Members of the College have been meeting with the Therapeutic Goods Administration (TGA) to review recent publications about the retention of gadolinium in the brain, and less conspicuously in other body regions, of patients exposed to gadolinium-based MRI contrast agents.
This statement is released in parallel with a public statement by the TGA on its website: www.tga.gov.au/alert/gadolinium-based-contrast-agents-mri-scans. It reflects the current views of the College and the TGA, based on literature available in July 2017.
While much remains to be discovered about the mechanism, dynamics and long-term consequences of gadolinium retention, available evidence indicates the following:
1) Small amounts of gadolinium are retained in the brain (and other tissues, notably bone) after gadolinium-based contrast administration
2) The extent, and possibly duration, of this retention varies with different contrast agents (and their chelating ligand); in general, retention appears greater with ligands with a linear molecular structure.
3) The chemical form or forms (and hence likely residence time) of retained gadolinium in human tissues is not known in detail, and may also vary with the chelating ligand used.
4) At present, no adverse effect of gadolinium retention has been demonstrated.
5) It is prudent to restrict the use of gadolinium-based contrast agents to situations where such use is reasonably expected to provide additional useful diagnostic information. This particularly applies to the repeated use of such agents in serial examinations.
6) The dose of gadolinium-based contrast agents should be limited to the minimum necessary to acquire the relevant diagnostic information.
7) In the context of the recent findings, particular care should be taken with the use of gadolinium-based contrast agents in the following patient groups:
- those with renal impairment - paediatric patients, for whom the consequences of long-term gadolinium retention are potentially of most concern - obstetric patients, where the extent and consequences of gadolinium retention in the placenta and/or foetus are not well understood.
Notably, ‘Routine’ use of contrast in these patients, where there is not a specific indication (such as monitoring, or reasonable suspicion, of enhancing tumour) should be reviewed.
8) Practitioners may wish to review their choice of gadolinium chelate.
9) Judicious use of marketed gadolinium-based contrast agents remains appropriate.
In view of (1) above, suppliers of gadolinium-based contrast agents will be asked by the TGA to update their product information.
The situation will be kept under review, and any material change in this advice promptly publicised. Gadolinium-based contrast agents marketed in Australia:
Some albumin binding and biliary excretion
50% biliary excretion