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Magnets, Gradients, and RF Coils of MR Scanners

Published on: 25th July, 2023

The topic of this paper is the parts of modern MR devices, which contain magnet coils. MR scanner magnets are made of four types of electromagnetic coils: 1) Main magnet, made of superconducting material. The main magnet of an MR (Magnetic Resonance Imaging) scanner creates a strong and uniform magnetic field around the patient being scanned. This magnetic field is typically in the range of 0.5 to 3 Tesla and is used to align the magnetic moments of the hydrogen atoms in the patient's body. The superconductors, which create the main magnetic field, should be cooled with liquid helium and liquid nitrogen. The main magnets made of superconductors should use a cryostat, with cooling vessels with liquid helium and liquid nitrogen, thermal insulation, and other protective elements of the magnet system. 2) The gradient magnetic field is made of three types of coils: x-coils, y-coils, and z-coils.  The X coil, made of resistive material, creates a variable magnetic field, horizontally, from left to right, across the scanning tube; 3) The Y coil creates a variable magnetic field, vertically, from bottom to top; 4) The Z coil creates a variable magnetic field, longitudinally, from head to toe, inside the scanning tube. RF coils are used to generate RF pulses to excite the hydrogen protons (spins) in the patient's body and detect the signals emitted by the protons when they return to their equilibrium state after the RF excitation is turned off.  The resulting interaction between the magnetic field and the aligned hydrogen atoms produces a signal that is used to generate the images seen in an MRI scan. The main magnetic field is what allows MR imaging to produce detailed anatomical and functional information non-invasively. The structure of the MR scanner magnet is complex. The resonant frequency changes at each point of the field in a controlled manner. Inside the copper core are embedded the windings of the main magnet made of superconducting material in the form of microfibers. A non-linear gradient field is created by coils of conductive material. It adds to the main magnetic field. Thus the resulting magnetic field is obtained. The types of magnets that exist in the basic configurations of MR scanners are analyzed. Scanners in the form of a closed cylindrical cavity generate their magnetic fields by passing current through a solenoid, which is maintained at the temperature of a superconductor. Exclusively used superconductors are niobium-titanium (NbTi), niobium-tin (Nb3Sn), vanadium-gallium (V3Ga), and magnesium-diboride (MgB2). Only magnesium diboride is a high-temperature superconductor, with a critical temperature Tc = 390K. The three remaining superconductors are low temperatures. New high-temperature superconductors have been discovered, as well as superconductors at room temperature. Newly discovered superconducting materials are not used in MR scanners.
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Timely initiation of breastfeeding and associated factors among mothers who have infants less than six months of age in Gunchire Town, Southern Ethiopia 2019

Published on: 9th April, 2020

OCLC Number/Unique Identifier: 8582297046

Background: Timely starting of breastfeeding is defined as the starting of breastfeeding within one hour after childbirth. Globally mothers who practiced breastfeeding within one hour were less than half in percent. In least developed countries like Eastern and Southern Africa including Ethiopia infant breastfeeding practice within one hour were low. The aim of this study was to assess timely initiation of breastfeeding and associated factors among mothers who have an infant less than six months of age in Gunchire town, Southern Ethiopia. Methods: The study was conducted from May 1 to 28, 2019 in Gunchire town. Data were collected by using a structured face to face interview questionnaire. The community based cross-sectional study was employed on 333 women. The study participants were selected by Simple random sampling techniques. The data were coded, entered, cleaned and analyzed by SPSS with windows version 21.0. Binary and multivariable logistic regression statistical model was used. Adjusted odds ratio with 95% CI was computed to see the strength of association. Results: In this study the magnitude of timely initiation of breastfeeding was 80.5%. Governmental employed mothers (AOR=2.914, 95% CI: 1.139, 7.46), Antenatal care follow up (AOR=5.99, 95% CI: 1.29, 27.81), Baby skin to skin contact (AOR=2.4, 95% CI: 1.092, 5.34), Vaginal delivery (AOR=5.82 95% CI: 1.68, 20.14) Institutional delivery (AOR=5.5, 95 CI%: 1.66, 18.3), Good knowledge of breastfeeding (AOR=4.02, 95% CI: 1.04, 15.59) and Breast disease (AOR=0.24, 95% CI: 0.08, 0.73) were significantly associated with timely starting of breastfeeding. Conclusion: More than two third of the mothers timely initiated breastfeeding within one hour after birth. Being governmentally employed, having Antenatal care follows up, skin to skin contact, mode of delivery, knowledge of mothers about breastfeeding and place of delivery were positively and significantly associated with timely initiation of breast feeding, whereas, breast disease was protective against timely starting of breastfeeding. Therefore, we would like to recommend Enamore woreda health office and Gunchire primary Hospital staffs work at MCH clinic to provide appropriate services and stimulate the mothers to initiate breastfeeding, skin to skin contact enhancing within the first hour of birth.
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Biomarkers for High Metabolic Burden in Neurologic Disease

