Gadolinium is a chemical element; it has symbol Gd and atomic number 64. Gadolinium is a silvery-white metal when oxidation is removed. It is a malleable and ductile rare-earth element. Gadolinium reacts with atmospheric oxygen or moisture slowly to form a black coating. Gadolinium below its Curie point of 20 °C (68 °F) is ferromagnetic, with an attraction to a magnetic field higher than that of nickel. Above this temperature it is the most paramagnetic element. It is found in nature only in an oxidized form. When separated, it usually has impurities of the other rare-earths because of their similar chemical properties.
Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves to generate images of the organs in the body. MRI does not involve X-rays or the use of ionizing radiation, which distinguishes it from computed tomography (CT) and positron emission tomography (PET) scans. MRI is a medical application of nuclear magnetic resonance (NMR) which can also be used for imaging in other NMR applications, such as NMR spectroscopy.
Gadolinium(III) chloride, also known as gadolinium trichloride, is GdCl3. It is a colorless, hygroscopic, water-soluble solid. The hexahydrate GdCl3∙6H2O is commonly encountered and is sometimes also called gadolinium trichloride. Gd3+ species are of special interest because the ion has the maximum number of unpaired spins possible, at least for known elements. With seven valence electrons and seven available f-orbitals, all seven electrons are unpaired and symmetrically arranged around the metal. The high magnetism and high symmetry combine to make Gd3+ a useful component in NMR spectroscopy and MRI.
Pentetic acid or diethylenetriaminepentaacetic acid (DTPA) is an aminopolycarboxylic acid consisting of a diethylenetriamine backbone with five carboxymethyl groups. The molecule can be viewed as an expanded version of EDTA and is used similarly. It is a white solid with limited solubility in water.
Mangafodipir is a contrast agent delivered intravenously to enhance contrast in magnetic resonance imaging (MRI) of the liver, and has potential to serve as an adjunct for various chemotherapeutic agents and during coronary intervention. It has two parts, a paramagnetic manganese(II) ion and the fodipir chelating agent. When freed from the organic ligand, the manganese shortens the longitudinal relaxation time (T1) in an MRI scan. Normal liver tissue absorbs the manganese more than abnormal or cancerous tissue, which makes the normal tissue appear brighter in MRIs. This enhanced contrast allows lesions to be more easily identified.
One alternative to mammography, breast MRI or contrast-enhanced magnetic resonance imaging (MRI), has shown substantial progress in the detection of breast cancer.
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.
During nuclear magnetic resonance observations, spin–lattice relaxation is the mechanism by which the longitudinal component of the total nuclear magnetic moment vector (parallel to the constant magnetic field) exponentially relaxes from a higher energy, non-equilibrium state to thermodynamic equilibrium with its surroundings (the "lattice"). It is characterized by the spin–lattice relaxation time, a time constant known as T1.
Nephrogenic systemic fibrosis is a rare syndrome that involves fibrosis of the skin, joints, eyes, and internal organs. NSF is caused by exposure to gadolinium in gadolinium-based MRI contrast agents (GBCAs) in patients with impaired kidney function. Epidemiological studies suggest that the incidence of NSF is unrelated to gender or ethnicity and it is not thought to have a genetic basis. After GBCAs were identified as a cause of the disorder in 2006, and screening and prevention measures put in place, it is now considered rare.
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 contrast agents (GBCAs). Such MRI contrast agents shorten the relaxation times of nuclei within body tissues following oral or intravenous administration.
Molecular imaging is broadly defined as the visualization of molecular and cellular processes on either a macro- or microscopic level. Because of its high spatial resolution and ability to noninvasively visualize internal organs, magnetic resonance (MR) imaging is widely believed to be an ideal platform for in vivo molecular imaging. For this reason, MR contrast agents that can detect molecular events are an active field of research. One group of compounds that has shown particular promise is enzyme-activated MR contrast agents.
Gadoteric acid, sold under the brand name Dotarem among others, is a macrocycle-structured gadolinium-based MRI contrast agent (GBCA). It consists of the organic acid DOTA as a chelating agent, and gadolinium (Gd3+), and is used in form of the meglumine salt (gadoterate meglumine). The paramagnetic property of gadoteric acid reduces the T1 relaxation time (and to some extent the T2 and T2* relaxation times) in MRI, which is the source of its clinical utility. Because it has magnetic properties, gadoteric acid develops a magnetic moment when put under a magnetic field, which increases the signal intensity (brightness) of tissues during MRI imaging.
Gadobenic acid 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.
The physics of magnetic resonance imaging (MRI) concerns fundamental physical considerations of MRI techniques and technological aspects of MRI devices. MRI is a medical imaging technique mostly used in radiology and nuclear medicine in order to investigate the anatomy and physiology of the body, and to detect pathologies including tumors, inflammation, neurological conditions such as stroke, disorders of muscles and joints, and abnormalities in the heart and blood vessels among others. Contrast agents may be injected intravenously or into a joint to enhance the image and facilitate diagnosis. Unlike CT and X-ray, MRI uses no ionizing radiation and is, therefore, a safe procedure suitable for diagnosis in children and repeated runs. Patients with specific non-ferromagnetic metal implants, cochlear implants, and cardiac pacemakers nowadays may also have an MRI in spite of effects of the strong magnetic fields. This does not apply on older devices, and details for medical professionals are provided by the device's manufacturer.
Delayed gadolinium-enhanced magnetic resonance imaging of cartilage or dGEMRIC measures the fixed-charge density and relative proteoglycan content of articular cartilage using the spin-lattice relaxation time or T1 relaxation time. Current research is investigating the clinical application of dGEMRIC as a quantitative tool for monitoring cartilage function in diseased or repair cartilage.
Blood pool agents (BPAs) are a class of magnetic resonance angiography contrast agents. Blood pool agents are differentiated from other contrast agents due to their high molecular weight and higher relaxivities. 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.
Val Murray Runge is an American and Swiss professor of radiology and the editor-in-chief of Investigative Radiology. Runge was one of the early researchers to investigate the use of gadolinium-based contrast agents for magnetic resonance imaging (MRI), giving the first presentation in this field, followed two years later by the first presentation of efficacy. His research also pioneered many early innovations in MRI, including the use of tilted planes and respiratory gating. His publication on multiple sclerosis in 1984 represented the third and largest clinical series investigating the role of MRI in this disease, and the first to show characteristic abnormalities on MRI in patients whose CT was negative.
Perfusion MRI or perfusion-weighted imaging (PWI) is perfusion scanning by the use of a particular MRI sequence. The acquired data are then post-processed to obtain perfusion maps with different parameters, such as BV, BF, MTT and TTP.
An MRI sequence in magnetic resonance imaging (MRI) is a particular setting of pulse sequences and pulsed field gradients, resulting in a particular image appearance.
Gadopiclenol, sold under the brand name Elucirem among others, is a contrast agent used with magnetic resonance imaging (MRI) to detect and visualize lesions with abnormal vascularity in the central nervous system and in the body. Gadopiclenol is a paramagnetic macrocyclic non-ionic complex of gadolinium.
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