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Objective: To compare the predictive effects of stone size and volume on the efficacy and safety of retrograde intrarenal surgery (RIRS) and to determine the cutoff values of stone volume for prediction of RIRS efficacy and safety. Methods: Patients who underwent RIRS between 2017 and 2021 in six referral centers were retrospectively included in the study. The database of the RIRsearch group, which was formed prospectively, was used for this retrospective analysis. The surgical results and complications of RIRS were evaluated according to stone size and stone volume and compared between these groups. Results: A total of 1128 patients were included. Operation time, intraoperative complication rate, and postoperative complication rate increased significantly as stone size and stone volume increased (P <.05). Stone size and volume were significant indicators for stone-free rates, but pairwise comparison showed that stone volume was a significantly better predictor of surgical success compared with stone size (P <.001). Stone size was not sufficient to predict postoperative complications, whereas stone volume predicted these complications with low performance. Conclusions: Stone volume was a better predictor for surgical success than stone size, and it was as reliable as stone size in predicting postoperative complications. [ABSTRACT FROM AUTHOR]

BACKGROUND: Soft ureteroscopic holmium laser lithotripsy is becoming increasingly popular as the preferred method for treating mid-to-lower ureteral stones. Studies have indicated that the size, composition, hardness, and fragility of the stones can impact the treatment's effectiveness. OBJECTIVE: To explore the relationship between stone volume, average CT value and operation time and efficiency before ureteral soft lens laser lithotripsy. METHODS: Our study on 126 patients undergoing ureteroscopic holmium laser lithotripsy for ureteral calculi from May 2020 to January 2022 categorized them into groups based on stone volume and CT value. We compared surgical outcomes and analyzed correlations between stone characteristics, operation parameters, and stone clearance rate to identify independent risk factors influencing treatment efficacy. RESULTS: Group A demonstrated significantly shorter operation durations and lower blood loss compared to Group B, along with higher single stone clearance rates and fewer postoperative complications. Similarly, Group C exhibited shorter operation times, reduced blood loss, higher stone clearance rates, and lower complication rates than Group D. Preoperative stone volume and CT value correlated positively with operation time and stone clearance rate, with both factors identified as independent risk factors affecting ureteral stone clearance following holmium laser lithotripsy. CONCLUSION: The stone volume and average CT value before ureteral soft lens laser lithotripsy show a positive correlation with operation time and efficiency, indicating that larger stone volumes and higher CT values lead to slower lithotripsy speeds and reduced operation efficiency. Furthermore, preoperative stone volume and average CT value are identified as independent risk factors for residual stones. [ABSTRACT FROM AUTHOR]

Purpose: To establish a prediction model for repeated shockwave lithotripsy (SWL) efficacy to help choose an appropriate treatment plan for patients with a single failed lithotripsy, reducing their treatment burden. Patients and Methods: The clinical records and imaging data of 304 patients who underwent repeat SWL for upper urinary tract calculi (UUTC) at the Urology Centre of Shiyan People’s Hospital between April 2019 and April 2023 were retrospectively collected. This dataset was divided into training (N = 217; 146 males [67.3%] and 71 females [32.7%]) and validation (N = 87; 66 males [75.9%] and 21 females [24.1%]) sets. The overall predictive accuracy of the models was calculated separately for the training and validation. Receiver operating characteristic (ROC) curves were plotted, and the area under the ROC curve (AUC) was calculated. The normalized importance of each independent variable (derived from the one-way analyses) in the input layer of the artificial neural network (ANN) model for the dependent variable (success or failure in repeat SWL) in the output layer was plotted as a bar chart. Results: This study included 304 patients, of whom 154 (50.7%) underwent successful repeat SWL. Predictive models were constructed in the training set and assessed in the validation set. Fourteen influencing factors were selected as input variables to build an ANN model: age, alcohol, body mass index, sex, hydronephrosis, hematuria, mean stone density (MSD), skin-to-stone distance (SSD), stone heterogeneity index (SHI), stone volume (SV), stone retention time, smoking, stone location, and urinary irritation symptom. The model’s AUC was 0.852 (95% confidence interval (CI): 0.8–0.9), and its predictive accuracy for stone clearance in the validation group was 83.3%. The order of importance of the independent variables was MSD > SV > SSD > stone retention time > SHI. Conclusion: Establishing an ANN model for repeated SWL of UUTC is crucial for optimizing patient care. This model will be pivotal in providing accurate treatment plans for patients with an initial unsuccessful SWL treatment. Moreover, it can significantly enhance the success rate of subsequent SWL treatments, ultimately alleviating patients’ treatment burden. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate whether computer program-estimated urolith stone volume (SV) was a better predictor of spontaneous passage (SP) compared with program-estimated stone diameter (PD) or manually measured stone diameter (MD), and whether utilizing SV and MD together provided additional value in SP prediction compared with MD alone. Materials and Methods: Retrospective analysis of patients with acute renal colic and single renal/ureteral stone on CT from July 2017 to April 2020. Diameter obtained from radiology reports or manually measured when report not available. Semiautomated stone analysis software (qSAS) was used to estimate SV and PD. ROC analysis was performed to compare accuracy of SV vs MD vs PD in predicting SP by 2, 4, and 6 weeks. Subgroup analysis was performed by stone size (

