Advancements in Uric Acid Stone Detection: Integrating Deep Learning with CT Imaging and Clinical Assessments in the Upper Urinary Tract.

INTRODUCTION: Among upper urinary tract stones, a significant proportion comprises uric acid stones. The aim of this study was to use machine learning techniques to analyze CT scans and blood and urine test data, with the aim of establishing multiple predictive models that can accurately identify uric acid stones. METHODS: We divided 276 patients with upper urinary tract stones into two groups: 48 with uric acid stones and 228 with other types, identified using Fourier-transform infrared spectroscopy. To distinguish the stone types, we created three types of deep learning models and extensively compared their classification performance. RESULTS: Among the three major types of models, considering accuracy, sensitivity, and recall, CLNC-LR, IMG-support vector machine (SVM), and FUS-SVM perform the best. The accuracy and F1 score for the three models were as follows: CLNC-LR (82.14%, 0.7813), IMG-SVM (89.29%, 0.89), and FUS-SVM (29.29%, 0.8818). The area under the curves for classes CLNC-LR, IMG-SVM, and FUS-SVM were 0.97, 0.96, and 0.99, respectively. CONCLUSION: This study shows the feasibility of utilizing deep learning to assess whether urinary tract stones are uric acid stones through CT scans, blood, and urine tests. It can serve as a supplementary tool for traditional stone composition analysis, offering decision support for urologists and enhancing the effectiveness of diagnosis and treatment.

Stone composition independently predicts stone size in 18,029 spontaneously passed stones.

PURPOSE: To evaluate whether the size of spontaneously passed stones (SPS) may be associated with clinical parameters. METHODS: A search for SPS was conducted in our electronic stone database, comprising data on stones analyzed over the last 33 years at our institution. Adults with upper urinary tract stones were included. Cases with stenotic urinary tract disease or past history of anastomotic urinary tract surgery were excluded. Stone size expressed as maximal stone diameter (MSD) and stone volume (SV) was compared between groups by one-way ANOVA. Logistic regression analyses were performed to identify predictors of MSD ≥ 6 mm. RESULTS: Overall mean MSD and SV for 18,029 SPS was 4.1 mm and 11.5 mm3, respectively, and significantly differed between stone composition groups (p < 0.001). The lowest mean MSD and SV were found for calcium oxalate monohydrate (3.6 mm and 9.0 mm3, respectively) and the highest mean MSD and SV were found for struvite (7.9 mm and 61.0 mm3, respectively). Stone composition and increasing age were found to be independent predictors of MSD ≥ 6 mm (both p < 0.001). Sex differentiation did not contribute as a predictor of MSD ≥ 6 mm. CONCLUSIONS: Stone composition and-to a lesser extent-age serve as independent predictors of size of spontaneously passed stones. Of particular importance, large spontaneously passed stones of ≥ 6 mm may be frequently found in cystine, brushite or struvite stone formers, whereas a minority of all calcium oxalate stones exceed that cutoff. Future studies shall evaluate these parameters as possible predictors of spontaneous stone passage.

The importance of citrates in treatment and prophylaxis of calcium oxalate urinary stones.

About 10% of the people is the subject of an episode of kidney stones during their lifetime, about 70% of these people undergoes relapses. About 80% of the urinary stones contains calcium, of wich 80% is formed of calcium oxalate, in pure form or associated with calcium phosphate. Therefore we can saythat in most cases (about 65%) the urinary stones are composedof calcium oxalate. Use of supplements of potassium citrate and magnesium citrate can help in the prevention of kidney stones of calcium oxalate, but mostly they can be used in the days before a shockwaves lithotripsy treatment to make the stones more fragile to the effect of the shock waves. A case of successful treatment with magnesium potassium citrate of a SWL resistant ureteral stone is presented.

[A Case of Atazanavir Urolithiasis Diagnosed by Stone Analysis].

