Accelerated free-breathing liver fat and [Formula: see text] quantification using multi-echo stack-of-radial MRI with motion-resolved multidimensional regularized reconstruction: Initial retrospective evaluation

Xiaodong Zhong; Marcel D Nickel; Stephan A R Kannengiesser; Brian M Dale; Fei Han; Chang Gao; Shu-Fu Shih; Qing Dai; Omar Curiel; Tsu-Chin Tsao; Holden H Wu; Vibhas Deshpande

doi:10.1002/mrm.30117

Accelerated free-breathing liver fat and $R_{2}^{*}$ quantification using multi-echo stack-of-radial MRI with motion-resolved multidimensional regularized reconstruction: Initial retrospective evaluation

Magn Reson Med. 2024 Apr 22. doi: 10.1002/mrm.30117. Online ahead of print.

Authors

Xiaodong Zhong^{1

2

3}, Marcel D Nickel⁴, Stephan A R Kannengiesser⁴, Brian M Dale⁵, Fei Han⁶, Chang Gao⁶, Shu-Fu Shih^{1

3}, Qing Dai^{1

3}, Omar Curiel⁷, Tsu-Chin Tsao⁷, Holden H Wu^{1

2

3}, Vibhas Deshpande⁸

Affiliations

¹ Department of Radiological Sciences, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA.
² Physics and Biology in Medicine Interdepartmental Program, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA.
³ Department of Bioengineering, Samueli School of Engineering, University of California Los Angeles, Los Angeles, California, USA.
⁴ MR Application Predevelopment, Siemens Healthineers AG, Erlangen, Germany.
⁵ MR R&D Collaborations, Siemens Medical Solutions USA, Inc, Cary, North Carolina, USA.
⁶ MR R&D Collaborations, Siemens Medical Solutions USA, Inc, Los Angeles, California, USA.
⁷ Department of Mechanical and Aerospace Engineering, University of California Los Angeles, Los Angeles, CA, USA.
⁸ MR R&D Collaborations, Siemens Medical Solutions USA, Inc, Austin, Texas, USA.

PMID: 38650444
DOI: 10.1002/mrm.30117

Abstract

Purpose: To improve image quality, mitigate quantification biases and variations for free-breathing liver proton density fat fraction (PDFF) and $R_{2}^{*}$ quantification accelerated by radial k-space undersampling.

Methods: A free-breathing multi-echo stack-of-radial MRI method was developed with compressed sensing with multidimensional regularization. It was validated in motion phantoms with reference acquisitions without motion and in 11 subjects (6 patients with nonalcoholic fatty liver disease) with reference breath-hold Cartesian acquisitions. Images, PDFF, and $R_{2}^{*}$ maps were reconstructed using different radial view k-space sampling factors and reconstruction settings. Results were compared with reference-standard results using Bland-Altman analysis. Using linear mixed-effects model fitting (p < 0.05 considered significant), mean and SD were evaluated for biases and variations of PDFF and $R_{2}^{*}$ , respectively, and coefficient of variation on the first echo image was evaluated as a surrogate for image quality.

Results: Using the empirically determined optimal sampling factor of 0.25 in the accelerated in vivo protocols, mean differences and limits of agreement for the proposed method were [-0.5; -33.6, 32.7] s^-1 for $R_{2}^{*}$ and [-1.0%; -5.8%, 3.8%] for PDFF, close to those of a previous self-gating method using fully sampled radial views: [-0.1; -27.1, 27.0] s^-1 for $R_{2}^{*}$ and [-0.4%; -4.5%, 3.7%] for PDFF. The proposed method had significantly lower coefficient of variation than other methods (p < 0.001). Effective acquisition time of 64 s or 59 s was achieved, compared with 171 s or 153 s for two baseline protocols with different radial views corresponding to sampling factor of 1.0.

Conclusion: This proposed method may allow accelerated free-breathing liver PDFF and $R_{2}^{*}$ mapping with reduced biases and variations.

Keywords: XD‐GRASP; motion‐resolved; proton density fat fraction R 2 * $$ {\mathrm{R}}_2^{\ast } $$ ; radial MRI; regularization; self‐gating.

Abstract

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