Use Of Computed Tomography-Based Nomogram In Adult Age Patients To Predict Success Rates After Shock Wave Lithotripsy For Renal Stones: A Single Center Experience.

BACKGROUND: The Triple D score is a novel and easy to use nomogram to predict shock-wave lithotripsy (SWL) outcomes. It is based on Computed Tomography (CT scan) parameters including stone density, skin-to-stone distance, and stone volume. However, its use has not been validated much as studies are sparse regarding its use. Our aim was to validate and evaluate accuracy of the Triple D scoring system in predicting SWL success rates. METHODS: It was a prospective study of 277 patients who had undergone SWL procedure for renal stones. They were evaluated by using non-contrast tomography, before undergoing SWL. CT scan-based parameters including distance of stone to skin (SSD), stone volume (SV), stone density was assessed. Computation of Cut off values was done with receiver operating characteristics analysis. Score was assigned on the basis of these cut-off values and success rate of SWL was determined. This score ranged from 0 (least favourable score) to 3 (most favourable score). RESULTS: Stone-free status was attained in 160 patients (57.7%), and 117 (42.3%) patients were labelled to have failed the procedure. Differences between these two groups in terms of Stone volume, stone density and skin to stone distance were significant. Triple D scores of zero,1, 2, and 3 had stone-free rates of 3.6%, 52.56%, 53.3%, and 93.1% respectively (p-vaue<0.001). CONCLUSIONS: Shock-wave lithotripsy outcomes can be predicted with use of Triple D score and hence, it's externally corroborated. It may help urologist in appropriate patient selection and hence decision making and patient counselling.

Role of Stone Heterogeneity Index in Determining Success of Shock Wave Lithotripsy in Urinary Calculi.

INTRODUCTION: Various stone factors can affect the outcome of shock wave lithotripsy (SWL). A novel factor called the stone heterogeneity index (SHI) may have an impact on stone free rates. The objective of this study was to assess the role of SHI in SWL outcomes. METHODS: Patients' medical records were reviewed for the collection of data variables. They were subjected to SWL, using an electromagnetic lithotripter machine (Storz Modulith SLX-MX). Computation of mean stone density (mean value of the Hounsfield units) and SHI was accomplished by generating elliptical regions of interest on the computed tomography (CT) scan images. Grouping was performed on the basis of stone free and failure outcomes. Relevant statistical tests were applied for continuous and categorical variables. P ≤ 0.05 was considered statistically significant. RESULTS: Overall, 385 subjects were included having a mean age of 38.4 ± 14.7 years. The cohort comprised 276 (71.7%) males and 109 (28.3%) female patients. A total of 234 (60.8%) patients were rendered successful (stone free after one session) while 151 (39.2%) of the patients were declared to have failed the SWL procedure. Stone length, stone density, and SHI values were 13.7 ± 7.6 mm, 935 ± 404, and 201 ± 107, respectively. The stone density, SHI, and stone length were significantly different between the two groups (p-values of 0.001, 0.02, and 0.04, respectively). CONCLUSIONS: SHI can be a helpful CT scan-based parameter to assess stone fragility. It can help clinicians in the judicious selection of patients before implementing SWL procedure. RELEVANCE FOR PATIENTS: Non-contrast CT-based stone parameters have been found to be effective for predictions of outcomes. SHI can be a helping tool to better predict SWL success rates when treating the renal stones.