Computed Tomography-Based Novel Prediction Model for the Outcome of Shockwave Lithotripsy in Proximal Ureteral Stones

How to estimate stone volume and its use in stone surgery: a comprehensive review

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.

Role of Noncontrast Computed Tomography Parameters in Predicting the Outcome of Extracorporeal Shock Wave Lithotripsy for Upper Urinary Stones Cases: A Meta-analysis

RATIONALE

Extracorporeal shock wave lithotripsy (ESWL) is widely considered the primary approach for managing urinary tract stones. This study aimed to assess the predictive factors associated with non-contrast computed tomography (NCCT)-based parameters of upper urinary stones in relation to the outcomes of ESWL.

MATERIALS AND METHODS

A systematic search was conducted in PubMed, ScienceDirect, Web of Science, and Cochrane Library to identify all relevant studies published up to June 3, 2023. Several NCCT-based parameters to predict ESWL outcomes, comprised of mean stone density (MSD), skin-to-stone distance (SSD), and stone size, were extracted and analyzed using Review Manager software.

RESULTS

Out of 979 publications screened, a total of 39 publications, involving 7869 patients, were enrolled in the analysis. The pooled estimate demonstrated significant differences between MSD, and stone size between successful and failure of stone fragmentation groups, in which lower values of these parameters are associated with successful ESWL outcomes.

CONCLUSION

The results from the current study suggested that lower NCCT parameters, notably MSD, SSD, and stone size, are significantly associated with successful ESWL outcome. However, additional large-scale prospective studies are required to utilize these parameters effectively, and the optimal cutoff value should be determined.

Role of Multidetector Computed Tomography Urography in the Evaluation of Obstructive Uropathy: A Review

Obstructive uropathy, a prevalent clinical problem, can irreparably harm the kidneys if not treated promptly. As a result, accurate diagnosis is necessary for prompt management. This study examines the utility of multidetector computed tomography (MDCT) urography in identifying obstructive uropathy. PubMed, Google, Embase, Medline, and other electronic databases were used to search the English-language literature. The search phrases were obstructive urinary infections or urinary bladder or kidneys or MDCT. The authors' expertise and experience in the subject area aided in archiving pertinent publications. Even though the dilated upper tract of the ureters can be seen, ultrasonography (USG) has limitations because it cannot show the middle portion of the ureters, even if they are dilated mostly due to bowel gas artifacts. The USG does not emphasize the functioning of the renal tract. To evaluate obstructive uropathy, MDCT urography plays a very important role. For speedy, effective therapy, it provides a quick diagnosis of the source of obstruction.

The effect of bioelectric impedance analysis on the success of extracorporeal shock wave lithotripsy

Bioelectric impedance analysis (BIA) is a non-invasive method that can show the distribution of fatty and lean mass of the body. In this study, we aimed to determine the effect of BIA on extracorporeal shock wave lithotripsy (SWL) success. Our secondary aim was to determine the factors predicting transition from a single SWL session to multiple sessions. Patients who underwent SWL due to kidney stones were prospectively included. Demographics, pre-procedural BIA parameters (fat percentage, obesity degree, muscle mass, total water and metabolic rate), stone parameters, and number of SWL sessions were recorded. Univariate and multivariate regression analyzes were made to determine independent risk factors for success. Then, the successful group was divided into two subgroups according to their SWL session number as one session or multiple sessions and multivariate regression analysis was made to determine independent risk factors. Stone-free status was achieved in 114 (61.2%) of 186 patients. Stone Hounsfield Unit (HU) (OR: 0.998, p = 0.004), stone volume (OR: 0.999, p = 0.023) and fat percentage (OR: 0.933, p = 0.001) were independent risk factors for stone-free status in multivariate analysis. HU value of the stone (OR: 1.003, p = 0.005) and age (OR: 1.032, p = 0.031) were determined as independent risk factors for transition to multiple sessions in the subgroup analysis of the successful group. Fat percentage, stone volume, and stone density were determined as factors affecting success in SWL. Routine use of BIA may be considered to predict success before SWL. The probability of SWL success in a single session decreases as the age and stone's HU value increase.

Role of Hounsfield Unit in Predicting Outcomes of Shock Wave Lithotripsy for Renal Calculi: Outcomes of a Systematic Review

PURPOSE OF REVIEW

Extracorporeal shock wave lithotripsy success rates depend on several stone and patient-related factors, one of which is stone density which is calculated on computed tomography scan in Hounsfield Units. Studies have shown inverse correlation between SWL success and HU; however, there remains considerable variation between studies. We performed a systematic review regarding the use of HU in SWL for renal calculi to consolidate the current evidence and address current knowledge gaps.

