Xu H. et al., 2025: The Association Between Stone Heterogenicity and the Success of Shock Wave Lithotripsy for High Density Upper Urinary Tract Stones: A Muti-Center Prospective Cohort.
Hanfeng Xu 1, Junlong Liu 2, Zheming Li 3, Chengshan Ge 4, Hongqiang Guo 5, Shiyu Song 6, Zhenhua Li 7, Song Bai 8
1Department of Urology, The First Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, China.
2Department of Urology, Shengjing Hospital of China Medical University, Shenyang, China.
3Department of Urology, Shengjing Hospital of China Medical University, Shenyang, China.
4The Fifth Hospital of Liaoyang City, Liaoyang, China.
5The Fifth Hospital of Liaoyang City, Liaoyang, China.
6Luhe Hospital of Yingkou City, Beijing, China.
7Department of Urology, Shengjing Hospital of China Medical University, Shenyang, China.
8Department of Urology, Shengjing Hospital of China Medical University, Shenyang, China.
Abstract
Objective: To prospectively investigate the predictive value of radiological stone heterogenicity for the success of shock-wave lithotripsy (SWL) in patients with high-density upper urinary tract stones.
Methods: This multi-center prospective study was conducted from June 2020 to December 2023. The radiological stone density index measured by computed tomography (CT) included the mean, standard deviation (SD), and coefficient variation (CV) of the Hounsfield Unit value of stones. The success was defined as no evidence of clinically significant stone fragments (≥4 mm) on a plain X-ray and ultrasound of the upper urinary tract 1 month after SWL. Binary logistic regression models were used to assess the odds ratios (ORs) and 95% confidence intervals (CIs).
Results: Finally, 533 patients with high-density upper urinary tract stones were enrolled in this study. There were 68.5% (379/533) patients experienced success after SWL treatment. After adjusted confounding variables, compared with the patients in the lowest quartile of stone density index, the odds ratios (95% CI) for the extreme quartile was 1.42 (0.71, 2.81, P for trend = .443), .03 (.01, .09, P for trend <.001), and .02 (.01, .07, P for trend <.001) for MSD, SD, and CV, respectively. Furthermore, this linear association was confirmed only for SD and CV regardless of gender, body mass index, stone size, and stone location.
Conclusion: This multi-center prospective study demonstrated a positive association between the stone heterogenicity and the success of SWL in patients with high-density upper urinary tract stones regardless of gender, body mass index, stone size, and stone location. However, this association was not observed in mean stone density.
Urology. 2025 Feb;196:57-63. doi: 10.1016/j.urology.2024.10.069. Epub 2024 Nov 20.
PMID: 39577810
Comments 1
It is well recognized that the internal structure of urinary stones is one factor that determines the disintegration properties. Accordingly, with many reflection surfaces such as that in stones with a high degree of porosity, fragmentation is improved compared with that in solid stones with little reflection. Successful SWL thus should be expected in stones with heterogeneous morphology.
It is, however, not easy to determine heterogeneity on radiographic images.
The authors of this report compared clinical outcome wih successful and unsuccessful SWL and concluded from the multicenter study that mean stone density expressed in HU was an insufficient variable for predicting disintegration. In contrast, the SD (standard deviation) of stone density and its CV(coefficient of variation) had a better predictive value. It is my understanding that these variables were derived from the NCCT image of the stone in one plane. Thereby they calculated a stone heterogeneity index.
CV= SD/MSD (mean stone densitry) x 100%
An association was found between CV and faile disintegration.
It had of course been of further interest to measure the variables in the volume of the stone. The reason for extensive measurements is that the statistical differences between CV in success and failure were small 14±4 and 10±3.
Hans-Göran Tiselius