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- Title
T1 bias in chemical shift-encoded liver fat-fraction: Role of the flip angle.
- Authors
Kühn, Jens‐Peter; Jahn, Christina; Hernando, Diego; Siegmund, Werner; Hadlich, Stefan; Mayerle, Julia; Pfannmöller, Jörg; Langner, Sonke; Reeder, Scott
- Abstract
Purpose To investigate flip angle (FA)-dependent T1 bias in chemical shift-encoded fat-fraction (FF) and to evaluate a strategy for correcting this bias to achieve accurate MRI-based estimates of liver fat with optimized signal-to-noise ratio (SNR). Materials and Methods Thirty-three obese patients, 14 men/19 women, aged 57.3 ± 13.9 years underwent 3 Tesla (T) liver MRI including MR-spectroscopy and four three-echo-complex chemical shift-encoded MRI sequences using different FAs (1°/3°/10°/20°). FF was estimated with R2* correction and multi-peak fat spectral modeling. The FF for each FA with and without T1 correction was compared with spectroscopy as a reference standard, using linear regression. Relative SNR of the magnitude data were assessed for each flip angle. Results The correlation between chemical shift-encoded MRI and spectroscopy was high (R2 ≍ 0.9). Without T1 correction, the agreement of both techniques showed no significant differences in slope ( PFlipAngle1° = 0.385/ PFlipAngle3° = 0.289) using low FA. High FA resulted in significant different slopes ( PFlipAngle10° = 0.016/ PFlipAngle20° = 0.014. T1 bias was successfully corrected using the T1 correction strategy (slope: PFlipAngle10° = 0.387/ PFlipAngle20° = 0.440). Additionally, the use of high FA (near the Ernst angle) improved the SNR of the magnitude data ( FA1 vs. FA3; respectively FA1 vs. FA10 P ≤ 0.001). Conclusion T1 bias is a strong confounder in the assessment of liver fat using chemical shift imaging with high FA. However, using a larger flip angle with T1 correction leads to higher SNR, and residual error after T1 correction is very small. J. Magn. Reson. Imaging 2014;40:875-883. © 2013 Wiley Periodicals, Inc.
- Publication
Journal of Magnetic Resonance Imaging, 2014, Vol 40, Issue 4, p875
- ISSN
1053-1807
- Publication type
Article
- DOI
10.1002/jmri.24457