SWL literature
SWL Literature

Kobayashi M. et al., 2021: Variables measured on three-dimensional computed tomography are preferred for predicting the outcomes of shock wave lithotripsy.

Kobayashi M, Waseda Y, Fuse H, Takazawa R.
Department of Urology, Tokyo Metropolitan Ohtsuka Hospital, 2-8-1 Minami-Ohtsuka, Toshima, Tokyo, 170-8476, Japan.
Department of Urology, Tokyo Metropolitan Ohtsuka Hospital, 2-8-1 Minami-Ohtsuka, Toshima, Tokyo, 170-8476, Japan.

Abstract

Purpose: Shock wave lithotripsy (SWL) is used to treat upper urinary tract stones. Recently, some volume analyzers have enabled preoperative assessment using three-dimensional computed tomography (3D-CT). We evaluated the efficacy of 3D-CT variables for predicting the outcomes of SWL.

Methods: The study population included 193 patients who underwent SWL between November 2014 and August 2020. In addition to conventional two-dimensional computed tomography (2D-CT) assessments, 3D-CT assessments of targeted stones were retrospectively performed, and stone size and stone density (SD) were measured. The successful and unsuccessful treatment groups were compared and risk factors for an unsuccessful first SWL session were investigated. The predictive accuracy of variables measured on 3D-CT was evaluated by receiver operating characteristic curves and multivariate analyses.

Results: The success rate of the first SWL session was 73.1%. Stone volume, mean SD and highest SD on 3D-CT were significantly higher in the unsuccessful group than in the successful group. Stone volume showed a higher area under the curve (AUC) than the estimated volumetric stone burden and stone diameter, which were measured on 2D-CT (0.729, 0.683, and 0.672, respectively). The AUCs of the mean SD and highest SD on 3D-CT were higher than those on 2D-CT (0.699, 0.680, 0.617, and 0.627, respectively). Multivariate analyses identified stone volume (≥ 0.29 ml), mean SD on 3D-CT (≥ 421 HU), and absence of hydronephrosis as independent predictive factors for unsuccessful SWL.

Conclusion: 3D-CT variables were promising predictors of the outcomes of SWL. Preoperative 3D-CT assessment is helpful for selecting favorable patients for SWL.
World J Urol. 2021 Oct 23. doi: 10.1007/s00345-021-03861-9. Online ahead of print. PMID: 34687343.

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Comments 1

Hans-Göran Tiselius on Thursday, May 26 2022 08:30

Today most reports on SWL conclude that in terms of stone-free rates this treatment modality is inferior to both URS and PCNL. Accordingly, the authors of this report emphasize the necessity to appropriately select patients for SWL by improved measurement of the stone burden.
The outcome of SWL with Sonolith i-move lithotripter was described as successful or unsuccessful and of the 193 patients included in the study a successful outcome was recorded in 141 (73%) but unsuccessful in 52 (27%). There was a dominance of patients with stones in the proximal ureter.
The conclusion from this retrospective analysis was that information on stone volumes obtained from 3D-CT measurements were more precise for predicting outcome of SWL than was prediction from calculated volumes based on measurements from 2D-CT. It is not surprising that the outcome of SWL was related to the more exact estimate of the stone volume.
It should be noted, however, that neither the calculated stone volume nor even any estimates of the stone surface area commonly are used clinically or in most scientific reports. Most commonly is the stone burden expressed as the largest stone diameter and for several stones as the very inexact sum of diameters!
Below is a table with optimal cut-off values for 2D-CT and 3D-CT as reported in the article:

https://www.storzmedical.com/images/blog/Kobayashi.JPG

Hans-Göran Tiselius

Today most reports on SWL conclude that in terms of stone-free rates this treatment modality is inferior to both URS and PCNL. Accordingly, the authors of this report emphasize the necessity to appropriately select patients for SWL by improved measurement of the stone burden. The outcome of SWL with Sonolith i-move lithotripter was described as successful or unsuccessful and of the 193 patients included in the study a successful outcome was recorded in 141 (73%) but unsuccessful in 52 (27%). There was a dominance of patients with stones in the proximal ureter. The conclusion from this retrospective analysis was that information on stone volumes obtained from 3D-CT measurements were more precise for predicting outcome of SWL than was prediction from calculated volumes based on measurements from 2D-CT. It is not surprising that the outcome of SWL was related to the more exact estimate of the stone volume. It should be noted, however, that neither the calculated stone volume nor even any estimates of the stone surface area commonly are used clinically or in most scientific reports. Most commonly is the stone burden expressed as the largest stone diameter and for several stones as the very inexact sum of diameters! Below is a table with optimal cut-off values for 2D-CT and 3D-CT as reported in the article: [img]https://www.storzmedical.com/images/blog/Kobayashi.JPG[/img] Hans-Göran Tiselius
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Sunday, June 26 2022
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