54 research outputs found
Interference and electromagnetic compatibility challenges in 5G wireless network deployments
5G wireless network technology is going operate within the environment of other electrical, electronic and electromagnetic devices, components and systems, with capability of high speed data connectivity acting as network transceiver stations with Massive MIMO for Internet of Things (IoT). Considering the level of interoperability, electromagnetic Interference and electromagnetic compatibility to avoid electromagnetic pulse effects (EMP) which is capable of not only causing network malfunctions but total devices and equipments failure in mission critical operations, like hospital MRI scan machines, security profiling and data handling or even personal healthcare devices like heart pacemaker. Electromagnetic energy coupling in PCB due to: radiation, reflection and Crosstalk generates reliability challenges affecting Signal Integrity between traces of multilayer boards stalks, power bus and packaging creating Electromagnetic interference (EMI) in PCB leading false clock response to system failure. Above were considered very essential when deploying 5G wireless network facility as presented in this paper
Hydrophobic concrete using waste paper sludge ash
The feasibility of using a low-cost super hydrophobic powder as water-resisting admixture or water-repellent surface coating for concrete has been investigated. The powder was produced from paper sludge ash (PSA), a by-product from the manufacture of recycled paper. The effect of hydrophobic PSA on workability, strength and transport properties, including sorptivity, water absorption, diffusivity, permeability and electrical conductivity is reported. Samples were prepared at water/cement ratio of 0.38, cured up to 28 days and conditioned at 50 °C to constant mass prior to testing. It was found that replacing Portland cement with 12% hydrophobic PSA reduced water absorption, sorptivity and conductivity by 84%, 86% and 85% respectively, with no major detrimental effects on hydration, strength and density. When used as a surface coating, the hydrophobic PSA reduced both absorption and sorptivity by 85â99% depending on the adhesive used. Samples surface coated with hydrophobic PSA showed excellent water repelling and self-cleaning characteristics
Identification of single-dose, dual-echo based CBV threshold for fractional tumor burden mapping in recurrent glioblastoma
BackgroundRelative cerebral blood volume (rCBV) obtained from dynamic susceptibility contrast (DSC) MRI is widely used to distinguish high grade glioma recurrence from post treatment radiation effects (PTRE). Application of rCBV thresholds yield maps to distinguish between regional tumor burden and PTRE, a biomarker termed the fractional tumor burden (FTB). FTB is generally measured using conventional double-dose, single-echo DSC-MRI protocols; recently, a single-dose, dual-echo DSC-MRI protocol was clinically validated by direct comparison to the conventional double-dose, single-echo protocol. As the single-dose, dual-echo acquisition enables reduction in the contrast agent dose and provides greater pulse sequence parameter flexibility, there is a compelling need to establish dual-echo DSC-MRI based FTB mapping. In this study, we determine the optimum standardized rCBV threshold for the single-dose, dual-echo protocol to generate FTB maps that best match those derived from the reference standard, double-dose, single-echo protocol.MethodsThe study consisted of 23 high grade glioma patients undergoing perfusion scans to confirm suspected tumor recurrence. We sequentially acquired single dose, dual-echo and double dose, single-echo DSC-MRI data. For both protocols, we generated leakage-corrected standardized rCBV maps. Standardized rCBV (sRCBV) thresholds of 1.0 and 1.75 were used to compute single-echo FTB maps as the reference for delineating PTRE (sRCBV < 1.0), tumor with moderate angiogenesis (1.0 < sRCBV < 1.75), and tumor with high angiogenesis (sRCBV > 1.75) regions. To assess the sRCBV agreement between acquisition protocols, the concordance correlation coefficient (CCC) was computed between the mean tumor sRCBV values across the patients. A receiver operating characteristics (ROC) analysis was performed to determine the optimum dual-echo sRCBV threshold. The sensitivity, specificity, and accuracy were compared between the obtained optimized threshold (1.64) and the standard reference threshold (1.75) for the dual-echo sRCBV threshold.ResultsThe mean tumor sRCBV values across the patients showed a strong correlation (CCC = 0.96) between the two protocols. The ROC analysis showed maximum accuracy at thresholds of 1.0 (delineate PTRE from tumor) and 1.64 (differentiate aggressive tumors). The reference threshold (1.75) and the obtained optimized threshold (1.64) yielded similar accuracy, with slight differences in sensitivity and specificity which were not statistically significant (1.75 threshold: Sensitivity = 81.94%; Specificity: 87.23%; Accuracy: 