Influence of Measurement Depth and Acquisition Parameters on Shear Wave Speed and Shear Wave Dispersion in Certified Phantoms Using a Canon Aplio Clinical Ultrasound Scanner

ARTICLE INFO Objective: The aim of the work described here was to investigate the relative contribution of confounding factors on liver shear wave speed (SWS) and shear wave dispersion slope (SWDS) measurements in three certified phantoms using a Canon Aplio clinical ultrasound scanner. Methods: A Canon Aplio i800 i-series ultrasound system (Canon Medical Systems Corporation, Otawara, Tochigi, Japan) with i8CX1 convex array (center frequency = 4 MHz) was used to examine dependencies caused by the depth, width and height of the acquisition box (AQB), the depth and size of the region of interest (ROI), the AQB angle and the pressure of the ultrasound probe on the surface of the phantom. Results: Results revealed that depth is the most significant confounder in both SWS and SWDS measurements. AQB angle, height and width and ROI size exhibited minimal confounding effects on measurements. For SWS, the most consistent measurement depth is when the top of the AQB is placed between 2 and 4 cm, and the ROI is located between 3 and 7 cm deep. For SWDS, results indicate that measurement values significantly decrease with depth from the surface of the phantom until approximately 7 cm deep, and consequently no stable area of AQB placement or ROI depth exists. Conclusion: In contrast to SWS, the same ideal acquisition depth range cannot necessarily be applied to SWDS measurements because of a significant depth dependency.

Automated summary

The objective of this study was to investigate the impact of confounding factors on liver shear wave speed (SWS) and shear wave dispersion slope (SWDS) measurements using a Canon Aplio clinical ultrasound scanner. It was found that depth had the most significant effect on both SWS and SWDS measurements. The angle, height, width, and ROI size had minimal impact on the measurements. For SWS measurements, the most consistent depth range was between 2 and 4 cm for the top of the acquisition box (AQB) and between 3 and 7 cm for the ROI. However, for SWDS measurements, there was no stable AQB placement or ROI depth due to a significant depth dependency.