Skin-liver distance and interquartile range-median ratio as determinants of interoperator concordance in acoustic radiation force impulse imaging

• Published in: Journal of medical ultrasound Vol. 27; no. 4; pp. 177 - 180
• Main Authors: Su, Shu, Wang, Wayland, Nadebaum, David, Nicoll, Amanda, Sood, Siddharth, Gorelik, Alexandra, Lai, Jeffrey, Gibson, Robert
• Format: Journal Article
• Language: English
• Published: India Wolters Kluwer India Pvt. Ltd 01.10.2019; Wolters Kluwer - Medknow
• Subjects: Original; fibrosis; Elasticity imaging techniques; liver; ultrasonography; obesity
• ISSN: 0929-6441; 2212-1552
• DOI: 10.4103/JMU.JMU_124_18

Context and Aims: The accuracy of acoustic radiation force impulse (ARFI) ultrasound compared to liver biopsy is higher when there is concordance between F-scores of two or more operators. We hypothesized that when the first operator interquartile range/median-velocity ratio (IMR) is <0.3 and skin-liver distance (SLD) is <2.5 cm, there is greater interoperator concordance and a second operator is not necessary. Subjects and Methods: Two-operator ARFI ultrasound measurements (F-score, SLD, and IMR) were recorded for 927 consecutive patients. Chi-squared testing compared interoperator concordance for SLD <2.5 cm versus SLD ≥2.5 cm and IMR <0.3 versus IMR ≥0.3 when SLD <2.5 cm, in each of the F-score groups of 0/1, 2, 3, and 4. Results: Statistically significant differences were demonstrated between SLD <2.5 cm and SLD ≥2.5 cm groups for F-scores 0/1 or 4 (P = 0.005) and F-scores 2 or 3 (P < 0.001). Concordance, when SLD measured <2.5 cm, was more than 85% for all F-score groups. In the SLD <2.5 cm group, concordance fell below 85% when IMR ≥0.3, for all F-scores except F2. Specifically, P values comparing IMR <0.3 and IMR ≥0.3 in the various first operator F-score groups were P = 0.040 for F0/F1, P = 0.580 for F2, P = 0.342 for F3, and P < 0.001 for F4. Conclusions: ARFI measurements from one operator can be considered acceptable when SLD <2.5 cm and IMR <0.3. Otherwise, adding a second operator can improve confidence in the result.