Utility of Contrast-Enhanced Ultrasound and 4-Dimensional Computed Tomography for Preoperative Detection and Localization of Parathyroid Adenomas Compared With Surgical Results.

OBJECTIVES: To investigate the accuracy, sensitivity, and specificity of contrast-enhanced ultrasound (CEUS) for detection of parathyroid adenomas and compare it to those of 4-dimensional computed tomography (4DCT), which has been established as a reliable, effective tool for preoperative localization of parathyroid adenomas. METHODS: About 27 patients with suspected parathyroid pathology underwent imaging evaluations with 4DCT and CEUS and 22 patients subsequently underwent surgical resection of parathyroid lesions. 4DCT and CEUS were performed and interpreted by consensus of two expert radiologists with extensive experience in each modality. Assessment for the side, z-axis (craniocaudal axis), and quadrant of the pathologically proven lesion was performed based on the surgical report. RESULTS: For single-gland disease, the accuracy for CEUS localization to the correct quadrant and side were 81.0 and 90.1% respectively. For single-gland disease, the accuracy for 4DCT localization to the correct quadrant and side were 81.0 and 90.5% respectively. 4DCT localization sensitivity and specificity were comparable to those for CEUS. 4DCT allowed for accurate diagnosis in multigland disease in contradistinction to CEUS. CONCLUSIONS: CEUS is a noninvasive, real-time imaging technique that has relatively high diagnostic confidence and accuracy of localization which are comparable to the accuracy of 4DCT for preoperative parathyroid adenoma detection, characterization, and localization. This technique should be considered for primary preoperative diagnosis, especially in younger patients.

A Comparison of WebRTC and Conventional Videoconferencing for Synchronized Remote Medical Image Presentation.

DICOM viewers must fulfill roles beyond primary diagnostic interpretation, including serving as presentation tools in teaching and multidisciplinary conferences, thereby enabling multiple individuals to review images collaboratively in real time. When in-person gathering is not possible, a variety of solutions have been deployed to maintain the ability for spatially separated users to view medical images simultaneously. These approaches differ in their backend architectures, utilization of application-specific optimizations, and ultimately in their end user satisfaction. In this work, we systematically compare the performance of conventional screensharing using a videoconferencing application with that of a custom, synchronized DICOM viewer linked using Web Real Time Communications (WebRTC) technology. We find superior performance for the WebRTC method with regard to image quality and latency across a range of simulated adverse network conditions, and we show how increasing the number of conference participants differentially affects the bandwidth requirements of the two viewing solutions. In addition, we compare these two approaches in a real-world teaching scenario and gather the feedback of trainee and faculty radiologists, who we found to favor the WebRTC method for its decreased latency, improved image quality, ease of setup, and overall experience. Ultimately, our results demonstrate the value of application-specific solutions for the remote synchronized viewing of medical imaging, which, given the recent increase in reliance on remote collaboration, may constitute a significant consideration for future enterprise viewer procurement decisions.

Pseudo Test-Retest Evaluation of Millimeter-Resolution Whole-Brain Dynamic Contrast-enhanced MRI in Patients with High-Grade Glioma.

