Gadolinium in Medical Imaging-Usefulness, Toxic Reactions and Possible Countermeasures-A Review

Abstract

Gadolinium (Gd) is one of the rare-earth elements. The properties of its trivalent cation (Gd³⁺) make it suitable to serve as the central ion in chelates administered intravenously to patients as a contrast agent in magnetic resonance imaging. Such Gd-chelates have been used for more than thirty years. During the past decades, knowledge has increased about potential harmful effects of Gd-chelates in patients with severe renal dysfunction. In such patients, there is a risk for a potentially disabling and lethal disease, nephrogenic systemic fibrosis. Restricting the use of Gd-chelates in persons with severely impaired renal function has decreased the occurrence of this toxic effect in the last decade. There has also been an increasing awareness of Gd-retention in the body, even in patients without renal dysfunction. The cumulative number of doses given, and the chemical structure of the chelate given, are factors of importance for retention in tissues. This review describes the chemical properties of Gd and its medically used chelates, as well as its toxicity and potential side effects related to injection of Gd-chelates.

Keywords: chelates; contrast induced nephropathy; gadolinium; gadolinium induced respiratory distress syndrome; gadolinium kinetics; gadolinium toxicity; nephrogenic systemic fibrosis; side effects of gadolinium chelates; treatment of gadolinium toxicity.

Figure 1

Chemical structure of a linear chelator, DTPA (top) and a macrocyclic chelator, DOTA (bottom), illustrating the ligands that bind to Gd. Macro-cyclic Gd(III) compounds are considered less likely to release free Gd(III) ions in the human body than linear chelates [1,2,3,4,5].