Two additional cases of metformin‐associated encephalopathy in patients with end‐stage renal disease undergoing hemodialysis

We report on two additional cases of metformin‐associated encephalopathy in patients with end‐stage renal disease (ESRD) undergoing hemodialysis. Two patients were seen at our hospital with abnormal neurological signs and symptoms. Magnetic resonance imaging (MRI) revealed the same pattern of high signal intensity in both basal ganglia in T2‐weighted images in the two patients. The two patients had started taking metformin 5 and 6 weeks earlier at the same dose of 1000 mg per day. Metformin was immediately stopped, and regular hemodialysis was conducted. Their signs and symptoms resolved completely after these measures. The high signal intensity in both ganglia in T2‐weighted MRI also disappeared. We should suspect metformin‐induced encephalopathy and withdraw the drug when presented with diabetic patients with chronic kidney disease and neurological signs and symptoms of unknown cause.     

Properties of a versatile nanoparticle platform contrast agent to image and characterize atherosclerotic plaques by magnetic resonance imaging

The need for more specific and selective contrast agents for magnetic resonance imaging motivated us to prepare a new nanoparticle agent based on high-density lipoproteins (HDL). This second generation contrast agent can be prepared in three different ways. The HDL nanoparticles (rHDL) were fully characterized by FPLC and gel electrophoresis. The flexibility of the platform also allows us to incorporate optical probes into rHDL for localization ex vivo by confocal fluorescence microscopy. The contrast-agent-containing nanoparticles were injected into mice that develop atherosclerotic lesions. Magnetic resonance imaging of the animals showed clear enhancement of the atherosclerotic plaques.     

磁共振弥散张量成像在评估脑梗死患者运动功能康复治疗效果中的应用价值

目的:探究磁共振弥散张量成像在评估脑梗死患者运动功能康复治疗效果中的应用价值。方法:选取138例脑梗死患者,采用磁共振弥散张量成像。观察患者不同分级及不同分级患者健侧、患侧康复前后FA变化情况。结果:138例脑梗死患者中,1级28例、2级45例、3级65例;康复后各级患者与康复前相比,其健侧和患侧FA均有显著降低;康复后1级患侧FA评分高于2级,2级高于3级,1级健侧FA评分低于2级,2级低于3级,对比有统计学意义(P<0.05)。结论:磁共振弥散张量成像在评估脑梗死患者运动功能康复治疗效果中的应用价值显著,值得临床推广。     

Nuclear magnetic resonance imaging with 90-nm resolution

Magnetic resonance imaging (MRI) is a powerful imaging technique that typically operates on the scale of millimetres to micrometres. Conventional MRI is based on the manipulation of nuclear spins with radio-frequency fields, and the subsequent detection of spins with induction-based techniques. An alternative approach, magnetic resonance force microscopy (MRFM), uses force detection to overcome the sensitivity limitations of conventional MRI. Here, we show that the two-dimensional imaging of nuclear spins can be extended to a spatial resolution better than 100 nm using MRFM. The imaging of 19F nuclei in a patterned CaF(2) test object was enabled by a detection sensitivity of roughly 1,200 nuclear spins at a temperature of 600 mK. To achieve this sensitivity, we developed high-moment magnetic tips that produced field gradients up to 1.4 x 10(6) T m(-1), and implemented a measurement protocol based on force-gradient detection of naturally occurring spin fluctuations. The resulting detection volume was less than 650 zeptolitres. This is 60,000 times smaller than the previous smallest volume for nuclear magnetic resonance microscopy, and demonstrates the feasibility of pushing MRI into the nanoscale regime.     

磁共振弥散加权成像和动态增强诊断前列腺疾病临床效果观察

目的:探究诊断前列腺疾病应用于磁共振弥散加权成像和动态增强的临床价值。方法:选择2018年6月-2019年5月本院收治的前列腺患者56例作为研究组对象,随机选出56例前列腺正常者作为对照组,两组患者均采用磁共振常规扫描、磁共振弥散加权成像以及动态扫描,并针对感兴趣区记录DWI信号强度与表面扩散系数ADC值。结果:研究组患者ADC值和DWI信号强度均高于对照组,且P<0.05,差异化显著,符合统计学意义。结论:磁共振弥散加权成像和动态增强诊断前列腺疾病,临床意义确切,能够有效提升前列腺癌的分期准确率,便于对病变部位做出诊断。     

Spontaneous cervical epidural hematoma in a patient with end-stage renal disease

Spontaneous spinal epidural hematoma (SEH) is extremely rare in patients with end-stage renal disease (ESRD). We report a case of a 71-year-old man with ESRD presented with progressive left limb weakness. Magnetic resonance imaging (MRI) revealed spinal cervical SEH involving C3-5 level. The patient received emergent decompression laminectomy with the evacuation of the epidural hematoma.     