Background Advances in sub-Nyquist-sampled dynamic contrast-enhanced (DCE) MRI enable monitoring of brain tumors with millimeter resolution and whole-brain coverage. Such undersampled quantitative methods need careful characterization regarding achievable test-retest reproducibility. Purpose To demonstrate a fully automated high-resolution whole-brain DCE MRI pipeline with 30-fold sparse undersampling and estimate its reproducibility on the basis of reference regions of stable tissue types during multiple posttreatment time points by using longitudinal clinical images of high-grade glioma. Materials and Methods Two methods for sub-Nyquist-sampled DCE MRI were extended with automatic estimation of vascular input functions. Continuously acquired three-dimensional k-space data with ramped-up flip angles were partitioned to yield high-resolution, whole-brain tracer kinetic parameter maps with matched precontrast-agent T1 and M0 maps. Reproducibility was estimated in a retrospective study in participants with high-grade glioma, who underwent three consecutive standard-of-care examinations between December 2016 and April 2019. Coefficients of variation and reproducibility coefficients were reported for histogram statistics of the tracer kinetic parameters plasma volume fraction and volume transfer constant (Ktrans) on five healthy tissue types. Results The images from 13 participants (mean age ± standard deviation, 61 years ± 10; nine women) with high-grade glioma were evaluated. In healthy tissues, the protocol achieved a coefficient of variation less than 57% for median Ktrans, if Ktrans was estimated consecutively. The maximum reproducibility coefficient for median Ktrans was estimated to be at 0.06 min-1 for large or low-enhancing tissues and to be as high as 0.48 min-1 in smaller or strongly enhancing tissues. Conclusion A fully automated, sparsely sampled DCE MRI reconstruction with patient-specific vascular input function offered high spatial and temporal resolution and whole-brain coverage; in healthy tissues, the protocol estimated median volume transfer constant with maximum reproducibility coefficient of 0.06 min-1 in large, low-enhancing tissue regions and maximum reproducibility coefficient of less than 0.48 min-1 in smaller or more strongly enhancing tissue regions. Published under a CC BY 4.0 license. Online supplemental material is available for this article. See also the editorial by Lenkinski in this issue.

Sparse precontrast T1 mapping for high-resolution whole-brain DCE-MRI.

PURPOSE: To develop and evaluate an efficient precontrast T1 mapping technique suitable for quantitative high-resolution whole-brain dynamic contrast-enhanced-magnetic resonance imaging (DCE-MRI). METHODS: Variable flip angle (VFA) T1 mapping was considered that provides 1 × 1 × 2 mm3 resolution to match a recent high-resolution whole-brain DCE-MRI protocol. Seven FAs were logarithmically spaced from 1.5° to 15°. T1 and M0 maps were estimated using model-based reconstruction. This approach was evaluated using an anatomically realistic brain tumor digital reference object (DRO) with noise-mimicking 3T neuroimaging and fully sampled data acquired from one healthy volunteer. Methods were also applied on fourfold prospectively undersampled VFA data from 13 patients with high-grade gliomas. RESULTS: T1 -mapping precision decreased with undersampling factor R, althoughwhereas bias remained small before a critical R. In the noiseless DRO, T1 bias was <25 ms in white matter (WM) and <11 ms in brain tumor (BT). T1 standard deviation (SD) was <119.5 ms in WM (coefficient of variation [COV] ~11.0%) and <253.2 ms in BT (COV ~12.7%). In the noisy DRO, T1 bias was <50 ms in WM and <30 ms in BT. For R ≤ 10, T1 SD was <107.1 ms in WM (COV ~9.9%) and <240.9 ms in BT (COV ~12.1%). In the healthy subject, T1 bias was <30 ms for R ≤ 16. At R = 4, T1 SD was 171.4 ms (COV ~13.0%). In the prospective brain tumor study, T1 values were consistent with literature values in WM and BT. CONCLUSION: High-resolution whole-brain VFA T1 mapping is feasible with sparse sampling, supporting its use for quantitative DCE-MRI.

Traumatic Neck and Skull Base Injuries.

Patients with blunt and penetrating traumatic injuries to the skull base and soft tissues of the neck present to the emergency department every day. Fortunately, truly life-threatening injuries to these regions are relatively uncommon. However, when encountered and not correctly diagnosed, these entities may result in severe morbidity or mortality. The radiologist plays a critical role recognizing these injuries, in which findings may often be subtle and the anatomy potentially challenging to identify. Multisection CT and CT angiography are commonly performed to assess these injuries in the emergency department. Vascular injury to the neck may result in dissection, occlusion, pseudoaneurysm formation, or frank extravasation resulting in stroke or death. Airway compromise may result from laryngotracheal injury. Injuries to the pharynx and esophagus may result in perforation. Injuries to the temporal bone may result in vascular injury to the internal carotid artery or facial nerve injury, which would require immediate surgery or intervention to prevent paralysis.©RSNA, 2019.

The effect of renin angiotensin system genetic variants in acute pancreatitis.

