Volume 75, Issue 1 pp. 115-125
Full Paper

Accelerating 4D flow MRI by exploiting vector field divergence regularization

Claudio Santelli

Claudio Santelli

Imaging Sciences and Biomedical Engineering, King's College London, United Kingdom

Institute for Biomedical Engineering, University and ETH Zurich, Switzerland

Drs. Santelli and Loecher contributed equally to this work.

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Michael Loecher

Michael Loecher

Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA

Drs. Santelli and Loecher contributed equally to this work.

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Julia Busch

Julia Busch

Institute for Biomedical Engineering, University and ETH Zurich, Switzerland

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Oliver Wieben

Oliver Wieben

Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA

Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin, USA

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Tobias Schaeffter

Tobias Schaeffter

Imaging Sciences and Biomedical Engineering, King's College London, United Kingdom

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Sebastian Kozerke

Corresponding Author

Sebastian Kozerke

Imaging Sciences and Biomedical Engineering, King's College London, United Kingdom

Institute for Biomedical Engineering, University and ETH Zurich, Switzerland

Correspondence to: Sebastian Kozerke, Ph.D., Institute for Biomedical Engineering, University and ETH Zurich, Gloriastrasse 35, 8092 Zurich. E-mail:[email protected]Search for more papers by this author
First published: 13 February 2015
Citations: 27

Abstract

Purpose

To improve velocity vector field reconstruction from undersampled four-dimensional (4D) flow MRI by penalizing divergence of the measured flow field.

Theory and Methods

Iterative image reconstruction in which magnitude and phase are regularized separately in alternating iterations was implemented. The approach allows incorporating prior knowledge of the flow field being imaged. In the present work, velocity data were regularized to reduce divergence, using either divergence-free wavelets (DFW) or a finite difference (FD) method using the ℓ1-norm of divergence and curl. The reconstruction methods were tested on a numerical phantom and in vivo data. Results of the DFW and FD approaches were compared with data obtained with standard compressed sensing (CS) reconstruction.

Results

Relative to standard CS, directional errors of vector fields and divergence were reduced by 55–60% and 38–48% for three- and six-fold undersampled data with the DFW and FD methods. Velocity vector displays of the numerical phantom and in vivo data were found to be improved upon DFW or FD reconstruction.

Conclusion

Regularization of vector field divergence in image reconstruction from undersampled 4D flow data is a valuable approach to improve reconstruction accuracy of velocity vector fields. Magn Reson Med 75:115–125, 2016. © 2015 Wiley Periodicals, Inc.

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