Characteristics of gadolinium-DTPA complex: a potential NMR contrast agent

TLDR

Gd-DTPA is a strongly paramagnetic, stable complex that is well tolerated in animals. Intravenously administered Gd-DTPA behaves like iodinated contrast agents, being predominantly renally excreted with over 90 % recovered within 24 h. Gd-DTPA markedly shortens proton relaxation times at concentrations below 0.01 mmol/L, is rapidly and safely excreted by the kidneys, shows no in‑vivo dissociation, and its strong relaxivity, stability, and high tolerance support its further development as an MRI contrast agent.

Abstract

Chelation of the rare-earth element gadolinium (Gd) with diethylenetriaminepentaacetic acid (DTPA) results in a strongly paramagnetic, stable complex that is well tolerated in animals. The strongly paramagnetic gadolinium complex reduces hydrogen-proton relaxation times even in low concentrations (less than 0.01 mmol/L). The pharmacokinetic behavior of intravenously delivered Gd-DTPA is similar to the well known iodinated contrast agents used in urography and angiography; excretion is predominantly through the kidneys with greater than 90% recovery in 24 hr. The intravenous LD50 of the meglumine salt of Gd-DTPA is 10 mmol/kg for the rat; in vivo there is no evidence of dissociation of the gadolinium ion from the DTPA ligand. The combination of strong proton relaxation, in-vivo stability, rapid urinary excretion, and high tolerance favors the further development and the potential clinical application of gadolinium-DTPA as a contrast enhancer in magnetic resonance imaging.