OBJECTIVES: We sought association of genetic variants in the renin-angiotensin system (RAS) and vitamin D system with acute pancreatitis (AP) development and severity. BACKGROUND: The endocrine RAS is involved in circulatory homeostasis through the pressor action of angiotensin II at its AT1 receptor. However, local RAS regulate growth and inflammation in diverse cells and tissues, and their activity may be suppressed by vitamin D. Intrapancreatic angiotensin II generation has been implicated in the development of AP. METHODS: Five hundred forty-four white patients with AP from 3 countries (United Kingdom, 22; Germany, 136; and The Netherlands 386) and 8487 control subjects (United Kingdom 7833, The Netherlands 717) were genotyped for 8 polymorphisms of the RAS/vitamin D systems, chosen on the basis of likely functionality. RESULTS: The angiotensin-converting enzyme I (rather than D) allele was significantly associated with alcohol-related AP when all cohorts were combined (P = 0.03). The renin rs5707 G (rather than A) allele was associated with AP (P = 0.002), infected necrosis (P = 0.025) and mortality (P = 0.046). CONCLUSIONS: The association of 2 RAS polymorphisms with AP suggests the need for further detailed analysis of the role of RAS/vitamin D in the genesis or severity of AP, particularly given the ready potential for pharmacological manipulation of this system using existing marketed agents. However, further replication studies will be required before any such association is considered robust, particularly given the significant heterogeneity of AP causation and clinical course.

Optic Nerve Sheath MR Imaging Measurements in Patients with Orthostatic Headaches and Normal Findings on Conventional Imaging Predict the Presence of an Underlying CSF-Venous Fistula.

BACKGROUND AND PURPOSE: Spontaneous spinal CSF leaks typically cause orthostatic headache, but their detection may require specialized and invasive spinal imaging. We undertook a study to determine the value of simple optic nerve sheath MR imaging measurements in predicting the likelihood of finding a CSF-venous fistula, a type of leak that cannot be detected with routine spine MR imaging or CT myelography, among patients with orthostatic headache and normal conventional brain and spine imaging findings. MATERIALS AND METHODS: This cohort study included a consecutive group of patients with orthostatic headache and normal conventional brain and spine imaging findings who underwent digital subtraction myelography under general anesthesia to look for spinal CSF-venous fistulas. RESULTS: The study group consisted of 93 patients (71 women and 22 men; mean age, 47.5 years; range, 17-84 years). Digital subtraction myelography demonstrated a CSF-venous fistula in 15 patients. The mean age of these 8 women and 7 men was 56 years (range, 23-83 years). The mean optic nerve sheath diameter was 4.0 mm, and the mean perioptic subarachnoid space was 0.5 mm in patients with a CSF-venous fistula compared with 4.9 and 1.2 mm, respectively, in patients without a fistula (P < .001). Optimal cutoff values were found at 4.4 mm for optic nerve sheath diameter and 1.0 mm for the perioptic subarachnoid space. Fistulas were detected in about 50% of patients with optic nerve sheath diameter or perioptic subarachnoid space measurements below these cutoff values compared with <2% of patients with optic nerve sheath diameter or perioptic subarachnoid space measurements above these cutoff values. Following surgical ligation of the fistula, optic nerve sheath diameter increased from 4.0 to 5.3 mm and the perioptic subarachnoid space increased from 0.5 to 1.2 mm (P < .001). CONCLUSIONS: Concerns about a spinal CSF leak should not be dismissed in patients with orthostatic headache when conventional imaging findings are normal, and simple optic nerve sheath MR imaging measurements can help decide if more imaging needs to be performed in this patient population.

Cybersecurity in radiology: Access of public hot spots and public Wi-Fi and prevention of cybercrimes and HIPAA violations.

OBJECTIVE: The purpose of this article is to review the steps that can be taken to ensure secure transfer of information over public and home networks, given the increasing utilization of mobile devices in radiology. CONCLUSION: With the rapid technologic developments in radiology, knowledge of various technical aspects is crucial for any practicing radiologist. Utilization of mobile devices, such as laptops, tablets, and even cellular phones, for reading radiologic studies has become increasingly prevalent. With such usage comes a need to ensure that both the user's and the patient's private information is protected. There are several steps that can be taken to protect sensitive information while using public networks. These steps include being diligent in reviewing the networks to which one connects, ensuring encrypted connections to web-sites, using strong passwords, and using a virtual private network and a firewall. As the role of information technology in modern radiology practice becomes more critical, these safety mechanisms must be addressed when viewing studies on any mobile device.

