Interlaboratory comparison of ultrasonic backscatter, attenuation, and speed measurements.

Madsen, Ernest L.; Dong, Feifei; Frank, Gary R.; Garra, Brian S.; Wear, Keith A.; Wilson, Thaddeus; Zagzebski, James A.; Miller, H. L.; Shung, K. K.; Wang, S. H.; Feleppa, Ernest J.; Liu, Tian; O’Brien, William D.; Topp, K. A.; Sanghvi, N. T.; Zaitsev, Alexey V.; Hall, Timothy J.; Fowlkes, J. Brian; Kripfgans, Oliver D.; Miller, J. G.

doi:10.7863/jum.1999.18.9.615

Cited by 182 publications

(120 citation statements)

References 29 publications

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“…Corrections for transmission through thin plastic layers over the parallel sample faces are significant for frequencies above about 2 MHz and are included in the data reduction. 25 These corrections include the effect of different acoustic impedances of water and TM materials.…”

Section: B Ultrasoundmentioning

confidence: 99%

“…The basic idea is displacement of water while monitoring the change in the pulse arrival time and amplitude of through-transmission tone burst pulses. 25 Adequate time is allowed for the samples to reach the 22°C temperature of the water bath before measurements were made. The parallel faces of the samples are maintained perpendicular to the ultrasound beam direction.…”

Section: B Ultrasoundmentioning

confidence: 99%

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Tissue mimicking materials for a multi‐imaging modality prostate phantom

et al. 2001

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Materials that simultaneously mimic soft tissue in vivo for magnetic resonance imaging ͑MRI͒, ultrasound ͑US͒, and computed tomography ͑CT͒ for use in a prostate phantom have been developed. Prostate and muscle mimicking materials contain water, agarose, lipid particles, protein, Cu ϩϩ , EDTA, glass beads, and thimerosal ͑preservative͒. Fat was mimicked with safflower oil suffusing a random mesh ͑network͒ of polyurethane. Phantom material properties were measured at 22°C. ͑22°C is a typical room temperature at which phantoms are used.͒ The values of material properties should match, as well as possible, the values for tissues at body temperature, 37°C. For MRI, the primary properties of interest are T1 and T2 relaxations times, for US they are the attenuation coefficient, propagation speed, and backscatter, and for CT, the x-ray attenuation. Considering the large number of parameters to be mimicked, rather good agreement was found with actual tissue values obtained from the literature. Using published values for prostate parenchyma, T1 and T2 at 37°C and 40 MHz are estimated to be about 1100 and 98 ms, respectively. The CT number for in vivo prostate is estimated to be 45 HU ͑Hounsfield units͒. The prostate mimicking material has a T1 of 937 ms and a T2 of 88 ms at 22°C and 40 MHz; the propagation speed and attenuation coefficient slope are 1540 m/s and 0.36 dB/cm/MHz, respectively, and the CT number of tissue mimicking prostate is 43 HU. Tissue mimicking ͑TM͒ muscle differs from TM prostate in the amount of dry weight agarose, Cu ϩϩ , EDTA, and the quality and quantity of glass beads. The 18 m glass beads used in TM muscle increase US backscatter and US attenuation; the presence of the beads also has some effect on T1 but no effect on T2. The composition of tissue-mimicking materials developed is such that different versions can be placed in direct contact with one another in a phantom with no long term change in US, MRI, or CT properties. Thus, anthropomorphic phantoms can be constructed.

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Section: B Ultrasoundmentioning

confidence: 99%

Section: B Ultrasoundmentioning

confidence: 99%

Tissue mimicking materials for a multi‐imaging modality prostate phantom

et al. 2001

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“…The solution is degassed under vacuum and allowed to settle for 20 min in specially designed sample holders of size 5 × 5 × 6.5 cm 3 in which the solution solidifies. The sound speed and the acoustic attenuation of the phantom at 25°C are measured using the sample replacement technique (Bloch et al 1998;Madsen et al 1999) with a pair of 7 mm diameter PVDF transducers (Sonic Concepts, Woodinville, WA, USA); measured bulk values for the sample used in this example were c = 1483 m/s and α = 0.35 dB/cm/MHz, respectively. The schematic diagram of the experimental set-up (calipers not shown) is presented in Fig.…”

