Unrecognized Variability in Interquartile Range-to-Median Ratio Measurement: An Opportunity for Standardization

Measurement variability hampers the growing implementation and utility of quantitative imaging biomarkers (QIBs) such as ultrasound shear wave elastography (SWE) for liver imaging. The American Institute of Ultrasound in Medicine (AIUM), through the Radiological Society of North America (RSNA) Quantitative Imaging Biomarkers Alliance (QIBA), has successfully pioneered a reduction in inter-vendor shear wave speed measurement variability by the development of standardized tissue stiffness phantoms and a detailed technical claims profile [ [1] Quantitative Imaging Biomarkers Alliance. QIBA Profile: Ultrasound measurement of shear wave speed for estimation of liver fibrosis, https://qibawiki.rsna.org/images/1/1b/QIBA_US_SWS_Profile_04.25.2022-clean_version.pdf; 2022 [03.07.23]. Google Scholar ]. The interquartile range-to-median (IQR/M) ratio [ [2] Barr RG Wilson SR Rubens D Garcia-Tsao G Ferraioli G. Update to the Society of Radiologists in Ultrasound Liver Elastography Consensus Statement. Radiology. 2020; 296: 263-274 Crossref PubMed Scopus (164) Google Scholar ] is a widely used quality metric, but differences between IQR calculation methods constitute an unrecognized source of variability that has not been addressed by existing guidelines. Standardization could help to improve exam repeatability, reproducibility, inter-vendor comparability and non-invasive diagnostic evaluation of liver fibrosis.