Optimal dose of hepatobiliary contrast agent for MR cholangiography: Experimental study in rats

AbstractThe purpose of this study is to clarify the optimal dose of gadolinium‐ethoxybenzyl‐diethylenetriaminepentaacetic acid (Gd‐EOB‐DTPA) for cholangiography in conventional T1‐weighted imaging. We divided 30 rats into three dose groups (3, 10, and 30 μmol/kg). For the in vitro study, we collected bile and measured the concentration of gadolinium in bile after Gd‐EOB‐DTPA injection. T1‐weighted images of the collected bile were obtained for measurement of signal intensity. For the in vivo study, we obtained T1‐weighted images before and after injection and evaluated bile duct/liver contrast by the signal intensity ratio and visual assessment of the images. The gadolinium concentration had an early peak; however, the signal intensity of the bile had a later peak because of the high gadolinium concentration during the early phase, which induced a T2‐shortening effect. Optimal bile duct/liver contrast was obtained in the 10‐μmol/kg groups at all time points. We conclude that the optimal dose of Gd‐EOB‐DTPA for MR cholangiography in rats is 10 μmol/kg, one‐third of the dose used in liver imaging.