Extended outlook: description, utilization, and daily applications of cloud technology in radiology.

OBJECTIVE: The purpose of this article is to discuss the concept of cloud technology, its role in medical applications and radiology, the role of the radiologist in using and accessing these vast resources of information, and privacy concerns and HIPAA compliance strategies. CONCLUSION: Cloud computing is the delivery of shared resources, software, and information to computers and other devices as a metered service. This technology has a promising role in the sharing of patient medical information and appears to be particularly suited for application in radiology, given the field's inherent need for storage and access to large amounts of data. The radiology cloud has significant strengths, such as providing centralized storage and access, reducing unnecessary repeat radiologic studies, and potentially allowing radiologic second opinions more easily. There are significant cost advantages to cloud computing because of a decreased need for infrastructure and equipment by the institution. Private clouds may be used to ensure secure storage of data and compliance with HIPAA. In choosing a cloud service, there are important aspects, such as disaster recovery plans, uptime, and security audits, that must be considered. Given that the field of radiology has become almost exclusively digital in recent years, the future of secure storage and easy access to imaging studies lies within cloud computing technology.

A cross-sectional study to test equivalence of low- versus intermediate-flip angle dynamic susceptibility contrast MRI measures of relative cerebral blood volume in patients with high-grade gliomas at 1.5 Tesla field strength.

Introduction: 1.5 Tesla (1.5T) remain a significant field strength for brain imaging worldwide. Recent computer simulations and clinical studies at 3T MRI have suggested that dynamic susceptibility contrast (DSC) MRI using a 30° flip angle ("low-FA") with model-based leakage correction and no gadolinium-based contrast agent (GBCA) preload provides equivalent relative cerebral blood volume (rCBV) measurements to the reference-standard acquisition using a single-dose GBCA preload with a 60° flip angle ("intermediate-FA") and model-based leakage correction. However, it remains unclear whether this holds true at 1.5T. The purpose of this study was to test this at 1.5T in human high-grade glioma (HGG) patients. Methods: This was a single-institution cross-sectional study of patients who had undergone 1.5T MRI for HGG. DSC-MRI consisted of gradient-echo echo-planar imaging (GRE-EPI) with a low-FA without preload (30°/P-); this then subsequently served as a preload for the standard intermediate-FA acquisition (60°/P+). Both normalized (nrCBV) and standardized relative cerebral blood volumes (srCBV) were calculated using model-based leakage correction (C+) with IBNeuro™ software. Whole-enhancing lesion mean and median nrCBV and srCBV from the low- and intermediate-FA methods were compared using the Pearson's, Spearman's and intraclass correlation coefficients (ICC). Results: Twenty-three HGG patients composing a total of 31 scans were analyzed. The Pearson and Spearman correlations and ICCs between the 30°/P-/C+ and 60°/P+/C+ acquisitions demonstrated high correlations for both mean and median nrCBV and srCBV. Conclusion: Our study provides preliminary evidence that for HGG patients at 1.5T MRI, a low FA, no preload DSC-MRI acquisition can be an appealing alternative to the reference standard higher FA acquisition that utilizes a preload.

Abnormal MIBG uptake in a neuroblastoma patient with right upper lobe atelectasis.

A 3-month-old boy with a history of an abdominopelvic neuroblastoma presented 1 week after tumor resection for a routine follow-up 123-I Meta-iodobenzylguanidine (MIBG) scan to assess for residual mass. The study demonstrated abnormal radiotracer uptake in the right upper lobe, which correlated on the SPECT/CT to an area of airspace consolidation thought to be secondary to atelectasis. To the best of our knowledge, there is one published case of MIBG radiotracer uptake in the lung correlating with pneumonia; however, there are no reported cases to date in the literature of focal pulmonary MIBG uptake corresponding to atelectasis.

