Gd(DTPA-BBA) as a contrast agent in magnetic resonance imaging in rats

Gadolinium (III) -di (benzyl carbamoylmethyl) diethylenetrinitrilotriacetic acid [Gd(DTPA-BBA)] is a newly developed paramagnetic complex designed for use as a hepatobiliary-specific contrast agent. The purpose of tl-lis stud y was to examine the relaxivity, biodistribution, and magnetic resonance (M R) imaging characteristics of Gd(DTPA-BBA) in rats. Our results showed that die T1 relaxivity of Gd(DTPA-BBA) (3.89 dm(3)/mmol/s in aqueous solution) was similar to that of Gd(III) diethylenetriamine-pentaacetate [Gd(DTPA)](2 -) (4.08 dm(3)/mmol/s) and Gd(III) benzyloxypropionicte-traacetate [Gd(BOPT A)](2-) (4.40 dm(3)/mmol/s). Biodistribution studies indicated that Gd(DTPA -BBA) exhibited hepatobiliary and urinary elimination. In MR imaging studie s, Gd(DTPA-BBA) provided biphasic enhance ment of normal liver parenchyma, which was characterized by an initial steep increase in enhancement followe d by a plateau. The initial relative enhancement (RE%) of the liver, at 1 m inute after administration of 0.2 mmol/kg Gd(DTPA-BBA) was 113 +/- 19. The plateau RE% of the liver (48 +/- 13) occurred within 10 minutes and persist ed for at least 60 minutes after injection of the contrast agent. In additi on, Gd(DTPA-BBA) provided better RE% of the liver than [Cd(DTPA)](2-). The contrast RE% of liver abscess capsules reached a plateau within 5 minutes a fter injection of 0.1 mmol/kg Gd(DTPA-BBA). Although the hepatic enhancemen t of Gd (DTPA-BBA) was inferior to that of [Gd(BOPTA)]2-, the results sugge st that Gd(DTPA-BBA) has potential as an MR contrast agent for nonspecific and hepatobiliary uses.