Gadolinium (chemical symbol Gd) is a metallic element that can be chelated into paramagnetic complexes for use as gadolinium contrast media.
Gadolinium is a silvery rare earth metal with the atomic number 64 and an atomic weight of 157.25.
The gadolinium ion is useful as an MRI agent because it has seven unpaired electrons, which is the greatest number of unpaired electron spins possible for an atom.
- detection of focal lesions (e.g. tumor, abscess, metastasis)
- imaging of vessels in MR angiography or MR venography
- calculating MR perfusion parameters (e.g. MTT, CBV, ktrans, Tmax)
Most gadolinium contrast agents are excreted through the renal system and therefore have a prolonged half-life in renal failure.
There is a recognized association between gadolinium administration and nephrogenic systemic fibrosis (NSF) in patients with renal failure 2. More recently concern has arisen of deposition of gadolinium in various tissues in the body (e.g. dentate nucleus of the cerebellum, globus pallidus) however, the clinical significance of these depositions is still unknown 4.
History and etymology
Gadolinium was discovered in 1880 by Jean Charles Galissard de Marignac, a Swiss chemist. It was the first eponymous chemical element, given its monicker in honor of John Gadolin, a Finnish chemist, who made his name by being the first to extract the rare earth elements in the 1790s. Interestingly the surname Gadolin is etymologically derived from the Hebrew word גדול (gadol) meaning big.