@misc{oai:repo.qst.go.jp:00064862,
 author = {Kishimoto, Riwa and Koyama, Atsuhisa and Obata, Takayuki and Omatsu, Tokuhiko and Suga, Mikio and Kandatsu, Susumu and Kamada, Tadashi and 岸本 理和 and 小畠 隆行 and 尾松 徳彦 and 神立 進 and 鎌田 正},
 month = {Nov},
 note = {PURPOSE
To assess the reliability and validity of shear wave velocity measurement of originally-made phantom using acoustic radiation force impulse (ARFI) technology in comparison with physically estimated velocity.
METHOD AND MATERIALS
We made gel phantoms in polyacrylamide hydrogel (storage modulus: 3.1/6.8/16/25kPa) and measured their shear wave velocity by mechanically fixed probe and by two operators (radiologist (Rd) and student (St)) manually ten times each. Shear wave velocity was measured with 4MHz convex (4C) and 9MHz linear (9L) probe using the application of virtual touch tissue quantification. We evaluated the reliability of shear wave velocity measurement with interclass correlation coefficient (ICC) and assessed the variation of shear wave velocity in examination status; probe/frequency, depth of region of interest (ROI), compression pressure and rigidity of phantom. We also compared shear wave velocity with physically estimated velocity.
RESULTS
The reliability of mechanically fixed measurement was extremely high both with 4C/9L (ICC:0.987/1.0). Intra-operator reliability of manually measurement was extremely high with 9L (ICC: Rd0.998/St0.999) and considerably high with 4C (ICC: Rd0.897/St0.957) by ten times measurement. With 9L probe, once measurement was enough and 3~5 times measurements were needed with 4C probe for high reliability. Inter-operator reliability was also very high (ICC:0.989). Shear wave velocity increased significantly with strengthening of compression pressure both with 4C/9L. There is no significant difference in depth of ROI with mechanically fixed measurement but with manually measurement, shear wave velocity was higher at deeper ROI. Shear wave velocity was approximate to physically estimated value with 9L probe but it was 15~30% lower than estimated value when we measured a firmer phantom with 4C probe.
CONCLUSION
Although the reliability of shear wave velocity measurement was high enough, measured velocity varied among measurement status and differed from physically estimated velocity up to 30%. We need to understand these peculiarities and particular attention should be given when we compare shear wave velocity with the other measurement value.
CLINICAL RELEVANCE/APPLICATION
Although the reliability of shear wave velocity measurement was considerably high, shear wave velocity varied among measurement status and was not always equivalent to physically estimated velocity., 98th Scientific Assembly and Annual Meeting},
 title = {Diagnostic Reliability and Validity of Ultrasonographic Tissue Quantification using Acoustic Radiation Force Impulse (ARFI) Elastography - Phantom Study},
 year = {2012}
}