Shear Wave Elastography: Comparing the Accuracy of Ultrasound Scanners Using Calibrated Phantoms in Experiment

The aim of the study was to compare the accuracy of shear wave elastography performed by ultrasonic scanners from different manufacturers and to develop the conversion coefficients to recalculate the stiffness values obtained with different instruments using a calibrated phantom.

Materials and Methods. A comparative analysis of the accuracy of stiffness measurements by shear wave point elastography was performed using three commercial ultrasonic scanners: Aixplorer (Supersonic Imagine, France), Acuson S2000 (Siemens, Germany), LOGIQ E9 (GE, USA), and the acoustic system Verasonics (Verasonics Inc., USA). The measurements were carried out using the calibrated phantom CIRS Model 049 Elasticity QA Phantom Spherical (Computerized Imaging Reference Systems Company, USA) that contained spherical inclusions of different stiffness.

Results. With all tested scanners, comparable stiffness values with deviations within the measurement error were obtained. For the less stiff spheres of type I and type II, the obtained values were consistent with to the phantom calibration. For the medium-stiff phantom matrix, the measured values were at the lower limit of the calibration range. With the stiff spheres of type III, we found values lower than those predicted by calibration; the deviation was less pronounced in the linear sensor of the LOGIQ E9 scanner. In all sensors, this discrepancy increased along with increasing stiffness of the object. We developed formulas for recalculating the stiffness values for all tested scanners grouped by pairs. For example, for the pair of linear sensors Acuson S2000–Aixplorer, the conversion formulas of the Young’s modulus E and the shear wave velocity V are as follows: E(Aixplorer, kPa)=3.11·V^2.06(Acuson S2000, m/s) and V(Acuson S2000, m/s)=0.58·E^0.48(Aixplorer, kPa).

Conclusion. All tested sensors and scanners have a comparable high accuracy of shear wave point elastography. The tested instruments are more accurate when measuring objects with low stiffness; as the stiffness increases, the deviations from the standard values become greater. The formulas proposed for recalculating the stiffness indices allow an accurate comparison between the shear wave elastography results obtained with different scanners. When used with the same object, the measured stiffness values increase in the row: Acuson S2000 → Aixplorer → LOGIQ E9.

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Safonov D.V., Rykhtik P.I., Shatokhina I.V., Romanov S.V., Gurbatov S.N., Demin I.Yu. Shear Wave Elastography: Comparing the Accuracy of Ultrasound Scanners Using Calibrated Phantoms in Experiment. Sovremennye tehnologii v medicine 2017; 9(4): 51, https://doi.org/10.17691/stm2017.9.4.06