RECENT FINDINGS

Database including MEDLINE, EMBASE, and Scopus were searched from inception through August 2022. Studies in English language analysing stone density/attenuation in adult patients undergoing SWL for renal calculi were included for assessment of Shockwave lithotripsy outcomes, use of stone attenuation to predict success, use of mean and peak stone density and Hounsfield unit density, determination of optimum cut-off values, nomograms/scoring systems, and assessment of stone heterogeneity. 28 studies with a total of 4,206 patients were included in this systematic review with sample size ranging from 30 to 385 patients. Male to female ratio was 1.8, with an average age of 46.3 years. Mean overall ESWL success was 66.5%. Stone size ranged from 4 to 30 mm in diameter. Mean stone density was used by two-third of the studies to predict the appropriate cut-off for SWL success, ranging from 750 to 1000 HU. Additional factors such as peak HU and stone heterogeneity index were also evaluated with variable results. Stone heterogeneity index was considered a better indicator for success in larger stones (cut-off value of 213) and predicting SWL stone clearance in one session. Prediction scores had been attempted, with researchers looking into combining stone density with other factors such as skin to stone distance, stone volume, and differing heterogeneity indices with variable results. Numerous studies demonstrate a link between shockwave lithotripsy outcomes and stone density. Hounsfield unit < 750 has been found to be associated with shockwave lithotripsy success, with likelihood of failure strongly associated with values over 1000. Prospective standardisation of Hounsfield unit measurement and predictive algorithm for shockwave lithotripsy outcome should be considered to strengthen future evidence and help clinicians in the decision making.

TRIAL REGISTRATION

International Prospective Register of Systematic Reviews (PROSPERO) database: CRD42020224647.

A novel model using computed tomography parameters to predict shock wave lithotripsy success in ureteral stones at different locations

OBJECTIVE

To combine non-contrast computerized tomography (NCCT)-based parameters with stone and patient characteristics that are already known to affect shock wave lithotripsy (SWL) success and assess this novel model's effectiveness in predicting SWL success for single ureteral stones in different locations.

MATERIALS AND METHODS

Data of patients treated by SWL for a single ureteral stone between January 2017 and January 2019 were retrospectively reviewed. Demographic parameters of patients and stone characteristics were combined with NCCT-based parameters. NCCT-based parameters included the presence or absence of hydronephrosis, perinephric stranding, periureteral edema, diameter of the proximal ureter, ureteral wall thickness (UWT) at ureteral stone site. The logistic regression method was used for the development of a useful predictive model. Subsequently, the receiver operating curve was used to determine cut-off levels, and a scoring system was developed for prediction of SWL success.

RESULTS

Stone-free rate was 77,1% (267/346) in the entire cohort. Univariate analysis revealed that age, stone volume, density, perinephric stranding, diameter of proximal ureter, and UWT, were associated with SWL success. In multivariate analysis, proximal ureteral stone location, stone volume, density, and UWT were independent predictors of SWL success. The formula used during logistic regression analysis was: 1/[1 + exp {-8.856 + 0.008 (stone volume) + 0.002 (stone density) + 0.673 (UWT) + 1026 (proximal ureteral stone)}]. The scores of 0, 1, 2, 3 and 4 were associated with 97,8%, 83,4%, 60,8%, 33,2% and 11,1% success rates, respectively, in the prediction model based on these parameters.

CONCLUSION

We conclude that our model can facilitate decision-making for SWL treatment of ureteral stones in different locations.

Variables measured on three-dimensional computed tomography are preferred for predicting the outcomes of shock wave lithotripsy

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.

Atlas of scoring systems, grading tools and nomograms in Endourology: A comprehensive overview from The TOWER Endourological Society research group

INTRODUCTION

With an increase in the prevalence of kidney stone disease (KSD), there has been a universal drive to develop reliable and user-friendly tools such as grading systems and predictive nomograms. An atlas of scoring systems, grading tools and nomograms in Endourology is provided in this paper.

METHODS

A comprehensive search of world literature was performed to identify nomograms, grading systems and classification tools in endourology related to KSD. Each of these were reviewed by the authors and have been evaluated in a narrative format with details on those which are externally validated and their respective citation count on google scholar.

RESULTS

A total of 54 endourological tools have been described in our atlas of endourological scoring systems, grading tools and nomograms. Of the tools, 23 (43%) are published in the last 3 years showing an increasing interest in this area. This includes 5 for percutaneous nephrolithotomy (PCNL), 6 for flexible ureteroscopy (fURS), 3 for semi-rigid URS (sURS), 9 for shockwave lithotripsy (SWL), 2 for stent encrustations, 3 for intra-operative appearance at the time of URS and 3 to classify intra-operative ureteric injury. There were 3 tools for renal colic assessment, one each for prediction of future stone event, stone classification and stone impaction and 2 for need of emergency intervention in ureteric stone. While 2 tools are related to stone recurrence, 6 are related to post-procedural complications. There are now 2 tools for simulation in endourology and 5 for patient reported outcome measures (PROMS).

CONCLUSIONS

A number of reliable and established tools exist currently in endourology. Each of these offers their own respective advantages and disadvantages. While nomograms and scoring systems can help in the decision making, these must be tailored to individual patients based on their specific clinical scenarios, expectations and informed consent.

