Utility of Stack-of-stars Acquisition for Hepatobiliary Phase Imaging without Breath-holding.

Purpose: Post-contrast liver magnetic resonance imaging is typically performed with breath-hold 3D gradient echo sequences. However, breath-holding for >10 s is difficult for some patients. In this study, we compared the quality of hepatobiliary phase (HBP) imaging without breath-holding using the prototype pulse sequences stack-of-stars liver acquisition with volume acceleration (LAVA) (LAVA Star) with or without navigator echoes (LAVA Star(navi+) and LAVA Star(navi-)) and Cartesian LAVA with navigator echoes (Cartesian LAVA(navi+)). Methods: Seventy-two patients were included in this single-center, retrospective, cross-sectional study. HBP imaging using the three LAVA sequences (Cartesian LAVA(navi+), LAVA Star(navi-), and LAVA Star(navi+)) without breath-holding was performed for all patients using a 3T magnetic resonance system. Two independent radiologists qualitatively analyzed (overall image quality, liver edge sharpness, hepatic vein clarity, streak artifacts, and respiratory motion/pulsation artifacts) HBP images taken by the three sequences using a five-point scale. Quantitative evaluations were also performed by calculating the liver-to-spleen, -lesion, and -portal vein (PV) signal intensity ratios. The results were compared between the three sequences using the Friedman test. Results: LAVA Star(navi+) showed the best image quality and hepatic vein clarity (P < 0.0001). LAVA Star navishowed the lowest image quality (P < 0.0001-0.0106). LAVA Star(navi+) images showed fewer streak artifacts than LAVA Star navi- images (P < 0.0001), while Cartesian LAVA(navi+) images showed no streak artifacts. Cartesian LAVA(navi+) images showed stronger respiratory motion/pulsation artifacts than the others (P < 0.0001). LAVA Star(navi-) images showed the highest liver-to-spleen ratios (P < 0.0001-0.0005). Cartesian LAVA navi+ images showed the lowest liver-to-lesion and -PV ratios (P < 0.0001-0.0108). Conclusion: In terms of image quality, the combination of stack-of-stars acquisition and navigator echoes is the best for HBP imaging without breath-holding.