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 this study was to examine the relaxivity, biodistribution, and magnetic resonance (MR) imaging characteristics of Gd(DTPA-BBA) in rats. Our results showed that the T1 relaxivity of Gd(DTPA-BBA) (3.89 dm3/mmol/s in aqueous solution) was similar to that of Gd(III) diethylenetriamine-pentaacetate [Gd(DTPA)]2- (4.08 dm3/mmol/s) and Gd(III) benzyloxypropionicte-traacetate [Gd(BOPTA)]2- (4.40 dm3/mmol/s). Biodistribution studies indicated that Gd(DTPA-BBA) exhibited hepatobiliary and urinary elimination. In MR imaging studies, Gd(DTPA-BBA) provided biphasic enhancement of normal liver parenchyma, which was characterized by an initial steep increase in enhancement followed by a plateau. The initial relative enhancement (RE%) of the liver, at 1 minute 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 persisted for at least 60 minutes after injection of the contrast agent. In addition, Gd(DTPA-BBA) provided better RE% of the liver than [Gd(DTPA)]2-. The contrast RE% of liver abscess capsules reached a plateau within 5 minutes after injection of 0.1 mmol/kg Gd(DTPA-BBA). Although the hepatic enhancement of Gd(DTPA-BBA) was inferior to that of [Gd(BOPTA)]2-, the results suggest that Gd(DTPA-BBA) has potential as an MR contrast agent for nonspecific and hepatobiliary uses.