Evaluation of computed tomography findings for success prediction after extracorporeal shock wave lithotripsy for urinary tract stone disease

Extracorporeal shock wave lithotripsy: retrospective study on possible predictors of treatment success and revisiting the role of non-contrast-enhanced computer tomography in kidney and ureteral stone disease

Extracorporeal shock wave lithotripsy (ESWL) is a safe and efficient treatment option for urinary stone disease. The overall stone-free rate (SFR) varies significantly. This study aimed to assess the influence of stone size, location, stone density, and skin-to-stone distance (SSD), on the outcome of ESWL. We assessed whether pre-treatment non-contrast-enhanced CT scan (NCCT) confers significant advantages compared to kidney-ureter-bladder film (KUB) only. We reviewed the medical records of 307 cases (165 men, 142 women) with renal and ureteral stones treated consecutively at our institution with ESWL between 2020 and 2023. 44 of these underwent a NCCT. The outcome of ESWL was defined in two ways: visible stone fragmentation on KUB, and the need for further treatment. Overall success of fragmentation was 85% (261 patients). 61% of patients (n = 184) didn't need any further treatment. Stone size and location correlated significantly with treatment outcomes regarding the need for further treatment (p = 0.004) and stone fragmentation (p = 0.016), respectively. Unlike mean SSD (p = 0.462), the mean attenuation value (MAV) significantly correlated with the need for retreatment (p = 0.016). MAV seems to be a better predictor of treatment success (AUC of the ROC curve: 0.729), compared to stone size (AUC: 0.613). The difference between groups (with and without NCCT) in both treatment outcomes did not reach statistical significance. During decision-making, information regarding SSD and MAV can be useful in more dubious scenarios. However, it appears that their inclusion doesn't provide substantial advantages when compared to relying solely on KUB.

Can shear wave elastography predict the success of shock‑wave lithotripsy used in renal stones treatment? A prospective study

OBJECTIVE

To evaluate the usage of shear wave elastography (SWE) in the prediction of the success rate of shock‑wave lithotripsy (SWL) treatment of renal stones.

PATIENTS AND METHODS

In the present study, SWL was performed for 100 patients presented with renal stones in the duration from May 2022 to August 2023. The patients were divided into 2 groups SWL responders and non-responders. The study compared between the 2 groups in terms of baseline parameters of the patients as age, sex, body mass index (BMI), stone size, stone location, stone density (HU), skin-to-stone distance (SSD), the degree of hydronephrosis and the stone elastography values.

RESULTS

There was no statistically significant relation between stone-free rate and degree of obstruction (p = 0.628), stone size (p = 0.390) upper calyceal location (p = 0.17), middle calyceal location (p = 0.66), and renal pelvis location (p = 1.0). Nevertheless, a statistically significant relation was found as regards lower calyceal location, stone density (HU), and stone Elastography values using multivariate analysis.

CONCLUSIONS

Measurement of stone density by shear wave elastography (SWE) can be used as an alternative to HU in decision-making before SWL. SWL success depends mainly on stone site, HU, and SWE values.

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.

Extracorporeal shock wave lithotripsy (ESWL) versus percutaneous nephrolithotomy (PCNL) or retrograde intrarenal surgery (RIRS) for kidney stones

BACKGROUND

Nephrolithiasis is a common urological disease worldwide. Extracorporeal shock wave lithotripsy (ESWL) has been used for the treatment of renal stones since the 1980s, while retrograde intrarenal surgery (RIRS) and percutaneous nephrolithotomy (PCNL) are newer, more invasive treatment modalities that may have higher stone-free rates. The complications of RIRS and PCNL have decreased owing to improvement in surgical techniques and instruments. We re-evaluated the best evidence on this topic in an update of a Cochrane Review first published in 2014.

OBJECTIVES

To assess the effects of extracorporeal shock wave lithotripsy compared with percutaneous nephrolithotomy or retrograde intrarenal surgery for treating kidney stones.

