Usability of shear wave elastography to predict the success of extracorporeal shock-wave lithotripsy: prospective pilot study.

The present study is intended to investigate the usability of shear wave elastography (SWE) in predicting the success of extracorporeal shock-wave lithotripsy (ESWL) used in kidney stone treatment. ESWL was performed on a total number of 52 patients diagnosed with kidney stones between May 2019 and July 2020. The presence of a residual stone greater than 4 mm was accepted as failure. The patients were divided into two groups as ESWL success and ESWL failure. SWE and Hounsfield unit (HU) measurements of stones were performed in all patients before ESWL. The two groups were compared in terms of age, gender, stone localisation, stone size, body mass index (BMI), skin-to-stone distance, HU, and SWE values of the stones. ESWL was successful in 30 of the 52 patients included in the study, while it failed in 22 of them. While the mean SWE value was 7.3 (7.9 ± 2.2) kPa in patients with success in ESWL, it was 14.6 (17.9 ± 10.2) kPa in those with failed ESWL. The mean HU was 883.5 (841.4 ± 191.1) in patients with success in ESWL and 1078 (1115.5 ± 183) in those with failed ESWL. Both SWE and HU values of the stones were found to be statistically significantly lower in the successful group (p < 0.05). It was seen that SWE and HU values were correlated to each other. The groups of successful and failed ESWL did not differ significantly in terms of age, gender distribution, stone size, BMI, and skin-to-stone distance (p > 0.05). With SWE, the hardness of the stone can be measured and its suitability for ESWL can be evaluated. It can be used as an alternative parameter to HU before ESWL treatment, since it has a lower cost compared to computed tomography (CT) and does not contain radiation.