Combining MR elastography and diffusion tensor imaging for the assessment of anisotropic mechanical properties: A phantom study

Qin, Eric C.; Sinkus, Ralph; Geng, Guangqiang; Cheng, Shaokoon; Green, Michael; Rae, Caroline; Bilston, Lynne E.

doi:10.1002/jmri.23797

Cited by 82 publications

(110 citation statements)

References 54 publications

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“…Similar empirical results have been shown with polyvinyl alcohol (PVA) phantoms in which a phantom was stretched and underwent multiple freeze-thaw cycles to induce anisotropy in the homogeneous material [28, 29]. Using a homogeneous phantom is much easier than embedding fibers in an external matrix [11, 15]. However, we have found that there is some residual compression that is maintained in the phantom at the end of the experiment, though this was not shown, so a particular phantom can only be used once.…”

Section: Discussionmentioning

confidence: 56%

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Characterization of transverse isotropy in compressed tissue-mimicking phantoms

Urban

Lopera

Aristizabal

et al. 2015

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Tissues such as skeletal muscle and kidneys have well-defined structure that affects the measurements of mechanical properties. As an approach to characterize the material properties of these tissues, different groups have assumed that they are transversely isotropic (TI) and measure the shear wave velocity as it varies with angle with respect to the structural architecture of the organ. To refine measurements in these organs, it is desirable to have tissue mimicking phantoms that exhibit similar anisotropic characteristics. Some approaches involve embedding fibers into a material matrix. However, if a homogeneous solid is under compression due to a static stress, an acoustoelastic effect can manifest which makes the measured wave velocities change with the compression stress. We propose to exploit this characteristic to demonstrate that stressed tissue mimicking phantoms can be characterized as a TI material. We tested six phantoms made with different concentrations of gelatin and agar. Stress was applied by the weight of a water container centered on top of a plate on top of the phantom. A linear array transducer and a V-1 Verasonics system were used to induce and measure shear waves in the phantoms. The shear wave motion was measured using a compound plane wave imaging technique. Autocorrelation was applied to the received in-phase/quadrature data. The shear wave velocity, c, was estimated using a Radon transform method. The transducer was mounted on a rotating stage so measurements were made every 10° over a range of 0-360°, where the stress is applied along 0-180° direction. The shear moduli were estimated. A TI model was fit to the data and the fractional anisotropy was evaluated. This approach can be used to explore many configurations of transverse isotropy with the same phantom, simply by applying stress to the tissue mimicking phantom.

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Section: Discussionmentioning

confidence: 56%

“…Two examples involve embedded fibers or materials in a matrix of surrounding tissue mimicking material [11, 15]. …”

Section: Introductionmentioning

confidence: 99%

Characterization of transverse isotropy in compressed tissue-mimicking phantoms

Urban

Lopera

Aristizabal

et al. 2015

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…Equation [13] invokes the incompressibility condition of Equation [6], which allowed us to neglect the z-derivative @ðr Á uÞ=@z. We note similarity to the elastic term of Equation [5] in Qin et al (33), however, with the principal difference that Equation [13] depends on three constants, whereas Qin et al reduced to two shear moduli. Our approach differs from that of Qin et al in that the element C 3333 is entirely unrelated to l 13 in accordance with the theory of elastic solids with TI symmetry.…”

Section: Shear Waves In Transversely Isotropic Mediamentioning

confidence: 86%

“…From this equation and Equation [4], the incompressible Poisson's ratios m 31 and m 12 are readily obtained by considering e 11 þ e 22 ¼ Àe 33 and e 22 þ e 33 = À e 11 corresponding to uniaxial loads along the x 3 and x 1 directions, respectively. Due to the symmetry of C of C iijj 5 C jjii , we find m ij ¼ m ji E j /E i yielding…”

Section: Theorymentioning

confidence: 99%

Three‐parameter shear wave inversion in MR elastography of incompressible transverse isotropic media: Application to in vivo lower leg muscles

Guo

Hirsch

Scheel

et al. 2015

Magnetic Resonance in Med

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“…A recent study demonstrated that the acquisition of all displacement components of a multifrequency vibration is very useful for increasing the spatial resolution and the quality of MRE-derived elastograms by applying a new least square error-based reconstruction method to 3D MRE data (Hirsch et al 2013a). There have been other developments in both multifrequency and monofrequency MRE that propose the acquisition of three components of the displacement vector (Murphy et al 2011, Hirsch et al 2013b, Johnson et al 2013, Pattison et al 2010, Qin et al 2013, Hirsch et al 2013, Romano et al 2012, Yasar et al 2013a). …”

Section: Introductionmentioning

confidence: 99%

Sample interval modulation for the simultaneous acquisition of displacement vector data in magnetic resonance elastography: theory and application

et al. 2013

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SampLe Interval Modulation -magnetic resonance elastography (SLIM-MRE) is introduced for simultaneously encoding all three displacement projections of a monofrequency vibration into the MR signal phase. In SLIM-MRE, the individual displacement components are observed using different sample intervals. In doing so, the components are modulated with different apparent frequencies in the MR signal phase expressed as a harmonic function of the start time of the motion encoding gradients and can thus be decomposed by applying a Fourier transform to the sampled multidirectional MR phases. In this work, the theoretical foundations of SLIM-MRE are presented and the new idea is implemented using a high field (11.7 T) vertical bore magnetic resonance imaging system on an inhomogeneous agarose gel phantom sample. The local frequency estimation-derived stiffness values were the same within the error margins for both the new SLIM-MRE method and for conventional MRE, while the number of temporally-resolved MRE experiments needed for each study was reduced from three to one. In this work, we present for the first time, monofrequency displacement data along three sensitization directions that were acquired simultaneously and stored in the same k-space.

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Combining MR elastography and diffusion tensor imaging for the assessment of anisotropic mechanical properties: A phantom study

Abstract: This study has demonstrated the feasibility of the proposed imaging technique for characterizing mechanical anisotropy of anisotropic materials and biological tissues, and validated the mechanical anisotropy results.

Cited by 82 publications

References 54 publications

Characterization of transverse isotropy in compressed tissue-mimicking phantoms

Characterization of transverse isotropy in compressed tissue-mimicking phantoms

Three‐parameter shear wave inversion in MR elastography of incompressible transverse isotropic media: Application to in vivo lower leg muscles

Sample interval modulation for the simultaneous acquisition of displacement vector data in magnetic resonance elastography: theory and application

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