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MRI Contrast Agent
MRI contrast agents are contrast agents used to improve the visibility of internal body structures in magnetic resonance imaging (MRI). The most commonly used compounds for contrast enhancement are gadolinium-based. Such MRI contrast agents shorten the relaxation times of nuclei within body tissues following oral or intravenous administration. In MRI scanners, sections of the body are exposed to a strong magnetic field causing primarily the hydrogen nuclei ("spins") of water in tissues to be polarized in the direction of the magnetic field. An intense radiofrequency pulse is applied that tips the magnetization generated by the hydrogen nuclei in the direction of the receiver coil where the spin polarization can be detected. Random molecular rotational oscillations matching the resonance frequency of the nuclear spins provide the "relaxation" mechanisms that bring the net magnetization back to its equilibrium position in alignment with the applied magnetic field. The magnitude of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contrast Agent
A contrast agent (or contrast medium) is a substance used to increase the contrast of structures or fluids within the body in medical imaging. Contrast agents absorb or alter external electromagnetism or ultrasound, which is different from radiopharmaceuticals, which emit radiation themselves. In x-rays, contrast agents enhance the radiodensity in a target tissue or structure. In MRIs, contrast agents shorten (or in some instances increase) the relaxation times of nuclei within body tissues in order to alter the contrast in the image. Contrast agents are commonly used to improve the visibility of blood vessels and the gastrointestinal tract. Several types of contrast agent are in use in medical imaging and they can roughly be classified based on the imaging modalities where they are used. Most common contrast agents work based on X-ray attenuation and magnetic resonance signal enhancement. Radiocontrast media For radiography, which is based on X-rays, iodine and barium are the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Food And Drug Administration
The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food safety, tobacco products, caffeine products, dietary supplements, Prescription drug, prescription and Over-the-counter drug, over-the-counter pharmaceutical drugs (medications), vaccines, biopharmaceuticals, blood transfusions, medical devices, electromagnetic radiation emitting devices (ERED), cosmetics, Animal feed, animal foods & feed and Veterinary medicine, veterinary products. The FDA's primary focus is enforcement of the Federal Food, Drug, and Cosmetic Act (FD&C), but the agency also enforces other laws, notably Section 361 of the Public Health Service Act, as well as associated regulations. Much of this regulatory-enforcement work is not d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blood Pool Agent
Blood pool agents (BPAs) are a class of magnetic resonance angiography contrast agents. Blood pool agents (also known as intravascular contrast agents) are differentiated from other contrast agents due to their high molecular weight and higher relaxivities.Geraldes CF, Laurent S, Classification and basic properties of contrast agents for magnetic resonance imaging, Contrast Media Mol Imaging, 2009;4:1-23. Their large size prevents diffusion through the vascular epithelium and leakage into the interstitial space, and because of this they stay in the vascular system for a longer time period. Most contrast agents, leave the vascular system within a few minutes, however blood pool agents remain in the circulation for up to an hour, extending the window available for imaging. Longer image acquisition times allow better signal-to-noise ratio and improved image resolution. Roles of blood pool agents Due to their extended time in the circulatory system, blood pool agents can be used for d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gadodiamide
Gadodiamide, sold under the brand name Omniscan, is a gadolinium-based MRI contrast agent (GBCA), used in magnetic resonance imaging (MRI) procedures to assist in the visualization of blood vessels. Medical uses Gadodiamide is a contrast medium used for cranial and spinal magnetic resonance imaging (MRI) and for general MRI of the body after intravenous administration. It provides contrast enhancement and facilitates visualisation of abnormal structures or lesions in various parts of the body including the central nervous system ( CNS). It crosses intact the blood brain barrier. Adverse effects It is one of the main GBCA associated with nephrogenic systemic fibrosis (NSF), a toxic reaction occurring in some people with kidney problems. No cases have been seen in people with normal kidney function. A 2015 study found gadolinium deposited in the brain tissue of people who had received gadodiamide. Other studies using post-mortem mass spectrometry found most of the deposit r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gadoversetamide
Gadoversetamide is a gadolinium-based MRI contrast agent, particularly for imaging of the brain, spine and liver The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for .... It is marketed under the trade name OptiMARK. Notes Organogadolinium compounds MRI contrast agents {{pharma-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gadoxetic Acid
