<unk>  is one of the  trade names for a gadolinium-based MRI contrast agent, usually administered as a salt of a complex of gadolinium with DTPA (diethylenetriaminepentacetate) with the chemical formula A2[Gd(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 and introduced as the first MRI contrast agent in 1987. 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) in NMR, which is the source of its clinical utility.
Marketed as Magnevist by Bayer Schering Pharma, it was the first intravenous contrast agent to become available for clinical use, and is in widespread use around the world.  Similar contrast agents are Dotarem (gadoterate) manufactured by Guerbet, MultiHance (gadobenate dimeglumine) and ProHance (gadoteridol) manufactured by Bracco, Omniscan (gadodiamide) manufactured by GE Healthcare, and OptiMARK (gadoversetamide) manufactured by Mallinckrodt.
Gadolinium based agents may cause a toxic reaction known as nephrogenic systemic fibrosis (NSF) in patients with severe kidney problems.
Compared to other gadolinium-based MRI contrast agents, Gadopentetate dimeglumine (Gd-DTPA2-) chelates allow delayed Gadolinium-enhanced Magnetic Resonance of Cartilage (dGEMRIC). The unique charge characteristic of this complex allows researchers to inversely measure spin-lattice relaxation times as they are related to the concentration of proteoglycan aggregates and charged glycosaminoglycan side chains in articular cartilage.
Gadopentetic acid
Acetylcysteine 
Fomepizole
Thiocarboxime
Codoxime
Cyclopentamine
Cyanocobalamin
Obidoxime