, and histopathologic examination. Inflammation was measured with both serum and bronchoalveolar lavage (BAL) levels of tumor necrosis factor α and interleukin-6. Rats in the TG did not differ from rats in the CG with respect to oxygenation. Pathologic examination demonstrated a trend toward more inflammatory infiltrate in the CG, yet the sizes of the contusions were larger in the TG. The CG trended toward decreased levels of interleukin-6 in the serum and BAL at both three and seven days. While BAL levels of tumor necrosis factor α were increased in the TG at three days compared to the CG, they trended toward a reduced amount at seven days. Our data do not support cyclooxygenase inhibition for treatment to decrease the respiratory compromise associated with PC in this model of rat PCs.

Intracranial high-resolution vessel wall magnetic resonance imaging evidence of vessel wall inflammation is present following stent retriever manipulation but absent following aspiration thrombectomy. This is presented in a case of rotatory vertebral artery compression causing multiple posterior circulation infarctions requiring multiple separate aspiration and stent retriever thrombectomies., (Copyright © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.)

By virtue of its information technology-oriented infrastructure, the specialty of radiology is uniquely positioned to be at the forefront of efforts to promote data sharing across the healthcare enterprise, including particularly image sharing. The potential benefits of image sharing for clinical, research, and educational applications in radiology are immense. In this work, our group-the Association of University Radiologists (AUR) Radiology Research Alliance Task Force on Image Sharing-reviews the benefits of implementing image sharing capability, introduces current image sharing platforms and details their unique requirements, and presents emerging platforms that may see greater adoption in the future. By understanding this complex ecosystem of image sharing solutions, radiologists can become important advocates for the successful implementation of these powerful image sharing resources., (Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.)

Background and Purpose: While there have been recent reports of brain retention of gadolinium following gadolinium-based contrast agent administration in adults, a retrospective series of pediatric patients has not previously been reported, to our knowledge. We investigated the relationship between the number of prior gadolinium-based contrast agent doses and increasing T1 signal in the dentate nucleus on unenhanced T1-weighted MR imaging. We hypothesized that despite differences in pediatric physiology and the smaller gadolinium-based contrast agent doses that pediatric patients are typically administered based on weighted-adjusted dosing, the pediatric brain would also demonstrate dose-dependent increasing T1 signal in the dentate nucleus., Materials and Methods: We included children with multiple gadolinium-based contrast agent administrations at our institution. A blinded reader placed ROIs within the dentate nucleus and adjacent cerebellar white matter. To eliminate reader bias, we also performed automated ROI delineation of the dentate nucleus, cerebellar white matter, and pons. Dentate-to-cerebellar white matter and dentate-to pons ratios were compared with the number of gadolinium-based contrast agent administrations., Results: During 20 years at our institution, 280 patients received at least 5 gadolinium-based contrast agent doses, with 1 patient receiving 38 doses. Sixteen patients met the inclusion/exclusion criteria for ROI analysis. Blinded reader dentate-to-cerebellar white matter ratios were significantly associated with gadolinium-based contrast agent doses (r s = 0.77, P = .001). The dentate-to-pons ratio and dentate-to-cerebellar white matter ratios based on automated ROI placement were also significantly correlated with gadolinium-based contrast agent doses (t = 4.98, P < .0001 and t = 2.73, P < .02, respectively)., Conclusions: In pediatric patients, the number of prior gadolinium-based contrast agent doses is significantly correlated with progressive T1-weighted dentate hyperintensity. Definitive confirmation of gadolinium deposition requires tissue analysis. Any potential clinical sequelae of gadolinium retention in the developing brain are unknown. Given this uncertainty, we suggest taking a cautious stance, including the use, in pediatric patients, of higher stability, macrocyclic agents, which in both human and animal studies have been shown to be associated with lower levels of gadolinium deposition, and detailed documentation of dosing. Most important, a patient should not be deprived of a well-indicated contrasted MR examination., (© 2016 by American Journal of Neuroradiology.)