A 70-year-old man was referred to our hospital for right back pain. His past history included human immunodeficiency virus infection, which had been treated with atazanavir for 7 years. Abdominal and pelvic computed tomographic scan showed right hydronephrosis due to a strongly suspected right ureteral radiolucent stone. He underwent indwelling of a right ureteral stent because of obstructive pyelonephritis due to the ureteral stone. After improvement of the pyelonephritis, he underwent transurethral ureterolithotripsy for the right ureteral stone. Stone analysis showed the atazanavir stone. He has been followed up for 8 months without evidence of recurrence. Herein, we report this rare case of an atazanavir stone in Japan, which was confirmed by calculus analysis, and present a review of the literature.

Case series demonstrating the clinical utility of dual energy computed tomography in patients requiring stents for urinary calculi.

Dual energy computed tomography (DECT) utilizes the material change in attenuation when imaged at two different energies to determine the composition of urinary calculi as uric acid or non-uric acid. We discuss a series of case reports illustrating DECT's ability to provide immediate determination of uric acid versus non-uric acid calculi and facilitate more informed clinical decision-making. Further, these cases demonstrate a unique population of patients with ureteral stents and percutaneous nephrostomy tubes that benefit from DECT's ability to create a virtual color contrast between an indwelling device and the stone material and thereby significantly impacting patient morbidity.

Proteomic analysis of a rare urinary stone composed of calcium carbonate and calcium oxalate dihydrate: a case report.

The objective of the present study was to investigate the matrix protein of a rare urinary stone that contained calcium carbonate. A urinary stone was extracted from a 34-year-old male patient with metabolic alkalosis. After X-ray diffractometry and infrared analysis of the stone, proteomic analysis was carried out. The resulting mass spectra were evaluated with protein search software, and matrix proteins were identified. X-ray diffraction and infrared analysis confirmed that the stone contained calcium carbonate and calcium oxalate dihydrate. Of the identified 53 proteins, 24 have not been previously reported from calcium oxalate- or calcium phosphate-containing stones. The protease inhibitors and several proteins related to cell adhesion or the cytoskeleton were identified for the first time. We analyzed in detail a rare urinary stone composed of calcium carbonate and calcium oxalate dihydrate. Considering the formation of a calcium carbonate stone, the new identified proteins should play an important role on the urolithiasis process in alkaline condition.

[Modern conservative (citrate) therapy for urate calculi in the ureters].

The results of conservative citrate therapy of 35 patients with urate calculi in ureter are presented. Due to the violation of the passage of urine in the upper urinary tract, the vast majority of patients (31 (88%)) underwent ureteral stenting to restore adequate flow of urine before treatment. In four patients, drainage of the upper urinary tract was not required. Citrate therapy allowed to achieve complete dissolution of calculi within 2 months in 25 (72%) patients. Another 14% of patients were able to reduce the size of the calculi, and in combination with contact ureterolithotripsy achieve complete discharge of calculi. Only in 14% of patients with urate calculi in ureter litholysis was ineffective. The used treatment option allows to avoid surgery in a large number of patients with urate lithiasis.

Correlation of metabolic syndrome with urinary stone composition.

OBJECTIVE: To determine the correlation between metabolic syndrome and the distribution of stone components in patients with urolithiasis. METHODS: Between January 2007 and December 2010, renal or ureteral stones were collected from 712 patients (432 males, 280 females) who underwent surgical intervention at three hospitals in South Korea. Metabolic syndrome was defined according to the latest definition of the International Diabetes Federation, using ethnicity- and sex-specific cut-off values for central obesity. Patients were assessed by factors used in metabolic syndrome. All urinary stones were analyzed using infrared spectrophotometry and categorized according to their main component. RESULTS: The patients' mean age was 55.9 years (range 19-93 years). Of the 712 patients, 347 (48.7%; 205 males, 142 females) had a diagnosis of metabolic syndrome. Calcium oxalate (71.5%), uric acid (15.3%), carbonate apatite (8.0%) and struvite (4.1%) calculi were found as the main stone components. Overall, the proportion of uric acid calculi was markedly higher in patients with rather than without metabolic syndrome (19.6 vs 11.2%; P=0.002). However, the proportion of calcium oxalate, carbonate apatite and struvite calculi did not differ between the two groups. The multivariable-adjusted odds ratio for uric acid calculi according to the metabolic syndrome components indicated that the presence of metabolic syndrome was associated with a 93% increased odds ratio of uric acid calculi compared with the absence of metabolic syndrome. Impaired fasting glucose and hypertriglyceridemia were independent risk factors for uric acid calculi. CONCLUSIONS: Metabolic syndrome is associated with a significantly increased risk of uric acid calculi development, especially those with impaired fasting glucose and hypertriglyceridemia.

