A method of imaging viscoelastic parameters with acoustic radiation force

Walker, William F.; Fernández, Francisco; Negron, L.A.

doi:10.1088/0031-9155/45/6/303

Cited by 155 publications

(86 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Either the excitation pulses can be used to monitor the tissue response, or shorter duration imaging pulses can be interspersed with pushing pulses for tissue monitoring. Walker [24] explored this approach, using both elastic material models, and a viscoelastic Voigt model to derive relative material properties from the tissue response [25]. Viola et al [26] have employed this approach to characterize blood coagulation in vitro in the operating room setting for timely feedback to anaesthesiologists and surgeons using sonorheometry.…”

Section: Steady-state Radiation Force Excitations In Soft Tissuesmentioning

confidence: 99%

Acoustic radiation force-based elasticity imaging methods

2011

View full text Add to dashboard Cite

Conventional diagnostic ultrasound images portray differences in the acoustic properties of soft tissues, whereas ultrasound-based elasticity images portray differences in the elastic properties of soft tissues (i.e. stiffness, viscosity). The benefit of elasticity imaging lies in the fact that many soft tissues can share similar ultrasonic echogenicities, but may have different mechanical properties that can be used to clearly visualize normal anatomy and delineate pathological lesions. Acoustic radiation force-based elasticity imaging methods use acoustic radiation force to transiently deform soft tissues, and the dynamic displacement response of those tissues is measured ultrasonically and is used to estimate the tissue's mechanical properties. Both qualitative images and quantitative elasticity metrics can be reconstructed from these measured data, providing complimentary information to both diagnose and longitudinally monitor disease progression. Recently, acoustic radiation force-based elasticity imaging techniques have moved from the laboratory to the clinical setting, where clinicians are beginning to characterize tissue stiffness as a diagnostic metric, and commercial implementations of radiation forcebased ultrasonic elasticity imaging are beginning to appear on the commercial market. This article provides an overview of acoustic radiation force-based elasticity imaging, including a review of the relevant soft tissue material properties, a review of radiation force-based methods that have been proposed for elasticity imaging, and a discussion of current research and commercial realizations of radiation force based-elasticity imaging technologies.

show abstract

Section: Steady-state Radiation Force Excitations In Soft Tissuesmentioning

confidence: 99%

Acoustic radiation force-based elasticity imaging methods

2011

View full text Add to dashboard Cite

show abstract

“…The approach used, magnetic resonance acoustic radiation force imaging ͑MR-ARFI͒, utilizes several components and concepts that have been described previously: ARFI imaging, 10,11 quasistatic MR elastography ͑MRE͒ measurements, 25 and a line scan MRI pulse sequence originally developed for diffusion imaging. 26 It differs from most previous MRI investigations that have mapped displacements induced focused ultrasound pulses 9,16,17,27 in that the pulses are applied so that the tissue or phantom material at the focus is presumed to be stationary during the encoding gradients instead of assuming cyclic motion, and it only requires one ultrasound pulse for each acquisition instead of multiple pulses applied with different delays with respect to the encoding gradients.…”

Section: Iia Mr-arfimentioning

confidence: 99%

“…A number of researchers have investigated alternative elastography approaches that employ one or more focused ultrasound beams to provide a local source of tissue displacement. [8][9][10][11][12][13][14][15][16][17] These methods take advantage of radiation force that produces a displacement at the focus on the order of a few microns. This local displacement in the longitudinal direction or the shear waves that propagate radially away from the focus as the tissue is pushed can then be mapped and related to mechanical tissue properties.…”

Section: Introductionmentioning

confidence: 99%

“…One relatively straightforward use of focused ultrasound as a source of local displacement is so-called acoustic radiation force impulse ͑ARFI͒ imaging. 10,11 In this method, the longitudinal tissue displacement at the ultrasound focus is measured using cross-correlation methods with ultrasound imaging. By systematically steering the focal zone to different points in the tissue, which can be done in near real time using the imaging probe itself as the focused ultrasound source, maps can be made of the local tissue displacement.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Magnetic resonance acoustic radiation force imaging