Section: Phantom Experimentsmentioning

confidence: 99%

Noninvasive Measurement of Local Thermal Diffusivity Using Backscattered Ultrasound and Focused Ultrasound Heating

Anand

Kaczkowski

2008

Ultrasound in Medicine & Biology

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Previously, noninvasive methods of estimating local tissue thermal and acoustic properties using backscattered ultrasound have been proposed in the literature. In this article, a noninvasive method of estimating local thermal diffusivity in situ during focused ultrasound heating using beamformed acoustic backscatter data and applying novel signal processing techniques is developed. A high intensity focused ultrasound (HIFU) transducer operating at subablative intensities is employed to create a brief local temperature rise of no more than 10°C. Beamformed radio-frequency (RF) data are collected during heating and cooling using a clinical ultrasound scanner. Measurements of the time-varying "acoustic strain", that is, spatiotemporal variations in the RF echo shifts induced by the temperature related sound speed changes, are related to a solution of the heat transfer equation to estimate the thermal diffusivity in the heated zone. Numerical simulations and experiments performed in vitro in tissue mimicking phantoms and excised turkey breast muscle tissue demonstrate agreement between the ultrasound derived thermal diffusivity estimates and independent estimates made by a traditional hot-wire technique. The new noninvasive ultrasonic method has potential applications in thermal therapy planning and monitoring, physiological monitoring and as a means of noninvasive tissue characterization.

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“…19 Ernest L. Madsen, PhD (University of Wisconsin, Madison, WI), oversaw the design, fabrication, and distribution of phantoms to 10 laboratories. Investigators performed measurements and submitted their results to Professor Madsen.…”

mentioning

confidence: 99%

Interlaboratory Comparison of Ultrasonic Backscatter Coefficient Measurements From 2 to 9 MHz

Wear

Stiles²,

Frank³

et al. 2005

Journal of Ultrasound in Medicine

144

119

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Objective. As are the attenuation coefficient and sound speed, the backscatter coefficient is a fundamental ultrasonic property that has been used to characterize many tissues. Unfortunately, there is currently far less standardization for the ultrasonic backscatter measurement than for the other two, as evidenced by a previous American Institute of Ultrasound in Medicine (AIUM)-sponsored interlaboratory comparison of ultrasonic backscatter, attenuation, and speed measurements (J Ultrasound Med 1999; 18:615-631). To explore reasons for these disparities, the AIUM Endowment for Education and Research recently supported this second interlaboratory comparison, which extends the upper limit of the frequency range from 7 to 9 MHz. Methods. Eleven laboratories were provided with standard test objects designed and manufactured at the University of Wisconsin (Madison, WI). Each laboratory was asked to perform ultrasonic measurements of sound speed, attenuation coefficients, and backscatter coefficients. Each laboratory was blinded to the values of the ultrasonic properties of the test objects at the time the measurements were performed. Results. Eight of the 11 laboratories submitted results. The range of variation of absolute magnitude of backscatter coefficient measurements was about 2 orders of magnitude. If the results of 1 outlier laboratory are excluded, then the range is reduced to about 1 order of magnitude. Agreement regarding frequency dependence of backscatter was better than reported in the previous interlaboratory comparison. For example, when scatterers were small compared with the ultrasonic wavelength, experimental frequency-dependent backscatter coefficient data obtained by the participating laboratories were usually consistent with the expected Rayleigh scattering behavior (proportional to frequency to the fourth power). Conclusions. Greater standardization of backscatter measurement methods is needed. Measurements of frequency dependence of backscatter are more consistent than measurements of absolute magnitude.

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Interlaboratory comparison of ultrasonic backscatter, attenuation, and speed measurements.

Cited by 182 publications

References 29 publications

Tissue mimicking materials for a multi‐imaging modality prostate phantom

Tissue mimicking materials for a multi‐imaging modality prostate phantom

Noninvasive Measurement of Local Thermal Diffusivity Using Backscattered Ultrasound and Focused Ultrasound Heating

Interlaboratory Comparison of Ultrasonic Backscatter Coefficient Measurements From 2 to 9 MHz

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