Published on: 15th February, 2024

Neurologic diseases are recognized to have multifactorial origins well beyond mere genetic predisposition. Nutritional burdens have been identified to contribute to neurodegeneration. Healthy diets are becoming increasingly appreciated to potentially play key roles in both the developing and developed world of reducing incidences of neurologic diseases, while unhealthy diets are acknowledged to be contributing to their rise.
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Factors Associated with Elevated Transcranial Doppler Ultrasound Velocities in Children With Sickle Cell Anemia in Mwanza, Tanzania

Published on: 28th July, 2023

Background: Stroke occurs in 11% of patients with SCA before 20 years of age. In Northwestern Tanzania, the prevalence of stroke among children living with SCA under the age 15 years is 16.9%, of which might be attributed to the absence of routine screening for the risk of stroke by using Transcranial Doppler Ultrasound (TCD). Screening with TCD allows preventive measures such as chronic blood transfusion to be done which has led to the reduction of stroke by 92%.Methods: This was a prospective analytical cross sectional study which enrolled 267 SCA children aged 2 to 16 years attending Bugando Medical Centre Pediatric Sickle Cell Clinic from July 2019 to June 2020. Assessment of factors associated with elevated TCD included a clinical history of stroke in sibling, death in sibling, temperature, oxygen saturation in room air, blood pressure, hemoglobin level and total white blood cell count. TCD was done by accessing transtemporal window and recording the highest time average mean of maximum velocity (TAMMV) of major vessels mainly, middle cerebral artery (MCA) and distal internal carotid artery (dICA).Results: The median age of enrolled was 6.6 (IQR: 4-9) years. The prevalence of elevated TCD (> 170 cm/s)was found to be 21% (56/267). By multivariate logistic regression, low oxygen saturation in room air, p - value = 0.037, OR 1.08 [95% CI 1.00-1.17] and low hemoglobin level, p - value = 0.001, OR 1.76 [95% CI 1.26-2.45] were statistically significantly associated with elevated TCD among children living with SCA.Conclusion: The high prevalence of elevated TCD velocity, with low hemoglobin and low oxygen saturation in room air as associated factors under multivariate logistic regression, warrants routine TCD screening for children with SCA aged 2 to 16 years.
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COVID-19 in pregnancy: Our experience at a tertiary maternity unit in France

