Staging hepatic fibrosis: comparison of gadoxetate disodium-enhanced and diffusion-weighted MR imaging--preliminary observations.

PURPOSE: To evaluate the utility of hepatocyte-phase gadoxetate disodium-enhanced magnetic resonance (MR) imaging in staging hepatic fibrosis and to compare it with diffusion-weighted imaging.
MATERIALS AND METHODS: This retrospective study had institutional review board approval, and the requirement for informed consent was waived. Gadoxetate disodium-enhanced and diffusion-weighted MR images obtained in 114 consecutive patients (70 men, 44 women; age range, 37-91 years) were evaluated. Liver-to-muscle signal intensity (SI) ratio on hepatocyte-phase images (SI(post)), contrast enhancement index calculated as SI(post) /SI(pre), where SI(pre) is liver-to-muscle SI ratio on nonenhanced images, and apparent diffusion coefficient (ADC) of the liver were measured. Necroinflammatory activity grades and hepatic fibrosis stages were histopathologically determined in 99 patients. Multiple regressions of SI(post), contrast enhancement index, ADC, serum albumin concentration, serum total bilirubin level, prothrombin time, and Child-Pugh score were examined to determine correlation with hepatic necroinflammatory activity grades and fibrosis stages.
RESULTS: Among the MR, hematologic, and clinical parameters, contrast enhancement index was most strongly correlated with fibrosis stage (r = -0.79, P < .001). Multiple regression analysis showed that the contrast enhancement index, ADC, and prothrombin time were significantly correlated (r(2) = 0.66, P < .05) with fibrosis stage and that the contrast enhancement index and serum total bilirubin level were weakly correlated (r(2) = 0.24, P < .05) with the necroinflammatory activity grade.
CONCLUSION: Gadoxetate disodium-enhanced MR imaging is more reliable for staging hepatic fibrosis than are diffusion-weighted MR imaging, hematologic, and clinical parameters. © RSNA, 2011.