Chronic tophaceous gout causing lumbar spinal stenosis.

Gout is a common cause of inflammatory arthritis, typically affecting the joints of the appendicular skeleton. In this report, we present the relatively less common scenario of chronic tophaceous gout affecting the lumbar spine and pelvis, complicated by compressive neuropathy, and notable for its advanced initial presentation in a young patient. We review the pathophysiology underlying gout and discuss its clinical and laboratory presentation. We also use our case as an example to present the radiographic, CT, and MR imaging features of gout affecting the lumbar spine, which can often present a diagnostic dilemma. Finally, we discuss therapeutic options for gout resulting in spinal canal compromise, which include interventions not commonly performed for gout elsewhere in the body.

Changes in Social Media Impact of the Radiological Literature During the Covid-19 Pandemic.

PURPOSE: The objective of this study was to determine how the social media impact of the radiological literature has changed during the Covid-19 pandemic. METHODS: Altmetric Attention scores were collected for all articles in five leading radiology journals over a 5-year period ending in June 2020, and temporal smoothing yielded the filtered Altmetric Attention (fAA) score. Natural language processing methods were used to label articles with major topic areas. A forecasting model was used to identify periods of outlier behavior in the fAA score aggregated across all journals, for each journal individually, and stratified by article topic area. The distributions of fAA scores prior to the onset of the pandemic were statistically compared to those during the pandemic. For journals exhibiting increased fAA scores, the frequency distributions of articles not related to Covid-19 was compared to that prior to the pandemic. RESULTS: During the pandemic, we found sustained outliers and statistically significant increases in the aggregate fAA score across all five journals, as well as for Radiology, American Journal of Roentgenology, and Academic Radiology individually. Articles related to Covid-19, thoracic imaging, and radiology education also experienced significantly increased fAA scores during the pandemic period. We did not find significantly decreased rates of publication of non-Covid articles in the journals experiencing elevated fAA scores. CONCLUSION: Social media engagement with the radiological literature significantly increased during the Covid-19 pandemic. This preferentially affected certain journals and articles addressing specific topics, reflecting the intense public interest in the diagnosis and treatment of Covid-19.

Imaging of the post-operative orbit and associated complications.

Dedicated post-operative radiological evaluation following ophthalmologic procedures is relatively uncommon. However, given the ever-growing ophthalmologic procedural advancements and the increasing utilization of neuroimaging for myriad indications, the orbits are often imaged incidentally in a delayed post-procedural state. Regardless of the clinical scenario, it is important for neuroradiologists and other specialists commonly exposed to orbital imaging to be aware of both expected and abnormal post-operative imaging findings because misinterpreted normal features or unrecognized complications can result in vision-threatening delays in treatment or mismanagement. In this review article, we discuss many common ophthalmologic procedures, their indications, and most likely complications. We also provide illustrative operative photographs and radiological imaging examples. By understanding the surgical intent, recognizing the devices that are commonly used, and developing familiarity with the appearance of post-operative complications, pitfalls in interpretation can be avoided and patient outcomes ultimately improved.

Efficient DCE-MRI Parameter and Uncertainty Estimation Using a Neural Network.

Quantitative DCE-MRI provides voxel-wise estimates of tracer-kinetic parameters that are valuable in the assessment of health and disease. These maps suffer from many known sources of variability. This variability is expensive to compute using current methods, and is typically not reported. Here, we demonstrate a novel approach for simultaneous estimation of tracer-kinetic parameters and their uncertainty due to intrinsic characteristics of the tracer-kinetic model, with very low computation time. We train and use a neural network to estimate the approximate joint posterior distribution of tracer-kinetic parameters. Uncertainties are estimated for each voxel and are specific to the patient, exam, and lesion. We demonstrate the methods' ability to produce accurate tracer-kinetic maps. We compare predicted parameter ranges with uncertainties introduced by noise and by differences in post-processing in a digital reference object. The predicted parameter ranges correlate well with tracer-kinetic parameter ranges observed across different noise realizations and regression algorithms. We also demonstrate the value of this approach to differentiate significant from insignificant changes in brain tumor pharmacokinetics over time. This is achieved by enforcing consistency in resolving model singularities in the applied tracer-kinetic model.

