Intra- and inter-observer variation and accuracy using different shear wave elastography methods to assess...

Area of Science:

• Medical Imaging
• Biophysics
• Ultrasound Technology

Background:

• Elastic properties of circumscribed tissues are clinically significant for diagnosing conditions affecting organs like lymph nodes, prostates, and brain tumors.
• Shear wave elastography (SWE) is a non-invasive ultrasound technique used to measure tissue stiffness.

Purpose of the Study:

• To compare the intra- and inter-observer variation and accuracy of point shear wave elastography (pSWE) versus 2D shear wave elastography (2D-SWE) in vitro.
• To evaluate the precision of 2D-SWE using variable regions of interest (vROI) in circumscribed objects.

Main Methods:

• Round elasticity phantom targets with varying stiffness (8-80 kPa) and diameters (10/20 mm) were measured using three ultrasound systems and four probes.
• Measurements were performed using both pSWE and 2D-SWE techniques with fixed (fROI) and variable (vROI) regions of interest.
• Four observers conducted each measurement twice, resulting in 3,604 total measurements.

Main Results:

• 2D-SWE demonstrated superior intra-observer agreement (ICC=0.971) compared to pSWE (ICC=0.872).
• Both methods exhibited low inter-observer variation (ICC=0.980).
• Accuracy differed significantly between pSWE with fROI and 2D-SWE with vROI, with the lowest error observed when the ROI was placed 3mm from the target border (mean relative error=0.15).

Conclusions:

• Commercial shear wave elastography systems show susceptibility to observational errors when estimating elastic properties of circumscribed tissues.
• The choice between fixed (pSWE) and variable (2D-SWE) regions of interest significantly impacts measurement accuracy.