Published on: 24th June, 2020

OCLC Number/Unique Identifier: 8625644678

Objectives: Our main objectives are to reveal the pregnancy and neonatal impacts of COVID-19 infection and to compare it to the results that are reported in the literature. Methods and materials: The characteristics of the admitted pregnant patients COVID-19 positive with their initial presentation, course at the hospital, and short term follow-up are exposed. Correlation of the age and gestational age with the severity of the disease was calculated. Results: Thirty five COVID-19 positive pregnant patients presented between the beginning of March and the end of April 2020. From 5 weeks till 41 weeks of gestation, all trimesters were included. The mean of age is 32 and the BMI equal 28.2. Associated comorbidities included not only diabetes and hypertension but also PCOS. The symptomatology was considered mild in most of the cases. The distribution of the symptoms included cough in 86%. 10 out of 35 delivered and cesarean was performed in 50% of the cases. The mean length of stay is 6 days. Neither maternal nor neonatal deaths occurred. There is a significant correlation between the age of the patient and the severity of the disease but this is not the case with gestational age. Conclusion: Our results were comparable to the literature in terms of initial presentation, associated comorbidities and the length of stay. Despite the fact that the cesarean rate was high, it was far below that of the literature. More data is still needed about COVID-19 in pregnancy.
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The necessity of emotion management for the general public: a comparison of diagnostic changes in two anger-related psychiatric disorders

Published on: 23rd December, 2022

Although emotion management is essential to mental health, public health has not paid much attention to emotional conditions or disorders. By analyzing a nine-year diagnostic trend and sociodemographic characteristics of two mental disorders: Hwabyung and Intermittent Explosive Disorder (IED), this study demonstrated the importance of managing emotions precautionarily.Data reconstructed from the National Health Insurance Service were used to analyze the yearly diagnostic trend in the two mental disorders characterized by anger.Hwabyung was more common among women and middle-aged individuals, despite the varied number of diagnoses by year. Between 2010 and 2018, IED diagnoses gradually rose, with the average rate of increase the highest in the 20s for male IED diagnoses in 2017. The low prevalence of the IED in Korea compared to other Western countries and the gender and age differences in both Hwabyung and IED diagnoses suggest the role of cultural influences related to emotions (or emotional management).Especially in light of the world’s emphasis on resilience to COVID-19, these results indicate how public emotional management is essential during stressful situations. The results also highlight the need for community mental health programs tailored to gender and age.
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Prostate cancer-associated thrombotic microangiopathy: A case report and review of the literature

Published on: 8th March, 2021

OCLC Number/Unique Identifier: 8980361223

Background: Thrombotic microangiopathy (TMA) is a rare and life-threatening complication of prostate carcinoma. Whether plasma exchange has a role in treatment remains a subject of debate. Here we present a case followed by a systematic review of the literature on this subject. Case report: We describe a 69-year old patient presenting with TMA, which was associated with an underlying metastatic prostate carcinoma. We conducted a search of similar cases in literature. Results: Our patient was treated and responded well on plasma exchange. Systematic review of the literature showed 17 additional cases of TMA associated with prostate carcinoma of which eleven were treated with plasma exchange with mostly good response. Conclusion: Based on current data we cannot exclude a potential role for plasma exchange in prostate cancer associated TMA.
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The role of cognitive distraction in sexual dysfunction in female medical resident doctors

Published on: 31st May, 2022

Introduction: Studies have shown a high prevalence of sexual dysfunction in Medical residents. Psychological, interpersonal, and sociocultural factors play an important role in sexual vulnerability. In addition, distraction or interference in the cognitive process of the erotic stimulus plays an important role in the development of sexual dysfunction. The aim of our study was to determine the prevalence of sexual dysfunctions among a sample of married female medical resident doctors and to explore its relation with cognitive distraction during sex.Subjects and methods: This was a cross-sectional study, which was carried out in October 2017 with 70 married female medical resident doctors. We used the Female Sexual Function Index (FSFI) for sexual functioning assessment and the cognitive distraction during sex scale. Results: The mean age of women was 30.52 years. They had been married for 6.04 years on the mean. The majority (74%) had children. According to the FSFI, 40% of resident doctors had sexual dysfunction. The mean cognitive distraction during sex score was 4.37.In our study, women with female sexual dysfunction reported significantly lower sexual desire score = 3.2 vs. 4.1 and p = 0.03) and arousal (score = 3.è vs. 4.7 and p = 10-3), decreased lubrication (score = 3.8 vs. 5.1; p = 10-3), less sexual satisfaction (score = 3.9 vs. 5.8; p = 10-3)and higher orgasm difficulties (score = 3.4 vs. 5.1; p = 10-3). Yet, our results highlighted that women with female sexual dysfunction presented significantly more cognitive distraction during sex (score = 3.9 vs. 4.6; p = 0.03). Conclusion: According to our study, it appears that the prevalence of FSD in medical resident doctors is considerable. Besides, intrusive thoughts and cognitive distraction during sexual intercourse are importantly associated with sexual functioning. Therefore, several measures should be implemented in this population to prevent or act on these factors.
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Prevalence of reported drug allergy and its impact on Beta lactam use with financial and health implications

