Simulation and analysis of magnetic resonance elastography wave images using coupled harmonic oscillators and Gaussian local frequency estimation

Braun, Jürgen; Buntkowsky, Gerd; Bernarding, Johannes; Tolxdorff, Thomas; Sack, Ingolf

doi:10.1016/s0730-725x(01)00387-3

Cited by 49 publications

(39 citation statements)

References 23 publications

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“…Equation [8] provides an analytical relation between the elastic moduli and phase velocity surface, showing that 12 , 13 , and the ratio E 3 /E 1 are the only elastic parameters that are relevant for group velocity inversion applied to incompressible, transversely isotropic media. Interestingly, it is not possible to deduce all three elastic parameters from a single component of u.…”

Section: Resultsmentioning

confidence: 99%

“…Since the ST-mode controls pure out-of-plane displacement in the case of transverse isotropy, c ST in Eq. [8] also applies to compressible media. Its shape is described by an ellipsoid whose axes are determined by 12 and 13 (14).…”

Section: Shear Waves In Transverse Isotropic Elastic and Incompressibmentioning

confidence: 99%

“…ST-and FT-waves are then separately visible so that v M () can be analyzed by the corresponding c M in Eq. [8]. In this paper the analysis of group velocities v() (assignable to an arbitrary wave mode M) is based on rays r() (with length r) emanating from the apparent point source of the waves.…”

Section: Shear Waves In Transverse Isotropic Elastic and Incompressibmentioning

confidence: 99%

“…The interest of physicians in imaging shear vibrations is based on the possibility of quantitatively testing in vivo stiffness variations, which would enable the detection of pathologies at an early stage. In MRE the sensitivity of wavelengths to elasticity changes is usually exploited to map elastic heterogeneities (5)(6)(7)(8)(9). In this way, local variations of wavelengths are analyzed in terms of local variations of the isotropic shear modulus using inversion algorithms.…”

mentioning

confidence: 99%

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Shear wave group velocity inversion in MR elastography of human skeletal muscle

Papazoglou

Rump

Braun

et al. 2006

Magnetic Resonance in Med

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108

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In vivo quantification of the anisotropic shear elasticity of soft tissue is an appealing objective of elastography techniques because elastic anisotropy can potentially provide specific information about structural alterations in diseased tissue. Here a method is introduced and applied to MR elastography (MRE) of skeletal muscle. With this method one can elucidate anisotropy by means of two shear moduli (one parallel and one perpendicular to the muscle fiber direction). The technique is based on group velocity inversion applied to bulk shear waves, which is achieved by an automatic analysis of wave-phase gradients on a spatiotemporal scale. The shear moduli are then accessed by analyzing the directional dependence of the shear wave speed using analytic expressions of group velocities in k-space, which are numerically mapped to real space. The method is demonstrated by MRE experiments on the biceps muscle of five volunteers, resulting in 5.5 ؎ 0.9 kPa and 29.3 ؎ 6.2 kPa (P < 0.05) for the medians of the perpendicular and parallel shear moduli, respectively. The proposed technique combines fast steadystate free precession (SSFP) MRE experiments and fully automated processing of anisotropic wave data, and is thus an interesting MRI modality for aiding clinical diagnosis. Magn Reson Med 56:489 -497, 2006.

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Section: Resultsmentioning

confidence: 99%

Section: Shear Waves In Transverse Isotropic Elastic and Incompressibmentioning

confidence: 99%

Section: Shear Waves In Transverse Isotropic Elastic and Incompressibmentioning

confidence: 99%

mentioning

confidence: 99%

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Shear wave group velocity inversion in MR elastography of human skeletal muscle