Calcium carbonate obstructive urolithiasis in a red kangaroo (Macropus rufus).

A 6-yr-old male red kangaroo (Macropus rufus) presented for a history of inappetance, abnormal behavior, and unconfirmed elimination for 6 hr prior to presentation. Based on abdominal ultrasound, abdominocentesis, and cystocentesis, a presumptive diagnosis of urinary tract obstruction with uroabdomen and hydronephrosis was reached. Abdominal radiographs did not assist in reaching an antemortem diagnosis. Postmortem examination confirmed a urinary bladder rupture secondary to urethral obstruction by a single urethrolith. Bilateral hydronephrosis and hydroureter were identified and determined to be a result of bilateral ureteroliths. Urolith analysis revealed a composition of 100% calcium carbonate. A dietary analysis was performed, implicating an increased Ca:P ratio from a food preparation miscommunication as a contributing factor. Appropriate husbandry changes were made, and mob surveillance procedures were performed, which resolved the urolithiasis risk for the remaining five animals.

Patients' poor performance status is an independent risk factor for urosepsis induced by kidney and ureteral stones.

This study was aimed to identify the risk factors for urosepsis caused by kidney and ureteral stones. One hundred and nine patients who had kidney or ureteral stones and who were treated with trans-ureteral lithotripsy (TUL) at our institution from 2016 to 2020 were included. We investigated the risk factors for urosepsis caused by kidney or ureteral stones that occurred prior to TUL. Thirty patients (28%) had urosepsis prior to TUL. Patients were divided into a urosepsis group (n = 30, 28%) and a non-urosepsis group (n = 79, 72%). Patients' characteristics (gender, age, performance status [PS] score, presence of diabetes mellitus, and skeletal muscle mass), as well as their stone and urine characteristics (stone size, presence of obstructive ureteral stones, stone composition, and urine and stone cultures), were compared between the two groups. When compared to the non-urosepsis group, patients with urosepsis were more likely to be older (p < 0.001), female (p < 0.001), with lower skeletal muscle mass (p < 0.001) and with poor PSs (p < 0.001). For stone and urine characteristics, infection stones (p = 0.01), positive urine (p < 0.001) and stone culture (p = 0.007) were more often detected in patients with urosepsis. A multivariate analysis showed patients' poor PS to be an independent risk factor for urosepsis due to kidney and ureteral stones (OR = 15.7; 95% CI = 2.2-115, p = 0.007). Our study revealed that the most significant risk factor for urosepsis caused by kidney and ureteral stones was the patients' poor PS.

Profile of the brushite stone former.