SEARCH METHODS

We performed a comprehensive search in CENTRAL, MEDLINE, Embase, and ClinicalTrials.gov with no restrictions on language or publication status. The latest search date was 6 December 2022.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and quasi-RCTs that compared ESWL with PCNL or RIRS for kidney stone treatment.

DATA COLLECTION AND ANALYSIS

Two review authors independently classified studies, extracted data, and assessed risk of bias. Our primary outcomes were treatment success rate at three months (defined as residual fragments smaller than 4 mm, or as defined by the study authors), quality of life (QoL), and complications. Our secondary outcomes were retreatment rate, auxiliary procedures rate, and duration of hospital stay. We performed statistical analyses using a random-effects model and independently rated the certainty of evidence using the GRADE approach.

MAIN RESULTS

We included 31 trials involving 3361 participants (3060 participants completed follow-up). Four trials were only available as an abstract. Overall mean age was 46.6 years and overall mean stone size was 13.4 mm. Most participants (93.8%) had kidney stones measuring 20 mm or less, and 68.9% had lower pole stones. ESWL versus PCNL ESWL may have a lower three-month treatment success rate than PCNL (risk ratio [RR] 0.67, 95% confidence interval [CI] 0.57 to 0.79; I2 = 87%; 12 studies, 1303 participants; low-certainty evidence). This corresponds to 304 fewer participants per 1000 (397 fewer to 194 fewer) reporting treatment success with ESWL. ESWL may have little or no effect on QoL after treatment compared with PCNL (1 study, 78 participants; low-certainty evidence). ESWL probably leads to fewer complications than PCNL (RR 0.62, 95% CI 0.47 to 0.82; I2 = 18%; 13 studies, 1385 participants; moderate-certainty evidence). This corresponds to 82 fewer participants per 1000 (115 fewer to 39 fewer) having complications after ESWL. ESWL versus RIRS ESWL may have a lower three-month treatment success rate than RIRS (RR 0.85, 95% CI 0.78 to 0.93; I2 = 63%; 13 studies, 1349 participants; low-certainty evidence). This corresponds to 127 fewer participants per 1000 (186 fewer to 59 fewer) reporting treatment success with ESWL. We are very uncertain about QoL after treatment; the evidence is based on three studies (214 participants) that we were unable to pool. We are very uncertain about the difference in complication rates between ESWL and RIRS (RR 0.93, 95% CI 0.63 to 1.36; I2 = 32%; 13 studies, 1305 participants; very low-certainty evidence). This corresponds to nine fewer participants per 1000 (49 fewer to 48 more) having complications after ESWL.

AUTHORS' CONCLUSIONS

ESWL compared with PCNL may have lower three-month success rates, may have a similar effect on QoL, and probably leads to fewer complications. ESWL compared with RIRS may have lower three-month success rates, but the evidence on QoL outcomes and complication rates is very uncertain. These findings should provide valuable information to aid shared decision-making between clinicians and people with kidney stones who are undecided about these three options.

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.

The comparison of perioperative outcomes between percutaneous nephrolithotomy and retrograde intrarenal surgery in elderly patients

OBJECTIVES

In this study, we aimed to compare the outcomes and complication rates of percutaneous nephrolithotomy (PCNL) and retrograde intrarenal surgery (RIRS) in elderly patients.

MATERIALS AND METHODS

Between April 2011 and January 2020, patients who underwent PCNL and RIRS for renal stone in elderly patients were retrospectively evaluated. The two groups' perioperative values, stone-free rates and complication rates were compared. Post-operative complications were noted according to the Clavien scoring system.

RESULTS

There were 89 and 72 patients in the PCNL and RIRS group respectively. The median age was 67 years in both the groups (P = .192). The stone size were 22.2 ± 3.5 mm and 19.9 ± 7.1 mm in the PCNL and RIRS group, respectively (P = .082). Stone-free rates were significantly higher in PCNL group (P = .021, P = .034). Also we found that overall complication and major complication rates were significantly higher in PCNL group (P = .016, P = .029).