Papazoglou

Rump

Braun

et al. 2006

Magnetic Resonance in Med

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108

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“…Stiff regions indicate an abnormality. Experiments that are devised to create displacement that will yield tissue mechanical properties include: ͑1͒ tissue is compressed; stiff tissue compresses less; the displacement is measured using ultrasound or MR; the Lamé parameter, , is imaged, ͑Oberai et al., 2004;Barbone and Bamber, 2002;Konofagou et al, 2000;Thitaikumar and Ophir, 2007͒; ͑2͒ a time harmonic excitation is applied; the maximum displacement at each point in the image plane is measured using ultrasound and the displacement is imaged ͑Gao et al, 1995;Taylor et al, 2000;Wu et al, 2002͒; or the displacement, using MR, is measured at 4 to 8 equally spaced times in a period cycle, the shear wave speed or the Lamé parameter, , is imaged ͑Greenleaf et al., 1996;Kruse et al, 2000;Braun et al, 2001;Manduca et al, 2001Manduca et al, , 2002Manduca et al, , 2003Ehman et al, 2006;Sinkus et al, 2007͒; ͑3͒ a traveling wave is created using: ͑a͒ a line source created by a sequence of interior radiation force pushes ͑Ber-coff et al., 2002, 2004͒, and a primarily shear wave, with a front, travels outward from the source; the speed of the wave front is imaged ͑McLaughlin and Renzi, 2006aRenzi, , 2006bTanter et al, 2008͒; a point source is created by an interior radiation force push and the local shear wave speed is determined by measuring the time to peak at a nearby location ͑Nightingale et al, 2001a͑Nightingale et al, , 2001bFahey et al, 2005;Palmeri et al, 2006͒; or ͑b͒ two harmonic sources that oscillate at different but nearly the same frequency; the traveling wave speed is imaged ͑Castaneda et al, 2009;Hoyt et al, 2006Hoyt et al, , 2007aHoyt et al, , 2007bHoyt et al, , 2007cHoyt et al, , 2008aHoyt et al, , 2008b…”

Section: Introductionmentioning

confidence: 99%

Shear wave speed recovery in sonoelastography using crawling wave data

Lin

McLaughlin

Renzi

et al. 2010

The Journal of the Acoustical Society of America

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The crawling wave experiment, in which two harmonic sources oscillate at different but nearby frequencies, is a development in sonoelastography that allows real-time imaging of propagating shear wave interference patterns. Previously the crawling wave speed was recovered and used as an indicator of shear stiffness; however, it is shown in this paper that the crawling wave speed image can have artifacts that do not represent a change in stiffness. In this paper, the locations and shapes of some of the artifacts are exhibited. In addition, a differential equation is established that enables imaging of the shear wave speed, which is a quantity strongly correlated with shear stiffness change. The full algorithm is as follows: ͑1͒ extract the crawling wave phase from the spectral variance data; ͑2͒ calculate the crawling wave phase wave speed; ͑3͒ solve a first-order PDE for the phase of the wave emanating from one of the sources; and ͑4͒ compute and image the shear wave speed on a grid in the image plane.

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Magnetic Resonance Elastography

Silva

Grimm

Glaser

et al. 2012

Nonlinear Inverse Problems in Imaging

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Often compared to the practice of manual palpation, magnetic resonance elastography is an emerging technology for quantitatively assessing the mechanical properties of tissue as a basis for characterizing disease. The potential of MRE as a diagnostic tool is rooted in the fact that normal and diseased tissues often differ significantly in terms of their intrinsic mechanical properties. MRE uses magnetic resonance imaging (MRI) in conjunction with the application of mechanical shear waves to probe tissue mechanics. This process can be broken down into three essential steps: 1. inducing shear waves in the tissue, 2. imaging the propagating shear waves with MRI, and 3. analyzing the wave data to generate quantitative images of tissue stiffness MRE has emerged as a safe, reliable and noninvasive method for staging hepatic liver fibrosis, and is now used in some locations as an alternative to biopsy. MRE is also being used in the ongoing investigations of numerous other organs and tissues, including, for example, the spleen, kidney, pancreas, brain, heart, breast, skeletal muscle, prostate, vasculature, lung, spinal cord, eye, bone, and cartilage. In the article that follows, some fundamental techniques and applications of MRE are summarized.

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Simulation and analysis of magnetic resonance elastography wave images using coupled harmonic oscillators and Gaussian local frequency estimation

Cited by 49 publications

References 23 publications

Shear wave group velocity inversion in MR elastography of human skeletal muscle

Shear wave group velocity inversion in MR elastography of human skeletal muscle

Shear wave speed recovery in sonoelastography using crawling wave data

Magnetic Resonance Elastography

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