Neonatal life support during magnetic resonance imaging

Magnetic resonance techniques are required frequently for the assessment of the brain of ill neonates. In the present study, the effects of a 1.5 T MR scanner on devices for life support were assessed. A ventilator (Dr?ger Babylog 2000) was tested in the 1.5 T magnet, using a neonatal ventilation tester and 1.5-5 m tubes. In a special MR incubator, temperature and humidity were measured at 1-min intervals. Infusion was tested with the pump outside the magnet room: infusion rates and time to alarm were tested with 7-m tubes. The ventilator performed normally at a magnetic field line of 2 mT, although the alarms failed. The incubator created a temperature of 35.9 degrees C and humidity of 40.7%, which was acceptable for examinations of 45 min. The alarm limits of the infusion pump placed outside the magnet at 7 m were within company limits. The study indicates that magnetic resonance examinations can be performed safely in ill preterm neonates who require life-support devices.     

Neonatal life support during magnetic resonance imaging

Magnetic resonance techniques are required frequently for the assessment of the brain of ill neonates. In the present study, the effects of a 1.5 T MR scanner on devices for life support were assessed. A ventilator (Dra¨ger Babylog 2000) was tested in the 1.5 T magnet, using a neonatal ventilation tester and 1.5-5 m tubes. In a special MR incubator, temperature and humidity were measured at 1-min intervals. Infusion was tested with the pump outside the magnet room: infusion rates and time to alarm were tested with 7-m tubes. The ventilator performed normally at a magnetic field line of 2 mT, although the alarms failed. The incubator created a temperature of 35.9°C and humidity of 40.7%, which was acceptable for examinations of 45 min. The alarm limits of the infusion pump placed outside the magnet at 7 m were within company limits. The study indicates that magnetic resonance examinations can be performed safely in ill preterm neonates who require life-support devices.     

Acquisition of electrophysiologic signals during magnetic resonance imaging

We describe a low cost system for acquiring electrophysiological signals during magnetic resonance imaging. The system consists of high common-mode-rejection and low noise operational amplifiers, coupled by fiber optic cables to a receiver located at the periphery of the magnetic field. The system minimizes noise introduction which would contaminate image signals.     

Evidence-based medicine training during residency: a randomized controlled trial of efficacy

Background  

Evidence-based medicine (EBM) has been widely integrated into residency curricula, although results of randomized controlled trials and long term outcomes of EBM educational interventions are lacking. We sought to determine if an EBM workshop improved internal medicine residents' EBM knowledge and skills and use of secondary evidence resources.     

Effectiveness of GP access to magnetic resonance imaging of the knee: a randomised trial

Background

GPs commonly see patients with knee problems. Magnetic resonance imaging (MRI) of the knee is an accurate diagnostic test for meniscus and ligament injuries of the knee, but there is uncertainty about the appropriate use of MRI and when it should enter the diagnostic pathway for patients with these problems.

Aim

To assess the effectiveness of GP referral to early MRI and a provisional orthopaedic appointment, compared with referral to an orthopaedic specialist without prior MRI for patients with continuing knee problems.

Design of study

Pragmatic multicentre randomised trial with two parallel groups.

Setting

A total of 553 patients consulting their GP about a continuing knee problem were recruited from 163 general practices at 11 sites across the UK.

Method

Patients were randomised to MRI within 12 weeks of GP referral including a provisional orthopaedic appointment, or orthopaedic appointment without prior MRI within a maximum of 9 months from GP referral. The primary outcome measures were the Short Form 36-item (SF-36) physical functioning scale and the Knee Quality of Life 26-item Questionnaire (KQoL-26) at 6, 12, and 24 months.

Results

Patients randomised to MRI improved mean SF-36 physical functioning scores by 2.81 (95% confidence interval [CI] = −0.26 to 5.89) more than those referred to orthopaedics (P = 0.072). Patients randomised to MRI improved mean KQoL-26 physical functioning scores by 3.65 (95% CI = 1.03 to 6.28) more than controls (P = 0.007). There were no other significant differences.

Conclusion

GP access to MRI yielded small, but statistically significant, benefits in patients'' knee-related quality of life but non-significant improvements in physical functioning.     

Predictors of panic symptoms during magnetic resonance imaging scans

This study examined the usefulness of a score derived from nine items of Wolpe and Lang’s (1964) Fear Survey Schedule (FSS) in predicting the number of symptoms consistent with panic reported by a large outpatient sample undertaking magnetic resonance imaging (MRI) scans. The items were those identified by Lukins, Davan, and Drummond (1997) as likely to reflect fears associated with the aversive characteristics of the MRI procedure (i.e., noise, confinement, and isolation) and were taken 1 week before the scan. The MRI-related FSS score was a better predictorof symptoms consistent with panic attack during the scan than (a) Rachman and Taylor’s (1993) Claustrophobia Questionnaire, (b) a score derived from nine FSS items reflecting common community fears, or (c) a measure of state anxiety. It is suggested that the brief MRI-related FSS scale can provide information important for planning patient management during MRI scans at a time when the information can be most useful.     

