Development of a radiomics model to discriminate ammonium urate stones from uric acid stones in vivo: A remedy for the diagnostic pitfall of dual-energy computed tomography.

BACKGROUND: Dual-energy computed tomography (DECT) is purported to accurately distinguish uric acid stones from non-uric acid stones. However, whether DECT can accurately discriminate ammonium urate stones from uric acid stones remains unknown. Therefore, we aimed to explore whether they can be accurately identified by DECT and to develop a radiomics model to assist in distinguishing them. METHODS: This research included two steps. For the first purpose to evaluate the accuracy of DECT in the diagnosis of uric acid stones, 178 urolithiasis patients who underwent preoperative DECT between September 2016 and December 2019 were enrolled. For model construction, 93, 40, and 109 eligible urolithiasis patients treated between February 2013 and October 2022 were assigned to the training, internal validation, and external validation sets, respectively. Radiomics features were extracted from non-contrast CT images, and the least absolute shrinkage and selection operator (LASSO) algorithm was used to develop a radiomics signature. Then, a radiomics model incorporating the radiomics signature and clinical predictors was constructed. The performance of the model (discrimination, calibration, and clinical usefulness) was evaluated. RESULTS: When patients with ammonium urate stones were included in the analysis, the accuracy of DECT in the diagnosis of uric acid stones was significantly decreased. Sixty-two percent of ammonium urate stones were mistakenly diagnosed as uric acid stones by DECT. A radiomics model incorporating the radiomics signature, urine pH value, and urine white blood cell count was constructed. The model achieved good calibration and discrimination {area under the receiver operating characteristic curve (AUC; 95% confidence interval [CI]), 0.944 (0.899-0.989)}, which was internally and externally validated with AUCs of 0.895 (95% CI, 0.796-0.995) and 0.870 (95% CI, 0.769-0.972), respectively. Decision curve analysis revealed the clinical usefulness of the model. CONCLUSIONS: DECT cannot accurately differentiate ammonium urate stones from uric acid stones. Our proposed radiomics model can serve as a complementary diagnostic tool for distinguishing them in vivo.

A multicenter study to develop a non-invasive radiomic model to identify urinary infection stone in vivo using machine-learning.

Urolithiasis is a common urological disease, and treatment strategy options vary between different stone types. However, accurate detection of stone composition can only be performed in vitro. The management of infection stones is particularly challenging with yet no effective approach to pre-operatively identify infection stones from non-infection stones. Therefore, we aimed to develop a radiomic model for preoperatively identifying infection stones with multicenter validation. In total, 1198 eligible patients with urolithiasis from three centers were divided into a training set, an internal validation set, and two external validation sets. Stone composition was determined by Fourier transform infrared spectroscopy. A total of 1316 radiomic features were extracted from the pre-treatment Computer Tomography images of each patient. Using the least absolute shrinkage and selection operator algorithm, we identified a radiomic signature that achieved favorable discrimination in the training set, which was confirmed in the validation sets. Moreover, we then developed a radiomic model incorporating the radiomic signature, urease-producing bacteria in urine, and urine pH based on multivariate logistic regression analysis. The nomogram showed favorable calibration and discrimination in the training and three validation sets (area under the curve [95% confidence interval], 0.898 [0.840-0.956], 0.832 [0.742-0.923], 0.825 [0.783-0.866], and 0.812 [0.710-0.914], respectively). Decision curve analysis demonstrated the clinical utility of the radiomic model. Thus, our proposed radiomic model can serve as a non-invasive tool to identify urinary infection stones in vivo, which may optimize disease management in urolithiasis and improve patient prognosis.

Prevalence of urolithiasis among the Uyghur children of China: a population-based cross-sectional study.

OBJECTIVES: To investigate the prevalence and associated factors of urolithiasis amongst Uyghur children. SUBJECTS AND METHODS: A cross-sectional survey was conducted of Uyghur children (aged ≤14 years) in the Kashgar Region of China, from July to December 2016. Children were selected by a two-stage random clustered sampling method, evaluated by urinary tract ultrasonography, low-dose computed tomography (CT) examination, blood and urine analysis, and a questionnaire. The prevalence by CT, the prevalence by self-report in the questionnaires, and the lifetime prevalence were evaluated. Binary logistic regression was used to estimate the associated factors. RESULTS: A total of 5605 children were selected and invited to participate in the study. In all, 4813 Uyghur children (2471 boys and 2342 girls), with an mean (SD; range) age of 75.79 (43.81; 2-177) months, were included in the final analysis, with a response rate of 85.9%. The prevalence of paediatric urolithiasis was 1.8% (95% confidence interval [CI] 1.5-2.2) by CT, 2.3% (95% CI 1.9-2.7) by self-report, and 3.6% (95% CI 3.0-4.1) for the overall life-time. The age-sex adjusted prevalence was 2.0% (95% CI 1.6-2.4) by CT. Binary logistic regression analysis showed that body mass index, urinary tract infection, a family history of urolithiasis, and excessive sweating could increase the risk of stone formation, whilst breast feeding and drinking water at midnight could decrease the risk. CONCLUSIONS: Urolithiasis is a major public health problem amongst Uyghur children, and strategies aimed at the prevention of urolithiasis are needed.

