Gadolinium

Gadolinium is a metallic element (atomic number 64) that can be chelated into paramagnetic agents that are injected intravenously during MR imaging (see MRI contrast).

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.

Gadolinium molecules shorten spin-lattice relaxation time (T1) of voxels in which they are present. As a result, on T1-weighted images they have a brighter signal. This can have a number of utilities:

Note, not all MR angiography, MR venography and MR perfusion sequences require intravenous contrast. 

Tissue that demonstrates enhancement following administration of gadolinium-containing IV contrast does so because of a combination of the following two mechanisms 3

  1. intravascular enhancement
  2. interstitial enhancement

Which dominates depends on the characteristics of the tissue. 

Most gadolinium contrast agents are excreted through the renal system and therefore have a prolonged half-life in renal failure. There is a recognised 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). 

Gadolinium-containing contrast agents can be divided into four groups according to whether they are linear or macrocyclic and whether they are ionic or non-ionic. 

Physics and Imaging Technology: MRI

Factors affecting T1

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Article information

rID: 18340
Section: Physics
Synonyms or Alternate Spellings:
  • Gadolinium (Gd)
  • Gadolinium ion

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