Objective: The purpose of this study was to investigate whether, at dynamic MRI of the upper abdominal organs, contrast enhancement with gadoxetic acid, a hepatobiliary contrast agent, is comparable with that achieved with an extracellular contrast agent.
Subjects and methods: Dynamic gadoxetic acid-enhanced MRI of the pancreas, spleen, kidney, liver, and abdominal aorta was performed on 50 patients; dynamic gadobutrol-enhanced MRI was performed on a control group of 50 patients; and the images were compared. Dynamic imaging with a T1-weighted volumetric interpolated breath-hold examination gradient-echo sequence (TR/TE, 3.35/1.35; flip angle, 12 degrees ) was performed before and 20 (arterial phase), 55 (portal venous phase), and 90 (hepatic venous phase) seconds after bolus injection of gadoxetic acid (0.25 mmol/mL) or gadobutrol (1.0 mmol/mL). Signal-to-noise ratios and enhancement indexes were calculated for each organ and time.
Results: All MR images in both groups were of diagnostic quality. During the early dynamic phases, significantly lower mean enhancement indexes were found in the gadoxetic acid group than in the gadobutrol group in the pancreas (portal venous phase, 0.66, 1.39, p <or= 0.001; hepatic venous phase, 0.51, 1.36, p <or= 0.001), spleen (portal venous phase, 1.54, 2.41, p <or= 0.001; hepatic venous phase, 1.19, 2.23, p <or= 0.001), renal cortex (portal venous phase, 1.76, 2.63, p <or= 0.001; hepatic venous phase, 1.60, 2.63, p <or= 0.001), and liver (portal venous phase, 0.76, 0.94, p = 0.016; hepatic venous phase, 0.76, 1.04, p <or= 0.001). In the abdominal aorta, the mean enhancement index was greater after bolus injection of gadoxetic acid (arterial phase, 3.33, 2.24, p <or= 0.005).
Conclusion: Early dynamic MRI of the upper abdominal organs, especially the spleen, pancreas, and kidney, benefits from the higher gadolinium concentration of gadobutrol than in the organ-specific contrast agent gadoxetic acid. Higher protein binding resulting in increased relaxivity of gadoxetic acid compensates for the low gadolinium concentration in the abdominal aorta.