Background and Purpose: Perimesencephalic subarachnoid hemorrhage (PSAH) is not consistently defined in the existing literature. The purpose of this study was to test the inter-observer variability and specificity for non-aneurysmal subarachnoid hemorrhage (SAH) of an anatomic definition of PSAH., Methods: Medical records of all patients who underwent catheter angiography for evaluation of non-traumatic SAH between July 2002 and April 2012 were reviewed. Patients with anterior circulation aneurysms were excluded. Three blinded reviewers assessed whether each admission CT scan met the following anatomic criteria for PSAH: (1) center of bleeding located immediately anterior and in contact with the brainstem in the prepontine, interpeduncular, or posterior suprasellar cistern; (2) blood limited to the prepontine, interpeduncular, suprasellar, crural, ambient, and/or quadrigeminal cisterns and/or cisterna magna; (3) no extension of blood into the Sylvian or interhemispheric fissures; (4) intraventricular blood limited to incomplete filling of the fourth ventricle and occipital horns of the lateral ventricles (ie, consistent with reflux); (5) no intraparenchymal blood., Results: 56 patients with non-aneurysmal SAH and 50 patients with posterior circulation or posterior communicating artery aneurysms were identified. Seventeen (16%) of the 106 admission CT scans met the anatomic criteria for PSAH. No aneurysm was identified in this subgroup. Inter-observer agreement was excellent with κ scores of 0.89-0.96 and disagreement in 2.8% (3/106) of cases., Conclusions: Our anatomic definition of PSAH correlated with a low risk of brain aneurysm and was applied with excellent inter-observer agreement., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/)

Rapid growth in the amount of data that is electronically recorded as part of routine clinical operations has generated great interest in the use of Big Data methodologies to address clinical and research questions. These methods can efficiently analyze and deliver insights from high-volume, high-variety, and high-growth rate datasets generated across the continuum of care, thereby forgoing the time, cost, and effort of more focused and controlled hypothesis-driven research. By virtue of an existing robust information technology infrastructure and years of archived digital data, radiology departments are particularly well positioned to take advantage of emerging Big Data techniques. In this review, we describe four areas in which Big Data is poised to have an immediate impact on radiology practice, research, and operations. In addition, we provide an overview of the Big Data adoption cycle and describe how academic radiology departments can promote Big Data development., (Copyright © 2016 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.)

The end-user of mobile device apps in the practice of clinical radiology should be aware of security measures that prevent unauthorized use of the device, including passcode policies, methods for dealing with failed login attempts, network manager-controllable passcode enforcement, and passcode enforcement for the protection of the mobile device itself. Protection of patient data must be in place that complies with the Health Insurance Portability and Accountability Act and U.S. Federal Information Processing Standards. Device security measures for data protection include methods for locally stored data encryption, hardware encryption, and the ability to locally and remotely clear data from the device. As these devices transfer information over both local wireless networks and public cell phone networks, wireless network security protocols, including wired equivalent privacy and Wi-Fi protected access, are important components in the chain of security. Specific virtual private network protocols, Secure Sockets Layer and related protocols (especially in the setting of hypertext transfer protocols), native apps, virtual desktops, and nonmedical commercial off-the-shelf apps require consideration in the transmission of medical data over both private and public networks. Enterprise security and management of both personal and enterprise mobile devices are discussed. Finally, specific standards for hardware and software platform security, including prevention of hardware tampering, protection from malicious software, and application authentication methods, are vital components in establishing a secure platform for the use of mobile devices in the medical field., (© RSNA, 2015.)

