Ultrasound point shear wave elastography assessment of liver and spleen stiffness: effect of training on repeatability of measurements.

OBJECTIVES: To evaluate reproducibility of measurements of spleen stiffness (SS) and liver stiffness (LS) at several sites by using point shear wave elastography (pSWE) and to investigate any training effect.
METHODS: Healthy volunteers were consecutively enrolled. Measurements of SS and LS were performed by an expert (observer 1) and a novice (observer 2) at three different sites of liver and spleen. To assess the effect of training the study was conducted in two periods (period 1 and period 2). Concordance correlation coefficient was used to assess intra-observer and inter-observer reproducibility.
RESULTS: A total of 92 subjects (67 men and 25 women) were enrolled in the study. Both intra-observer and inter-observer agreement were higher for the liver than for the spleen. Overall, the highest intra-observer and inter-observer agreement were obtained for the assessment of LS through intercostal space, and for measurements at this site there was a significantly better performance of observer 2 after the training period. For both observers, training improved the repeatability of SS measurements at all sites. A good intra-observer agreement was obtained only for measurements at the spleen lower pole.
CONCLUSIONS: The results of this study show that a learning curve in pSWE acquisition should be taken into account both for SS and LS measurements. KEY POINTS: Reproducibility of SS measurements depends on the expertise of the operator. To achieve good reproducibility between measurements a training period is required. A learning curve in pSWE acquisition should be taken into account. SS measurements are less reproducible than LS measurements.