2008

View full text Add to dashboard Cite

Acoustic radiation force impulse imaging is an elastography method developed for ultrasound imaging that maps displacements produced by focused ultrasound pulses systematically applied to different locations. The resulting images are "stiffness weighted" and yield information about local mechanical tissue properties. Here, the feasibility of magnetic resonance acoustic radiation force imaging ͑MR-ARFI͒ was tested. Quasistatic MR elastography was used to measure focal displacements using a one-dimensional MRI pulse sequence. A 1.63 or 1.5 MHz transducer supplied ultrasound pulses which were triggered by the magnetic resonance imaging hardware to occur before a displacement-encoding gradient. Displacements in and around the focus were mapped in a tissue-mimicking phantom and in an ex vivo bovine kidney. They were readily observed and increased linearly with acoustic power in the phantom ͑R 2 = 0.99͒. At higher acoustic power levels, the displacement substantially increased and was associated with irreversible changes in the phantom. At these levels, transverse displacement components could also be detected. Displacements in the kidney were also observed and increased after thermal ablation. While the measurements need validation, the authors have demonstrated the feasibility of detecting small displacements induced by low-power ultrasound pulses using an efficient magnetic resonance imaging pulse sequence that is compatible with tracking of a dynamically steered ultrasound focal spot, and that the displacement increases with acoustic power. MR-ARFI has potential for elastography or to guide ultrasound therapies that use low-power pulsed ultrasound exposures, such as drug delivery.

show abstract

“…The Voigt model has been previously applied to describe the response of soft tissue to acoustic radiation force (Erpelding et al, 2005;Walker et al, 2000). Applied forces are opposed by the sum of viscous and elastic forces, producing an exponential displacement time profile with a time constant given by the ratio of the viscous drag coefficient to the spring constant.…”

Section: Time Constantsmentioning

confidence: 99%

Mapping age-related elasticity changes in porcine lenses using bubble-based acoustic radiation force

Erpelding

Hollman

O’Donnell

2007

Experimental Eye Research

View full text Add to dashboard Cite

Bubble-based acoustic radiation force aims to measure highly localized tissue viscoelastic properties. In the current investigation, acoustic radiation force was applied to laser-induced bubbles to measure age-related changes in the spatial distribution of elastic properties within in vitro porcine lenses. A potential in vivo technique to map lens elasticity is crucial to understanding the onset of presbyopia and develop new treatment options. Bubble-based acoustic radiation force was investigated as a technique to measure the spatial elasticity distribution of the lens in its natural state without disrupting the lens capsule.Laser-induced optical breakdown (LIOB) generated microbubbles in a straight line across the equatorial plane of explanted porcine lenses with 1 mm lateral spacing. Optical breakdown occurs when sufficiently high threshold fluence is attained at the focus of femtosecond pulsed lasers, inducing plasma formation and bubble generation. A two-element confocal ultrasonic transducer applied 6.5 ms acoustic radiation force-chirp bursts with the 1.5 MHz outer element while monitoring bubble position within the lens using pulse-echoes with the 7.44 MHz inner element. A crosscorrelation method was used to measure bubble displacements and determine exponential time constants of the temporal responses. Maximum bubble displacements are inversely proportional to the local Young's modulus, while time constants are indicative of viscoelastic properties.The apparent spatial elasticity distributions in 41 porcine lenses, ranging from 4 months to 5 years in age, were measured using bubble-based acoustic radiation force. Bubble displacements decrease closer to the porcine lens center, suggesting that the nucleus is stiffer than the cortex. Bubble displacements decrease with increasing lens age, suggesting that porcine lenses become stiffer with age. Bubble-based acoustic radiation force may be well-suited as a potential in vivo technique to spatially map elastic properties of the lens and guide therapeutic procedures aimed at restoring accommodation.

show abstract

A method of imaging viscoelastic parameters with acoustic radiation force

Cited by 155 publications

References 19 publications

Acoustic radiation force-based elasticity imaging methods

Acoustic radiation force-based elasticity imaging methods

Magnetic resonance acoustic radiation force imaging

Mapping age-related elasticity changes in porcine lenses using bubble-based acoustic radiation force

Contact Info

Product

Resources

About