Abstract:
PURPOSE:In conventional three-dimensional magnetic resonance elastography, motion encoding gradients (MEGs) synchronized to a mechanical excitation are applied separately in each direction to encode tissue displacement generated by the corresponding waves. This requires long acquisition times that introduce errors due to patient motion and may hinder clinical deployment of magnetic resonance elastography. In this article, a framework for MEGs sequence design is proposed to reduce scanning time and increase signal-to-noise ratio. THEORY AND METHODS:The approach is based on applying MEGs in all three directions simultaneously with varying parameters, and formulation of the problem as a linear estimation of the wave properties. Multidirectional MEGs sequences are derived by setting the problem in an experimental design framework. Such designs are implemented and evaluated on simulation and phantom data. RESULTS:Estimation error of the displacement using the proposed MEGs designs is reduced up to a factor of two in comparison with a unidirectional design with a same number of acquisitions. Alternatively, for the same error, scanning time is reduced up to a factor of three using the multidirectional designs. CONCLUSION:The proposed framework generalizes acquisition of magnetic resonance elastography, and allows quantification of design performance, and optimization-based derivation of designs.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Nir G,Sahebjavaher RS,Sinkus R,Salcudean SEdoi
10.1002/mrm.25280subject
Has Abstractpub_date
2015-04-01 00:00:00pages
1514-25issue
4eissn
0740-3194issn
1522-2594journal_volume
73pub_type
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