Objective: Our study aimed to evaluate the success rate of ESWL and identify relevant treatment-specific factors affecting treatment outcomes, as well as to assess the accuracy of the updated Triple D scoring system and compare it with older systems. Material and Methods: A prospective study of 71 patients who received ESWL treatment for renal stones that were 5–15 mm in size was completed. The patient having no residual stones or residual stones lesser than 4 mm after ESWL was identified as a treatment success. Univariate and multivariate logistic regression and ROC curves were used to identify important factors for treatment outcomes. Results: Successful treatment was achieved for 66.2% of patients. The stone volume (SV), mean stone density (MD), and delivered power to the stone volume unit ratio (SMLI/SV) were defined as the most critical factors influencing ESWL success. An updated Triple D score system with a, SMLI/SV ratio could be an alternative to older systems and reach an even higher accuracy. A limitation of this study is the limited sample size due to the COVID-19 pandemic. Conclusions: Our results show that the three factors that most influence the success of ESWL are the stone size, mean stone density, and SMLI/SV ratio. Based on this, we present a simple updated triple D score system to predict ESWL success, which could be implemented in future clinical practice. [ABSTRACT FROM AUTHOR]

Objective:This study aimed to investigate peri-/postoperative effects of three-dimensional measurement of stone size in patients who underwent retrograde intrarenal surgery, where preoperative stone size calculations determine the operation decisions and prognosis. Another aim is to determine a limit value in cm3 for retrograde intrarenal surgery and to predict stone-free status based on this limit value.Materials and Methods:Data of 184 patients were retrospectively analysed. Patients were divided into two groups according to whether the stone-free status was achieved. Postoperative stone-free status and related effective parameters were analysed statistically.Results:No significant difference was found between age, gender, Hounsfield unit, length of hospital stay, secondary retrograde intrarenal surgery, renal unit abnormality, stone side, stone opacity, presence of additional ureteral stone, hydronephrosis and preoperative Double-J stent placement with stone-free rate. Subsequent interventions for residual stones, number of stones, stone sizes in cm2 and cm3 and operation time were determined as parameters that significantly affected the stone-free rate. As a result of the receiver operating characteristic analysis, the threshold stone size was 1.54 cm3.Conclusion:More accurate indications can be determined by calculating the volume of the stone. Retrograde intrarenal surgery success decreases in stones >1.54 cm3 by volume calculation. A different method such as percutaneous nephrolithotomy should be considered with higher preference for stones above this value.

