Repeatability and Reproducibility of a Clinically Based QUS Phantom Study and Methodologies

Abstract

The purpose of this study is to evaluate the repeatability and reproducibility (R&R) of quantitative ultrasound (QUS) estimates, specifically attenuation coefficient (AC) and backscattering coefficient (BSC), using the same Siemens 3000 clinical ultrasound scanner. Additionally, the purpose of this work is to detail the measurement and analysis methodology. Repeatability is closeness of agreement between measures obtained with the same method under same conditions (same sonographer and same transducer) and reproducibility is closeness of agreement between measures obtained with the same method under different conditions (different sonographers and/or different transducers). Calibrated phantoms were scanned by two sonographers using two transducers in each session for multiple sessions over a period of four months. The phantom scans occurred as part of a clinical QUS liver study in human research participants spanning a spectrum of obesity and liver disease severity. The scanner was adjusted in each participant to obtain the highest quality liver B-mode images prior to acquiring data from the phantoms for which no scanner adjustments were made. The R&R were analyzed and estimated using the unweighted sums of squares ANOVA approach by applying two random effect models. The measurement variance caused by repeatability and reproducibility is small (AC: 2.4–3.2×10−4 [dB/cm-MHz]2; 10log10BSC: 0.23–0.27 dB2). The reproducibility variance is statistically significantly lower than the repeatability variance. The total R&R was not influenced by phantom properties over a wide range representing those found in liver in vivo.

Quantitative Ultrasound and the Pancreas: Demonstration of Early Detection Capability

“…The ex vivo AC and BSC were obtained by using a through‐transmission technique in the pulse‐echo mode and a planar reference method, respectively. The comprehensive implementation details are documented in work by Han et al and briefly summarized as follows. The ex vivo AC was computed by comparing the echo signals from the Plexiglas with and without the pancreas tissue placed in the acoustic path.…”

Novel Method for Ultrasound‐Derived Fat Fraction Using an Integrated Phantom

“…The AUROCs for predicting steatosis grade 1 versus 2 or higher were 0.8, 0.854, and 0.96 for AC, BSC, and MRI-PDFF. Additionally, good AC and BSC repeatability and reproducibility in liver-mimicking phantoms 40 and in human liver 41,42 has been reported.…”

Quantitative Ultrasound and B-Mode Image Texture Features Correlate with Collagen and Myelin Content in Human Ulnar Nerve Fascicles

“…where ACphantom(f) is the pre-computed reference phantom AC and γ(f) is the slope of the straight line that fits the log spectrum difference of the backscattered echoes in the tissue of interest and the reference phantom as a function of depth (Han, et al 2017).…”

“…Similar to the AC, the BSC depends on the frequency of the imaging pulse, because the backscattering occurs on tissue microstructures that are small in comparison to the wavelength (Mamou and Oelze 2013) . The BSC can be calculated using the reference phantom method following attenuation compensation using the equation (Han, et al 2017) :…”