Assessment of liver viscoelasticity using multifrequency MR elastography

Asbach, Patrick; Klatt, Dieter; Hamhaber, Uwe; Braun, Jürgen; Somasundaram, Rajan; Hamm, Bernd; Sack, Ingolf

doi:10.1002/mrm.21636

Cited by 237 publications

(203 citation statements)

References 22 publications

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“…This multidimensional information was combined into two maps of viscoelastic parameters which are related to the elasticity and viscosity of the tissue. Our previous studies using MMRE in the liver [23,34,35] have shown that the liver is a highly viscous organ giving rise to signif- icant dispersion of the shear modulus values within the applied range of drive frequencies (25 Hz to 62.5 Hz). Notably, MDEV-inversion used here sacrifices the dispersion-related information in order to stabilize the inversion and improve the certainty and precision of elastograms (i. e. |G * |-and φ-maps).…”

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confidence: 99%

Patient-Activated Three-Dimensional Multifrequency Magnetic Resonance Elastography for High-Resolution Mechanical Imaging of the Liver and Spleen

Guo

Hirsch

Streitberger

et al. 2013

Fortschr Röntgenstr

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Purpose: To introduce a novel in-vivo three-dimensional multifrequency magnetic resonance elastography (3D-MMRE) method for high-resolution mechanical characterization of the liver and spleen. Materials and Methods: Ten healthy volunteers were examined by abdominal single-shot 3D-MMRE using a novel patient-activated trigger system with respiratory control. 10 contiguous slices with 2.5?mm cubic voxel resolution, 3 wave components, 8 time steps, and 2 averages were acquired at 7 mechanical excitation frequencies from 30 to 60?Hz. The total imaging time was approximately 15?min. For postprocessing, multifrequency dual elasto-visco (MDEV) inversion was used to calculate high-resolution mechanical parameter maps of the abdomen including the liver and spleen. Results: Two parameters maps were generated from each image slice to capture the magnitude and the phase angle of the complex shear modulus. Both parameters depicted the mechanical structures of the abdomen with unprecedented high spatial resolution. Spatially averaged group mean values of the liver and spleen are 1.27???0.17 kPa and 2.01???0.69 kPa, indicating a significantly higher asymptomatic stiffness of the spleen compared to the liver. Conclusion: Patient-activated respiratory-gated 3D-MMRE combined with MDEV inversion provides highly resolved mechanical maps of the liver and spleen that are superior to previous elastograms measured by abdominal MRE. Citation Format: ??Guo J, Hirsch S, Streitberger KJ et?al. Patient-Activated Three-Dimensional Multifrequency Magnetic Resonance Elastography for High-Resolution Mechanical Imaging of the Liver and Spleen. Fortschr R?ntgenstr 2014; 186: 260???266

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confidence: 99%

Patient-Activated Three-Dimensional Multifrequency Magnetic Resonance Elastography for High-Resolution Mechanical Imaging of the Liver and Spleen

Guo

Hirsch

Streitberger

et al. 2013

Fortschr Röntgenstr

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“…Thus, we will estimate the experimental specificities of SE-MRE and DENSE-MRE as ␦⌽ SM ϭ r SM ⅐ ⌽ SM (Eqs. [15,16]) and ␦⌽ DM ϭ r DM ⅐ ⌽ SM (Eqs. [12,15]).…”

Section: Spectral Properties Estimation (Experiments and Estimation)mentioning

confidence: 99%

“…[15,16]) and ␦⌽ DM ϭ r DM ⅐ ⌽ SM (Eqs. [12,15]). DENSE-MRE, SE-MRE and FEHM spectral properties (sensitivity, specificity) are calculated using Eqs.…”

Section: Spectral Properties Estimation (Experiments and Estimation)mentioning

confidence: 99%

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Application of DENSE‐MR‐elastography to the human heart

Robert

Sinkus

Gennisson

et al. 2009

Magnetic Resonance in Med

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Typically, MR-elastography (MRE) encodes the propagation of monochromatic acoustic waves in the MR-phase images via sinusoidal gradients characterized by a detection frequency equal to the frequency of the mechanical vibration. Therefore, the echo time of a conventional MRE sequence is typically longer than the vibration period which is critical for heart tissue exhibiting a short T 2 . Thus, fast acquisition techniques like the so-called fractional encoding of harmonic motions were developed for cardiac applications. However, fractional encoding of harmonic motions is limited since it is two orders of magnitude less sensitive to motion than conventional MRE sequences for low-frequency vibrations. Here, a new sequence is derived from the so-called displacement encoding with stimulated echoes (DENSE) sequence. This sequence is more sensitive to displacement than fractional encoding of harmonic motions, and its spectral specificity is equivalent to conventional MRE sequences. The theoretical spectral properties of this new motion-encoding technique are validated in a phantom and excised pork heart specimen. An excellent agreement is found for the measured displacement fields using classic MRE and displacement encoding with stimulated echoes MRE (8% maximum difference). In addition, initial in vivo results on a healthy volunteer clearly show propagating shear waves at 50 Hz. Thus, displacement encoding with stimulated echoes MRE is a promising technique for motion encoding within short T 2 * materials.

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“…Magnetic Resonance Elastography (MRE) can directly visualise and measure tissue elasticity [5][6][7][8], and has been applied to resolve stiffness characteristics of a variety human tissues and organs, such as muscle [9][10][11][12], breast [13][14][15][16][17], liver [18][19][20] and the brain [21][22][23][24][25][26][27][28][29]. MRE acquisition requires application of mechanical waves to tissue within the MRI, phase-contrast MR pulse sequence extended with motion encoding gradient (MEGs), and sophisticated inverse problem methods to identify an elastic modulus map of the tissue.…”

Section: Introductionmentioning

confidence: 99%