High prevalence of pediatric urinary tract stones in Xinjiang Uyghur.

The aim of the study was to report the characteristics of urolithiasis in Uyghur patients from Xinjiang, China. The composition of stones collected from 1863 patients in the Uyghur region of Xinjiang was analyzed. The median age of patients was 17 years [25th and 75th percentiles: 2, 36]. The stones were delivered by 1299 males (69.7%) and 564 females (30.3%). Calcium oxalate was the predominant stone component in 42.1% of the patients, followed by ammonium urate in 20.6%. Females had formed more stones of magnesium ammonium phosphate 8.9 vs. 5.6% (p = 0.010) and carbonate apatite 6.2 vs. 3.3% (p = 0.004). In contrast uric acid was more common in males than in females; 21.6 vs. 15.1% (p = 0.001). In this series, pediatric patients (age range 0-18) were more likely to present with a stone (51.5%, p < 0.001). Moreover, the largest number of pediatric stones was recorded in children 1-2 years old (37.9%, p < 0.001). The occurrence of ammonium urate stones was extremely high (52.4%) in children with an age below 1 year. There was a downward trend for ammonium urate with age in both children and adults (p for trend < 0.001, respectively). In contrast the frequency of uric acid declined with age in pediatric patients, but increased in adults (p for trend < 0.001, respectively). This study provides a basis for further considerations on the management of Xinjiang Uyghur patients and emphasize the severity of pediatric stone problems.

Composition of urinary tract stones formed by children in two populations in the Uyghur region of China.

BACKGROUND: To retrospectively compare the composition of urinary tract stones formed by Uyghur children from the southern (Kashgar) and northern (Urumchi) parts of the Xinjiang region. METHODS: The chemical composition of urinary tract calculi formed by 855 Uyghur children from the two regions in Xinjiang (366 Kashgar and 489 Urumchi) was compared retrospectively. Stone composition was determined by infrared spectroscopy. Factors that might have been of relevance for the findings such as age, gender, stone location and geographic region were also considered. RESULTS: Kashgar children were younger than Urumchi children (2.8 ± 2.7 vs. 4.3 ± 3.7 years, p < 0.001). Although ammonium urate was the dominant stone component in the whole population, calcium oxalate was most common in children from Urumchi. The mean occurrence of ammonium urate, calcium oxalate and uric acid differed significantly between stones formed by Kashgar and Urumchi children (52.5% vs. 29.2%, 18.9% vs. 29.4%, 12.3% vs. 20.9%; respectively, p < 0.001). Renal stones were less frequently recorded in Kashgar children than in Urumchi children (65.8% vs. 91.6%, p < 0.001). Interestingly, bladder stones were more common in children from Kashgar (28.4% vs. 3.7%; p < 0.001). CONCLUSION: Uyghur children from the southern part of Xinjiang apparently had a more serious form of stone disease than children from the northern part and the occurrence of stones dominated by ammonium urate stones was extremely high in children from the southern part of the region.

Kidney Stone Composition in Third-World Areas: What Kashgar Tells Us?

OBJECTIVE: To analyze urinary stone compositions in patients from Kashgar, China. MATERIALS AND METHODS: We analyzed the components of urinary stones in 732 consecutive patients with urolithiasis admitted to the First and Second People's Hospital of Kashgar Prefecture, Xinjiang, from July 2014 to November 2016. The patients were divided into two groups by ages: group A, 0 to 18 years and group B, >18 years old. The distributions of various stone compositions were analyzed and correlated with the gender and age. RESULTS: The mean age of group A was 3.90 ± 4.09 years and that of group B was 39.88 ± 16.40 years. The overall gender ratio (male:female) was 2.27:1. Ammonium acid urate (AAU) stone was the most frequent stone, male 35.83% and female 33.48%. Female patients were significantly more common than male patients in calcium apatite stone (p = 0.004). Of all 732 cases, patients younger than 18 years were more than patients older than 18 years (58.47% vs 41.53%). The majority of the patients (77.87%) had the stone located in the upper urinary tract. Two peak ages for both genders were noted in 1 to 3 years and 19 to 40 years group of the patients. In group of 1 to 3 years patients, male were more than female (37.60% vs 24.55%, p = 0.001), whereas in the group of 10 to 18 years patients, female were more than male (10.71% vs 4.13%). AAU was the predominant stone component in group <1 year (70. 5%, p < 0.01, as compared with other groups.). Uric acid stone was more prevalent in group >60 years (66.8%, p < 0.01) than in other groups. Patients in 1 to 3 years were in the peak age group of AAU stones in both the upper and lower urinary tract. CONCLUSION: Most of the patients with urolithiasis diagnosed and treated in Kashgar are <18 years old, especially younger than 3 years old. The most frequent stone component in this area was AAU. More than 50% patients <18 years old had AAU stone. The mechanisms that could trigger the high prevalence of AAU stone in patients <18 years old are worth further investigation.

