Intra- and inter-observer variation and accuracy using different shear wave elastography methods to assess circumscribed objects – a phantom study.

Abstract

Aims: The elastic properties of circumscribed tissues (e.g., tendons, lymph nodes, prostates, brain tumors) are of considerable clinical interest. The purpose of this study was thus to compare the Intra-/Inter-observer variation and accuracy in vitro of point shear wave elastography (pSWE) with that of 2D-SWE and to assess 2D-SWE’s precision with variable ROI (vROI) incircumscribed objects.Material and methods: Round targets (Elasticity QA Phantom Model 049) were examined for varying degrees of stiffness (8, 14, 45, and 80 kPa) and diameters (20/10 mm). Three ultrasound systems and four probes were applied (pSWE: Acuson/S3000 9L4/4C1 and Epiq7 C51, 2D-SWE: Aplio/500 PVT375BT). Three different ROIs were used, namely fixed ROI (fROI) and variable ROI: rectangular-best-fitted ROI, and round-best-fitted ROI. Each measurement was performed twice by four observers.Results: A total of 3,604 measurements were conducted. The intra-observer variation of 2D-SWE measurements indicated better agreement (Intraclass Correlation Coefficient (ICC) = 0.971; 95% CI=[0.945; 0.985]), than for the pSWE measurements (ICC = 0.872; 95% CI=[0.794; 0.92]). With both methods, the shear wave elastography applied showed low inter-observer variation: ICC = 0.980; 95% CI=[0.970; 0.987]. However, a significant difference was observed between fROI (pSWE) and vROI (2D-SWE) on circumscribed objects in terms of accuracy. The lowest degree of observationerror was detected in situations where the ROI was not “best fitted”, but placed within the target of 3mm from the border (target diameter: 20mm; mean relative error = 0.15).Conclusions: When estimating the elastic properties of circumscribed tissues, the different measurement techniques performed by commercial shear wave elastography systems reveal a strong susceptibility for observational errors, depending upon the fixed vs. variable ROI of the pSWE vs. 2D-SWE technique.

Quantitative and Qualitative Approach for Shear Wave Elastography in Superficial Lymph Nodes

“…Another factor to take into consideration is the stiffness measurement technique itself (i.e the size and the placement of the ROI) that might differ from one study to another. Indeed, the size of the ROI has been shown to be related to the diagnostic performance and reproducibility of SWE measurements (Lee et al, 2013;Moon et al, 2017;Seliger et al, 2017;Skerl et al, 2015). In our study, we preferred a ROI as large as possible due to the heterogeneity of the LNs and in order to include most of the LNs.…”

Reliability of quantitative point shear-wave ultrasound elastography on vastus medialis muscle and quadriceps and patellar tendons

“…Thanks to the fact that these techniques provide respectively semi-quantitative and quantitative elasticity parameters, they have gained interest for applications in a number of areas such as liver, breast, thyroid and in musculoskeletal system [5][6][7][8][9].…”

Ultrasonographic and elastographic biometry in adult major salivary glands: a preliminary case-control report

“…Fifth, the procedure of ultrasound was dependent on the operator and might result in some observer bias. Therefore considerable intra-observer and inter-observer variability existed in elastography measurement and were reported in breast lesions 25 , circumscribed objects 26 , and potentially in our study. In order to avoid inter-observer variation, in the current study, the US procedure was performed by one physician and the images were interpreted by the same examiner, while inter-observer reproducibility for liver and spleen was reported to be excellent 27,28 .…”