Gadoxetic Acid-Enhanced Hepatobiliary-Phase Magnetic Resonance Imaging for Delineation of Focal Nodular Hyperplasia: Superiority of High-Flip-Angle Imaging

Objective The aim of this study was to investigate whether hepatobiliary-phase (HBP) flip-angle (FA) increase to 25 degrees improves conspicuity of focal nodular hyperplasia (FNH) and enables HBP delay reduction. Methods This was a retrospective study of 23 patients with 46 FNHs. In each patient, HBP was performed with reduced-delay high FA (early/high), standard-delay high FA (late/high), and standard-delay standard FA (standard). Relative enhancement of liver and FNH periphery, FNH periphery-to-liver contrast ratio, and FNH periphery-to-central scar contrast ratio were compared between each HBP. Results Early/high, late/high, and standard HBPs were performed after 13.00 2.12, 19.12 +/- 3.10, and 19.68 +/- 3.22 minutes, respectively. Liver and FNH periphery relative enhancement, FNH periphery-to-liver contrast ratio, and FNH periphery-to-central scar contrast ratio were higher for early/high and late/high than for standard HBP (P < 0.001 to P = 0.0048). Conclusions Increasing FA to 25 degrees improves delineation of FNHs in HBP. Combining FA increase with delay reduction is superior to standard HBP and is sufficient for FNH characterization.