WordNet

directly relevant to a matter especially a law case; "his support made a material difference"; "evidence material to the issue at hand"; "facts likely to influence the judgment are called material facts"; "a material witness"
the tangible substance that goes into the makeup of a physical object; "coal is a hard black material"; "wheat is the stuff they use to make bread" (同)stuff
things needed for doing or making something; "writing materials"; "useful teaching materials"
a person judged suitable for admission or employment; "he was university material"; "she was vice-presidential material"
information (data or ideas or observations) that can be used or reworked into a finished form; "the archives provided rich material for a definitive biography"
concerned with or affecting physical as distinct from intellectual or psychological well-being; "material needs"; "the moral and material welfare of all good citizens"- T.Roosevelt
concerned with worldly rather than spiritual interests; "material possessions"; "material wealth"; "material comforts"
derived from or composed of matter; "the material universe"
put in opposition to show or emphasize differences; "The middle school teacher contrasted her best students work with that of her weakest student"
the opposition or dissimilarity of things that are compared; "in contrast to", "by contrast" (同)direct contrast
the act of distinguishing by comparing differences
the range of optical density and tone on a photographic negative or print (or the extent to which adjacent areas on a television screen differ in brightness)
the perceptual effect of the juxtaposition of very different colors
to show differences when compared; be different; "the students contrast considerably in their artistic abilities" (同)counterpoint
strikingly different; tending to contrast; "contrasting (or contrastive) colors" (同)contrastive

PrepTutorEJDIC

〈U〉〈C〉『材料』,『原料』;(物の)構成要素 / 〈U〉〈C〉『生地』,服地 / 〈U〉(小説・社会調査などの)『資料』,データ《+『for』+『名』》 / 《複数形で》用具,器具 / 『物質の』,有形の / 『物質的な』 / (精神的・知的な面に対して)肉体的,感覚的 / 重要な;不可欠の / (法律上)重要な,決め手になる
(違いを示すために)(二つのもの)'を'『対照させる』,対比する;(…と)…'を'対照させる《+『名』+『with』+『名』》 / (…と)『対照する』,対照的に引き立つ《+『with』+『名』》 / 〈U〉(…との)『対照』,対比《+『with』(『to』)+『名』》 / 〈C〉〈U〉(…間の)対照的な差,(特に色・明るさの)対照,コントラスト《+『between』+『名』+『and』+『名』》,(…との)著しい相違《+『to』+『名』》 / 〈C〉(…と)対照的な人(物)《+『to』+『名』》

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/10/01 02:42:26」(JST)

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[Wiki en表示]

A medical contrast medium (or contrast agent) is a substance used to enhance the contrast of structures or fluids within the body in medical imaging.^[1] It is commonly used to enhance the visibility of blood vessels and the gastrointestinal tract.

Types[edit]

Several types of contrast media are in use in medical imaging and they can roughly be classified based on the imaging modalities where they are used. Although other types exist, most common contrast agents work based on X-ray attenuation and magnetic resonance signal enhancement.

X-ray attenuation[edit]

Main article: Radiocontrast agent

Iodine and barium are the most common types of contrast medium for enhancing x-ray-based imaging methods. Various sorts of iodinated contrast media exist, with variations occurring between the osmolarity, viscosity and absolute iodine content of different media. Non-ionic dimers are favored for their low osmolarity and toxicity, but have a correspondingly higher price attached to their use.^[2]

MR signal enhancing[edit]

Main article: MRI contrast agent

This would include gadolinium for use in magnetic resonance imaging as a MRI contrast agent. In the 3+ oxidation state the metal has 7 unpaired f electrons. This causes water around the contrast agent to relax quickly, enhancing the quality of the MRI scan.

Ultrasound scattering and frequency shift[edit]

Main article: Contrast-enhanced ultrasound

Microbubble contrast agents are used to aid the sonographic examination, specifically echocardiograms, for the detection of a cardiac shunt. These bubbles are composed of agitated saline solution, most of which are too large to pass through the lung capillaries. Therefore, the only ones that reach the left side of the heart pass through an abnormal connection between the two sides of the heart, a so-called right-to-left shunt. In addition, pharmaceutically prepared microbubbles are composed of tiny amounts of nitrogen or perfluorocarbons strengthened and supported by a protein, lipid, or polymer shell. These are small enough to pass through the capillaries and are used to increase the contrast in the left ventricle, improving the visualization of its walls. The drop in density on the interface between the gas in the bubble and the surrounding liquid strongly scatters and reflects the ultrasound back to the probe. This process of backscattering gives the liquid with these bubbles a high signal, which can be seen in the resulting image.