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. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the additional utility of an automated method of estimating volume for stones being treated with shockwave lithotripsy (SWL) using computed tomography (CT) images compared to manual measurement. Utility was assessed as the ability to accurately measure stone burden before and after SWL treatment, and whether stone volume is a better predictor of SWL outcome than stone diameter. 72 patients treated with SWL for a renal stone with available CT scans before and after treatment were included. Stone axes measurement and volume estimation using ellipsoid equations were compared to volume estimation using software using CT textural analysis (CTTA) of stone images. There was strong correlation (r > 0.8) between manual and CTTA estimated stone volume. CTTA measured stone volume showed the highest predictive value (r2 = 0.217) for successful SWL outcome on binary logistic regression analysis. Three cases that were originally classified as 'stone-free with clinically insignificant residual fragments' based on manual axis measurements actually had a larger stone volume based on CTTA estimation than the smallest fragments remaining for cases with an outcome of 'not stone-free'. This study suggests objective measurement of total stone volume could improve estimation of stone burden before and after treatment. Current definitions of stone-free status based on manual measurements of residual fragment sizes are not accurate and may underestimate remaining stone burden after treatment. Future studies reporting on the efficacy of different stone treatments should consider using objective stone volume measurements based on CT image analysis as an outcome measure of stone-free state. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to investigate peri-/postoperative effects of three-dimensional measurement of stone size in patients who underwent retrograde intrarenal surgery, where preoperative stone size calculations determine the operation decisions and prognosis. Another aim is to determine a limit value in cm3 for retrograde intrarenal surgery and to predict stone-free status based on this limit value. Materials and Methods: Data of 184 patients were retrospectively analysed. Patients were divided into two groups according to whether the stonefree status was achieved. Postoperative stone-free status and related effective parameters were analysed statistically. Results: No significant difference was found between age, gender, Hounsfield unit, length of hospital stay, secondary retrograde intrarenal surgery, renal unit abnormality, stone side, stone opacity, presence of additional ureteral stone, hydronephrosis and preoperative Double-J stent placement with stone-free rate. Subsequent interventions for residual stones, number of stones, stone sizes in cm2 and cm3 and operation time were determined as parameters that significantly affected the stone-free rate. As a result of the receiver operating characteristic analysis, the threshold stone size was 1.54 cm³. Conclusion: More accurate indications can be determined by calculating the volume of the stone. Retrograde intrarenal surgery success decreases in stones >1.54 cm3 by volume calculation. A different method such as percutaneous nephrolithotomy should be considered with higher preference for stones above this value. [ABSTRACT FROM AUTHOR]

Introduction: Current literature suggests various predictors related to the stone and patient, which could influence stone fragmentation and clearance rates. Aim: To establish clinical characteristics of stone disease for patients undergoing extracorporeal shockwave lithotripsy (ESWL) which may predict the success of the procedure. Material and methods: One hundred and nine patients with renal stone disease diagnosed by non-contrast computed tomography (NCCT) who underwent ESWL between January 2015 and December 2019 were included in the study. Endpoints: patient being stone free (SF) or when < 4 mm fragments were detected. Age, gender, location, skin-to-stone distance, maximum stone length, stone volume, stone surface area, mean stone Hounsfield units (HU) and highest HU score were explored in uni- and multivariate regression analysis. Results: Stone size revealed the highest prognostic power for ESWL failure, where OR for stone volume and stone surface area were 1.06 (1.03-1.10) and 1.04 (1.02-1.06), respectively (all p < 0.01) while a tendency was observed for skin-to-stone distance 1.02 (1.00-1.03). The amount of energy applied during the procedure to one cubic millimeter of stone volume (SMLI/stone volume) was predictive for treatment success (OR = 0.60, 95% CI: 0.41-0.87, p < 0.01). Stone volume (OR = 1.06, 95% CI: 1.00-1.14, p = 0.01) and stone surface area (OR = 1.03, 95% CI: 1.01-1.06, p = 0.02) remained as statistically significant prognostic factors for treatment failure. Conclusions: Both greater stone volume and stone surface area, as well as lower power delivered per stone volume unit during the ESWL procedure, were found to be significant factors and could be useful to predict treatment failure. [ABSTRACT FROM AUTHOR]

Objective To analyze the influencing factors for stone clearance after retrograde intrarenal stone surgery(RIRS) in patients with nephrolithiasis and the predictive efficacy of preoperative cumulative stone diameter(CSD) and stone volume on stone clearance. Methods A total of 200 consecutive kidney stone patients who underwent elective RIRS in the Second Affiliated Hospital of Zhengzhou University from June 2018 to January 2020 were selected. According to stone clearance status after RIRS, they were divided into the stone clearance group(167 patients) and residual stone group(33 patients). Univariate and multivariate Logistic regression analyses were used to analyze the influencing factors for the stone clearance after RIRS in kidney stone patients. Receiver operating characteristic(ROC) curves were drawn to analyze the value of preoperative CSD and stone volume for predicting stone clearance after RIRS in patients with nephrolithiasis.Results Significant differences were found in the number of stones, CSD, and stone volume between the stone clearance group and the residual stone group(all P<0.05); the results of multivariate analysis showed that CSD and stone volume were significant influencing factors for stone clearance after RIRS. When CSD≤26 mm, CSD had similar predictive ability as stone volume(P<0.05); when CSD>26 mm, CSD was less predictive than stone volume(P<0.05). When the number of stones was 1, CSD showed similar predictive value as stone volume(P>0.05); when the number of stones was 2 to 3, CSD showed similar predictive value as stone volume(P>0.05); when the number of stones was ≥4, the CSD showed no statistical significance for the assessment of stone clearance after RIRS(P>0.05), but stone volume still showed some predictive value(P<0.05).Conclusions CSD and stone volume are influencing factors for stone clearance after RIRS in patients with nephrolithiasis; preoperative CSD and stone volume are effective predictors for stone clearance after RIRS in nephrolithiasis patients with CSD≤26 mm or stone number<4, and stone volume is a valid predictor for stone clearance after RIRS in nephrolithiasis patients with CSD > 26 mm or stone number≥4. [ABSTRACT FROM AUTHOR]

