Dixon water-fat separation in PROPELLER MRI acquired with two interleaved echoes

• Published in: Magnetic resonance in medicine Vol. 75; no. 2; pp. 718 - 728
• Main Authors: Schär, Michael, Eggers, Holger, Zwart, Nicholas R., Chang, Yuchou, Bakhru, Akshay, Pipe, James G.
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.02.2016; Wiley Subscription Services, Inc
• Subjects: Adipose Tissue; Adult; Blades; Blurring; Body Water; Brain - anatomy & histology; Data acquisition; Dixon; Echoes; fat suppression; Female; Healthy Volunteers; Humans; Image acquisition; Image Enhancement - methods; Image Processing, Computer-Assisted - methods; Image quality; Liver - anatomy & histology; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; Male; Motion; motion correction; Motion simulation; Noise standards; off-resonance correction; PROPELLER; Robustness; Separation; Signal-To-Noise Ratio; water-fat separation; fat suppression; water-fat separation; off-resonance correction; motion correction; PROPELLER; Dixon
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.25656

Purpose To propose a novel combination of robust Dixon fat suppression and motion insensitive PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) MRI. Methods Two different echoes were acquired interleaved in each shot enabling water‐fat separation on individual blades. Fat, which was blurred in standard PROPELLER because the water‐fat shift (WFS) rotated with the blades, was shifted back in each blade. Additionally, field maps obtained from the water‐fat separation were used to unwarp off‐resonance–induced shifts in each blade. PROPELLER was then applied to the water, corrected fat, or recombined water‐fat blades. This approach was compared quantitatively in volunteers with regard to motion estimation and signal‐to‐noise ratio (SNR) to a standard PROPELLER acquisition with minimal WFS and fat suppression. Results Shifting the fat back in each blade reduced errors in the translation correction. SNR in the proposed Dixon PROPELLER was 21% higher compared with standard PROPELLER with identical scan time. High image quality was achieved even when the volunteers were moving during data acquisition. Furthermore, sharp water‐fat borders and image details were seen in areas where standard PROPELLER suffered from blurring when acquired with a low readout bandwidth. Conclusion The proposed method enables motion‐insensitive PROPELLER MRI with robust fat suppression and reduced blurring. Additionally, fat images are available if desired. Magn Reson Med 75:718–728, 2016. © 2015 Wiley Periodicals, Inc.