In vivo evaluation of the chemical composition of urinary stones using dual-energy CT.

OBJECTIVE: The purpose of this article is to evaluate in vivo the chemical composition of urinary stones using dual-source and dual-energy CT, with crystallography as the reference standard. MATERIALS AND METHODS: Forty patients (mean [± SD] age, 49 ± 17 years) with known or suspected nephrolithiasis underwent unenhanced abdominal CT for urinary tract evaluation using a dual-energy technique (tube voltages, 140 and 80 kVp). For each stone 5 mm or larger in diameter, we evaluated the site, diameter, CT density, surface (smooth vs rough), and stone composition. Patients were treated with extracorporeal shock wave lithotripsy (n = 34), percutaneous nephrolithotomy (n = 4), or therapeutic ureterorenoscopy (n = 2). Collected stones underwent crystallography, and the agreement with the results of dual-energy CT was calculated with the Cohen kappa coefficient. The correlation among stone composition, diameter, and CT density was estimated using the Kruskal-Wallis test. RESULTS: Thirty-one patients had a single stone and nine had multiple stones, for a total of 49 stones. Forty-five stones were in the kidneys, and four were in the ureters; 23 had a smooth surface and 26 had a rough surface. The mean stone diameter was 12 ± 6 mm; mean CT density was 783 ± 274 HU. According to crystallography, stone composition was as follows: 33 were calcium oxalate, seven were cystine, four were uric acid, and five were of mixed composition. Dual-energy CT failed to identify four stones with mixed composition, resulting in substantial agreement between dual-energy CT and crystallography (Cohen κ = 0.684). Stone composition was not correlated with either stone diameter (p = 0.920) or stone CT density (p = 0.185). CONCLUSION: CT showed excellent accuracy in classifying urinary stone chemical composition, except for uric acid-hydroxyapatite mixed stones.

A consecutive series of patients undergoing trans-urethral cystolithotripsy with ballistic lithotripsy by a tertiary referral center for neurogenic bladder.

Background and aim of the work Patients with neurogenic bladder (NB) have an increased risk of developing bladder stones due to bladder catheter, incomplete bladder emptying, recurrent urinary tract infections, and immobilization. In these patients, minimally invasive treatments are usually adopted, as noninvasive extracorporeal shockwave lithotripsy is limited by the risk of not clearing all stone fragments, and open surgery is usually discouraged. The aim of our study was to present our experience with trans-urethral cystolithotripsy (TUCL) in patients treated by a tertiary referral center for NB. Methods We retrospectively collected pre-, intra- and post-operative data from our patients, who underwent TUCL from October 2013 to October 2019. The procedure was performed with a 24 Fr cystoscope and a ballistic lithotripter. Lapaxy was performed with Ellik bladder evacuator. All procedures were performed by two expert surgeons. Stone-free rate (SFR) was defined as the percentage of patients with absence of residual fragments > 2 mm in diameter. Results We performed consecutively 90 TUCLs in 75 patients during the selected period. SFR was 94.1%. Intra- and post-operative complications occurred in one (1.1%) patient. Our statistical analysis outlined the SFR was affected in a statistically significant way by sex, NB etiology, stone cumulative diameter, and operative time. Conclusion Our series proved the safety and efficacy of TUCL with ballistic lithotripsy in NB patients. Further multicenter randomized controlled trials are mandatory to validate definitively TUCL as the gold standard therapy for bladder urolithiasis in NB patients, and to identify risk factors limiting the SFR.