生物医学诊疗用磁性微纳材料

磁性微气泡是由包膜微气泡和磁性纳米粒子组成的微纳复合结构,由于其具有超声对比剂和核磁共振对比剂的双重特性,已被应用于双模造影领域。声致穿孔现象（Sonoporation）使得磁性微气泡能介导多种生物学效应,使其在药物输运和基因转染等方面有潜在的应用价值,而磁性微气泡与各种生物分子（抗体、肿瘤标记物等）的偶联,又扩展了磁性微气泡的应用领域,可用于分子影像诊断和靶向治疗肿瘤等方面,可以说磁性微气泡是新一代的生物医学诊疗用磁性微纳材料。总结了磁性微气泡的制备方法,磁性纳米颗粒与微气泡的结合方式,磁性微气泡的功能扩展,以及磁性微气泡在生物医学诊疗领域的实验研究,最后对磁性微气泡在未来的发展方向提出了一些构想,展望了磁性微气泡在诊疗学上广阔的应用前景。     

Measurement of particle separation by magnetic resonance imaging

Magnetic resonance imaging (MRI) of water in filtration devices made from glass and/or plastic not only visualizes in three dimensions all the structural components, but also the time course of the particle separation process.     

Pore structure and sorption properties of silica aerogels studied by magnetic resonance imaging and pulsed-field gradient spectroscopy

Magnetic resonance imaging (MRI) has provided direct visualization of gaseous xenon and methane in the void spaces of aerogels, offering unique information and insights into the pore structure and molecular diffusivities of occluded sorbates. Nuclear magnetic resonance (NMR) pulsed-field gradient (PFG) techniques were used to characterize exchange and diffusive motion of sorbed xenon gas at equilibrium. PFG measurements showed evidence of anisotropic diffusion; nominal self-diffusivity coefficients of xenon on the order of D = 10(-7) m2/s were determined. Based on a mathematical relationship for the restricted diffusion of gases in confined environments, an expression for estimating the mean free path was derived, from which the average pore size could be obtained from the extrapolated value of the diffusion coefficient to low xenon pressures.     

Remotely detected NMR for the characterization of flow and fast chromatographic separations using organic polymer monoliths

An application of remotely detected magnetic resonance imaging is demonstrated for the characterization of flow and the detection of fast, small molecule separations within hypercrosslinked polymer monoliths. The hyper-cross-linked monoliths exhibited excellent ruggedness, with a transit time relative standard deviation of less than 2.1%, even after more than 300 column volumes were pumped through at high pressure and flow. Magnetic resonance imaging enabled high-resolution intensity and velocity-encoded images of mobile phase flow through the monolith. The images confirm that the presence of a polymer monolith within the capillary disrupts the parabolic laminar flow profile that is characteristic of mobile phase flow within an open tube. As a result, the mobile phase and analytes are equally distributed in the radial direction throughout the monolith. Also, in-line monitoring of chromatographic separations of small molecules at high flow rates is shown. The coupling of monolithic chromatography columns and NMR provides both real-time peak detection and chemical shift information for small aromatic molecules. These experiments demonstrate the unique power of magnetic resonance, both direct and remote, in studying chromatographic processes.     

多孔介质断面可视化与孔隙度测量的MRI方法

磁共振成像(MRI)是一种无损的可视化检测手段,其应用范围逐渐由医学影像领域扩展到工程领域.多孔介质断面孔隙度分析通常是将样品进行磨片处理后采用显微镜、扫描电镜成像等方法,但是这种方法会造成样品无法重复利用.本文采用玻璃砂作为多孔介质样品,应用MRI多断面快速扫描技术对样品进行了成像实验.获取了样品一系列扫描片层的骨架...     

一种可阻止非特异性蛋白质吸附的新型聚乳酸材料——聚乙二醇接枝聚乳酸

通过直接酰胺化反应,用氨基封端聚乙二醇(H2N-PEG-NH2)对马来酸酐改性聚乳酸(MPLA)进行了本体改性。用红外、核磁和差示扫描技术对改性材料进行了表征,用FITC荧光标记牛血清白蛋白(FITC-BSA)对材料的非特异性吸附进行了检测。结果表明,聚乙二醇被成功地接枝到MPLA上,与聚乳酸(PLA)和MPLA相比,得到的产物(PPLA)明显降低了对牛血清白蛋白的非特异性吸附,仅为PLA的37.3%。     

Application of magnetic resonance imaging techniques to particulate systems

Magnetic resonance imaging (MRI) is a well-established technique in the medical field, typically for imaging liquid water in the human body, but it is increasingly being used in the field of engineering and materials science. A particular section of this is in the area of particulate systems and granular material flows. MRI is being used to provide a unique insight into particle distribution and motion with in situ measurements. In this paper we discuss how judicious choice and development of imaging technique applied to various different granular systems can provide us with valuable new data on the processes occurring in granular flows. Experimental results focus on rotating bed segregation, velocity imaging in vertical fluidized beds and phase-resolved velocity distributions within vertical vibro-fluidized beds. A discussion of the various imaging techniques used to acquire these data is also given.     

