MRI in the Evaluation of Cryptogenic Stroke and Embolic Stroke of Undetermined Source.

Cryptogenic stroke refers to a stroke of undetermined etiology. It accounts for approximately one-fifth of ischemic strokes and has a higher prevalence in younger patients. Embolic stroke of undetermined source (ESUS) refers to a subgroup of patients with nonlacunar cryptogenic strokes in whom embolism is the suspected stroke mechanism. Under the classifications of cryptogenic stroke or ESUS, there is wide heterogeneity in possible stroke mechanisms. In the absence of a confirmed stroke etiology, there is no established treatment for secondary prevention of stroke in patients experiencing cryptogenic stroke or ESUS, despite several clinical trials, leaving physicians with a clinical dilemma. Both conventional and advanced MRI techniques are available in clinical practice to identify differentiating features and stroke patterns and to determine or infer the underlying etiologic cause, such as atherosclerotic plaques and cardiogenic or paradoxical embolism due to occult pelvic venous thrombi. The aim of this review is to highlight the diagnostic utility of various MRI techniques in patients with cryptogenic stroke or ESUS. Future trends in technological advancement for promoting the adoption of MRI in such a special clinical application are also discussed.

P-ANCA Vasculitis Presenting with Orbital Infiltration.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) may affect the eye or orbit, and ophthalmic manifestations of AAV are associated with higher mortality than other inflammatory eye diseases. Perinuclear ANCA (p-ANCA) vasculitis is an uncommon cause of orbital inflammation. A 70-year-old woman with chronic kidney disease presented with a 1-year history of orbital mass and edema around her OD. Fundoscopy revealed 360° optic disc elevation OD. MRI orbits showed an infiltrative, intra- and extraconal lesion extending through the right orbital apex to the cavernous sinus. Labwork and orbital biopsy were consistent with p-ANCA vasculitis, and the patient's ocular symptoms improved after methylprednisolone. Diagnosis of AAV is complicated by a wide diversity of symptoms, and this case highlights an unusual presentation of p-ANCA vasculitis in the orbit. Ophthalmologists have an important role in diagnosing systemic conditions such as AAV by initiating the proper inflammatory workup.

Functional MRI and Diffusion Tensor Imaging in Migraine: A Review of Migraine Functional and White Matter Microstructural Changes.

Migraine is a complex and heterogenous disorder whose disease mechanisms remain disputed. This narrative review summarizes functional MRI (fMRI) and diffusion tensor imaging (DTI) findings and interprets their association with migraine symptoms and subtype to support and expand our current understanding of migraine pathophysiology. Our PubMed search evaluated and included fMRI and DTI studies involving comparisons between migraineurs vs healthy controls, migraineurs with vs without aura, and episodic vs chronic migraineurs. Migraineurs demonstrate changes in functional connectivity (FC) and regional activation in numerous pain-related networks depending on migraine phase, presence of aura, and chronicity. Changes to diffusion indices are observed in major cortical white matter tracts extending to the brainstem and cerebellum, more prominent in chronic migraine and associated with FC changes. Reported changes in FC and regional activation likely relate to pain processing and sensory hypersensitivities. Diffuse white matter microstructural changes in dysfunctional cortical pain and sensory pathways complement these functional differences. Interpretations of reported fMRI and DTI measure trends have not achieved a clear consensus due to inconsistencies in the migraine neuroimaging literature. Future fMRI and DTI studies should establish and implement a uniform methodology that reproduces existing results and directly compares migraineurs with different subtypes. Combined fMRI and DTI imaging may provide better pathophysiological explanations for nonspecific FC and white matter microstructural differences.

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.

Treatment of Bifocal Periprosthetic Fractures above and below a Knee after Tumor using Spanning Ilizarov Device: A Case Report.

Introduction: Multiple treatment options and internal and external devices have been recommended for periprosthetic fractures management around total knee arthroplasty. Case Report: We present the case of the high-energy bifocal periprosthetic fractures of the femur and the tibia after total knee prosthesis following excision of a tumor. One of the fractures was an open tibial fracture Gustilo Type IIIB and the other - comminuted subtrochanteric fracture of the femur with extrusion of periprosthetic cement pieces out from the bone defect. The Ilizarov circular external fixator was used for the skeletal stabilization and early functional treatment in this compound case. Conclusion: The use of Ilizarov external fixator for patients with complex periprosthetic fractures, who present severe technical difficulties in bone stabilization, especially by concomitant severe soft-tissue damage after high-energy injuries, is a good surgical alternative.

Structural MRI in Migraine: A Review of Migraine Vascular and Structural Changes in Brain Parenchyma.

Migraine is a complex and common disorder that affects patients around the world. Despite recent advances in this field, the exact pathophysiology of migraine is still not completely understood. Structural MRI sequences have revealed a variety of changes to brain parenchyma associated with migraine, including white matter lesions, volume changes, and iron deposition. This Review highlights different structural imaging findings in various types of migraine and their relationship to migraine characteristics and subtypes in order to improve our understanding of migraine, its pathophysiologic mechanisms, and how to better diagnose and treat it.