Objective: A variant of perimesencephalic subarachnoid hemorrhage (PSAH) has been described characterized by blood centered in the quadrigeminal cistern and limited to the superior vermian and perimesencephalic cisterns. Herein, three cases of quadrigeminal PSAH are presented., Materials and Methods: Medical records of all patients who underwent digital subtraction angiography for evaluation of non-traumatic SAH between July 2002 and April 2012 were reviewed. Patients with anterior circulation aneurysms were excluded. Two blinded reviewers identified admission noncontrast CT scans with pretruncal and quadrigeminal patterns of PSAH., Results: The total cohort included 106 patients: 53% (56/106) with one or more negative digital subtraction angiograms and 47% (50/106) with posterior circulation or posterior communicating artery aneurysms. Three patients with quadrigeminal PSAH were identified, two with nonaneurysmal SAH and one with a posterior circulation aneurysm. Seventeen patients (16%; 17/106) with pretruncal PSAH were identified, none of whom were found to have an aneurysm. The quadrigeminal pattern comprised 11% (2/19) of cases of pretruncal or quadrigeminal nonaneurysmal PSAH., Conclusion: A small subset of patients with nonaneurysmal PSAH present with blood centered in the quadrigeminal cistern, and the etiology of this pattern may be similar to that of the classic pretruncal variant. However, patients with quadrigeminal PSAH must still undergo thorough vascular imaging, including at least two digital subtraction angiograms, to exclude a ruptured aneurysm., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Background: Staged endovascular embolization of large arteriovenous malformations (AVMs) is frequently performed to gradually reduce flow and prevent abrupt hemodynamic changes. While feeding artery aneurysms have been associated with increased risk of hemorrhage in the setting of AVMs, decisions regarding if and when to treat these aneurysms vary. Acute, fatal rupture of a feeding artery aneurysm following embolization of a large, unruptured AVM has been infrequently reported in the literature., Case Description: A 69-year-old female presented with headache and mild left hemiparesis referable to a 5 cm right fronto-parieto-temporal AVM with surrounding vasogenic edema. The AVM was associated with numerous bilateral feeding artery aneurysms (the largest was a 2 cm right middle cerebral artery (MCA) bifurcation aneurysm). There was also a large, partially thrombosed venous varix. Staged embolization of the AVM was performed. Several hours after the third stage of her embolization, she became obtunded, with a fixed and dilated right pupil. Head computed tomography (CT) showed a large intraparenchymal hemorrhage with midline shift in the right sylvian fissure, remote from the AVM nidus. She was taken to surgery for a decompressive craniectomy and hematoma evacuation. The MCA aneurysm was confirmed to be the source of hemorrhage and it was clipped. Despite aggressive medical and surgical treatments, the patient died., Conclusions: An increase in AVM feeding artery pressure following endovascular embolization may contribute to the rupture of a feeding artery aneurysm. For this reason, treatment of large arterial aneurysms on feeding pedicles should be considered prior to embolization of the AVM nidus., (© The Author(s) 2015.)

Angioplasty and stenting for intracranial atherosclerotic stenosis (ICAS) are a last resort for patients with high-grade intracranial stenosis with multiple ischemic events unresponsive to medical therapy. Medical management, consisting of aggressive risk factor control and dual antiplatelet therapy, is superior to angioplasty and stenting for the prevention of future stroke. Future studies of angioplasty and stenting in this population are important, as the stroke risk on medical therapy is 12 % at 1 year and post-procedure stroke rates are similar to rates with medical treatment. There are many issues that will need to be resolved for stenting to offer any benefit, however. Procedural risks of hemorrhagic and ischemic stroke are unacceptably high. High-risk subgroups, potentially based on hemodynamic factors, will need to be identified for future interventional trials. Nevertheless, it is still reasonable to consider angioplasty and stenting for selected patients with multiple recurrent events despite aggressive medical management, but benefits are unclear at this time.

Purpose: The aim of this study was to evaluate national trends in paracentesis and thoracentesis procedures and the relative roles of specialty groups providing these services., Methods: Medicare Physician Supplier Procedure Summary Master Files from 1993 to 2008 were analyzed for paracentesis and thoracentesis procedure codes. Using physician specialty identifier codes, procedure volumes were extracted for radiologists, primary care physicians, and surgeons for both procedures. Volume data were extracted for gastroenterologists and pulmonary and critical care medicine physicians, respectively, for paracentesis and thoracentesis. Frequency by site of service was similarly evaluated. Relative changes were calculated., Results: Between 1993 and 2008, paracentesis procedures on Medicare fee-for-service beneficiaries increased by 133% (from 64,371 to 149,699), and thoracentesis procedures decreased by 14% (from 147,363 to 127,444). Services by radiologists increased by 964% (from 10,456 to 111,275) and 358% (from 14,531 to 66,602), respectively, while all other targeted groups experienced declines. For paracentesis, radiologist and gastroenterologist procedure shares changed from 16% and 32%, respectively, in 1993 to 74% and 6% in 2008. For thoracentesis, radiologist and pulmonary and critical care medicine physician shares changed from 10% and 49% to 52% and 27%. Relative shifts in site of service to the hospital outpatient setting occurred for both procedures., Conclusions: Since 1993, paracentesis procedures on Medicare beneficiaries have more than doubled, while thoracentesis volumes have declined slightly. Radiologists now far exceed gastroenterologists and pulmonary and critical care medicine physicians, respectively, as the predominant providers of these services. Those shifts are likely attributable to both the incremental safety of imaging guidance and also the unfavorable economics of these procedures., (Copyright © 2010 American College of Radiology. Published by Elsevier Inc. All rights reserved.)