Oral administration of a low-cost negative contrast agent: a three-year experience in routine practice

A low cost, well tolerated, and effective gastrointestinal contrast agent is needed for abdominal MRI. The authors tested, in vitro and in routine practice, a mixture of 192 g of barium sulfate (Micropaque HD oral, Guerbet, France) diluted in 500 ml of gastric antacid (Maalox, Rohrer, Fort Washington, PA). Its T1 and T2 relaxation times were 324 and 14 msec, respectively (.2 T). This contrast agent was used in routine practice in 789 patients (.5 T). It had a low signal intensity in 86% and 82% of the cases on T1- and T2-weighted sequences, respectively. No side effect due to magnetic susceptibility was seen, even with gradient-echo sequences. The dilution of barium sulfate in gastric antacid, instead of water, causes a low signal intensity on all sequences for a low barium sulfate concentration (38% w/v). This product is an effective and low cost contrast agent in routine practice.     

O-GLYCBASE version 2.0: a revised database of O-glycosylated proteins

Depiction of small-bowel pathologic conditions was optimized with use of a negative luminal contrast agent, spectral fat suppression, and gadolinium enhancement in an excised gut phantom. The method was applied in nine patients in conjunction with standard enteroclysis examinations. Bulk susceptibility effects of oral magnetic particles were canceled with use of a diamagnetic methylcellulose suspension. In the ileum, fat suppression and contrast between bowel wall and lumen was judged good or excellent in eight and nine patients, respectively. In eight of nine patients, additional mesenteric findings were depicted.     

硫酸钡比浊法测定氧化铁中硫酸根

在盐酸介质中,钡离子与硫酸根离子生成难溶的硫酸钡,使溶液混浊,采用乙醇作稳定剂,利用分光光度法计进行比色,可测定氧化铁中硫酸根。该法手续简便、准确性高。     

Susceptibility changes following bolus injections

The general mechanism of bulk magnetic susceptibility (BMS) induced MRI contrast following a bolus injection is elaborated. Combining radiolabeled tracer data for the first pass of a bolus injection through the human brain with the application of Wiedemann's law allows us to calculate the lower limit for the time course of the vascular BMS following the injection of any contrast agent. Superparamagnetic iron oxide particles produce a much larger effect than any mononuclear Ln(III) chelate. We also calculate the BMS changes occurring after a dilution bolus injection (of isosmolal physiological saline) subsequent to a prior slow infusion of an intravascular contrast agent. This technique bears some resemblance to the increasingly important approach that exploits changes in only the level of blood oxygenation. The calculation indicates that contrast changes after the dilution bolus injection are smaller than those following Ln(III) agent injections but larger than those due to changes in blood oxygenation and suggests a way to possibly enhance the latter. We present an in vivo study demonstrating the dilution bolus injection technique in the mouse brain, and that features its rapid repeatability. Extrapolation of these results to the human, however, indicates that the saline volumes required for venous injections, except possibly for cardiac studies, would be prohibitively large. Smaller, catheter-delivered arterial bolus injections are feasible. We also suggest a method for using an agent bolus injection to measure the parenchymal BMS, and thus the iron content, of pathologically iron-loaded tissue.     

Communications culture in digital networks]

MR Cholangiopancreatography (MRCP) and MR Urography (MRU) are promising recent imaging modalities. Oral magnetic particles (Abdoscan, Nycomed SA, Oslo, Norway) is an oral negative contrast agent eliminating signal intensity of the gastro-intestinal tract thus improving image quality at MRCP and MRU.     

Magnetic susceptibility of an atomized 304L stainless steel powder: Particle size effect

The magnetic susceptibility of a nitrogen atomized 304L stainless steel powder is measured as function of external magnetic field intensity and particle size using the Faraday method. The dependence on field strength reveals a varying additional ferromagnetic contribution to the para-magnetic susceptibility. With increasing mean diameter of either size fractions or individual particles, it first decreases steeply to a minimum value and then increases more steadily to finally level off. This results from the precipitation of a small, size-dependent amount of primary ferrite during the atomization process, as a consequence of a modification of the solidification mode with particle diameter, i.e., with particle cooling rate. The calculated ferrimagnetic contribution of surface iron oxide is negligible.     

MR imaging contrast enhancement based on intermolecular zero quantum coherences

A new method for magnetic resonance imaging (MRI) based on the detection of relatively strong signal from intermolecular zero-quantum coherences (iZQCs) is reported. Such a signal would not be observable in the conventional framework of magnetic resonance; it originates in long-range dipolar couplings (10 micrometers to 1 millimeter) that are traditionally ignored. Unlike conventional MRI, where image contrast is based on variations in spin density and relaxation times (often with injected contrast agents), contrast with iZQC images comes from variations in the susceptibility over a distance dictated by gradient strength. Phantom and in vivo (rat brain) data confirm that iZQC images give contrast enhancement. This contrast might be useful in the detection of small tumors, in that susceptibility correlates with oxygen concentration and in functional MRI.     

