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.
Diatrizoate, also known as amidotrizoate, Gastrografin, is a contrast agent used during X-ray imaging. This includes visualizing veins, the urinary system, spleen, and joints, as well as computer tomography. It is given by mouth, injection into a vein, injection into the bladder, through a nasogastric tube, or rectally.
Magnetic resonance angiography (MRA) is a group of techniques based on magnetic resonance imaging (MRI) to image blood vessels. Magnetic resonance angiography is used to generate images of arteries in order to evaluate them for stenosis, occlusions, aneurysms or other abnormalities. MRA is often used to evaluate the arteries of the neck and brain, the thoracic and abdominal aorta, the renal arteries, and the legs.
A contrast agent 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-ray imaging, contrast agents enhance the radiodensity in a target tissue or structure. In magnetic resonance imaging, contrast agents shorten the relaxation times of nuclei within body tissues in order to alter the contrast in the image.
Molecular imaging is a field of medical imaging that focuses on imaging molecules of medical interest within living patients. This is in contrast to conventional methods for obtaining molecular information from preserved tissue samples, such as histology. Molecules of interest may be either ones produced naturally by the body, or synthetic molecules produced in a laboratory and injected into a patient by a doctor. The most common example of molecular imaging used clinically today is to inject a contrast agent into a patient's bloodstream and to use an imaging modality to track its movement in the body. Molecular imaging originated from the field of radiology from a need to better understand fundamental molecular processes inside organisms in a noninvasive manner.
Lipiodol, also known as ethiodized oil, is a poppyseed oil used by injection as a radio-opaque contrast agent that is used to outline structures in radiological investigations. It is used in chemoembolization applications as a contrast agent in follow-up imaging. Lipiodol is also used in lymphangiography, the imaging of the lymphatic system. It has an additional use in gastric variceal obliteration as a dilutant that does not affect polymerization of cyanoacrylate.
Gadopentetic acid, sold under the brand name Magnevist, is a gadolinium-based MRI contrast agent.
Iohexol, sold under the trade name Omnipaque among others, is a contrast agent used for X-ray imaging. This includes when visualizing arteries, veins, ventricles of the brain, the urinary system, and joints, as well as during computed tomography. It is given by mouth, injection into a vein, or into a body cavity.
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.
Gadoversetamide is a gadolinium-based MRI contrast agent, particularly for imaging of the brain, spine and liver. It is marketed under the trade name OptiMARK.
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.
Gadobutrol (INN) (Gd-DO3A-butrol) is a gadolinium-based MRI contrast agent (GBCA).
Iobitridol is a pharmaceutical drug used as an iodine-based radiocontrast agent in X-ray imaging. It is injected into blood vessels, joints, or body cavities such as the uterus, and filtered out by the kidneys. Its most common adverse effect is nausea. Severe allergic reactions are rare.
Ioxaglic acid is pharmaceutical drug used as an iodinated contrast medium for X-ray imaging. It has low osmolality, typically resulting in fewer side effects than high-osmolality media. It is manufactured by Guerbet, but marketing in the US has been discontinued. As of 2021, it may still be available in some European countries.
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.
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.
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.
Ammonia (13N) is a medication for diagnostic positron emission tomography (PET) imaging of the myocardium.
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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