Gadoxetic acid is a gadolinium-based MRI contrast agent. Its salt, gadoxetate disodium, is marketed as Primovist in Europe and Eovist in the United States by Bayer HealthCare Pharmaceuticals. Medical uses It is used to increase the T1 signal intensity while imaging the liver lesions such as benign cysts, haemangioma, and liver cancer. It is excreted into bile by active secretion. Pharmacokinetics In those with end-stage renal failure, the clearance rate is only 17% with terminal half-life of 12 times longer than the those with normal renal function. See also * Gadobenic acid * Gadopentetic acid Gadopentetic acid, sold under the brand name Magnevist, is a gadolinium-based MRI contrast agent. It is usually administered as a salt of a complex of gadolinium with DTPA (''d''iethylene''t''riamine''p''ent''a''cetate) with the chemical formul ... References External links * * MRI contrast agents Organogadolinium compounds Phenol ethers {{pharmacology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gadobenate
Gadobenic acid (INN, brand name Multihance) is a complex of gadolinium with the ligand BOPTA. In the form of the methylglucamine salt meglumine gadobenate ( INNm) or gadobenate dimeglumine (USAN), it is used as a gadolinium-based MRI contrast medium. BOPTA is a derivative of DTPA in which one terminal carboxyl group, –C(O)OH is replaced by -C–O–CH2C6H5. Thus gadobenic acid is closely related to gadopentetic acid. BOPTA itself was first synthesized in 1995. In the "gadobenate" ion gadolinium ion is 9-coordinate with BOPTA acting as an 8-coordinating ligand. The ninth position is occupied by a water molecule, which exchanges rapidly with water molecules in the immediate vicinity of the strongly paramagnetic complex, providing a mechanism for MRI contrast enhancement. 139La NMR studies on the diamagnetic La-BOPTA2− complex suggest that the Gd complex maintains in solution the same kind of coordination as found, by X-ray crystallography X-ray crystallography is the exper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gadopentetic Acid
Gadopentetic acid, sold under the brand name Magnevist, is a gadolinium-based MRI contrast agent. It is usually administered as a salt of a complex of gadolinium with DTPA (''d''iethylene''t''riamine''p''ent''a''cetate) with the chemical formula A2 d(DTPA)(H2O) when cation A is the protonated form of the amino sugar meglumine the salt goes under the name "gadopentetate dimeglumine". It was described in 1981 by Hanns-Joachim Weinmann and colleagues and introduced as the first MRI contrast agent in 1987 by the Schering AG. It is used to assist imaging of blood vessels and of inflamed or diseased tissue where the blood vessels become "leaky". It is often used when viewing intracranial lesions with abnormal vascularity or abnormalities in the blood–brain barrier. It is usually injected intravenously. Gd-DTPA is classed as an acyclic, ionic gadolinium contrast medium. Its paramagnetic property reduces the T1 relaxation time (and to some extent the T2 and T2* relaxation times) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linear Molecular Geometry
In chemistry, the linear molecular geometry describes the geometry around a central atom bonded to two other atoms (or ''ligands'') placed at a bond angle of 180°. Linear organic molecules, such as acetylene (), are often described by invoking sp orbital hybridization for their carbon centers. According to the VSEPR model (Valence Shell Electron Pair Repulsion model), linear geometry occurs at central atoms with two bonded atoms and zero or three lone pairs ( or ) in the AXE notation. Neutral molecules with linear geometry include beryllium fluoride () with two single bonds, carbon dioxide () with two double bonds, hydrogen cyanide () with one single and one triple bond. The most important linear molecule with more than three atoms is acetylene (), in which each of its carbon atoms is considered to be a central atom with a single bond to one hydrogen and a triple bond to the other carbon atom. Linear anions include azide () and thiocyanate (), and a linear cation is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gadoteridol
Gadoteridol (INN) is a gadolinium-based MRI contrast agent, used particularly in the imaging of the central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all par .... It is sold under the brand name ProHance. References * {{Contrast media Organogadolinium compounds MRI contrast agents ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gadobutrol
Gadobutrol (INN) (Gd-DO3A-butrol) is a gadolinium-based MRI contrast agent (GBCA). It received marketing approval in Canada and the United States. As of 2007, it was the only GBCA approved at 1.0 molar concentrations. Gadobutrol is marketed by Bayer AG as Gadovist, and by Bayer HealthCare Pharmaceuticals as Gadavist. In India, it is also marketed by Vivere Imaging as Viv-butrol. Medical uses Gadobutrol is a medicinal product used in diagnostic magnetic resonance imaging (MRI) in adults and children. It provides contrast enhancement during cranial, spinal, breast, or other investigations. In the central nervous system, Gadobutrol works by highlighting any areas with disrupted blood brain barrier (BBB) and/or abnormal vascularity. In breast tissue, Gadobutrol exposes the presence and extent of malignant breast disease. Similarly, gadobutrol is also used in contrast-enhanced magnetic resonance angiography (CE-MRA) for the diagnosis of stroke, detection of tumor perfusion, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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