Published on: 22nd August, 2017

OCLC Number/Unique Identifier: 7317598807

Background:While recognition and documentation of true drug allergy is critically important, most physicians acknowledge that its prevalence is likely overestimated, often on the basis of historical, sometimes anecdotal evidence. Correct or not, once applied, drug allergy labels may result in altered, potentially inferior therapy, increased costs and prolonged hospitalisation. Objective:Estimate the point prevalence, accuracy and symptomatology of self-reported drug allergy in a typical, large NHS Acute Trust adult inpatient population. In the subset with penicillin allergy (PA), estimate additional management costs from the use of alternative antibiotics and readmission rates in the previous 5 years. Methods:Data on self-reported drug allergies were extracted from 440 adult inpatient prescription charts over a 4 month period. Where penicillin allergy (PA) was reported, alternative antibiotic regimens were recorded and their additional costs calculated. Hospital electronic records were used to assess readmission rates of PA patients. Results:194/440 inpatients (44.5%) reported at least one drug allergy. Antibiotic allergy was most commonly reported (51%), followed by analgesic (23%) and antiemetic (12%) allergy. PA accounted for 76% of reported antibiotic allergy. The commonest reported symptoms were cutaneous (42%) and gastrointestinal (18%). Where antibiotic therapy was required for patients with PA to manage acute infections, Ciprofloxacin, Clarithromycin, Teicoplanin, Clindamycin and Cefuroxime were the most commonly employed alternatives. Extrapolation of these figures to include the entire Trust inpatient population suggested that the use of alternative antibiotics in PA patients incurred additional annual expenditure of £268,000. Further, 87% of PA patients had been admitted more than once in the preceding 5 years, with 74% requiring further courses of antibiotics during these admissions. Conclusion:Self-reported drug allergy, and in particular PA, is common in hospital inpatient populations and, in addition to the potentially unnecessary hazards to individual patients resulting from the use of alternative antibiotics, results in a considerable additional financial burden to the healthcare system. This problem could be eliminated by the provision of a nationwide and equitable tertiary Allergy service.
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Cortical spreading depolarizations in the context of subarachnoid hemorrhage and the role of ketamine

Published on: 23rd March, 2021

OCLC Number/Unique Identifier: 9026724760

Delayed cerebral ischemia (DCI) is one of the main complications of spontaneous subarachnoid haemorrhage and one of its causes is the cortical spreading depolarizations (CSDs). Cortical spreading depolarizations are waves of neuronal and glial depolarizations in which there is loss of neuronal ionic homeostasis with potassium efflux and sodium and calcium influx. In damaged brain areas and brain areas at risk, such as those adjacent to subarachnoid haemorrhage (SAH), CSDs induce microvascular vasoconstriction and, therefore, hypoperfusion and spread of ischemia. Several studies have been devoted to minimize secondary injuries that occur hours to days after an acute insult. Ketamine, a drug until recently contraindicated in the neurosurgical population for potentially causing intracranial hypertension, has re-emerged as a potential neuroprotective agent due to its pharmacodynamic effects at the cellular level. These effects include anti-inflammatory mechanisms, and those of microthrombosis and cell apoptosis controls, and of modulation of brain excitotoxicity and CSDs. A literature review was performed at PubMed covering the period from 2002 to 2019. Retrospective studies confirmed the effects of ketamine on the control of CSDs and, consequently, of DCI in patients with SAH, but did not show improvement in clinical outcome. The influence of ketamine on the occurrence/development of DCI needs to be further confirmed in prospective randomized studies
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