基于低场磁共振的脉冲序列设计和成像研究

目的 利用低场磁共振序列设计平台探讨脉冲序列的设计方法,并分析评价成像质量.方法 在低场磁共振平台上,基于序列编码语言及脉冲和编码梯度的最佳施加时间来设计成像序列,并对含油和硫酸铜的样品管进行成像,然后根据T1、T2、质子密度、回波时间、重复时间等基本成像参数对样品管图像进行比较和验证.结果 探索出磁共振成像序列设计的基本方法和流程,并且获得了清晰的磁共振图像.结论 低场磁共振可作为基础研究平台用以设计成像序列并进行成像.在进一步的研究中,可针对不同组织部位设计具有特异性效果的脉冲序列,以将磁共振技术更好地应用于临床.     

Prevention of asthma during the first 5 years of life: a randomized controlled trial

BACKGROUND: Early life exposures may be important in the development of asthma and allergic disease. OBJECTIVE: To test house dust mite (HDM) avoidance and dietary fatty acid modification, implemented throughout the first 5 years of life, as interventions to prevent asthma and allergic disease. METHODS: We recruited newborns with a family history of asthma antenatally and randomized them, separately, to HDM avoidance or control and to dietary modification or control. At age 5 years, they were assessed for asthma and eczema and had skin prick tests for atopy. RESULTS: Of 616 children randomized, 516 (84%) were evaluated at age 5 years. The HDM avoidance intervention resulted in a 61% reduction in HDM allergen concentrations (microg/g dust) in the child's bed but no difference in the prevalence of asthma, wheeze, or atopy (P > .1). The prevalence of eczema was higher in the active HDM avoidance group (26% vs 19%; P = .06). The ratio of omega-6 to omega-3 fatty acids in plasma was lower in the active diet group (5.8 vs 7.4; P < .0001). However, the prevalence of asthma, wheezing, eczema, or atopy did not differ between the diet groups (P > .1). CONCLUSION: Further research is required to establish whether other interventions can be recommended for the prevention of asthma and allergic disease. CLINICAL IMPLICATIONS: House dust mite avoidance measures and dietary fatty acid modification, as implemented in this trial during infancy and early childhood, did not prevent the onset of asthma, eczema, or atopy in high-risk children.     

Evaluation of knee cartilage thickness: A comparison between ultrasound and magnetic resonance imaging methods

Background

Establishing clinically accessible measures of cartilage health is critical for assessing effectiveness of protocols to reduce risk of osteoarthritis (OA) development and progression. Cartilage thickness is one important measure in describing both OA development and progression. The objective was to determine the relationship between ultrasound and MRI measures of cartilage thickness in the medial femoral condyle.

Negative BOLD during tongue movement: A functional magnetic resonance imaging study

The aim of this functional magnetic resonance imaging (fMRI) study was to evaluate negative blood oxygen level-dependent (BOLD) signals during voluntary tongue movement. Deactivated (Negative BOLD) regions included the posterior parietal cortex (PPC), precuneus, and middle temporal gyrus. Activated (Positive BOLD) regions included the primary somatosensory-motor area (SMI), inferior parietal lobule, medial frontal gyrus, superior temporal gyrus, insula, lentiform nucleus, and thalamus. The results were not consistent with previous studies involving unilateral hand and finger movements showing the deactivation of motor-related cortical areas including the ipsilateral MI. The areas of Negative BOLD in the PPC and precuneus might reflect specific neural networks relating to voluntary tongue movement.     

咀嚼时局部脑活动的功能性核磁共振成像

目的：应用功能性核磁共振成像（fMRI）探测人吸嚼时的大脑功能活动。方法：要求人在无任何其它躯体活动条件下咀嚼肌以10s运动20s休息的频率进行。选用8例成人冠状切面和横轴面的头部磁共振片,观察脑功能活动情况。结果：①在咀嚼时脑的广泛区域是激活的;②在相对应的咀嚼活动中有优势半球的激活区;③第I躯体感觉区激活的方式远较第I躯体运动区多样化;④在额叶中4例年轻观察对象出现了广泛的神经元激活区,但在老年人很少出现这样的激活区。结论：咀嚼活动除了它本身的功能运动外,在维持脑的活动方面具有重要的作用。同时也说明fMRI在研究活体人脑功能活动方面是一个相当有效的方法。     

A hybrid, inverse approach to the design of magnetic resonance imaging magnets

This paper describes a hybrid numerical method of an inverse approach to the design of compact magnetic resonance imaging magnets. The problem is formulated as a field synthesis and the desired current density on the surface of a cylinder is first calculated by solving a Fredholm equation of the first kind. Nonlinear optimization methods are then invoked to fit practical magnet coils to the desired current density. The field calculations are performed using a semi-analytical method. The emphasis of this work is on the optimal design of short MRI magnets. Details of the hybrid numerical model are presented, and the model is used to investigate compact, symmetric MRI magnets as well as asymmetric magnets. The results highlight that the method can be used to obtain a compact MRI magnet structure and a very homogeneous magnetic field over the central imaging volume in clinical systems of approximately 1 m in length, significantly shorter than current designs. Viable asymmetric magnet designs, in which the edge of the homogeneous region is very close to one end of the magnet system are also presented. Unshielded designs are the focus of this work. This method is flexible and may be applied to magnets of other geometries.     

A review of diffusion tensor magnetic resonance imaging computational methods and software tools

In this work we provide an up-to-date short review of computational magnetic resonance imaging (MRI) and software tools that are widely used to process and analyze diffusion-weighted MRI data. A review of different methods used to acquire, model and analyze diffusion-weighted imaging data (DWI) is first provided with focus on diffusion tensor imaging (DTI). The major preprocessing, processing and post-processing procedures applied to DTI data are discussed. A list of freely available software packages to analyze diffusion MRI data is also provided.