Solvent relaxation by uniformly magnetized solute spheres. The classical-quantal connection

RATIONALE AND OBJECTIVES: Large magnetic entities, with diameters in the range of 4 nm to 4 microns, are becoming of increasing interest for magnetic resonance imaging (MRI). The smaller are iron oxide nanoparticles, used for the RE system, and the larger are deoxygenated blood cells, for functional MRI. It can be useful to model such systems as magnetized solute spheres in water. Classical computations of 1/T2 have been reported for the larger particles, in the micron range, where the computational complexities are simplified by Monte Carlo methods. For smaller particles, the quantum mechanical (quantal) expressions for outer sphere relaxation, for both 1/T1 and 1/T2, have been available for some time, and are particularly simple to apply at MRI fields. The questions that arise, and which the author addresses, are how to interrelate the classical and quantal approaches and when to use which. METHODS: The author compares published results of Monte Carlo calculations of 1/T2 for diamagnetic polystyrene solute spheres of various sizes in water, made paramagnetic by addition of dysprosium-(DTPA)2-, with quantum mechanical outer sphere theory applied to the same system. The latter includes the usual assumption of motional narrowing and yields both 1/T1 and 1/T2. RESULTS: For particles with diameters less than about 1 micron, both approaches give identical results for 1/T2. For larger particles, the conditions for motional narrowing breakdown, and quantal theory overestimates 1/T2. In addition, in the particular system studied, relaxation becomes so effective near solute that there is insufficient time for all water molecules to experience their maximal effect. Classical theory handles this well whereas quantal theory does not. CONCLUSIONS: In comparing the classical and quantal approaches, one balances computational complexity but broader applicability with more limited but far simpler mathematics. In addition, because the quantal approach shows that 1/T1 and 1/T2 are intimately related, the author suggests, by analogy, how to extend classical methods to computation of 1/T1.     

Current uses of gadolinium chelates for clinical magnetic resonance imaging examination of the liver

The use of gadolinium chelates has become an integral part of magnetic resonance imaging (MRI) of the liver and extrahepatic abdomen. Although liver specific contrast agents are now available, gadolinium chelates continue to offer significant advantages for abdominal MRI. The gadolinium chelates uniquely provide important information about tumor perfusion that is key in our assessment of liver masses. These paramagnetic contrast agents assist with liver lesion detection, characterization, and in establishing the volume of viable perfused tumor. Gadolinium chelates are equally important for MRI of the extrahepatic abdomen. The interstitial accumulation of these agents within peritoneal, omental, and gastrointestinal tumor produces marked enhancement and is key in accurate tumor staging. Depiction of lesions within solid visceral organs such as the pancreas, kidneys, and spleen is also improved following gadolinium injection. The versatility of this workhorse contrast agent assures that gadolinium chelates will continue to occupy a central role in any busy abdominal MRI practice.     

Characterization of Fe(III)-deferoxamine and Mn(II)-pectin as magnetic resonance imaging contrast agents

To find new contrast agents for magnetic resonance imaging (MRI), the spin-lattice relaxation time (T1)-reducing activities of metal complexes of EDTA, N-hydroxyethyethylenediamine-N,N',N'-triacetic acid (HEDTA), diethylenetriamine-N,N,N',N',N'-pentaacetic acid (DTPA), deferoxamine, mugineic acid, and pectin with Fe(III) or Mn(II) were investigated. Strong activity was found in Fe(III)-deferoxamine, Fe(III)-mugineic acid, or Mn(II)-pectin. In the actual MRI tomogram, Fe(III)-deferoxamine exhibited a contrast-enhancing effect comparable with that of Gd(III)-DTPA, and a much stronger effect was observed for Mn(II)-pectin. Fe(III)-deferoxamine and the Mn(II)-pectin appear to be candidates, respectively, as a new intravenous contrast agent and an oral gastrointestinal one.     