CONCLUSION

Despite there was higher stone clearance in PCNL, the complication rates were higher compared with RIRS. So RIRS might be a safe alternative treatment method to PCNL in older patients.

Mini-percutaneous nephrolithotomy is a safe alternative to extracorporeal shockwave lithotripsy for high-density, renal stones: a prospective, randomised trial

OBJECTIVES

To compare the outcomes of miniaturised percutaneous nephrolithotomy (mini-PCNL) and extracorporeal shockwave lithotripsy (ESWL) in the management of 10-20 mm, non-lower pole, renal stones.

PATIENTS AND METHODS

This prospective randomised double-arm trial was conducted at a tertiary care hospital in Egypt from February to December 2020. Adult patients with single, non-lower pole, high-density (≥1000 HU) renal stones were randomised to receive mini-PCNL or ESWL. The stone-free rate (SFR); operative, fluoroscopy and hospitalisation times; blood loss; auxiliary procedures; retreatment; unscheduled hospital readmission; and complications were compared between the groups.

RESULTS

The primary analysis included 34 patients in the mini-PCNL group and 33 in the ESWL group. Overall, the SFR was 97.1% in the mini-PCNL group vs 30.3% in the ESWL group (P < 0.001). All patients in the ESWL group required retreatment, and none of them were stone-free after the first ESWL session. None of the patients in the mini-PCNL group required retreatment. The overall operative time, fluoroscopy time, auxiliary procedure, retreatment, and unscheduled hospital readmission were significantly higher in the ESWL group. The hospital stay and decrease in the haemoglobin level were significantly higher in the mini-PCNL group. The groups were comparable for the overall complication rate.

CONCLUSIONS

Mini-PCNL is more effective than ESWL for treating 10-20 mm, high-density, non-lower pole renal stones. Mini-PCNL has the advantages of a high SFR and abolishing the need for retreatment and re-hospitalisation.

Can the Hounsfield unit predict the success of medical expulsive therapy using silodosin in 4- to 10-mm distal ureteral stones?

OBJECTIVE

We aimed to investigate the predictive ability of the Hounsfield unit (HU) on non-contrast computed tomography (NCCT) for the success of medical expulsive therapy (MET) using silodosin in distal ureteric stones of 4-10 mm.

METHODOLOGY

The data of patients who underwent MET were retrospectively screened. The patients were divided into two groups as Groups 1 and 2 depending on the presence or absence of stone expulsion, respectively. In addition to HU calculated using the NCCT images, state of the collecting systems, daily fluid intake, number of emergency department visits, and number of pain attacks were compared.

RESULTS

A total of 88 patients were included in the study. Sixty-four patients (72.7%) expelled the stone after MET while the treatment was not successful in 24 patients (27.3%). The stone area was significantly larger in Group 2 (28.4 ± 15.7 mm² vs 46.8 ± 16.1 mm² ; P < .001). NCCT-HU was calculated as 542.5 ± 256.8 for Group 1 and 873.1 ± 335.2 for Group 2, indicating a significant difference (P < .001). The mean number of pain attacks was 1.5 ± 1.2 in Group 1 and 2.2 ± 1.4 in Group 2 (P = .048). The number of visits to the emergency department significantly differed between Groups 1 and 2 (1.1 ± 1.0 and 1.8 ± 1.3, respectively; P = .010).

CONCLUSIONS

In this study, HU and stone area values calculated on NCCT were found to be effective factors in predicting the treatment success for MET. Therefore, we consider that it would be useful to consider these parameters in the selection of an appropriate treatment for distal ureteric stones.

Can ureteral wall thickness (UWT) be used as a potential parameter for decision-making in uncomplicated distal ureteral stones 5-10 mm in size? A prospective study

OBJECTIVE

To evaluate the correlation between ureteral wall thickness (UWT) and stone passage (SP) and its cut-off value in distal uncomplicated ureteral stones.

