Image-guided point-shear-wave elastography: a valid and reliable technique for liver fibrotic staging

Purpose Despite progressive implementation of image-guided point-shear wave elastography (pSWE) in guidelines as an alternative to transient elastography for the staging of fibrotic liver disease, pSWE is not widely adopted in clinical workflow. More information on reliability and validity of pSWE systems is needed. Therefore, we performed a phantom study to evaluate the validity and reliability of pSWE with ultrasound systems. Methods Validity and reliability of pSWE measurements from three ultrasound systems were evaluated. Measurements were performed on an elasticity phantom with reference elasticities of 7 +/- 1 (low) (median +/- interquartile range (IQR)), 14 +/- 2 (medium) and 26 +/- 3 (high) kPa. Measurements were repeated in tenfold for each reference at 2, 3 and 4 cm depth. Results were considered valid when median elasticity +/- IQR was between the uncertainty limits (IQR) for each reference elasticity value and reliable when IQR/median < 0.30. Results pSWE with the systems provided valid results for all reference elasticities and focal depths, except for overestimation of high reference elasticity at 2 and 4 cm depth for one system (41.5 +/- 4.3 and 39.0 +/- 1.2 kPa, respectively). Measurements were reliable with a maximum IQR/median of 0.13, well below the guideline of IQR/median < 0.30. Discussion The results support the use of pSWE as an alternative to invasive or non-image guided noninvasive techniques for liver fibrotic staging. Conclusions pSWE with ultrasound systems from different vendors is valid and reliable and can therefore be implemented to optimize clinical workflow by performing imaging and elastography simultaneously.