PURPOSE: The incidence of brushite stones has increased during the last 3 decades and we report our experience with brushite stone formers. MATERIALS AND METHODS: From 1996 to 2008 we identified 82 patients with brushite urinary calculi. After institutional review board approval a review of our prospectively collected database was performed. RESULTS: There were 54 (65.9%) male and 28 (34.1%) female stone formers. Mean age was 44 years (range 4 to 84). Prior stone events were reported by 69 (84.1%) patients with 54 (78.3%) having received shock wave lithotripsy. Bilateral calculi were present in 28 (34.1%) patients. Mean stone area was 29.2 mm(2) (range 2 to 130). Surgery was performed in 80 patients including 63 (76.8%) percutaneous nephrolithotomy, 8 (9.8%) ureteroscopy, 3 (3.7%) shock wave lithotripsy, and 6 (7.3%) ureteroscopy and percutaneous nephrolithotomy. After primary and secondary procedures 76 (92.7%) patients were rendered stone-free. Metabolic urine studies were available in 45 patients. All patients demonstrated 1 or more abnormalities, with hypercalciuria (greater than 250 mg daily for women and greater than 275 mg daily for men) in 38 (80.9%), urine pH greater than 6.2 in 29 (61.7%), urine volume less than 2 l in 27 (57.4%), hypocitraturia (less than 320 mg daily) in 22 (46.8%), hyperuricosuria (greater than 750 mg daily in women, greater than 800 mg daily in men) in 8 (17%) and hyperoxaluria (greater than 32 mg daily in women and greater than 43 mg daily in men) in 5 (10.6%). Recurrent stone events occurred in 31 (37.8%) patients at a mean of 33 (range 2 to 118) months from treatment. CONCLUSIONS: Brushite stone formers are a treatment challenge. Almost a third will present with bilateral stones and the stone burden is sizeable. Nearly 80% of patients report having prior shock wave lithotripsy and recurrent stone events occurred approximately 3 years after treatment. All patients with brushite stones in this cohort had an underlying metabolic abnormality and specifically brushite stones should be heralded as a marker for hypercalciuria. Based on these data we recommend all brushite stone formers undergo 24-hour urine studies and have close long-term followup.

Stone-targeted dual-energy CT: a new diagnostic approach to urinary calculosis.

OBJECTIVE: The objective of our study was to assess a stone-targeted low-dose protocol for the detection and characterization of urinary tract stones using a dual-energy CT scanner. SUBJECTS AND METHODS: Thirty-nine patients (20 men, 19 women; age range, 22-87 years; average age, 47 years) with suspected renal colic in which ureteral stones were shown at low-dose unenhanced CT were enrolled in the study. Stone composition could be established in 24 patients, and these patients represent our study population regarding the CT characterization of stones. All examinations were performed with a preliminary low-dose unenhanced CT acquisition of the whole urinary system that was immediately followed by a limited (scanning length, 5 cm) dual-energy acquisition of the region containing the ureteral stone. Stone characterization was assessed using a dual-energy software tool available on the system. Two experienced radiologists who were blinded to the chemical composition of the stones retrospectively reviewed images and analyzed data to determine the composition of the stones. Their results were compared with the biochemical analysis results obtained by stereomicroscopy and infrared spectrometry. RESULTS: Based on in vitro-measured data, our combined protocol reduced dose by up to 50% compared with a full dual-energy acquisition; in addition, the calculated radiation doses of our protocol in patients are comparable to those of low-dose single- and dual-energy protocols. In 24 patients, 24 ureteral stones considered to be responsible for symptoms and detected at low-dose unenhanced CT were also shown at dual-energy CT. Correct chemical composition was obtained by dual-energy analysis in all 24 ureteral calculi regarding the characterization of uric acid (n = 3), calcium salt (n = 18), and combined uric acid-calcium salt (n = 3) stones. CONCLUSION: The use of dual-energy CT attenuation values made it possible to characterize all ureteral calculi, discriminating uric acid stones from calcium salt stones. The increment in radiation exposure due to contemporary scanning with two tubes at different energy levels can be substantially reduced using a limited stone-targeted dual-energy protocol.

Predictors of success in shock wave lithotripsy of renal and ureteral stones.

In many centers, shock wave lithotripsy (SWL) is a commonly used modality for the treatment of both renal and ureteral calculi. It is non-invasive, may be performed using minimal anesthesia, and has a high level of patient acceptance. The focus of the present review is to highlight patient and stone characteristics which affect the outcomes of SWL, in order to define which patients are proper candidates for this treatment.

[Two cases of infants with acute renal failure due to bilateral obstructive ureteral stones associated with rotavirus gastroenteritis].