Adverse effects[edit]

While modern contrast media are generally safe to use,^[2] medical conditions can be caused by the administration of various contrast media. Reactions can range from minor to severe, sometimes resulting in death^[3] with death being about 0.9 per 100,000 cases. To better understand the reactions and to efficiently manage patients at risk, it is useful to classify them.^[4] Risk factors for developing severe reactions include strong allergies, bronchial asthma, cardiac disease and beta-blocker use.^[5]^[6] While the previously suspected IL-2 medication is no risk for the acquisition of adverse events.^[7]

A common misconception that even exists among healthcare professionals is that an allergy to contrast media is related to an allergy to seafood (usually shellfish) because both share iodine in common, implicating iodine as a source.^[8]^[9] Numerous studies have shown that although iodine is common in contrast media, iodine is not the cause of allergic reactions to contrast media and instead the more likely culprit are the inert ingredients and the patient's past history of having other strong allergic reactions.^[10] One important distinction is that allergic effects are by definition immunoglobulin E related histamine storms and studies have shown that contrast media cause no such reaction in vivo ^[11] thereby refuting the possibility that contrast media or the iodine in it is likely to be an allergen. Although it may seem contradictory, the few rare cases of contrast medium mediated IgE are exceedingly rare compared to all adverse reactions and when they happen, are often because the patient already has multiple risk factors that suggest the patient has other allergy related problems.^[5]

Historically, contrast media was sometimes highly dangerous but these dangers were not well-understood during the development of the early types of contrast media, such as Thorotrast.

References[edit]

^ "contrast agent" at Dorland's Medical Dictionary
^ ^a ^b Thomson, K; Varma, D (2010). "Safe use of radiographic contrast media". Australian Prescriber, 33:19-22. Available at http://www.australianprescriber.com/magazine/33/1/19/22/
^ Caro, J. Jaime; Evelinda Trindade, Maurice McGregor (1991). "The Risks of Death and of Severe Nonfatal Reactions with High- vs Low Osmolarity Contrast Media: A Meta-analysis". American Journal of Roentgenology (American Roentgen Ray Society) 156 (4): 825–832. PMID 1825900.
^ Böhm I, Heverhagen JT, Klose KJ. Classification of acute and deleayed contrast media-induced reactions: proposal of a three-step system. Contrast Media & Molecular Imaging 2012;7(6):537-41 url=http://onlinelibrary.wiley.com/doi/10.1002/cmmi.1475/pdf
^ ^a ^b Brockow, K.; et al. (11 Jan 2005). "Management of hypersensitivity reactions to iodinated contrast media". Allergy (European Journal of Allergy & Clinical Immunology) 60 (2): 150–158. doi:10.1111/j.1398-9995.2005.00745.x. PMID 15647034.
^ Boehm I. Contrast media and patients at risk: asthma. Acta Radiologica 2009; 50(3): 348
^ Boehm I. Is interleukin-2 (still) a risk factor for adverse reactions in concert with radiographic contrast medium injection? Acta Radiol 2009; 50(7): 752-3
^ Coakley, Fergus; David M. Panicek (October 1997). "Iodine Allergy: An Oyster Without a Pearl?". American Journal of Roentology (AJR) 169 (4): 951–952.
^ http://www.wdxcyber.com/ngen22.htm
^ Boehm, Ingrid (August 2008). "Seafood Allergy and Radiocontrast Media: Are Physicians Propagating a Myth?". The American Journal of Medicine (Elsevier) 121 (8): e19. doi:10.1016/j.amjmed.2008.03.035. PMID 18691465.
^ Carr, Denis H.; Archi C. Walker (1984). "Contrast Media Reactions: experimental evidence against the allergy theory". British Journal of Radiology (British Institute of Radiology) 57 (678): 469–473. doi:10.1259/0007-1285-57-678-46. PMID 6722447.

UpToDate Contents

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1. 造影剤誘発性腎症の病因、臨床的特徴、および診断 pathogenesis clinical features and diagnosis of contrast induced nephropathy
2. 造影剤誘発性腎症の予防 prevention of contrast induced nephropathy
3. 造影剤に対する即時型過敏反応：再発反応の予防 immediate hypersensitivity reactions to radiocontrast media prevention of recurrent reactions
4. 核磁気共鳴画像法の原理 principles of magnetic resonance imaging
5. 肝胆道のCT撮影 computed tomography of the hepatobiliary tract

English Journal

Physiological effects of nanoparticles on fish: A comparison of nanometals versus metal ions.