Objective: Current interventional guidelines refer to the cumulative stone diameter to choose the appropriate surgical modality (ureteroscopy [URS], extracorporeal shockwave lithotripsy [ESWL] and percutaneous nephrolithotomy [PCNL]). The stone volume (SV) has been introduced recently, to better estimate the stone burden. This review aimed to summarize the available methods to evaluate the SV and its use in urolithiasis treatment., Material and Methods: A comprehensive review of the literature was performed in December 2022 by searching Embase, Cochrane and Pubmed databases. Articles were considered eligible if they described SV measurement or the stone free rate after different treatment modalities (SWL, URS, PCNL) or spontaneous passage, based on SV measurement. Two reviewers independently assessed the eligibility and the quality of the articles and performed the data extraction., Results: In total, 28 studies were included. All studies used different measurement techniques for stone volume. The automated volume measurement appeared to be more precise than the calculated volume. In vitro studies showed that the automated volume measurement was closer to actual stone volume, with a lower inter-observer variability. Regarding URS, stone volume was found to be more predictive of stone free rates as compared to maximum stone diameter or cumulative diameter for stones >20 mm. This was not the case for PCNL and SWL., Conclusions: Stone volume estimation is feasible, manually or automatically and is likely a better representation of the actual stone burden. While for larger stones treated by retrograde intrarenal surgery, stone volume appears to be a better predictor of SFR, the superiority of stone volume throughout all stone burdens and for all stone treatments, remains to be proven. Automated volume acquisition is more precise and reproducible than calculated volume., (Copyright © 2023 AEU. Published by Elsevier España, S.L.U. All rights reserved.)

Objectives: To validate AutoMated UroLithiasis Evaluation Tool (AMULET) software for kidney stone volumetry and compare its performance to standard clinical practice. Materials and Methods: Maximum diameter and volume of 96 urinary stones were measured as reference standard by three independent urologists. The same stones were positioned in an anthropomorphic phantom and CT scans acquired in standard settings. Three independent radiologists blinded to the reference values took manual measurements of the maximum diameter and automatic measurements of maximum diameter and volume. An “expected volume” was calculated based on manual diameter measurements using the formula: \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\usepackage{upgreek}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} $$V = \frac { 4 } { 3 } \pi { r^3 } $$ \end{document} Results: Ninety-six stones were analyzed in the study. We had initially aimed to assess 100. Nine were replaced during data acquisition due of crumbling and four had to be excluded because the automated measurement did not work. Mean reference maximum diameter was 13.3 mm (5.2–32.1 mm). Correlation coefficients among all measured outcomes were compared. The correlation between the manual and automatic diameter measurements to the reference was 0.98 and 0.91, respectively ( p  < 0.001). Mean reference volume was 1200 mm3 (10–9000 mm3). The correlation between the “expected volume” and automatically measured volume to the reference was 0.95 and 0.99, respectively ( p  < 0.001). Conclusions: Patients' kidney stone burden is usually assessed according to maximum diameter. However, as most stones are not spherical, this entails a potential bias. Automated stone volumetry is possible and significantly more accurate than diameter-based volumetric calculations. To avoid bias in clinical trials, size should be measured as volume. However, automated diameter measurements are not as accurate as manual measurements. [ABSTRACT FROM AUTHOR]