We report on 2 infants with acute renal failure caused by bilateral obstructive ureteral stones associated with rotavirus gastroenteritis. A 28-month boy and a 13-month boy with several days history of watery diarrhea and vomiting were referred to our hospital because of anuria. They were diagnosed acute post-renal failure due to obstructive bilateral ureteral stones based on the findings of ultrasound scan and computed tomography. Immediately, percutaneous nephrostomy tubes were inserted for urinary drainage, serum levels of creatinine and uric acid returned to normal within several days. Sandy stones were excreted through the nephrostomy tubes with urine after urinary alkalization, which were proved to be mainly ammonium acid urate. Ammonium acid urate is rare in developed countries, but some cases of bilateral urolithiasis causing acute renal failure in infants with rotavirus gastroenteritis were reported in recent years. It has been known that the cause of acute renal failure is renal azotemia resulting from sustained hypovolemia, but post-renal causes due to ammonium acid urate stones should be taken into consideration.

[Clinico-experimental rationale of choice of optimal contact pneumatic ureterolithotripsy].

We studied morphobiomechanical properties of the ureters of 134 adult people, results of treatment of 178 patients suffering from ureterolithiasis which were divided into two groups: the comparison group (n = 97) in which contact lithotripsy was carried out without power dosage lithotripter and the study group (n = 81) in which stone decomposition results were analysed with account of impulse duration and power of the shock wave estimated with special tables for an individual patient. We developed expert tables presenting optimal regimens for power pneumatic lithotriptor for fragmentation of a concrement with the least traumatic effect taking into account sex, age of the patient, size, chemical composition and location of the concrement. The above expert tables can be used in urological departments practicing contact ureterolithotripsy for ureterolithiasis, and in medical high schools for teaching students.

Evaluation and comparison of scoring systems for predicting stone-free status after flexible ureteroscopy for renal and ureteral stones.

OBJECTIVE: To evaluate four predictive scores for stone-free rate (SFR) after flexible ureterorenoscopy (f-URS) with holmium-YAG laser fragmentation of renal and ureteral lithiasis. METHODS: We carried out a retrospective analysis of 800 f-URS procedures performed in our institution between January 2009 and December 2016. For each procedure, a single surgeon calculated the following scores: S.T.O.N.E score; Resorlu Unsal Stone Score (RUSS); modified Seoul National University Renal Complexity (S-ReSC) score; and Ito's score. RESULTS: Overall SFR was 74.1%. Univariate analysis demonstrated that stone size (p<0.0001), stone volume (p<0.0001), stone number (p = 0.004), narrow lower pole infundibulopelvic angle (IPA) (p = 0.003) and lower pole location + IPA <45° (p = 0.011) were significantly associated with SFR. All scores differed between the stone-free and non-stone-free groups. Area under the curve of the receiving operator characteristics curve was calculated for each score: 0.617 [95%CI: 0.575-0.660] for the S.T.O.N.E score; 0.644 [95%CI: 0.609-0.680] for the RUSS; 0.651 [95%CI: 0.606-0.697] for the S-ReSC score; and 0.735 [95%CI: 0.692-0.777] for Ito's nomogram. CONCLUSION: All four scores were predictive of SFR after f-URS. Ito's score was the most sensitive. However, the performance of all scores in this analysis was lower than in developmental studies.

Oral chemolysis is an effective, non-invasive therapy for urinary stones suspected of uric acid content.

Despite the possible benefit from avoiding stone surgery with all its possible complications, oral chemolysis is rarely performed in patients with urinary stones suspected of uric acid content. Among the reasons for its limited use is the sparse and low-quality data on its efficacy and the lack of reliable factors predicting its outcome. We thus performed a retrospective single-center cohort study of 216 patients (median patient age 63 years) with 272 renal (48%) and/or ureteral (52%) stones treated with oral chemolysis from 01/2010 to 12/2019. Patients with low urine pH (< 6), low stone density upon non-contrast enhanced computed tomography (NCCT), radiolucent urinary stones on plain radiography, and/or a history of uric acid urolithiasis were included. Potassium citrate and/or sodium/magnesium bicarbonate were used for alkalization (target urine pH 6.5-7.2). Median stone size was 9 mm, median stone density 430 Hounsfield Units. Patients with ureteral stones < 6 mm were excluded since stones this small are very likely to pass spontaneously. The stone-free status of each patient was evaluated after 3 months using NCCT. Oral chemolysis was effective with a complete and partial response rate of stones at 3 months of 61% and 14%, respectively; 25% of stones could not be dissolved. Lower stone density (OR = 0.997 [CI 0.994-0.999]; p = 0.008) and smaller stone size (OR = 0.959 [CI 0.924-0.995]; p = 0.025) significantly increased the success rate of oral chemolysis in multivariate logistic regression analysis. More precise stone diagnostics to exclude non-uric-acid stones could further improve outcome.