Shaw BJ, Handy RD.AbstractThe use of nanoscale materials is growing exponentially, but there are also concerns about the environmental hazard to aquatic biota. Metal-containing engineered nanoparticles (NPs) are an important group of these new materials, and are often made of one metal (e.g., Cu-NPs and Ag-NPs), metal oxides (e.g., ZnO and TiO(2) NPs), or composite of several metals. The physiological effects and toxicity of trace metals in the traditional dissolved form are relatively well known and the overall aim of this review was to use our existing conceptual framework of metal toxicity in fish to compare and contrast the effects of nanometals. Conceptually, there are some fundamental differences that relate to bioavailability and uptake. The chemistry and behaviour of nanometals involves dynamic aspects of aggregation theory, rather than the equilibrium models traditionally used for free metal ions. Some NPs, such as Cu-NPs, may also release free metal ions from the surface of the particle. Biological uptake of NPs is not likely via ion transporters, but endocytosis is a possible uptake mechanism. The body distribution, metabolism, and excretion of nanometals is poorly understood and hampered by a lack of methods for measuring NPs in tissues. Although data sets are still limited, emerging studies on the acute toxicity of nanometals have so far shown that these materials can be lethal to fish in the mg-μgl(-1) range, depending on the type of material. Evidence suggests that some nanometals can be more acutely toxic to some fish than dissolved forms. For example, juvenile zebrafish have a 48-h LC(50) of about 0.71 and 1.78mgl(-1) for nano- and dissolved forms of Cu respectively. The acute toxicity of metal NPs is not always explained, or only partly explained, by the presence of free metal ions; suggesting that other novel mechanisms may be involved in bioavailability. Evidence suggests that nanometals can cause a range of sublethal effects in fish including respiratory toxicity, disturbances to trace elements in tissues, inhibition of Na(+)K(+)-ATPase, and oxidative stress. Organ pathologies from nanometals can be found in a range of organs including the gill, liver, intestine, and brain. These sublethal effects suggest some common features in the sublethal responses to nanometals compared to metal salts. Effects on early life stages of fish are also emerging, with reports of nanometals crossing the chorion (e.g., Ag-NPs), and suggestions that the nano-forms of some metals (Cu-NPs and ZnO NPs) may be more toxic to embryos or juveniles, than the equivalent metal salt. It remains possible that nanometals could interfere with, and/or stimulate stress responses in fish; but data has yet to be collected on this aspect. We conclude that nanometals do have adverse physiological effects on fish, and the hazard for some metal NPs will be different to the traditional dissolved forms of metals.
Environment international.Environ Int.2011 Aug;37(6):1083-97. Epub 2011 Apr 6.
The use of nanoscale materials is growing exponentially, but there are also concerns about the environmental hazard to aquatic biota. Metal-containing engineered nanoparticles (NPs) are an important group of these new materials, and are often made of one metal (e.g., Cu-NPs and Ag-NPs), metal oxides
PMID 21474182

Multiscale FE method for analysis of bone micro-structures.

Podshivalov L, Fischer A, Bar-Yoseph PZ.SourceLaboratory for CAD and Life Cycle Engineering, Faculty of Mechanical Engineering, Technion, Israel; Computational Biomechanics Laboratory, Faculty of Mechanical Engineering, Technion, Israel.
Journal of the mechanical behavior of biomedical materials.J Mech Behav Biomed Mater.2011 Aug;4(6):888-99. Epub 2011 Mar 9.
Bones are composed of hierarchical bio-composite materials characterized by complex multiscale structural geometry and behavior. The architecture and the mechanical properties of bone tissue differ at each level of hierarchy. Thus, a multiscale approach for mechanical analysis of bone is imperative.
PMID 21616470

Japanese Journal

Is contrast material needed after treatment of malignant lymphoma in positron emission tomography/computed tomography?

Nakamoto Yuji,Nogami Munenobu,Sugihara Ryo,Sugimura Kazuro,Senda Michio,Togashi Kaori
Annals of nuclear medicine 25(2), 93-99, 2011-02
… Debate still exists as to whether intravenous contrast media during the CT stage of a PET/CT scan should be used. … The purpose of this study was to investigate the clinical value of contrast agent in PET/CT in patients with lymphoma following treatment. …
NAID 120003018170