Influence of Examiners’ Experience and Region of Interest Location on Semiquantitative Elastography Validity and Reliability

Abstract

Semi-quantitative elastography is a promising imaging technique to evaluate tissue stiffness differences, providing data regarding relative stiffness differences between two targets. The aims of this study were to assess the validity, inter-examiner reliability and variability of semi-quantitative elastography for calculating strain ratios (SR) in a homogeneous gel phantom in different locations within the image. A diagnostic accuracy study was performed in a homogeneous stiffness phantom. Four examiners participated (two novice and two experienced). Each examiner assessed the SR in two locations. Difference between examiners, variability of measurements, SR error and absolute error, mean error of the measurements and coefficient of variation were calculated. The agreement between examiners, validity and variability of measurements were higher in the central area than the lateral areas of the images. Thus, the experience of the examiner was relevant for the concordance of the measurements in the lateral areas of the images (SR difference of 0.14 ± 0.05; p < 0.001), but not for the central area (SR difference of 0.05 ± 0.02; p > 0.05). Our data suggested that semi-quantitative elastography is an accurate tool for assessing small magnitude stiffness differences within the same image in central areas, but the experience of the examiner is a determinant factor.

Inter-Examiner Disagreement for Assessing Cervical Multifidus Ultrasound Metrics Is Associated with Body Composition Features

“…However, US is not free of disadvantages. Some of the main limitations of this tool are related to the US physics principles limiting the visualization of several locations where sound cannot be reflected [ 37 ], the operator-dependence (which is closely associated with the examiner’s experience and the region of interest’s location in the image) [ 38 ], and the histological properties of the tissues [ 28 ]. Regarding the latter issue, US reliability estimates are worse in clinical populations compared with healthy subjects following the same procedures [ 25 , 26 , 27 , 28 , 39 ].…”

Convergent Validity between Electromyographic Muscle Activity, Ultrasound Muscle Thickness and Dynamometric Force Measurement for Assessing Muscle

“…However, important limitations should be acknowledged. First, US is an operator-dependent method and certain exams require the examiner to be experienced so as to ensure good validity, reliability, sensibility and specificity [ 13 ]. Thus, due to the US interaction with the tissues (i.e., attenuation and refraction), some artifacts impede the visualization of some structures, including intra-articular elements or deep structures [ 14 ].…”

Body Composition and Demographic Features Do Not Affect the Diagnostic Accuracy of Shear Wave Elastography

“…Strain elastography is highly subjective since the external and internal forces are difficult to standardize, the magnitude of the stiffness difference between two areas is unknown, and longitudinal assessments are limited [ 10 ]. However, it should be noted that both methods are based on ultrasound waves and associated artifacts such as attenuation, shadowing, anisotropy, and the location of the region of interest may equally influence the results reproducibility in both modalities [ 11 ]. The rationale for conducting this study is that limited evidence has analyzed if non-operator-dependent factors such as patients’ demographics and body composition characteristics are associated with increased SWE errors, despite the large number of studies assessing the test–retest reliability of SWE in calculating the stiffness properties of musculoskeletal structures [ 12 , 13 , 14 , 15 , 16 , 17 , 18 ].…”