Impact of Gadoxetic Acid Dilution on Arterial Phase Image Quality in Liver MRI: A Phase-by-Phase Analysis

Background: Gadoxetic acid-enhanced MRI is essential for detecting and characterizing focal liver lesions. However, transient severe motion artifacts in the arterial phase can degrade image quality. Gadoxetic acid dilution has been proposed to mitigate these artifacts, but its impact on multiple arterial phase acquisition remains unclear. Objective: To evaluate the effect of gadoxetic acid dilution on image quality across multiple arterial phases in liver MRI, incorporating a phase-by-phase analysis. Methods: This retrospective study included 81 patients (52 men, 29 women; mean age 70.1 years) who underwent serial gadoxetic acid-enhanced MRI with undiluted and diluted contrast (1:1 saline dilution). MRI was performed on 1.5 T and 3.0 T scanners with a standardized injection rate of 1.0 mL/s. Two radiologists independently rated anatomic conspicuity, respiratory motion artifacts, and overall image quality using a Likert scale (1 to 5 with higher scores indicating better quality). A phase-by-phase analysis was conducted after a three-month washout period. Wilcoxon signed-rank tests were used for statistical comparisons, and inter-rater agreement was assessed with quadratic kappa coefficients. Results: Inter-observer agreement was substantial (ƙ = 0.602–0.702). Phase-by-phase analysis revealed significant improvement in image quality for the first three arterial phases (p = 0.003, 0.005, 0.050). Although the diluted method showed higher scores, the differences were not statistically significant in anatomic conspicuity (3.73 vs. 3.59, p = 0.110), respiratory artifacts (3.54 vs. 3.41, p = 0.291), and overall image quality (3.67 vs. 3.51, p = 0.083). Conclusions: Gadoxetic acid dilution improves image quality in early arterial phases of liver MRI, suggesting its potential to reduce motion artifacts.