PATIENTS AND METHODS

In the prospective study from January 2019 to January 2020 at a tertiary care hospital, we reviewed 212 patients aged above 18 years with single, symptomatic, radiopaque, and distal ureteric stone sized 5-10 mm, who were treated with MET (Silodosin 8 mg once daily) until SP or a maximum of 4 weeks. There were 2 groups: responders and non-responders. Demographic data of the patients and all stone radiological parameters including stone size, laterality, density, UWT, the diameter of the ureter proximal to the stone (PUD), and the degree of hydronephrosis were recorded and compared between the 2 groups.

RESULTS

There were 126 (59.4%) in the responder group and 86 (40.6%) in the non-responder group. On univariate analysis, gender, stone density, stone size, PUD, UWT, and the degree of hydronephrosis were significant factors for stone passage. However, using multivariate analysis, only UWT and the degree of hydronephrosis were significant. ROC analysis showed that 3.75 mm is the cut-off value for UWT, with 86% and 87.3% sensitivity and specificity, respectively.

CONCLUSIONS

UWT and hydronephrosis can be used as potential predictors for SP and can help with decision-making in patients with uncomplicated 5-10 mm lower ureteric stones.

Outcome groups and a practical tool to predict success of shock wave lithotripsy in daily clinical routine

PURPOSE

To improve outcome prediction of extracorporeal shock wave lithotripsy (SWL) by development of a model based on easily available clinical and radiographical predictors and suitable for daily clinical use.

MATERIALS AND METHODS

We evaluated predictive factors for SWL success in 517 consecutive patients suffering from urinary calculi who underwent SWL between 2010 and 2018. Analyses included descriptive statistics, receiver operating characteristic statistics and logistic regression. Predictive value was improved by combining parameters using model selection and recursive partitioning.

RESULTS

Of the 517 patients, 310 (60.0%) had a successful SWL. Best individual predictor of SWL success was mean attenuation (MAV), with an area under the curve (AUC) of 0.668, and an optimal cutpoint (OC) of 987.5 HU. The best multivariable model, including MAV, stone size, skin to stone distance (SSD), presence of an indwelling stent, and four interaction effects, yielded an AUC of 0.736. Recursive partitioning would categorize patients into three outcome groups with high (76.9%), intermediate (41%) and low (10%) success probability. High probability of SWL success (76.9%) was found for patients with a stone with MAV ≤ 987 HU or with MAV > 987 HU but stone size ≤ 11 mm and SSD (45°) ≤ 88 mm.

CONCLUSION

A model based on four established predictors, and provided as an Excel^®-Tool, can clearly improve prediction of SWL success. In addition, patients can be classified into three defined outcome groups based on simple cutpoint combinations. Both tools improve informed decision-making in daily clinical practice and might reduce failure rates.

Flexible ureteroscopy lithotripsy combined with metallic ureteral stents for the treatment of patients with upper urinary tract calculi

Flexible ureteroscopy lithotripsy (FURS) is the most common treatment for patients with upper urinary tract calculi (diameter, <2 cm). The purpose of this prospective study was to assess the efficacy of FURS combined with metallic ureteral stents (MUS) for the treatment of upper urinary tract calculi. A total of 38 patients with upper urinary tract calculi were recruited in the present study, to compare the efficacy between FURS and FURS combined with MUS (FURS-MUS). The results demonstrated that FURS-MUS shortened operative time compared with FURS (35.2±1.2 vs. 57.4±1.7 min, respectively; P<0.01). Data also indicated that the clearance rate in FURS-MUS and FURS was decreased from 94.5 and 87.8%, respectively (P<0.05). FURS-MUS treatment decreased the duration of postoperative hospital stay compared with FURS (4.5±0.5 vs. 7.5±1.5 days, respectively; P<0.05). These data demonstrated that FURS-MUS significantly increased postoperative inflammation score compared with FURS (6.2±0.8 vs. 4.2±1.0, respectively; P<0.05). The complication rate and blood loss exhibited no significant difference between FURS-MUS and FURS (complication rate, 6.5% vs. 5.9%, respectively; blood loss, 4.2% vs. 4.6%, respectively). FURS-MUS significantly decreased inflammatory cytokines and risk of sepsis, and improved readmission rate, stone recurrence and progression-free survival compared with patients treated with FURS. In conclusion, these data suggested that FURS-MUS may be an efficient, minimally invasive and reproducible operation for patients with upper urinary tract calculi.

