A new lipophilic gadolinium chelate as a tissue‐specific contrast medium for MRI

Abstract Gd‐Ethoxybenzyl‐DTPA (Gd‐EOB‐DTPA) is a highly water‐soluble paramagnetic contrast agent. Due to its protein binding of about 10% and its lipophilic residue, Gd‐EOB‐DTPA exhibits both renal (30% of the dose) and hepatobiliary (70%) excretion in rats. Despite its lipohilic character, the compound displays a low toxicity (LD 50 = 7.5 mmol/kg). T 1 ‐relaxivity of 5.3 liters mmol −1 s −1 in water, 8.7 liters mmol −1 s −1 in plasma, and 16.9 liters mmol −1 s −1 in rat liver together with the hepatocellular uptake explain the liverspecific contrast enhancement of Gd‐EOB‐DTPA. The diagnostic dose is considerably lower than the amount of Magnevist used in abdominal imaging. The preclinical studies suggest its clinical role as being a hepatobiliary contrast agent for MRI. © 1991 Academic Press, Inc.