红土镍矿含碳球团半熔融渣中金属颗粒团聚机理的研究

研究了在1 350℃的温度下,还原剂煤粉、熔剂氧化钙、添加剂硫酸钙和焙烧时间对红土镍矿含碳球团半熔融渣中金属颗粒团聚效果的影响。发现熔剂氧化钙的用量是影响金属颗粒团聚效果的最主要因素,添加16%的氧化钙时形成的软熔渣最有利于金属颗粒的团聚。过剩的煤粉不利于金属颗粒的团聚,当C/O为0.8时,煤粉能够充分被利用,金属颗粒的团聚效果最好,此时,镍的金属化率超过90%,铁的金属化率为65%左右,选择性还原效果已经达到要求。添加剂硫酸钙能够显著降低金属颗粒的表面张力,有利于金属颗粒的团聚,但过多的硫酸钙会导致金属颗粒的破碎,不利于金属的回收,合适的硫酸钙添加量为1%。当红土镍矿球团中添加C/O为0.8的煤粉、16%的氧化钙和1%的硫酸钙时,于1 350℃下焙烧60min,可以使团聚生成的大于1 mm的金属颗粒达到还原所得金属总量的79%,金属颗粒团聚效果好,回收率高。     

Cellulose as a gastrointestinal US contrast agent

Ultrasound (US) imaging of the abdomen often is compromised by artifacts due to adjacent bowel gas. In an attempt to decrease gas artifacts and improve US image quality, the authors evaluated the use of cellulose preparations as gastrointestinal US contrast agents. Optimal homogeneity and reflectivity were evaluated in phantom solutions, and two suitable agents were selected for clinical trial. Ten volunteers underwent abdominal US imaging before and after contrast agent administration on three separate occasions. The volunteers drank 800 mL of freshly degassed water and two different gastrointestinal US contrast agents. US images obtained before and after administration of contrast material were evaluated by five radiologists and scored for bowel marking, visualization of abdominal anatomy, and image degradation by bowel gas. Compared with water, the orally administered US contrast agents improved visualization of bowel and abdominal anatomy, with diminished gas artifact.     

铬酸钡分光光度法测定铁矿石中硫

铁矿石中硫含量影响到成品钢质量,因此硫含量的快捷准确测定极其重要。在780 ℃下碳酸钠和氧化锌混合熔剂半熔铁矿石样品,将其中的硫转换为硫酸盐后,用沸水溶解硫酸盐并过滤,同时用20 g/L热碳酸钠溶液多次洗涤沉淀,用铬酸钡分光光度法测量滤液中硫酸盐含量,从而建立了分光光度法测定铁矿石中硫含量的方法。条件优化试验表明:需用热的碳酸钠溶液洗涤沉淀与烧杯才能保证铁矿石中的SO₄^2-全部留存在液体中;添加铬酸钡溶液后煮沸时间应大于2 min才能保证铬酸钡全部转化为硫酸钡;添加铬酸钡煮沸后的溶液需用氨水(1+1)调至pH值大于10,Cr(VI)才能完全以CrO₄^2-的形式存在,从而不影响测定结果。铁矿石中硫质量分数为0.014 %~0.30 %时与吸光度呈线性关系,线性相关系数为0.999 3。方法检出限为0.003 7 %,定量限为0.026 0 %,表观摩尔吸光系数为5.75×10² L·mol^-1·cm^-1。为了验证硫元素不同存在形态的测定偏差,按照实验方法对单质硫、亚硫酸钠、硫酸钠、硫化亚铁以及铁矿石的标准物质分别进行测定,测定结果的相对误差为-3.63%~3.77%。选择3个实验组,按照实验方法对铁矿石中硫含量进行测定,每个实验组分别按照实验方法平行测定7次,结果的相对标准偏差(RSD,n=3)为3.7%,测定结果与国标法GB/T 6730.16—2016中硫酸钡重量法相吻合。     

Neonatal intensive care: decision making in the face of prognostic uncertainty

Liver-specific MR imaging contrast agents consist of iron oxide particles or specially designed paramagnetic complexes targeting either the reticulo-endothelial system of the liver or the hepatocytes. These agents enhance the relaxation of water molecules in normal liver tissue and are excluded from abnormal tissue, such as metastases. Relaxation enhancement provides a map of normal liver function, increasing conspicuity of focal abnormalities. Understanding the indications and use of these agents is a central challenge for radiologists practicing liver MR imaging.     

Changes in Fos-like immunoreactivity evoked by maturation of the sneeze reflex triggered by nasal air puff stimulation in kittens

The contrast-enhanced magnetic resonance imaging (MRI) signal is rarely a direct measure of contrast concentration; rather it depends on the effect that the contrast agent has on the tissue water magnetization. To correctly interpret such studies, an understanding of the effects of water movement on the magnetic resonance (MR) signal is critical. In this review, we discuss how water diffusion within biological compartments and water exchange between these compartments affect MR signal enhancement and therefore our ability to extract physiologic information. The two primary ways by which contrast agents affect water magnetization are discussed: (1) direct relaxivity and (2) indirect susceptibility effects. For relaxivity agents, for which T1 effects usually dominate, the theory of relaxation enhancement is presented, along with a review of the relevant physiologic time constants for water movement affecting this relaxation enhancement. Experimental issues that impact accurate measurement of the relaxation enhancement are discussed. Finally, the impact of these effects on extracting physiologic information is presented. Susceptibility effects depend on the size and shape of the contrast agent, the size and shape of the compartment in which it resides, as well as the characteristics of the water movement through the resulting magnetic field inhomogeneity. Therefore, modeling of this effect is complex and is the subject of active study. However, since susceptibility effects can be much stronger than relaxivity effects in certain situations, they may be useful even without full quantitation.     

