Shear-wave generation using acoustic radiation force: in vivo and ex vivo results

Nightingale, Kathryn R.; McAleavey, Stephen A.; Trahey, Gregg E.

doi:10.1016/j.ultrasmedbio.2003.08.008

Cited by 564 publications

(399 citation statements)

References 31 publications

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“…One of the benefits of the Helmholtz algorithm, as implemented by several groups (Oliphant et al, 2001;Bercoff et al, 2004;Nightingale et al, 2003), is that a priori knowledge of the shear wave's propagation direction is not necessary. The Lateral TTP algorithm, as implemented in this manuscript, has assumed that shear waves are propagating parallel to the lateral dimension (perpendicular to the central axis of the excitation), thus limiting the axial extent of its application to the DOF of the excitation beam, as demonstrated in Figure 1.…”

Section: Discussionmentioning

confidence: 99%

“…This method has been successfully applied when ultrasound or magnetic resonance imaging has been used to track tissue displacements (Oliphant et al, 2001;Bercoff et al, 2004;Sandrin et al, 2002;Nightingale et al, 2003), but as Equation 3 indicates, second-order spatial and temporal derivatives of displacement are required for the shear wave speed reconstruction. Given the jitter that exists when ultrasonically estimating displacement, appreciable filtering and smoothing of displacement data must be performed prior to processing (Oliphant et al, 2001;Bercoff et al, 2004).…”

Section: Shear Wave Reconstructionmentioning

confidence: 99%

“…Inversion of the Helmholtz equation to reconstruct shear wave speed from displacement data has been used in ARFI and supersonic imaging (Nightingale et al, 2003;Bercoff et al, 2004). One drawback to this reconstruction method is having to perform secondorder differentiation of displacement data in space and time.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Quantifying Hepatic Shear Modulus In Vivo Using Acoustic Radiation Force

Palmeri

Wang

Dahl

et al. 2008

Ultrasound in Medicine & Biology

617

510

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The speed at which shear waves propagate in tissue can be used to quantify the shear modulus of the tissue. As many groups have shown, shear waves can be generated within tissues using focused, impulsive, acoustic radiation force excitations, and the resulting displacement response can be ultrasonically tracked through time. The goals of the work herein are two-fold: first, to develop and validate an algorithm to quantify shear wave speed from radiation force-induced, ultrasonicallydetected displacement data that is robust in the presence of poor displacement signal-to-noise ratio (SNR), and second, to apply this algorithm to in vivo datasets acquired in human volunteers in order to demonstrate the clinical feasibility of using this method to quantify the shear modulus of liver tissue in longitudinal studies. The ultimate clinical application of this work is non-invasive quantification of liver stiffness in the setting of fibrosis and steatosis.In the proposed algorithm, time to peak (TTP) displacement data in response to impulsive acoustic radiation force outside the region of excitation (ROE) are used to characterize the shear wave speed of a material, which is used to reconstruct the material's shear modulus. The algorithm is developed and validated using finite element method (FEM) simulations. Using this algorithm on simulated displacement fields, reconstructions for materials with shear moduli (μ) ranging from 1.3-5 kPa are accurate to within 0.3 kPa, while stiffer shear moduli ranging from 10-16 kPa are accurate to within 1.0 kPa. Ultrasonically tracking the displacement data, which introduces jitter in the displacement estimates, does not impede the use of this algorithm to reconstruct accurate shear moduli.Using in vivo data acquired intercostally in 20 volunteers with body mass indices (BMI) ranging from normal to obese, liver shear moduli have been reconstructed between 0.9 and 3.0 kPa, with an average precision of ±0.4 kPa. These reconstructed liver moduli are consistent with those reported in the literature (μ = 0.75-2.5 kPa) with a similar precision (±0.3 kPa). Repeated intercostal liver shear modulus reconstructions were performed on 9 different days in 2 volunteers over a 105 day period, yielding an average shear modulus of 1.9 ± 0.50 kPa (1.3-2.5 kPa) in the first volunteer, and 1.8 ± 0.4 kPa (1.1-3.0 kPa) in the second volunteer. The simulation and in vivo data to date demonstrate that this method is capable of generating accurate and repeatable liver stiffness measurements and appears promising as a clinical tool for quantifying liver stiffness.

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Section: Discussionmentioning

confidence: 99%

Section: Shear Wave Reconstructionmentioning

confidence: 99%

See 1 more Smart Citation

Quantifying Hepatic Shear Modulus In Vivo Using Acoustic Radiation Force

Palmeri

Wang

Dahl

et al. 2008

Ultrasound in Medicine & Biology

617

510

View full text Add to dashboard Cite

show abstract

“…Typically, there are two main ways to measure the shear wave speed: direct inversion of the Helmholtz equation (Oliphant et al 2001;Nightingale et al 2003;Bercoff et al 2004) and time-of-flight measurement (Mclaughlin and Renzi 2006;Palmeri et al 2008). However, these methods mainly use ultrasound to detect tissue displacement due to shear waves and the detection sensitivity is typically limited to tenths of a micron and above (Walker and Trahey, 1995).…”

Section: Introductionmentioning

confidence: 99%

Shear Wave Elasticity Imaging Based on Acoustic Radiation Force and Optical Detection

et al. 2012

Ultrasound in Medicine & Biology

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Abstract:Tissue elasticity is closely related to the velocity of shear waves within biological tissue.Shear waves can be generated by an acoustic radiation force and tracked by, e.g., ultrasound or MRI measurements. This has been shown to be able to non-invasively map tissue elasticity in depth and has great potential in a wide range of clinical applications including cancer and cardiovascular diseases. In this study a highly sensitive optical measurement technique is proposed as an alternative way to track shear waves generated by the acoustic radiation force.A CCD camera was used to capture diffuse photons from tissue mimicking phantoms illuminated by a laser source at 532nm. CCD images were recorded at different delays after the transmission of an ultrasound burst, and were processed to obtain the time of flight for the shear wave. A differential measurement scheme involving generation of shear waves at two different positions was used to improve the accuracy and spatial resolution of the system. The results from measurements on both homogeneous and heterogeneous phantoms were compared to measurements from other instruments, and demonstrate the feasibility and accuracy of the technique for imaging and quantifying elasticity. The relative error in estimation of shear wave velocity can be as low as 5.5% with a spatial resolution of 2 mm.The system is shown to be highly sensitive and is able to track shear waves propagating over several centimetres given the ultrasound excitation amplitude and the phantom material used in this study. It was also found that the reflection of shear waves from boundaries between regions with different elastic properties can cause significant bias in the estimation of elasticity, which also applies to other shear wave tracking techniques. This bias can be reduced at the expense of reduced spatial resolution.

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“…The spatial distribution of the radiation force field is determined by both the acoustic excitation parameters and the tissue properties. ARFI technique (Nightingale et al 2003;Palmeri et al 2008) involves the mechanical excitation of tissue using localized, focused, impulsive radiation force excitations. This results in shear-wave propagation away from the region of excitation.…”

Section: Radiation Force Based Elastographymentioning

confidence: 99%