Combined Gadoxetic Acid and Gadofosveset Enhanced Liver MRI: A Feasibility and Parameter Optimization Study

Purpose: Demonstration of feasibility and protocol optimization for the combined use of gadofosveset trisodium with gadoxetic acid for delayed T1-weighted liver MRI. Methods: Eleven healthy volunteers underwent hepatobiliary phase imaging at 3 Tesla (T) using gadoxetic acid. Multiple breathheld T1-weighted three-dimensional spoiled gradient echo sequences were performed at varying flip angles before and after injection of gadofosveset. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured to determine optimal T1-weighting. Examples of three patients with focal liver lesions were acquired. Results: The addition of gadofosveset to the hepatobiliary phase of gadoxetic acid renders vessels isointense to liver tissue at low flip angles due to increased vessel SNR (P<0.001). The lowest CNR of liver relative to portal vein (CNR = 15; 95% confidence interval [ CI]: - 14-44) was observed at a 10 degrees flip angle. The highest CNR of liver relative to muscle (CNR = 214; 95% CI: 191-237) was observed at a 20 degrees flip angle. The combined enhancement leads to homogenously enhanced liver tissue and liver vasculature. Cysts were detected in three volunteers and metastases were detected in two patients. In these anecdotal cases the cysts and metastases stood out as conspicuous focal hypointensities on combined gadoxetic acid and gadofosveset enhanced images. Conclusion: Combined gadoxetic acid and gadofosveset enhanced liver MRI is feasible, with low flip angles minimizing contrast between vessels and liver. Further clinical studies are needed to confirm that low flip angles provide an optimal combination of sensitivity and specificity for lesion detection in patients. (C) 2015 Wiley Periodicals, Inc.