Objectives To determine the optimal method for assessing stone volume, and thus stone burden, by comparing the accuracy of scalene, oblate, and prolate ellipsoid volume equations with three-dimensional (3 D)-reconstructed stone volume., Kidney stone volume may be helpful in predicting treatment outcome for renal stones. While the precise measurement of stone volume by 3 D reconstruction can be accomplished using modern computer tomography ( CT) scanning software, this technique is not available in all hospitals or with routine acute colic scanning protocols. Therefore, maximum diameters as measured by either X-ray or CT are used in the calculation of stone volume based on a scalene ellipsoid formula, as recommended by the European Association of Urology., Methods In all, 100 stones with both X-ray and CT (1-2-mm slices) were reviewed. Complete and partial staghorn stones were excluded., Stone volume was calculated using software designed to measure tissue density of a certain range within a specified region of interest., Correlation coefficients among all measured outcomes were compared. Stone volumes were analysed to determine the average 'shape' of the stones., Results The maximum stone diameter on X-ray was 3-25 mm and on CT was 3-36 mm, with a reasonable correlation ( r = 0.77)., Smaller stones (<9 mm) trended towards prolate ellipsoids ('rugby-ball' shaped), stones of 9-15 mm towards oblate ellipsoids (disc shaped), and stones >15 mm towards scalene ellipsoids., There was no difference in stone shape by location within the kidney., Conclusions As the average shape of renal stones changes with diameter, no single equation for estimating stone volume can be recommended., As the maximum diameter increases, calculated stone volume becomes less accurate, suggesting that larger stones have more asymmetric shapes., We recommend that research looking at stone clearance rates should use 3 D-reconstructed stone volumes when available, followed by prolate, oblate, or scalene ellipsoid formulas depending on the maximum stone diameter. [ABSTRACT FROM AUTHOR]

The lithiasic size is a determining factor in selecting the most suitable treatment, surgical or medical. However, the method for obtaining a reliable lithiasic size is not standardized. Our objetives are to determine the differences between the estimated lithiasic sizes shown by plain radiography test and by computerized axial tomography (CT) scan (using different techniques) in relation to the actual size, and to establish which is the ideal type of imaging for this purpose. We present an in vitro model with lithiasis obtained in cooperation with four centers. Inclusion criteria: lithiasis >0.5 cm, intact, and visible via simple radiography. A sample of 245 lithiases was obtained, with 87 rejected as they did not fulfill the inclusion criteria. Initially the three main actual diameters of each lithiasis were measured with a calibrator, then a plain X-ray and a CT scan were taken of the samples to determine the surface size in cm 2 for simple radiography; surface size and volume in cm 3 for CT scan, in bone window and soft tissue (Toshiba Aquillion 64, sections of 0.5 mm, 120 Kv, 250 mA). The tomographic area was calculated by employing the formula recommended by the European Association of Urology and scanner software. The actual, radiographic and tomographic measurements were taken by three different researchers who were unaware of the results obtained by the each other. The statistics program IBM SPSS Statistics ® 19 was used. Differences were analyzed using the Wilcoxon sign test. The bone window CT scan slightly overestimated the actual lithiasic size (0.12 vs. 0.17 cm 3), while in soft tissue window the actual volume was practically doubled (0.12 vs. 0.21 cm 3) ( p < 0.05). We did not find statistically significant differences in the comparison between actual surface size (0.39 cm 2) and bone window CT scan size when using the EAU formula or scanner software (0.36/0.37 cm 2). Resulting measurements in soft tissue window tended to significantly overestimate the surface size, although only slightly (0.42/0.44 cm 2), whilst the plain radiography underestimated it slightly but significantly (0.37 cm 2). CT scan, using the bone window, is the technical methodology with which the greatest in vitro accuracy in which actual lithiasis measurements can be estimated, although the craniocaudal diameter measurement will be overestimated. Using soft tissue window gives an overestimated size. [ABSTRACT FROM AUTHOR]

Objective: The aim of the investigation was to determine the influence of such parametric characteristics of the stone such as size and volume on the duration of tulium laser disintegration of the urinary stone and to determine which of these parameters is more effective to use like prognostic criterion for the duration of the planned surgical intervention in the percutaneous nephrolithotripsy., Materials and Methods: Overall 52 patients (27 females and 25 males) with an average age of 56,9 (25-79) years participated in the present study. All patients underwent percutaneous nephrolithotripsy with disintegration of the kidney stone by thulium energy. Inclusion criteria were: stone size more or equal 2 cm, stone density >1100 HU. Exclusion criteria were: patients with a single kidney, urinary tract divertions, coagulopathy. The average operation time was 30 (15-100) minutes, with an average puncture time of 3.15 (1-10) minutes and lithotripsy time of 28 (14-98) minutes. To determine the volume we used the method of automatic lithometry according to CT data using the software: Vitrea ver. 4.1.52. The size of the stone was determined by the longest length in one of the plane. During the study it was found that the average size of the stone was 28.25 (20-58) mm and the average volume was 2579.4 (250-9990) mm3. To confirm our assumption, we decided to determine the dependence of the time of disintegration of the stone on the size and volume of the stone. For this purpose, we graphically presented the correlation of these parameters., Results: We have drawn 2 graphs reflecting the dependence of lithotripsy time parameters on the size and volume characteristics of the stone. As a result of comparing these parameters we found that size is a prognostically less reliable predictor of lithotripsy time, and is not characterized by a linear distribution, in contrast to the stone volume., Conclusions: Thereby, the main stereoscopic characteristic of a stone is a volume, which should be the primary guide in selecting the preferred method of treatment as well as in predicting the operative time and associated risks.