Role of pretreatment Doppler ultrasound in the prediction of factors affecting stone-clearance post-shockwave lithotripsy for ureteral stones: a prospective study

PURPOSE

To identify the role of Doppler US (DUS) in the prediction of factors affecting stone-clearance post-SWL for ureteral stones in addition to its role in prediction of pretreatment stone impaction.

METHODS

We prospectively included patients with ureteric stone for SWL between October 2018 and September 2019. Patient's demographics were collected. Using DUS, resistive index (RI), Δ RI, and ureteric jets were evaluated in both kidneys. Also, stone site, volume, density, skin to stone distance, degree of hydronephrosis, ureteral wall thickness (UWT) were evaluated by NCCT. Univariate and multivariate logistic regression analyses were performed to identify factors that contribute to treatment success. Correlation between ipsilateral RI with other radiological findings predicting stone impaction was done.

RESULTS

A total of 93 patients were finally included (61 males and 32 females). The mean age was 31.4 ± 7.7 years. The success rate (absence of significant residuals post 1 month by NCCT) was 51.6%. In multivariate analysis, the presence of ureteric jet, ipsilateral lower RI, and ipsilateral lower UWT were independent factors for treatment success (P = 0.0001, 0.002, and 0.03, respectively). Also, ipsilateral absence of ureteric jet, increased hydronephrosis, and increased UWT were correlated with higher ipsilateral RI in prediction of stone impaction. Ipsilateral higher RI was found to achieve higher accuracy in stone impaction prediction (PPV of 94.8%).

CONCLUSION

Pretreatment DUS is a useful, non-invasive with a less irradiative tool for prediction of stone impaction and stone-free rate post-SWL for ureteric stones.

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.

The clinical role of X-ray computed tomography to predict the clinical efficiency of extracorporeal shock wave lithotripsy

AIM

To evaluate the clinical efficiency of computed tomography for diagnostics of patients with urolithiasis and the choice of treatment strategy.

MATERIAL AND METHODS

The study was carried out at the Urological Clinic of I.M. Sechenov First Moscow State Medical University and included 1044 patients with urinary stones. The ultimate goal of this study was to predict the clinical efficiency of extracorporeal shock wave lithotripsy using a combination of computed tomography and densitometry. Extracorporeal shock wave lithotripsy was performed on "Siemens Lithostar Plus," "Siemens Modularis Uro," and "Dornier Gemini" lithotripters. Statistical analysis of clinical data included evaluation of individual sampling groups and calculation of weighted arithmetic mean ( M).

RESULTS

The efficiency of extracorporeal shock wave lithotripsy has been determined primarily using X-ray analysis of the concrement outlines and the structure (homogeneous or heterogeneous) of its central zone. However, in terms of efficiency and repetition rate (the number of fragmentation procedures required for complete clearance) of extracorporeal shock wave lithotripsy, the mean density of the concrement along the whole length of its three-dimensional structure (expressed in Hounsfield units) appeared to be the most reliable and informative predictive index in this study.

CONCLUSION

The combination of computed tomography with densitometry in the treatment of patients with urolithiasis allows one (1) to determine the exact localization, size, X-ray structure, and structural density of urinary stones and (2) to predict, on the basis of densitometric data histograms, the clinical efficiency and repetition rate of extracorporeal shock wave lithotripsy with due regard to the X-ray structure of peripheral and central zones, and mean density (in Hounsfield units) of urinary concrements.