Trigeminal neuralgia associated with a variant of persistent trigeminal artery.

A persistent trigeminal artery variant (PTAV) is an anomalous vessel that originates from the internal carotid artery and directly supplies the cerebellum without interposition of the basilar artery. This anatomic variant is usually found incidentally on imaging but can rarely have clinical implications. We describe a case of a 74-year-old woman presenting with multiple years of lower jaw pain attributed to trigeminal neuralgia, unresolved with medication. A persistent trigeminal artery variant compressing the trigeminal nerve was identified on magnetic resonance imaging and magnetic resonance angiography. The characteristic imaging findings of PTAV are essential for identifying an etiology of medically refractory trigeminal neuralgia and may assist with preoperative planning.

Anaplastic meningioma seeding of the abdominal wall following calvarial bone flap preservation.

Meningiomas are common intracranial tumors that rarely metastasize. We present a highly unusual case of a 42-year-old man with direct seeding of meningioma to the abdominal wall. The patient had a history of multiple operations for a recurrent intracranial meningioma with decompressive craniectomy and preservation of the calvarial bone flap by implantation into the subcutaneous layer of the anterior abdominal wall. Following removal of the bone flap, a new abdominal wall mass was identified, consistent with iatrogenic implantation of anaplastic meningioma.

Advanced Imaging Techniques in Diagnosis of Posterior Reversible Encephalopathy Syndrome (PRES).

Diagnosis of Posterior Reversible Encephalopathy Syndrome (PRES) in some circumstances can be challenging and structural imaging may not be sufficient to distinguish it from other differential diagnostic considerations. Advanced imaging techniques, such as MR spectroscopy or positron emission tomography (PET) can provide additional information to determine the diagnosis. Other techniques, such as susceptibility weighted imaging (SWI) improves detection of hemorrhage which has prognostic role. CT or MR Perfusion as well as Single-Photon Emission Computed Tomography (SPECT) are more useful to understand the underlying vasculopathic changes in PRES and may answer some of the unresolved controversies in pathophysiology of this complex disease. In this review we summarized the findings of previous studies using these advanced methods and their utilities in diagnosis or prognosis of PRES.

Metastatic meningioma: Case report of a WHO grade I meningioma with liver metastases and review of the literature.

Meningioma represents the most frequently diagnosed primary brain tumor, accounting for over one-third of central nervous system neoplasms. The majority of tumors are categorized as benign. However, albeit rarely, meningiomas may metastasize to distant sites. We describe a 78-year-old man with a history of recurrent World Health Organization grade I meningioma managed who presented for evaluation of weakness and urinary retention. A computed tomography scan obtained in the emergency department revealed multiple scattered low-density liver lesions. Subsequent magnetic resonance imaging showed a 5.5-centimeter heterogeneous enhancing mass with 2 smaller enhancing lesions suspicious for a primary or secondary malignant neoplasm. Microscopic examination of a tissue sample obtained via liver biopsy demonstrated a metastatic spindle cell neoplasm with histologic features compatible with a diagnosis of World Health Organization grade I transitional meningioma. The patient was referred to hematology/oncology for systemic therapy.

Posterior Reversible Encephalopathy Syndrome (PRES): Pathophysiology and Neuro-Imaging.

Posterior reversible encephalopathy syndrome (PRES) represents a unique clinical entity with non-specific clinical symptoms and unique neuroradiological findings. This syndrome may present with a broad range of clinical symptoms from headache and visual disturbances to seizure and altered mentation. Typical imaging findings include posterior-circulation predominant vasogenic edema. Although there are many well-documented diseases associated with PRES, the exact pathophysiologic mechanism has yet to be fully elucidated. Generally accepted theories revolve around disruption of the blood-brain barrier secondary to elevated intracranial pressures or endothelial injury. In this article, we will review the clinical, typical, and atypical radiological features of PRES, as well as the most common theories behind the pathophysiology of PRES. Additionally, we will discuss some of the treatment strategies for PRES related to the underlying disease state.