84.58% and 1.64 threshold: Sensitivity = 84.48%; Specificity: 84.97%; Accuracy: 84.73%).ConclusionsThe optimal sRCBV threshold for single-dose, dual-echo protocol was found to be 1.0 and 1.64 for distinguishing tumor recurrence from PTRE; however, minimal differences were observed when using the standard threshold (1.75) as the upper threshold, suggesting that the standard threshold could be used for both protocols. While the prior study validated the agreement of the mean sRCBV values between the protocols, this study confirmed that their voxel-wise agreement is suitable for reliable FTB mapping. Dual-echo DSC-MRI acquisitions enable robust single-dose sRCBV and FTB mapping, provide pulse sequence parameter flexibility and should improve reproducibility by mitigating variations in preload dose and incubation time
Value of prominent flow voids without cord edema in the detection of spinal arteriovenous fistulae
Purpose: To determine the prevalence of spinal dural arteriovenous fistulae (SDAVF) in patients presenting with prominent vascular flow voids on imaging without other imaging findings suggestive of SDAVF. Methods: We retrospectively identified patients from January 1, 2005 to March 1, 2012 who underwent spinal angiography for suspected SDAVF with prominent vascular flow voids on prior imaging. We excluded patients with other major spinal pathology or other imaging findings of SDAVF including cord hyperintensity, enhancement, or expansion. We calculated the proportion of patients with positive findings for SDAVF on angiography and evaluated the prevalence of SDAVF for this finding alone and in correlation with clinical findings. Results: 18 patients underwent spinal angiography for prominent flow voids on imaging without other spinal pathology or imaging findings of SDAVF. Three had a SDAVF detected on angiography. The prevalence of SDAVF in this population was low, only 17% (95% CI 6-39%). All of the patients with positive angiography findings had myelopathy, increasing the prevalence to 100% if the additional clinical finding of myelopathy was present. Conclusions: Prominent flow voids without other imaging findings suggestive of SDAVF is poorly predictive of the presence of a SDAVF, unless myelopathy is present clinically. © 2014 Alhilali et al
Evaluation of the intervertebral disk angle for the assessment of anterior cervical diskoligamentous injury.
BACKGROUND AND PURPOSE: The anterior diskoligamentous complex is important for cervical spinal stability. Subjective widening of the disk space after trauma has been used to gauge disruption of the anterior diskoligamentous complex on CT scanning, but no quantitative CT measurements exist to evaluate injury. The purpose of our study was to evaluate if an increased intervertebral disk angle could serve as a more sensitive, reproducible indicator of disruption of the anterior diskoligamentous complex compared with subjective assessment.
MATERIALS AND METHODS: The intervertebral disk angle was retrospectively measured on CT scanning for 122 disk levels with disruption of the anterior diskoligamentous complex by MR imaging and 1095 disk levels with an intact anterior diskoligamentous complex by MR imaging. The intervertebral disk angle was measured between the anterior superior endplate and anterior inferior endplate, with angle apex at the midposterior disk. Area under the receiver operating characteristic curves for subjective disk widening and specific angle values were obtained. Intervertebral disk angle reproducibility was also evaluated.
RESULTS: Intervertebral disk angle measurements were substantially reproducible. No disk with an intact anterior diskoligamentous complex had an intervertebral disk angle greater than 18° or 2 standard deviations from the average intervertebral disk angle of the remaining disks. The area under the receiver operating characteristic curve for a criterion of subjective disk widening was 0.58. The area under the receiver operating characteristic curve for objective criteria, an intervertebral disk angle greater than 13 or above 1 standard deviation from normal values, was 0.85. The maximal area under the receiver operating characteristic curve was achieved if an intervertebral disk angle greater than 2 SD from the average angle of the other disks was used (0.86).
CONCLUSIONS: Subjective disk widening does not accurately detect disruption of the anterior diskoligamentous complex on CT scanning; an elevated intervertebral disk angle provides a more sensitive and objective measurement to help direct further imaging in trauma patients
Effect of the Suboccipital Musculature on Symptom Severity and Recovery after Mild Traumatic Brain Injury.
BACKGROUND AND PURPOSE: Neck musculature mass has been suggested as a biomechanical contributor to injury severity in mild traumatic brain injury. We sought to determine how the cross-sectional areas of the suboccipital muscles affect symptom severity, neurocognitive performance, and recovery time in patients with mild traumatic brain injury.
