Ultraschall Med 2016; 37 - SL19_5
DOI: 10.1055/s-0036-1587808

Shear wave elastography: interobserver agreement and influencing factors for liver stiffness measurement

WK Jeong 1, K Yoon 2, JA Hwang 1, JE Lee 1, JB Kim 1
  • 1Samsung Medical Center, Radiology, Seoul, Korea, Republic of
  • 2Hanyang University Guri Hospital, Radiology, Gyeonggi-do, Korea, Republic of

Purpose: To evaluate the interobserver reproducibility of 2-dimensional shear wave elastography (2D-SWE) in measuring liver stiffness and to investigate the clinical and measurement factors related to the reproducibility.

Material and methods: This study used the cohort of rheumatoid arthritis patients who have been treated with methotrexate and were enrolled under informed consent between August 2011 and August 2012. Two staff radiologists performed SWE by turns at the same day. The measurement was repeated 5 times, and the median value was considered as the liver stiffness. We investigated clinical factors such as age, sex, serum cholesterol, ALT level, BMI, and waist circumference. We also considered the mean standard deviations (SD) of region of interest and mean size of ROI (ROI) as a measurement factor to investigate the relationship with LS. To investigate interobserver agreement of LS and SD between the first and second observations, we calculated concordance correlation coefficient. To explore the interobserver difference, we calculated the absolute difference of liver stiffness between two consequent observations. As well as the clinical factors, SD and ROI were considered as possible influencing factors. Uni- and multivariate linear regression analyses were also performed.

Result: One hundred and seventy six patients (M:F = 40:136; mean age, 55 ± 9.3 years) were subsequently enrolled. Concordance correlation coefficients for LS and SD were 0.76 and 0.62, respectively. Univariate linear regression analysis showed that BMI, waist circumference, SD, and ROI had significant correlation with interobserver difference of liver stiffness (p = 0.020, p = 0.019, p < 0.001, and p < 0.001, respectively). On the other hand, multivariate linear regression analysis revealed that only SD and ROI had significant correlation with interobserver difference of liver stiffness (p < 0.001 and p = 0.021, respectively).

Conclusion: Interobserver agreement of liver stiffness measurement using 2D-SWE was moderate to good. Mean SD and mean size of ROI were significant factors related to interobserver difference.