Temporary bridging trans-hip external fixation in damage control orthopaedics treatment after severe combat trauma: A clinical case series.

The role of external fixation in Damage Control Orthopaedics has been well described. Temporary external fixation has been recommended to provide relative bone stability while the soft tissue heals, prior to formal open reduction and internal fixation. Temporary bridging external fixation, that spans the joint, is recommended as primary skeletal stabilization in complex intra-articular and peri-articular fractures, in extensive peri-articular soft-tissue damage around the knee, ankle, elbow and wrist joints. Works devoted to temporary trans-hip external fixation in treatment of complex high-energy injuries are relatively rare. The purpose of this article is to present our experience in using temporary hip spanning external fixation during primary treatment of six patients suffered from complex open intra-articular and peri-articular fractures of the proximal femoral bone with extensive soft tissue damage due to war blast or high-velocity gunshot trauma. Primary management was based on the concept of Advanced Trauma Life Support and Damage Control Orthopaedics. Conversion to definitive bone reconstruction was performed on the next stage of the treatment after general and local stabilization.

VWI-APP: Vessel wall imaging-dedicated automated processing pipeline for intracranial atherosclerotic plaque quantification.

BACKGROUND: Quantitative plaque assessment based on 3D magnetic resonance (MR) vessel wall imaging (VWI) has been shown to provide valuable numerical markers of the burden and risk of intracranial atherosclerotic disease (ICAD). However, plaque quantification is currently time-consuming and observer-dependent due to the demand for heavy manual effort. A VWI-dedicated automated processing pipeline (VWI-APP) is desirable. PURPOSE: To develop and evaluate a VWI-APP for end-to-end quantitative analysis of intracranial atherosclerotic plaque. METHODS: We retrospectively enrolled 91 subjects with ICAD (80 for pipeline development, 10 for an end-to-end pipeline evaluation, and 1 for demonstrating longitudinal plaque assessment) who had undergone VWI and MR angiography. In an end-to-end evaluation, diameter stenosis (DS), normalized wall index (NWI), remodeling ratio (RR), plaque wall contrast ratio (CR), and total plaque volume (TPV) were quantified at each culprit lesion using the developed VWI-APP and a computer-aided manual approach by a neuroradiologist, respectively. The time consumed in each quantification approach was recorded. Two-sided paired t-tests and intraclass correlation coefficient (ICC) were used to determine the difference and agreement in each plaque metric between VWI-APP and manual quantification approaches. RESULTS: There was no significant difference between VWI-APP and manual quantification in each plaque metric. The ICC was 0.890, 0.813, 0.827, 0.891, and 0.991 for DS, NWI, RR, CR, and TPV, respectively, suggesting good to excellent accuracy of the pipeline method in plaque quantification. Quantitative analysis of each culprit lesion on average took 675.7 s using the manual approach but shortened to 238.3 s with the aid of VWI-APP. CONCLUSIONS: VWI-APP is an accurate and efficient approach to intracranial atherosclerotic plaque quantification. Further clinical assessment of this automated tool is warranted to establish its utility in the risk assessment of ICAD lesions.

Utility of Neuroimaging in the Management of Chronic and Acute Headache.

Imaging plays an important role in identifying the cause of the much less common secondary headaches. Such headaches may be caused by a variety of pathologic conditions which can be categorized as intracranial and extracranial. Idiopathic intracranial hypertension imaging findings include "empty sella," orbital changes, and dural venous sinus narrowing. Intracranial hypotension (ICH) is frequently caused by CSF leaks. Imaging findings include loss of the CSF spaces, downward displacement of the brain, as well as dural thickening and enhancement. Severe cases of ICH may result in subdural hematomas. A variety of intracranial and skull base tumors may cause headaches due to dural involvement. Extracranial tumors and lesions that frequently present with headaches include a variety of sinonasal tumors as well as mucoceles. Neurovascular compression disorders causing headaches include trigeminal and glossopharyngeal neuralgia. Imaging findings include displacement and atrophy of the cranial nerve caused by an adjacent arterial or venous structure.

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.

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.

Cerebrovascular disease in pregnancy and puerperium: perspectives from neuroradiologists.

Pregnancy-related cerebrovascular disease is a serious complication of pregnancy and puerperium. The etiology and pathological mechanisms of cerebrovascular disease are complex, involving changes in the cardiovascular, endocrine, and immune systems. Vascular risk factors during pregnancy and puerperium may cause vasospasm and endothelial cell damage leading to cerebral ischemia, hemorrhage, posterior reversible encephalopathy syndrome (PRES), and reversible cerebral vasoconstriction syndrome. Arterial or venous obstruction may damage the blood-brain barrier (BBB) and impede venous return, resulting in cerebral edema, hemorrhage, and intracranial hypertension. Pregnancy with hypercoagulability may threaten the lives of both the mother and the developing fetus. With improvements in stroke treatment during pregnancy and puerperium, neuroradiologists have gained new insights into this problem. This article reviews the pathogenesis, imaging findings, and risk factors of stroke during pregnancy and puerperium, focusing on imaging diagnosis and prognostic assessment.