A novel method for prediction of stone composition: the average and difference of Hounsfield units and their cut-off values

PURPOSE

The purpose of the study was to investigate the predictive value of stone measurements by including a novel method on non-contrast computed tomography (NCCT) images for stone composition.

METHODS

We retrospectively evaluated patients who had stone analysis, NCCT images, and underwent percutaneous nephrolithotomy between 2013 and 2016. Patient characteristics, stone measurements on NCCT images, and stone analysis results were evaluated. Hounsfield unit (HU) values (maximum (HU_max), minimum (HU_min), and average (HU_ave) of HU values) were investigated on NCCT images. HU_diff was calculated as the difference between the HU_max and the HU_min values. Patients were divided into seven stone groups and data were compared. Then patients were separately divided into two groups according to mineral complexity (mono-mineral and multi-mineral groups) and calcium-based (calcium and other stone groups) evaluation.

RESULTS

In the study, 115 patients were evaluated. Age, gender, HU_min, HU_max, and HU_ave were significantly different between the stone groups. HU_diff and HU_ave were found to be 341.5 HU (AUC = 0.719, p = 0.017) and 1051.5 HU (AUC = 0.701, p = 0.029) as cut-off, respectively. Seventy of 72 > 341.5 HU_diff patients and 64 of 67 > 1051.5 HU_ave patients had multi-mineral stones (p = 0.001, OR 9.26, and p = 0.028, OR 4.27), respectively. In multivariate analysis, > 341.5 HU_diff rate was significantly higher in multi-mineral and calcium stone groups; HU_ave was also significantly higher in the calcium stone group.

CONCLUSIONS

HU_diff and HU_ave were significant predictors of mineral complexity. HU_diff of < 341.5 HU showed 81.8% sensitivity and 67.2% specificity for identification of mono-mineral stones.

Predicting the effectiveness of extracorporeal shock wave lithotripsy on urinary tract stones. Risk groups for accurate retreatment

INTRODUCTION

Extracorporeal shock wave lithotripsy (ESWL) is a non-invasive, safe and effective treatment for urinary tract lithiasis. Its effectiveness varies depending on the location and size of the stones as well as other factors; several sessions are occasionally required. The objective is to attempt to predict its success or failure, when the influential variables are known beforehand.

MATERIAL AND METHODS

We analysed 211 patients who had had previous CT scans and were treated with ESWL between 2010 and 2014. The influential variables in requiring retreatment were studied using binary logistic regression models (univariate and multivariate analysis): maximum density, maximum diameter, area, location, disintegration and distance from the adipose panniculus. With the influential variables, a risk model was designed by assessing all possible combinations with logistic regression (version 20.0 IBM SPSS).

RESULTS

The independent influential variables on the need for retreatment are: maximum density >864HU, maximum diameter >7.5mm and pyelocaliceal location. Using these variables, the best model includes 3risk groups with a probability of requiring significantly different retreatment: group 1-low risk (0 variables) with 20.2%; group 2-intermediate risk (1-2 variables) with 49.2%; and group 3-high risk (3 variables) with 62.5%.

CONCLUSIONS

The density, maximum diameter and pyelocaliceal location of the stones are determinant factors in terms of the effectiveness of treatment with ESWL. Using these variables, which can be obtained in advance of deciding on a treatment, the designed risk model provides a precise approach in choosing the most appropriate treatment for each particular case.

Is scoring system of computed tomography based metric parameters can accurately predicts shock wave lithotripsy stone-free rates and aid in the development of treatment strategies?

Objective:

The objective was to determine the predicting success of shock wave lithotripsy (SWL) using a combination of computed tomography based metric parameters to improve the treatment plan.

Patients and Methods:

Consecutive 180 patients with symptomatic upper urinary tract calculi 20 mm or less were enrolled in our study underwent extracorporeal SWL were divided into two main groups, according to the stone size, Group A (92 patients with stone ≤10 mm) and Group B (88 patients with stone >10 mm). Both groups were evaluated, according to the skin to stone distance (SSD) and Hounsfield units (≤500, 500–1000 and >1000 HU).

