Medical ultrasound: imaging of soft tissue strain and elasticity

Wells, P.N.T.; Liang, Haidong

doi:10.1098/rsif.2011.0054

Cited by 440 publications

(355 citation statements)

References 249 publications

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“…The contact area between the holder and the phantom is much smaller than the phantom surface to avoid any change in the contact area during experiment. Preload was to keep the phantom from moving but was kept as small as 0.3 N. For details on calculating Young's modulus using this method please see (Wells and Liang 2011).…”

Section: Initial Measurements and Validationmentioning

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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Section: Initial Measurements and Validationmentioning

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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“…[1,3] Sonoelastography also known as virtual or electronic palpation is a novel technique used for measurement of tissue stiffness. [21] Compared to manual palpation which has a historical importance in physical examination, [22] SE has an advantage of evaluating deeper lesions and furthermore it is semi-quantifiable. The basic principle of this technique is that an abnormal tissue (i.e.…”

Section: Discussionmentioning

confidence: 99%

Comparison of sonoelastography with sonourethrography and retrograde urethrography in the evaluation of male anterior urethral strictures

Talreja

Tomar

Yadav

et al. 2016

Turkish Journal of Urology

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Objective: Retrograde urethrography (RUG) is the most common and preferred imaging modality for imaging of the anterior urethral strictures despite its well-known limitations and disadvantages. Sonourethrography (SUG) was introduced in 1988 to overcome the limitations of RUG and to provide more accurate results. As proper selection of imaging modality is very important for planning the treatment, various advances in this area are required. One of the major factors for recurrence of stricture disease is spongiofibrosis. Sonoelastography (SE) is a newer technique, tried in various other pathologies. In this study, we have used this technique for the first time to assess its efficacy in the evaluation of anterior urethral stricture disease by comparison with RUG and SUG. Material and methods:Between August 2014 and May 2015, 77 patients with clinical features of anterior urethral stricture disease were included in the study and evaluated by RUG followed by SUG and SE for stricture location, length, depth of spongiofibrosis and periurethral pathologies. The results were then correlated with operative and histopathological findings. Results:Overall diagnostic accuracy of SE, SUG, and RGU for the estimation of stricture location, and length were estimated 92.68% vs. 91.54%, 79% vs. 78.87% and 80.48% vs. 43.66%, respectively, while for depth of spongiofibrosis SE, and SUG had accuracy rates of 87.3%, 48%, respectively. The mean length measured on SE was nearest to the mean intra-operative stricture length (21.34+11.8 mm). SE findings significantly correlated with the colour of bladder mucosa on cystoscopic examination (p=0.003) whereas the association was nonsignificant (p=0.127) for difficulty in incision. While a nonsignificant correlation existed between SUG findings related both to the colour of the bladder mucosa and difficulty in incision on cystoscopy, SE findings had a significant association (p<0.001) with histopathology findings for severe degree of fibrosis. Conclusion:Sonoelastography estimates stricture site and length better in comparison with RUG and SUG. It estimates degree of spongiofibrosis which serves as an important prognostic factor for stricture recurrence more accurately than SUG.

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“…37,38 The surface tension for blood and air is taken from Apfel and Holland 39 and the viscosity from Yang and Church. 25 The elasticity of tissue is assumed to span G = 0 − 10 MPa, 40,41 with upper values corresponding to atherosclerotic tissue. 42 A wide range of relaxation times have been reported, 43,44 which usually depend on the loading; mathematically meaningful relaxation times, satisfying Eq.…”

Section: Tissue Constitutive Model and Properties: The Zener Viscomentioning

confidence: 99%

Nonlinear oscillations following the Rayleigh collapse of a gas bubble in a linear viscoelastic (tissue-like) medium

Hua

Johnsen

2013

Physics of Fluids

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In a variety of biomedical engineering applications, cavitation occurs in soft tissue, a viscoelastic medium. The present objective is to understand the basic physics of bubble dynamics in soft tissue. To gain insights into this problem, theoretical and numerical models are developed to study the Rayleigh collapse and subsequent oscillations of a gas bubble in a viscoelastic material. To account for liquid compressibility and thus accurately model large-amplitude oscillations, the Keller-Miksis equation for spherical bubble dynamics is used. The most basic linear viscoelastic model that includes stress relaxation, viscosity, and elasticity (Zener, or standard linear solid) is considered for soft tissue, thereby adding two ordinary differential equations for the stresses. The present study seeks to advance past studies on cavitation in tissue by determining the basic effects of relaxation and elasticity on the bubble dynamics for situations in which compressibility is important. Numerical solutions show a clear dependence of the oscillations on the viscoelastic properties and compressibility. The perturbation analysis (method of multiple scales) accurately predicts the bubble response given the relevant constraints and can thus be used to investigate the underlying physics. A third-order expansion of the radius is necessary to accurately represent the dynamics. Key quantities of interest such as the oscillation frequency and damping, minimum radius, and collapse time can be predicted theoretically. The damping does not always monotonically decrease with decreasing elasticity: there exists a finite non-zero elasticity for which the damping is minimum; this value falls within the range of reported tissue elasticities. Also, the oscillation period generally changes with time over the first few cycles due to the nonlinearity of the system, before reaching an equilibrium value. The analytical expressions for the key bubble dynamics quantities and insights gained from the analysis may prove valuable in the development and optimization of certain biomedical applications. C 2013 AIP Publishing LLC. [http://dx

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Medical ultrasound: imaging of soft tissue strain and elasticity

Cited by 440 publications

References 249 publications

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

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

Comparison of sonoelastography with sonourethrography and retrograde urethrography in the evaluation of male anterior urethral strictures

Nonlinear oscillations following the Rayleigh collapse of a gas bubble in a linear viscoelastic (tissue-like) medium

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