Factors affecting success in the treatment of proximal ureteral stones larger than 1 cm with extracorporeal shockwave lithotripsy in adult patients

The aim of the study was to analyze the factors predicting success for the treatment of proximal ureteral stones larger than 1 cm with extracorporeal shockwave lithotripsy (SWL) in adult patients. Between January 2014 and December 2018, 480 adult patients in total underwent SWL and data were retrospectively evaluated. Patients with multiple ureteral stones, solitary kidney, congenital abnormality, skeletal system abnormality, history of previous urinary system surgery and SWL, renal insufficiency, patients who could not tolerate SWL and pediatric patients were excluded from the study. The remaining 415 patients were divided into two groups as success (Group 1, n = 307) and failure (Group 2, n = 108). The overall success rate was 73.9%. The values of stone size, Hounsfield Unit (HU), skin to stone distance (SSD), ureteral wall thickness (UWT), proximal ureter diameter, renal pelvis diameter, hydronephrosis grade, and duration of renal colic were significantly higher in Group 2 compared to Group 1. In binary logistic regression analyses, HU, UWT, and proximal ureter diameter were found to be independent predictors. HU, UWT, and proximal ureter diameter had sensitivity and specificity of 92-92%, 88-23%, and 87-46%, with cutoff values of 740 HU, 2.5 mm and 8.5 mm, respectively. The area under the curve values were 0.96, 0.97, and 0.96 for HU, UWT, and proximal ureter diameter, respectively. The CT-based parameters, including HU, UWT, and proximal ureter diameter are independent predictive factors with excellent accuracy for the treatment of proximal ureteral stones larger than 1 cm with SWL in adult patients. Based on these factors, SWL can be considered for proximal ureteral stones larger than 1 cm.

The Predictive Role of Abdominal Fat Parameters and Stone Density on SWL Outcomes

BACKGROUND

Our aim was to detect the role of radiological abdominal fat parameters by tomography and stone density by plain X-ray on extracorporeal Shock Wave Lithotripsy (SWL) stone-free rate.

METHODS

The patients who had undergone SWL for a single opaque renal stone < 2 cm in diameter and proximal ureteric stone < 1 cm in diameter were collected retrospectively. The characteristics of patients and stones were recorded. The stone attitude, HU, abdominal fat parameters, paraperirenal fat area, perirenal infiltration and severity of hydronephrosis with pre-treatment Non- Contrast Computed Tomography (NCCT) and stone density with radiography were evaluated by a radiologist. Four weeks after the last SWL; all patients were evaluated by plain X-ray and categorized as Stone Free (SF) and Residual Fragment (RF) group.

RESULTS

51 patients with renal stones and 88 patients with proximal ureteral stones were included in the study. 24 (47%) and 63 (71%) patients were classified as SFfor renal and ureteral stones respectively. Only stone size was an independent predictor for stone-free rates after SWL for renal and proximal ureteral stones on multivariate analysis. The Receiver Operating Characteristic (ROC) curves for renal calculi revealed that creatinine level, stone size, stone attitude, Houns-Field Unit (HU) and Skin-to-Stone Distance (SSD) were the predictive factors for the SWL outcome (p< 0.05). The ROC curve for ureteral calculi demonstrated that HU, stone size and attitude were the predictive factors (p< 0.05).

CONCLUSION

All abdominal fat parameters and the stone density were not related to SWL failure. A large follow-up with more patients is essential to confirm the role of radiological parameters on the outcome of SWL.

Assessing Cost-Effectiveness of New Technologies in Stone Management

Diagnosis, treatment, and follow-up are all influential in determining the overall cost to the health care system for kidney stones. New innovations in the field of nephrolithiasis have been abundant, including disposable ureteroscopes, ultrasound-guided approaches to percutaneous nephrolithotomy, and advanced laser lithotripters. Identifying cost-effective treatment strategies encourages practitioners to be thoughtful about providing value-based high-quality care and remains on important principle in the treatment of urinary stone disease.

Can intervals in extracorporeal shock wave lithotripsy sessions affect success in the treatment of upper ureteral stones?

Introduction

Managing upper ureteral stones with shock wave lithotripsy (SWL) has been done for many years. However, no conclusive data have been found on the intervals required between repeated SWL sessions.

Aim

To identify the most optimal intervals between SWL sessions.

Material and methods

Between September 2015 and December 2016, 80 patients undergoing elective outpatient lithotripsy who required repeated SWL sessions for ureteral stones were evaluated. These patients were categorised into two groups according to different SWL session intervals. The intervals between SWL sessions (n = 40) for the first group lasted one day, whereas those for the second group (n = 40) lasted 1 week. The data recorded during SWL included visual analogue scale (VAS) scores, total number of shocks, total energy used and number of sessions. The stone clearance rates, number of urinary tract infections, complication rates and VAS scores were compared between the two groups.

Results

All patients’ clinical outcomes after SWL therapy are shown in Table I. The stone clearance rate for group 1 was 70%, whereas that for group 2 was 72.5% (p = 0.805). Additionally, the number of urinary tract infections, complications and VAS scores were similar for both groups. In group 1, 3 patients had steinstrasse, two suffered from severe renal colic, and one had a urinary tract infection. In group 2, 3 patients endured steinstrasse, and 2 patients experienced severe renal colic during the study.

Conclusions

Short-interval SWL sessions are safe and effective for treating upper ureteral stones, and such sessions do not increase complication rates.