MATERIALS AND METHODS: Sixty-four consecutive patients with mild traumatic brain injury underwent MR imaging and serial neurocognitive testing with the Immediate Post-Concussion Assessment and Cognitive Test. Cross-sectional areas of the rectus capitis posterior musculature were retrospectively obtained at C1, and cross-sectional areas of the remaining 7 suboccipital muscles were measured at C2. Cross-sectional area reproducibility was evaluated. Overall and individual muscle cross-sectional areas were correlated with symptom severity, neuropsychological testing, recovery time, and headache.
RESULTS: Sixty-four patients with mild traumatic brain injury had imaging through C1, and 43 had imaging through C2. Reproducibility of cross-sectional area measurements was substantial (correlation coefficients = 0.9517-0.9891). Lower cross-sectional area of the rectus capitis posterior minor was correlated with greater symptom severity (r = 0.596, P \u3c .0001), longer recovery time (r = 0.387, P = .002), poor verbal memory performance (r = 0.285, P = .02), and headache (r = 0.39, P = .001). None of the other cross-sectional areas were associated with symptom severity, recovery time, neurocognitive testing, or headache.
CONCLUSIONS: In mild traumatic brain injury, the rectus capitis posterior minor is the only suboccipital muscle whose cross-sectional area is associated with symptom severity and worse outcome. Given the unique connection of this muscle to the dura, this finding may suggest that pathology of the myodural bridge contributes to symptomatology and prognosis in mild traumatic brain injury
Differences in Callosal and Forniceal Diffusion between Patients with and without Postconcussive Migraine.
BACKGROUND AND PURPOSE: Posttraumatic migraines are common after mild traumatic brain injury. The purpose of this study was to determine if a specific axonal injury pattern underlies posttraumatic migraines after mild traumatic brain injury utilizing Tract-Based Spatial Statistics analysis of diffusion tensor imaging.
MATERIALS AND METHODS: DTI was performed in 58 patients with mild traumatic brain injury with posttraumatic migraines. Controls consisted of 17 patients with mild traumatic brain injury without posttraumatic migraines. Fractional anisotropy and diffusivity maps were generated to measure white matter integrity and were evaluated by using Tract-Based Spatial Statistics regression analysis with a general linear model. DTI findings were correlated with symptom severity, neurocognitive test scores, and time to recovery with the Pearson correlation coefficient.
RESULTS: Patients with mild traumatic brain injury with posttraumatic migraines were not significantly different from controls in terms of age, sex, type of injury, or neurocognitive test performance. Patients with posttraumatic migraines had higher initial symptom severity (
CONCLUSIONS: Injuries to the corpus callosum and fornix/septohippocampal circuit were seen in patients with mild traumatic brain injury with posttraumatic migraines, with injuries in the fornix/septohippocampal circuit correlating with decreased performance on neurocognitive testing
A multi-disciplinary model of risk factors for fatal outcome in posterior reversible encephalopathy syndrome
PURPOSE: To evaluate the relative impact of clinical data, imaging findings, and CSF laboratory values on clinical outcome in patients with posterior reversible encephalopathy syndrome (PRES). METHODS: 47 patients with PRES who underwent a lumbar puncture were retrospectively evaluated. Fatal outcome was defined as death directly ascribed to PRES toxicity. Univariate and multivariate analyses were used to evaluate the association between fatal outcome and clinical factors (demographics, PRES etiology), imaging findings (signal abnormality severity, atypical distribution, restricted diffusion, hemorrhage, enhancement, angiographic abnormalities), and lumbar puncture results (appearance, cell count, glucose, protein, culture results). RESULTS: Nine patients (19.1%) had a fatal outcome. Odds of a fatal outcome increased nearly 5-fold with hemorrhage on imaging (Adjusted Odds Ratio (AOR) 4.8, 95% CI 3.8-6.0, p=0.03) and nearly doubled with low CSF glucose (AOR 1.9, 95% CI 1.5-2.5, p=0.02). Hypertensive encephalopathy as an etiology was associated with a fatal outcome (AOR 1.6, 95% CI 1.3-2.9, p=0.02), while toxemia of pregnancy was protective, with a 75% decreased risk (AOR 0.25, 95% CI 0.15-0.43, p=0.02). CONCLUSION: Clinical, imaging, and CSF laboratory findings all influence outcome in PRES, with a low CSF glucose, hypertensive encephalopathy, and imaging findings of hemorrhage associated with increased risk of fatal outcome
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