Validation of differences in backscatter coefficients among four ultrasound scanners with different beamforming methods
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The backscatter coefficient (BSC) indicates the absolute scatterer property of a material, independently of clinicians and system settings. Our study verified that the BSC differed among the scanners, transducers, and beamforming methods used for quantitative ultrasound analyses of biological tissues.
Measurements were performed on four tissue-mimicking homogeneous phantoms containing spherical scatterers with mean diameters of 20 and 30 µm prepared at concentrations of 0.5 and 2.0 wt%, respectively. The BSCs in the different systems were compared using ultrasound scanners with two single-element transducers and five linear high- or low-frequency probes. The beamforming methods were line-by-line formation using focused imaging (FI) and parallel beam formation using plane wave imaging (PWI). The BSC of each system was calculated by the reference phantom method. The mean deviation from the theoretical BSC computed by the Faran model was analyzed as the benchmark validation of the calculated BSC.
The BSCs calculated in systems with different properties and beamforming methods well concurred with the theoretical BSC. The mean deviation was below ± 2.8 dB on average, and within the approximate standard deviation (± 2.2 dB at most) in all cases. These variations agreed with a previous study in which the largest error among four different scanners with FI beamforming was 3.5 dB.
The BSC in PWI was equivalent to those in the other systems and to those of FI beamforming. This result indicates the possibility of ultra-high frame-rate BSC analysis using PWI.
KeywordsBackscatter coefficient Single-element transducer Linear phased array transducer Focused imaging Plane wave imaging
This work was partly supported by JSPS Core-to-Core Program, and KAKENHI Grant numbers 17H05280 and 17J07762. We also acknowledge financial support from the Institute for Global Prominent Research and the Frontier Science Program of Graduate School of Science and Engineering at Chiba University.
Compliance with ethical standards
Conflict of interest
The authors declare that there are no conflicts of interest.
This article does not contain any studies with human or animal subjects performed by any of the authors.
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