Pharmacokinetics of gadolinium-based contrast agents

Gadolinium-based contrast agents are used routinely in magnetic resonance imaging (MRI). They can be detected over a long period of time in some tissues (skin, brain, bone). What is known on the pharmacokinetics of gadolinium-based contrast agents and on gadolinium deposition in various tissues? Fundamental research and expert recommendations are discussed. Gadolinium-based contrast agents are distributed rapidly within the body and are eliminated by the kidneys. A fast initial elimination (half-life approximately 2 h) is followed by a slow elimination phase (half-life approximately 6 days), reflecting slow release from tissues. Deposition in the brain was observed mainly after administration of linear, non-ionic contrast agents. Whether gadolinium deposition in tissues consists of chelated or free gadolinium and whether otherwise healthy subjects are affected to a similar extent, is unclear. Currently, there are no proven risks associated with gadolinium deposition in the brain. Risks and benefits should be considered on an individual basis before MRI with gadolinium-based contrast agents (expected benefit, potentially undetected risks, available alternatives and their risks). Quantification of gadolinium in urine or blood from patients is not meaningful and should not be done outside clinical studies.