CC BY-NC-ND 4.0 · Ultrasound Int Open 2018; 04(02): E54-E60
DOI: 10.1055/a-0619-6058
Original Article
Eigentümer und Copyright ©Georg Thieme Verlag KG 2018

Influencing Factors of 2D Shear Wave Elastography of the Muscle – An Ex Vivo Animal Study

Marga B Rominger
Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
,
Pascal Kälin
Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
,
Monika Mastalerz
Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
,
Katharina Martini
Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
,
Volker Klingmüller
Eidgenossische Technische Hochschule Zurich, Computer Vision Laboratory, Zurich, Switzerland
,
Sergio Sanabria
Eidgenossische Technische Hochschule Zurich, Computer Vision Laboratory, Zurich, Switzerland
,
Thomas Frauenfelder
Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
› Author Affiliations
Further Information

Publication History

received 22 December 2017
revised 27 March 2018

accepted 29 March 2018

Publication Date:
05 July 2018 (online)

Abstract

Objective To evaluate measurement confounders on 2D shear wave elastography (2D-SWE) elastography of muscle.

Materials and Methods Ex vivo, porcine muscle was examined with a GE LOGIQ E9 ultrasound machine with a 9 L linear (9 MHz) and C1-6 convex probe (operating at 2.5 or 6 MHz). The influence of different confounders on mean shear wave velocity (SWVmean) was analyzed: probes, pressure applied by probe, muscle orientation, together with the impact of different machine settings such as frequency, placement depth and size of region of interest (ROI). The mean of twelve repeated SWVmean measurements (m/s) and coefficient of variation (CV; standard deviation/mean in %) were assessed for each test configuration.

Results Reproducibility (CV) and maximum possible tissue depth of the linear probe were inferior to the convex probe. With the linear probe, there was a linear decrease of SWVmean with placement depth from 4.56 m/s to 1.81 m/s. A significant increase of SWVmean (p<0.001) was observed for larger ROI widths (range 3.96 m/s to 6.8 m/s). A change in the machine operation mode ('penetration' instead of 'general') led to a significant increase of SWVmean (p=0.04). SWVmean in the longitudinal direction of muscle was significantly higher than in cross section (p<0.001) (e. g. 4.56 m/s versus 3.42 m/s). An increase of linear probe pressure significantly increased muscle SWVmean from 5.29 m/s to 7.21 m/s (p<0.001).

Conclusions 2D-SWE of muscle is influenced by a wealth of parameters. Therefore, standardization of measurement is advisable before application in clinical research studies and routine patient assessment.