Results:

Both groups were comparable in baseline data and stone characteristics. About 92.3% of Group A rendered stone-free, whereas 77.2% were stone-free in Group B (P = 0.001). Furthermore, in both group SWL success rates was a significantly higher for stones with lower attenuation <830 HU than with stones >830 HU (P < 0.034). SSD were statistically differences in SWL outcome (P < 0.02). Simultaneous consideration of three parameters stone size, stone attenuation value, and SSD; we found that stone-free rate (SFR) was 100% for stone attenuation value <830 HU for stone <10 mm or >10 mm but total number SWL sessions and shock waves required for the larger stone group were higher than in the smaller group (P < 0.01). Furthermore, SFR was 83.3% and 37.5% for stone <10 mm, mean HU >830, SSD 90 mm and SSD >120 mm, respectively. On the other hand, SFR was 52.6% and 28.57% for stone >10 mm, mean HU >830, SSD <90 mm and SSD >120 mm, respectively.

Conclusion:

Stone size, stone density (HU), and SSD is simple to calculate and can be reported by radiologists to applying combined score help to augment predictive power of SWL, reduce cost, and improving of treatment strategies.

Arguments for choosing extracorporeal shockwave lithotripsy for removal of urinary tract stones

At a time when there is an almost unlimited enthusiasm and preference among urologists for endoscopic stone removal, we have found it essential to meet some of the frequently presented arguments on why extracorporeal shockwave lithotripsy (SWL) should not be used. We have based our considerations in this brief article on our 30-35 years' experience with the non-invasive or least invasive technique that SWL represents. Stone disintegration, requirement of repeated treatment sessions, the concern of residual fragments, complications and economic aspects are some points that are discussed.

How do stone attenuation and skin-to-stone distance in computed tomography influence the performance of shock wave lithotripsy in ureteral stone disease?

Background

Shock wave lithotripsy (SWL) is a noninvasive, safe, and efficient treatment option for ureteral stones. Depending on stone location and size, the overall stone-free rate (SFR) varies significantly. Failure of stone disintegration results in unnecessary exposure to shock waves and radiation and requires alternative treatment procedures, which increases medical costs. It is therefore important to identify predictors of treatment success or failure in patients who are potential candidates for SWL before treatment. Nowadays, noncontrast computed tomography (NCCT) provides reliable information on stone location, size, number, and total stone burden. The impact of additional information provided by NCCT, such as skin-to-stone distance (SSD) and mean attenuation value (MAV), on stone fragmentation in ureteral stone disease has hardly been investigated separately so far. Thus, the objective of this study was to assess the influence of stone attenuation, SSD and body mass index (BMI) on the outcome of SWL in ureteral stones.

Methods

We reviewed the medical records of 104 patients (80 men, 24 women) with ureteral stone disease treated consecutively at our institution with SWL between 2010 and 2013. MAV in Hounsfield Units (HU) and SSD were determined by analyzing noncontrast computed tomography images. Outcome of SWL was defined as successful (visible stone fragmentation on kidney, ureter, and bladder film (KUB)) or failed (absent fragmentation on KUB).

Results

Overall success of SWL was 50 % (52 patients). Median stone attenuation was 956.9 HU (range 495–1210.8) in the group with successful disintegration and 944.6 (range 237–1302) in the patients who had absent or insufficient fragmentation. Median SSD was 125 mm (range 81–165 mm) in the group treated successfully and 141 mm (range 108–172 mm) in the patients with treatment failure. Unlike MAV (p = 0.37), SSD (p < 0.001) and BMI (p = 0.008) significantly correlated with treatment outcome.

Conclusion

The choice of treatment for ureteral stones should be based on stone location and size as considered in the AUA and EAU guidelines on urinary stone disease. In ambiguous cases, SSD and BMI can be used to assist in the decision. In this study, MAV showed no correlation with fragmentation rate of SWL.