Impaction and Prediction: Does Ureteral Wall Thickness Affect the Success of Medical Expulsive Therapy in Pediatric Ureteral Stones?

OBJECTIVE: The study aimed to evaluate the predictive value of ureteral wall thickness (UWT) and stone-related parameters for medical expulsive therapy (MET) success with an alpha blocker in pediatric upper ureteral stones. PATIENTS AND METHODS: A total of 35 children receiving MET ureteral stones (<10 mm) were evaluated. Patients were divided into 2 subgroups where MET was successful in 18 children (51.4%) and unsuccessful in 17 children (48.6%). Prior to management, stone size, stone density (in Hounsfield unit), degree of hydronephrosis, and UWT were evaluated with patient demographics and recorded. The possible predictive value of these parameters in success rates and time to stone expulsion were evaluated in a comparative manner between the 2 groups. RESULTS: The overall mean patient age and stone size values were 5.40 ± 0.51 years and 6.24 ± 0.28 mm, respectively. Regarding the predictive values of these parameters for the success of MET, while stone size and UWT were found to be highly predictive for MET success, patients age, body mass index, stone density, and degree of hydronephrosis had no predictive value on this aspect. CONCLUSIONS: Our findings indicated that some stone and anatomical factors may be used to predict the success of MET in pediatric ureteral stones in an effective manner. With this approach, unnecessary use of these drugs that may cause a delay in removing the stone will be avoided, and the possible adverse effects of obstruction as well as stone-related clinical symptoms could be minimized.

Super-Mini Percutaneous Nephrolithotomy in the Treatment of Pediatric Nephrolithiasis: Evaluation of the Initial Results.

OBJECTIVE: To evaluate the efficacy and safety of super-mini percutaneous nephrolithotomy (SMP) in the treatment of pediatric kidney stones. PATIENTS AND METHODS: We reviewed the records of 111 children with renal stones treated with SMP technique in four different centers between September 2014 and September 2015. The indications for SMP treatment in all these kids were either previously failed shock wave lithotripsy or retrograde intrarenal surgery approaches, according to their parents' preferences. Nephrostomy tracts used in the SMP system ranged from 10F to 14F in size. Lithotripsy was performed using either a Holmium laser or pneumatic lithotripter. Perioperative and postoperative parameters along with operative data were recorded in detail and stone components were analyzed by infrared spectroscopy. RESULTS: This study included 71 boys and 40 girls with a mean age of 3.90 ± 3.53 years (range 0.5-15). The mean stone burden was 1.4 ± 0.6 cm (range 0.8-4.8). Mean operative time was 39.4 ± 26.2 minutes (range 7-105). The mean hemoglobin drop was 10.2 ± 7.1 g/L (range 0-25) and no transfusion was needed. Significant complications were observed in 17 (15.3%) children with 10 and 7 cases in Clavien grade I and grade II, respectively. Complete stone clearance on postoperative day 1 and on 3-month follow-up was 84.7% (94/111) and 90.1% (100/111), respectively. Ninety-five (85.6%) children did not require any type of catheters (total tubeless). The mean hospital stay was 2.7 ± 1.5 days (range 1-7). CONCLUSIONS: Our preliminary data demonstrated that SMP was safe and effective. SMP could be a feasible treatment option for pediatric stone disease. Further randomized controlled trials are still needed to prove the efficacy of using the SMP system in children, particularly in those with larger stones.

Super-mini percutaneous nephrolithotomy (SMP): a new concept in technique and instrumentation.

OBJECTIVE: To present a novel miniature endoscopic system designed to improve the safety and efficacy of percutaneous nephrolithotomy, named the 'super-mini percutaneous nephrolithotomy' (SMP). PATIENTS AND METHODS: The endoscopic system consists of a 7-F nephroscope with enhanced irrigation and a modified 10-14 F access sheath with a suction-evacuation function. This system was tested in patients with renal stones of <2.5 cm, in a multicentre prospective non-randomised clinical trial. In all, 146 patients were accrued in 14 centres. Nephrostomy tract dilatation was carried out to 10-14 F. The lithotripsy was performed using either a Holmium laser or pneumatic lithotripter. A nephrostomy tube or JJ stent was placed only if clinically indicated. RESULTS: SMP was completed successfully in 141 of 146 patients. Five patients required conversion to larger nephrostomy tracts. The mean (sd) stone size was 2.2 (0.6) cm and the mean operative duration was 45.6 min. The initial stone-free rate (SFR) was 90.1%. The SFR at the 3-month follow-up was 95.8%. Three patients required auxiliary procedures for residual stones. Complications occurred in 12.8% of the patients, all of which were Clavien grade ≤II and no transfusions were needed. In all, 72.3% of the patients did not require any kind of catheter, while 19.8% had JJ stents and 5.7% had nephrostomy tubes placed. The mean hospital stay was 2.1 days. CONCLUSIONS: SMP is a safe and effective treatment for renal stones of <2.5 cm. SMP may be particularly suitable for patients with lower pole stones and stones that ae not amenable to retrograde intrarenal surgery.