Effect of respiratory motion on free-breathing 3D stack-of-radial liver R 2 ∗ relaxometry and improved quantification accuracy using self-gating

• Published in: Magnetic resonance in medicine Vol. 83; no. 6; p. 1964
• Main Authors: Zhong, Xiaodong, Armstrong, Tess, Nickel, Marcel D, Kannengiesser, Stephan A R, Pan, Li, Dale, Brian M, Deshpande, Vibhas, Kiefer, Berthold, Wu, Holden H
• Format: Journal Article
• Language: English
• Published: United States 01.06.2020
• Subjects: Humans; Image Interpretation, Computer-Assisted; Imaging, Three-Dimensional; Liver - diagnostic imaging; Magnetic Resonance Imaging; Motion; PDFF; self-gating; Dixon; motion compensation; respiratory motion
• ISSN: 1522-2594
• DOI: 10.1002/mrm.28052

To develop an accurate free-breathing 3D liver mapping approach and to evaluate it in vivo. A free-breathing multi-echo stack-of-radial sequence was applied in 5 normal subjects and 6 patients at 3 Tesla. Respiratory motion compensation was implemented using the inherent self-gating signal. A breath-hold Cartesian acquisition was the reference standard. Proton density fat fraction and were measured and compared between radial and Cartesian methods using Bland-Altman plots. The normal subject results were fitted to a linear mixed model (P < .05 considered significant). Free-breathing stack-of-radial without self-gating exhibited signal attenuation in echo images and artifactually elevated apparent values. In the Bland-Altman plots of normal subjects, compared to breath-hold Cartesian, free-breathing stack-of-radial acquisitions of 22, 30, 36, and 44 slices, had mean differences of 27.4, 19.4, 10.9, and 14.7 s with 800 radial views, and they had 18.4, 11.9, 9.7, and 27.7 s with 404 views, which were reduced to 0.4, 0.9, -0.2, and -0.7 s and to -1.7, -1.9, -2.1, and 0.5 s with self-gating, respectively. No substantial proton density fat fraction differences were found. The linear mixed model showed free-breathing radial results without self-gating were significantly biased by 17.2 s averagely (P = .002), which was eliminated with self-gating (P = .930). Proton density fat fraction results were not different (P > .234). For patients, Bland-Altman plots exhibited mean differences of 14.4 and 0.1 s for free-breathing stack-of-radial without self-gating and with self-gating, respectively, but no substantial proton density fat fraction differences. The proposed self-gating method corrects the respiratory motion bias and enables accurate free-breathing stack-of-radial quantification of liver .