COVID-19 Crisis Effect: Experience at Two Orthopedic Trauma Units.

BACKGROUND: The coronavirus disease-2019 (COVID-19) crisis has affected how hospitals work and has had an effect on orthopedic surgery. OBJECTIVES: To compare patient management and low-energy and high-energy trauma treatment at two orthopedic trauma units during the COVID-19 crisis and to clarify resource demands and preparedness in orthopedic clinics during the state of emergency caused by the COVID-19 pandemic. METHODS: This retrospective study was conducted at two orthopedic trauma units from 14 March 2019 to 14 April 2019 and from 14 March 2020 to 14 April 2020. RESULTS: The proportion of patients admitted in the multi-trauma orthopedic unit decreased by one-third, the mean time interval from admission to surgery significantly decreased, and the number of surgeries and mean length of stay in hospital decreased in 2020 compared to the same test period in 2019. In the orthopedic trauma unit, the number of patients and surgeries also decreased. CONCLUSIONS: Our study highlights changes in orthopedic injury characteristics in two orthopedic units during the COVID-19 crisis in Latvia and compares these changes to data from the same time period one year earlier.

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.

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.

Vertebral Artery Dissection.

A 40-year-old woman was referred to physical therapy with complaints of headaches. Examination raised suspicion of a "thunderclap headache," a condition characterized by sudden, intense headaches correlated with bleeding in and around the brain. The patient was referred to a neurologist, who ordered magnetic resonance angiography of the head and neck, which identified a partial dissection of the right vertebral artery. A subsequent computed tomography angiogram confirmed the dissection. J Orthop Sports Phys Ther 2020;50(6):344. doi:10.2519/jospt.2020.8858.

Blood-Brain Barrier Disruption as a Potential Target for Therapy in Posterior Reversible Encephalopathy Syndrome: Evidence From Multimodal MRI in Rats.

Background: To explore blood-brain barrier disruption in hypertensive posterior reversible encephalopathy syndrome. Methods: The hypertension rat models were successfully established and scanned on 7T micro-MRI. MRI parameter maps including apparent diffusion coefficient, T1 value, and perfusion metrics such as cerebral blood volume, cerebral blood flow, mean transit time and time to peak maps, were calculated. Results: The ADC values of the experimental group were higher than those of the control group both in cortical (P < 0.01) and subcortical (P < 0.05) regions. Voxel-wise analysis of ADC maps localized vasogenic edema primarily to the posterior portion of the brain. The increase in cerebral blood volume and cerebral blood flow values were found in the cortical and subcortical regions of rats with acute hypertension. No correlation was found between perfusion metrics and mean arterial pressure. The Evans blue dye content was higher in the posterior brain region than the anterior one (P < 0.05). Conclusions: Cerebral vasogenic edema resulting from acute hypertension supports the hypothesis of posterior reversible encephalopathy syndrome as the result of blood-brain barrier disruption, which maybe the potential therapeutic target for intervention.

Application of FLAIR Vascular Hyperintensity-DWI Mismatch in Ischemic Stroke Depending on Semi-Quantitative DWI-Alberta Stroke Program Early CT Score.

Objective: Diffusion-weighted imaging (DWI)-Alberta Stroke Program Early CT Score (ASPECTS) is a simple, widely used method to estimate the size of the infarct. Our aim is to determine whether there is a relationship between DWI-ASPECTS and fluid-attenuated inversion recovery (FLAIR) vascular hyperintensity (FVH)-DWI mismatch and to better quantify FVH-DWI mismatch to assess the prognosis of cerebral infarction. Materials and Methods: A retrospective analysis of 109 patients with MCA stenosis or occlusion with cerebral infarction was performed by dividing this cohort into FVH-DWI match group and FVH-DWI mismatch group based on FVH and DWI results. The clinical and imaging data of these two groups of patients were reviewed and analyzed to identify associations between FVH-DWI mismatch and prognosis of patients for preservation of neurological function. Correlation between DWI-ASPECTS and FVH-DWI mismatch was also performed. Results: FVH-DWI mismatch was present in 66/109 (60.55%) patients, and FVH-DWI match was present in 43/109 (39.45%). Patients with FVH-DWI mismatch had higher DWI-ASPECTS (7.0 vs. 4.0, P < 0.001) and lower mRS at 3 months (3.0 vs. 4.0, P < 0.001) than patients without FVH-DWI mismatch. Multiple regression analysis suggested that DWI-ASPECTS (OR = 4.7, 95% CI = 2.5-9.2, P < 0.001) remained significantly associated with FVH-DWI mismatch. Two threshold points for DWI-ASPECTS of 3 and 8 can be used to distinguish whether there is a mismatch in FVH-DWI by smooth curve fitting. Conclusions: The DWI-ASPECTS score was an independent predictor of FVH-DWI mismatch. At DWI-ASPECTS ≤ 3, the FVH-DWI mismatch offers no prognostic value; whereas, at DWI-ASPECTS ≥ 8, the FVH-DWI mismatch had the highest prognostic value. DWI-ASPECTS can roughly determine whether there is a FVH-DWI mismatch in order to select optimal clinical treatment and accurately assess prognosis.