Comparison of Ultrasound Attenuation and Backscatter Estimates in Layered Tissue-Mimicking Phantoms among Three Clinical Scanners

Abstract

Backscatter and attenuation coefficient estimates are needed in many quantitative ultrasound strategies. In clinical applications, these parameters may not be easily obtained because of variations in scattering by tissues overlying a region of interest (ROI). The goal of this study is to assess the accuracy of backscatter and attenuation estimates for regions distal to nonuniform layers of tissue-mimicking materials. In addition, this work compares results of these estimates for “layered” phantoms scanned using different clinical ultrasound machines. Two tissue-mimicking phantoms were constructed, each exhibiting depth-dependent variations in attenuation or backscatter. The phantoms were scanned with three ultrasound imaging systems, acquiring radio frequency echo data for offline analysis. The attenuation coefficient and the backscatter coefficient (BSC) for sections of the phantoms were estimated using the reference phantom method. Properties of each layer were also measured with laboratory techniques on test samples manufactured during the construction of the phantom. Estimates of the attenuation coefficient versus frequency slope, α0, using backscatter data from the different systems agreed to within 0.24 dB/cm-MHz. Bias in the α0 estimates varied with the location of the ROI. BSC estimates for phantom sections whose locations ranged from 0 to 7 cm from the transducer agreed among the different systems and with theoretical predictions, with a mean bias error of 1.01 dB over the used bandwidths. This study demonstrates that attenuation and BSCs can be accurately estimated in layered inhomogeneous media using pulse-echo data from clinical imaging systems.

Real-time implementation of a dual-mode ultrasound array system: In vivo results

“…With the availability of HPC FPGA/GPU platforms for postbeamforming processing of DMUA data, it will be possible to employ quantitative imaging methods such as those described in [36] for mechanical property measurements, in [15] for thermal property measurement, and in [37] for nonlinearity imaging. Of course, traditional and modern quantitative imaging techniques [38]- [41] can still be used to characterize structural changes due to lesion formation. With these quantitative imaging methods, it will be possible to use the DMUA as a theranostic system providing diagnostic quality imaging of the tissue response to therapeutic HIFU.…”

Using speckle statistics to improve attenuation estimates for cervical assessment

“…To extend the results from theoretical simulations to real life ultrasound images, two three layered phantom were used [59]. Phantom 1 has constant attenuation whereas phantom 2 has constant backscatter.…”

“…The size of the scatterer's varies from 5 to 43µm. Table 12 summarizes the properties of the phantom 1 (details about phantom construction [59]). Whereas, table 13 summarizes the property of phantom 2.…”

Estimation of quantitative ultrasound parameters derived from backscatter coefficients using plane wave compounding - A comparative simulation study

“…BSCs are derived from backscatter power spectrum estimates after compensating for system-dependent effects such as the transmitted pressure waveform and the diffraction pattern of the imaging system. Appropriate and consistent compensation is typically achieved using substitution methods and reference phantom methods for single element [2], [3] and array [4] transducers, respectively.…”

“…Backscattered data was analyzed at depths between 10 and 50 mm, using data blocks of 14λ axially by 12 lines (roughly equivalent to 7.2 beamwidths) laterally. The bandwidth cutoff criterion for backscatter coefficient analysis was chosen as 7 dB higher than the noise floor, in accordance with previous studies [4], [13]. QUS parameters were estimated by performing an exhaustive ESD search in the range between 2 and 120 μm with a step size of 1 mm.…”