A new ultrasound tissue-equivalent material.

Burlew, M M; Madsen, Ernest L.; Zagzebski, James A.; Banjavic, Richard A.; Sum, Satha

doi:10.1148/radiology.134.2.7352242

Cited by 196 publications

(89 citation statements)

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“…A further simplification is that a good approximation for the density of most soft tissues is that of water (ρ = 1 g-cm −3 ) (Burlew et al 1980). Technically, the shear modulus of a material refers to a static stress, and in attenuating materials the quantity calculated above can vary with frequency (Auld 1990).…”

Section: Summary Of Inversion Processingmentioning

confidence: 99%

Magnetic resonance elastography of the brain

et al. 2008

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The purpose of this study was to obtain normative data using magnetic resonance elastography (MRE) to: [a] obtain estimates of the shear modulus of human cerebral tissue in vivo, and [b] assess a possible age dependence of the shear modulus of cerebral tissue in healthy adult volunteers. MR elastography studies were performed on tissue-simulating gelatin phantoms and 25 healthy adult volunteers. The data were analyzed using spatio-temporal filters and a local frequency estimating algorithm. Statistical analysis was performed using a paired t-test. The mean shear stiffness of cerebral white matter was 13.6 kPa (95% CI 12.3 to 14.8 kPa); while that of gray matter was lower at 5.22 kPa (95% CI 4.76 to 5.66 kPa). The difference was statistically significant (p < 0.0001).

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Section: Summary Of Inversion Processingmentioning

confidence: 99%

Magnetic resonance elastography of the brain

et al. 2008

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“…Hence, in translating the nonlinearity propagation seen in water to that seen in tissue for the same beam, for most tissue types it is the change in absorption which is the overwhelming consideration, not the change in B/A (Duck 2010). The absorption coefficients for soft tissue in the literature are for lower signal amplitudes than the ∼1 GPa levels found in this paper, and vary considerably (Burley et al 1980;Goss, Johnston & Dunn 1980;Damianou, Sanghvi & Fry 1997;Bailey et al 2003;Zderic et al 2004;Liu et al 2006;Coussios & Roy 2008). To reduce the range of values available even for the restricted amplitude range of clinical diagnostic device output, it is a standard practice to 'derate' the field values measured in water by 0.3 dB cm −1 MHz −1 , and for the data specific to the tissues and amplitudes occurring in this paper, this is also applied to the predicted values here to estimate the signals that would be detected were the fields to propagate through soft tissue.…”

Section: The Effect Of Tissuementioning

confidence: 56%

The collapse of single bubbles and approximation of the far-field acoustic emissions for cavitation induced by shock wave lithotripsy

et al. 2011

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Recent clinical trials have shown the efficacy of a passive acoustic device used during shock wave lithotripsy (SWL) treatment. The device uses the far-field acoustic emissions resulting from the interaction of the therapeutic shock waves with the tissue and kidney stone to diagnose the effectiveness of each shock in contributing to stone fragmentation. This paper details simulations that supported the development of that device by extending computational fluid dynamics (CFD) simulations of the flow and near-field pressures associated with shock-induced bubble collapse to allow estimation of those far-field acoustic emissions. This is a required stage in the development of the device, because current computational resources are not sufficient to simulate the far-field emissions to ranges of O(10 cm) using CFD. Similarly, they are insufficient to cover the duration of the entire cavitation event, and here simulate only the first part of the interaction of the bubble with the lithotripter shock wave in order to demonstrate the methods by which the far-field acoustic emissions resulting from the interaction can be estimated. A free-Lagrange method (FLM) is used to simulate the collapse of initially stable air bubbles in water as a result of their interaction with a planar lithotripter shock. To estimate the far-field acoustic emissions from the interaction, this paper developed two numerical codes using the Kirchhoff and Ffowcs William-Hawkings (FW-H) formulations. When coupled to the FLM code, they can be used to estimate the far-field acoustic emissions of cavitation events. The limitation of the technique is that it assumes that no significant nonlinear acoustic propagation occurs outside the control surface. Methods are outlined for ameliorating this problem if, as here, computational resources cannot compute the flow field to sufficient distance, although for the clinical situation discussed, this limitation is tempered by the effect of tissue absorption, which here is incorporated through the standard derating procedure. This approach allowed identification of the sources of, and explanation of trends seen in, the characteristics of the far-field emissions observed in clinic, to an extent that was sufficient for the development of this clinical device.

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“…Phantoms or test objects containing agar-based TMMs have been produced for a number of years based on the material developed at the University of Wisconsin (Burlew et al 1980). A contemporary agar-based TMM has been designed and established as part of an International Electrotechnical Commission project (IEC 2001;Teirlinck, Bezemer, Kollmann, Lubbers, Hoskins, Fish, Fredfeldt, & Schaarschmidt 1998).…”

Section: Tissue Mimicking Materialsmentioning

confidence: 99%