Hounsfield units-a significant predictor of lasering time and energy in the management of upper urinary tract stones using Holmium: Yttrium-Aluminum Garnet lasers.

PURPOSE: To study the impact of stone density as assessed by Hounsfield units (HU) on total laser energy (TLE) used and total laser time (TLT) spent in complete fragmentation of upper urinary tract stones. In addition, we also studied the impact of stone composition on the laser energy and time required for fragmentation. METHODS: Thirty consecutive patients fulfilling inclusion and exclusion criteria were included in the study. Patients with renal or proximal ureteral stones with a size of 5-20 mm were included. Stone fragmentation was performed using Ho:YAG 100 W laser and TLT and TLE were correlated with the HU and stone composition. RESULTS: The mean stone diameter was 10.83 ± 3.5 mm and the mean HU was 893 ± 315. The mean TLE and TLT were 8.86 ± 3.12 kJ and 18.46 ± 6.9 min, respectively. We observed a strong positive correlation between HU and TLE (r = 0.84, p value < 0.001) and between HU and TLT (r = 0.58, p value = 0.001). However, the stone composition did not influence the lasering energy (p value = 0.36) and lasering time (p value = 0.30). Stone diameter also had significant positive correlation with TLE (r = 0.41; p = 0.02) and TLT (r = 0.54; p- 0.002). When controlling for stone size the correlation of HU with TLE (r = 0.83; p < 0.001) and TLT (r = 0.52; p = 0.004) remained significant. CONCLUSIONS: HU and stone diameter are significant predictors of TLE and TLT when using Ho:YAG laser for stone fragmentation. However, stone composition and stone location failed to show any significant effect on either of these parameters.

Effect of low dose radiation computerized tomography protocols on distal ureteral calculus detection.

PURPOSE: Unenhanced multidetector computerized tomography is the imaging modality of choice for urinary calculi but exposes patients to substantial radiation doses with a subsequent risk of radiation induced secondary malignancy. We compared ultra low dose and conventional computerized tomography protocols for detecting distal ureteral calculi in a cadaveric model. MATERIALS AND METHODS: A total of 85 calcium oxalate stones 3 to 7 mm long were prospectively placed in 14 human cadaveric distal ureters in 56 random configurations. The intact kidneys, ureters and bladders were placed in a human cadaveric vehicle and computerized tomography was performed at 140, 100, 60, 30, 15 and 7.5 mA seconds while keeping other imaging parameters constant. Images were independently reviewed in random order by 2 blinded radiologists to determine the sensitivity and specificity of each mA second setting. RESULTS: Overall sensitivity and specificity were 98% and 83%, respectively. Imaging using 140, 100, 60, 30, 15 and 7.5 mA second settings resulted in 98%, 97%, 97%, 96%, 98% and 97% sensitivity, and 83%, 83%, 83%, 86%, 80% and 84% specificity, respectively. Interobserver agreement was excellent (kappa >0.87). There was no significant difference in sensitivity or specificity at any mA second settings. All false-negative results were noted for 3 mm calculi at a similar frequency at each mA second setting. CONCLUSIONS: Ultra low dose computerized tomography protocols detected distal ureteral calculi in a fashion similar to that of conventional computerized tomography protocols in a cadaveric model. These protocols may decrease the radiation dose up to 95%, reducing the risk of secondary malignancies.