含铅重晶石中硫酸钡的测定

对含铅重晶石中硫酸钡的重选试验的流程分析建立分析方法.试样用0.6 mol/L盐酸处理,除去碳酸钡、硫酸钙、铅及铁等杂质,采用铬酸钡容量法与电感耦合等离子体原子发射光谱法（mP-AES）进行含铅重晶石重选试验中硫酸钡分析.ICP-AES法测定硫酸钡范围0.0005％ ～ 15％,铬酸钡容量法测定硫酸钡范围：10％ ～ 99.9％.应用于重选硫酸钡试验回收,平衡效果良好.     

高含铁南非氧化锰矿浸出除钾钠试验研究

高纯硫酸锰行业采用氧化锰矿还原焙烧后浸出制取硫酸锰溶液,通常在除钾钠过程中需要额外加入大量的硫酸亚铁,成本较高。本文中介绍采用含铁量较高的南非氧化锰矿焙烧后浸出的试验,在除钾钠过程中不额外添加硫酸亚铁,仅利用矿石中含铁成分进行溶液中钾钠的去除,试验表明除钾钠效果良好,滤液钾含量2.4mg/l,钠含量5.4mg/l。     

利用湿法炼锌赤铁矿法沉铁渣制备铁红工艺

针对赤铁矿渣中存在杂质,影响其综合回收利用的问题,开展赤铁矿渣高温水热法脱杂,制备铁红的研究。研究了不同酸度、温度、时间和液固比条件,对铁红产品中铁、锌、硫含量以及锌、硫脱除率和铁溶出率的影响。实验结果表明:pH值为1,温度220 ℃,保温时间3 h,液固比6∶1,转速400 r·min?1条件下,铁红产品中铁质量分数由58.66%上升为66.83%;赤褐铁类矿物含铁由占总铁质量分数94.05%,上升为97.79%;硫质量分数由2.96%下降至0.82%;锌质量分数由1.03%下降至0.18%。经X射线衍射检测,与赤铁矿渣相比,铁红产品中氧化铁信号峰值提高,杂峰减少。通过扫描电镜/能量散射X射线分析,铁红产品表面附着的硫酸盐等杂质经高温水热法处理后明显减少;实验前后,赤铁矿渣与铁红产品颗粒形貌与大小没有发生变化。实验处理后的铁红产品经检测,满足国家标准氧化铁红含铁量C级,水溶物和水溶性氯化物及硫酸盐含量III型,筛余物2型,105 ℃挥发物V₂型,来源a型标准。      

钢铁厂含铁粉尘综合利用研究进展

分析了钢铁厂含铁粉尘的组成和特征,比较了国内外钢铁企业处理含铁粉尘的不同方法,对以含铁粉尘制备氧化铁红、磁性材料、聚合硫酸铁和氧化铁脱硫剂等多种高附加值铁系产品的原理及工艺进行了综述,并评述了含铁粉尘综合利用的前景.     

MR imaging of pelvic lymph nodes in primary pelvic carcinoma with ultrasmall superparamagnetic iron oxide (Combidex): preliminary observations

The potential of ultrasmall superparamagnetic iron oxide (Combidex)-enhanced MRI of pelvic lymph nodes in patients with primary pelvic carcinoma is evaluated. Fifteen histologically classified lymph nodes in six patients with known primary pelvic cancer (four prostate; one rectum; one uterus) were evaluated with T2-weighted fast spin-echo (FSE) and T2*-weighted gradient-echo (GRE) MRI at 1.5T 12 to 48 hours after intravenous administration of Combidex at a dose of 1.7 mg Fe/kg. Quantitative image evaluation was performed by comparing signal intensity of individual nodes on pre- and postcontrast images. All patients proceeded to pelvic lymph-node biopsy or surgical dissection, where six were found to be benign and nine were malignant. Of the 15 lymph nodes, four nodes showed a decrease in signal intensity. Of these, three, in which signal loss was homogenous were benign, and one, in which the signal-intensity decrease was heterogeneous, was malignant (micrometastases). No signal change was noted in 11 of 15 lymph nodes of which three were benign (inflammatory) and eight were malignant. Combidex is a promising MR contrast agent for evaluating pelvic lymph nodes. Our preliminary observations suggest that the agent is most useful for classifying normal lymph nodes.