Methotrexate-immobilized poly(ethylene glycol) magnetic nanoparticles for MR imaging and drug delivery

We report the development of a biostable methotrexate-immobilized iron oxide nanoparticle drug carrier that may potentially be used for real-time monitoring of drug delivery through magnetic resonance imaging. Methotrexate (MTX) was immobilized on the nanoparticle surface via a poly(ethylene glycol) self-assembled monolayer (PEG SAM). The cytotoxicity of the nanoparticle-drug conjugate (NP-PEG-MTX) to target cells was studied with 9L glioma cells. Cellular uptake experiments showed that the uptake of NP-PEG-MTX conjugates by glioma cells was considerably higher than that of control nanoparticles. Magnetic resonance imaging in 9L cells cultured with NP-PEG-MTX of various concentrations showed significant contrast enhancement. NP-PEG-MTX demonstrated higher cytotoxicity in 9L cells to free MTX in vitro. Leucovorin, an MTX antidote, was used to rescue the cells that had been exposed to NP-PEG-MTX or free MTX, and the experiment verified the biocompatibility of NP-PEG-MTX conjugates and the MTX on NP-PEG-MTX conjugates to be the true source of the cytotoxicity to the target cells. TEM results showed that NP-PEG-MTX conjugates were internalized into the 9L cellular cytoplasm and retained its crystal structure therein for up to 144 h, as identified by electron diffraction. This prolonged particle retention may allow physicians to image tumor cells exposed to the NP-PEG-MTX conjugate over an extended therapeutic time course.     

Visualization of air bubbles by magnetic resonance imaging

Magnetic resonance imaging (MRI) of water can be used to locate and measure air bubbles inside complex fluid-processing equipment, such as water filters, blood filters, and kidney dialysis modules. Importantly, not only can the bubble itself be studied, but it is also possible to investigate the effect of the bubble on the proper functioning of the item of the equipment in question.     

计算机核磁共振成像技术研究

磁共振成像(Magnetic Resonance Imaging简称MRI),是继CT之后医学影像诊断技术的又一重大进展。它的基本原理来自于1946年美国学者Bloch和Purcell的发现:在外磁场的作用下,某些绕主磁场(外磁场)进动的自旋的质子(包括人体中的氢质子)在短暂的射频电波作用下,进动角增大,当射频电波停止后,那些质子又会逐渐恢复到原来的状态,并同时释放与激励波频率相同的射频信号,这一物理现象被称为核磁共振。Bloch和Purcell因这一贡献而获得1952年的诺贝尔物理奖。时隔27年后,英国学者Lauterbur利用这一原理,通过在主磁场中附加一个梯度磁场,并逐点诱发核磁共振无线电波,然后经过复杂的计算机处理与重建,获得一幅二维的磁共振图像。     

Medical applications of magnetic nanoparticles

In recent years biomedical research indicated, that magnetic nanoparticles can be a promising tool for several applications in vitro and in vivo. In medicine many approaches were investigated for diagnosis and therapy and offered a great variety of applications. Magnetic cell separation, magnetic resonance imaging (MRI), magnetic targeted delivery of therapeutics or magnetically induced hyperthermia are approaches of particular clinical relevance. For medical use, especially for in vivo application it is of great importance that these particles do not have any toxic effects or incompatibility with biological organism. Investigations on applicable particles induced a variability of micro- and nanostructures with different materials, sizes, and specific surface chemistry.     

Hollow magnetic nanoparticles: synthesis and applications in biomedicine

Magnetic hollow particles (MHP) are widely used in biomedicine field due to their biocompatibility, low-toxicity, low-density and the large fraction void space in the MHP, which have been successfully used to encapsulate and control drugs release, and magnetic resonance imaging (MRI). This review focuses on all kinds of MHP preparation method, compares the advantages and disadvantages in the process of synthesis, and introduces especially the special formation mechanisms such as the Kirkendall effect and Ostwald ripening. Both the compatible interior space and good magnetism of magnetic hollow structures enable them promising and unique candidates as biomedicine vehicles. Particularly, the progress of MHP widely used in the biomedical engineering applications containing drug delivery and magnetic resonance imaging are described. The main problems and the directions in the future researches are pointed out.     

Renal dysplasia masquerading as a renal mass in a child on hemodialysis

Pathological renal mass is uncommon in children. It is important to differentiate this from a benign mass or mass‐like lesion (pseudomass) for proper management. Renal dysplasia is a common finding in patients with end stage renal disease and can mimic a renal mass. Here, we report a 16‐year‐old girl on hemodialysis who was found to have a nodular right renal mass in the sonogram. Magnetic resonance imaging confirmed the nodular mass. She underwent right nephrectomy and the histopathology revealed features of renal dysplasia and end stage kidney disease without any evidence of malignancy. No further treatments were necessary. This case demonstrates that a nodular renal mass in dialysis patients does not always mean malignancy and could be a pseudomass from severe renal dysplasia. Since a sonogram may not be able to clearly define the etiology of solid mass in these patients, further evaluations including a renal histology and/or other imaging modalities are often necessary.