OBJECTIVE To evaluate the efficacy of stone volume measured using a three-dimensional (3D) reconstruction of preoperative non-contrast computed tomography (NCCT) as an independent predictor of success after extracorporeal shock wave lithotripsy (ESWL) of upper urinary tract calculi. PATIENTS AND METHODS We evaluated preoperative NCCT in 94 patients who had ESWL for solitary upper urinary tract calculi of 4–20 mm in diameter. Axial images were used to measure the skin-to-stone distance (SSD), Hounsfield Unit (HU) density and axial stone diameter. Stone volume was calculated on a volume-rendered 3D image for each stone. Maximum stone length was determined by comparative measurements of each stone in coronal, sagittal and axial planes, and was also measured on a plain abdominal film before ESWL. For ESWL we used the DoliS lithotripter (Dornier Medical Systems, Marrietta, GA, USA). A plain film at 6 weeks was used to categorize patients as stone-free (SF) or with residual stone. RESULTS In all, 58 (62%) patients were SF and 36 (38%) had RS; the mean stone volume was significantly different between these groups (274 vs 464 µL, P = 0.002). Logistic regression analysis showed that stone volume was the strongest predictor of SF status ( P < 0.001), compared to peak HU ( P = 0.015), mean HU ( P = 0.04) and axial stone diameter ( P = 0.006). The body mass index, SSD and maximum stone length on NCCT or a plain film did not predict success. A stone volume of <500 µL best predicted treatment success ( P < 0.001) with 72% of patients with a stone volume of <500 µL having a successful outcome, vs only 27% with a stone volume of >500 µL. CONCLUSION Our study suggests that stone volume is an optimal predictor of SF status after ESWL of solitary upper urinary tract calculi. [ABSTRACT FROM AUTHOR]

Objectives: We researched to detect the optimal method for evaluating stone volume, by comparing the ellipsoid formula and 3D reconstructed volume to gold standard of water displacement volume using 3D printed models., Methods: We retrospectively analyzed out patient database and evaluated 27 patients who had percutaneous nephrolithotripsy. From the DICOM data of patient's preoperative CT images, stone structures were obtained using an image identification system. All DICOM files were saved in the stereolithography file format and a 3D printed model was created. True stone volume was found by water displacement method using this model and this volume compared with ellipsoid formula and 3D-reconstructed volume., Results: Stone volume on water displacement ranged from 0.38-29.8cm3 with a median of 17.5cm3, stone volume on ellipsoid formula ranged from 0.46-34.7cm3 with a median of 19.6cm3 and stone volume on CT based 3D-reconstructed ranged from 0.48-31.8cm3 with a median of 18.9cm3. There was a significant difference between ellipsoid formula and water displacement ( p <   0.0001 ); however, there was no difference between 3D-reconstructed volume and water displacement ( p = 0.051 )., Conclusion: Stone volume calculation using CT based 3D-reconstructed algorithm improves the accuracy of stone volume estimation and this measurement is superior to ellipsoid formula.

Objective: The objective of this prospective study is to evaluate the consistency of renal stone volume estimation using dual-energy CT across scanner model and reconstruction algorithm configurations., Subjects and Methods: Patients underwent scanning with routine kidney stone composition protocols on both second- and third-generation dual-source CT scanners. Images were reconstructed using filtered back projection and iterative reconstruction (IR). In addition, a modified IR kernel on the third-generation CT scanner was evaluated. Individual kidney stone volumes were determined and compared., Results: No significant difference was noted in measured volumes between filtered back-projection data, IR data from the second-generation scanner, and the modified IR kernel data (p > 0.05). The third-generation commercially available IR kernel yielded lower volumes than did the other configurations (p < 0.0001)., Conclusion: With the use of a modified kernel for the third-generation scanner, patients being monitored for changes in kidney stone volume can undergo scanning performed with second- or third-generation dual-energy CT scanners, and the images obtained can be reconstructed with either filtered back projection or IR without the introduction of bias into kidney stone volume measurements.