Can a dual-energy computed tomography predict unsuitable stone components for extracorporeal shock wave lithotripsy?

PURPOSE: To assess the potential of dual-energy computed tomography (DECT) to identify urinary stone components, particularly uric acid and calcium oxalate monohydrate, which are unsuitable for extracorporeal shock wave lithotripsy (ESWL). MATERIALS AND METHODS: This clinical study included 246 patients who underwent removal of urinary stones and an analysis of stone components between November 2009 and August 2013. All patients received preoperative DECT using two energy values (80 kVp and 140 kVp). Hounsfield units (HU) were measured and matched to the stone component. RESULTS: Significant differences in HU values were observed between uric acid and nonuric acid stones at the 80 and 140 kVp energy values (p or =90%, calcium oxalate dihydrate group: monohydrate<90%). Significant differences in HU values were detected between the two groups at both energy values (p<0.001). CONCLUSIONS: DECT improved the characterization of urinary stone components and was a useful method for identifying uric acid and calcium oxalate monohydrate stones, which are unsuitable for ESWL.

Evaluation of low-dose dual energy computed tomography for in vivo assessment of renal/ureteric calculus composition

PURPOSE: This study aimed to assess the accuracy of low-dose dual-energy computed tomography (DECT) in predicting the composition of urinary calculi. MATERIALS AND METHODS: A total of 52 patients with urinary calculi were scanned with a 128-slice dual-source DECT scanner by use of a low-dose protocol. Dual-energy (DE) ratio, weighted average Hounsfield unit (HU) of calculi, radiation dose, and image noise levels were recorded. Two radiologists independently rated study quality. Stone composition was assessed after extraction by Fourier transform infrared spectroscopy (FTIRS). Analysis of variance was used to determine if the differences in HU values and DE ratios between the various calculus groups were significant. Threshold cutoff values to classify the calculi into separate groups were identified by receiver operating characteristic curve analysis. RESULTS: A total of 137 calculi were detected. FTIRS analysis differentiated the calculi into five groups: uric acid (n=17), struvite (n=3), calcium oxalate monohydrate and dihydrate (COM-COD, n=84), calcium oxalate monohydrate (COM, n=28), and carbonate apatite (n=5). The HU value could differentiate only uric acid calculi from calcified calculi (p80% sensitivity and specificity to differentiate them. The DE ratio could not differentiate COM from COM-COD calculi. No study was rated poor in quality by either of the observers. The mean radiation dose was 1.8 mSv. CONCLUSIONS: Low-dose DECT accurately predicts urinary calculus composition in vivo while simultaneously reducing radiation exposure without compromising study quality.

Multimodal Treatments of Cystine Stones: An Observational, Retrospective Single-Center Analysis of 14 Cases

PURPOSE: To document the experiences of a single institution in evaluating the clinical courses and treatment outcomes of patients with cystine stones. MATERIALS AND METHODS: The clinical data of 14 patients with cystine stones who were treated at our institution from March 1994 to July 2012 were reviewed. These data included age at first visit, gender, family history, body mass index, presence of a single kidney, stone locations, stone burden, routine urinalysis, and culture. In addition, we also analyzed data on surgery, shock wave lithotripsy, medical treatment, stone recurrence or regrowth, and overall treatment success rates. RESULTS: The mean age of our patients at their first visit was 19.6+/-5.0 years, and eight patients were males. The median stone burden and mean urine pH before each surgery were 6.5 cm2 and 6.5+/-0.9, respectively. Two patients had a family history of cystine stones. Patients underwent surgery an average of 2.7 times. The median interval between surgeries was 27.3 months, and 1 open surgery, 12 percutaneous nephrolithotomies, and 25 ureterorenoscopies were performed. Potassium citrate or sodium bicarbonate was used in nine cases. D-Penicillamine was continuously used in three patients. Patients had an average incidence of 3.2 recurrences or regrowth of stones during the median follow-up period of 60.5 months. CONCLUSIONS: Patients with cystine stones have high recurrence or regrowth rates and relatively large stone burdens. Adequate treatment schedules must therefore be established in these cases to prevent possible deterioration of renal function.

Chemical analysis of urinary calculi in Haryana.

Quantitative chemical analysis of 225 urinary calculi (128 Renal, 57 bladder and 40 ureter) collected from hospitals of different districts of Haryana was carried out. CaOxM was found to be present as a major component in all the stones analysed, while MAP, HA, CA and UA were found in 83.7%, 83.6%, 13% and 78.9% cases, respectively. The content of CaOxM was found to be higher in renal stones as compared to ureter and bladder stones, while the concentration of MAP was higher in bladder stones as compared to kidney and ureter stones. HA content was higher in ureter and UA was higher in bladder stones as compared to other urinary stones.

Upper urinary tract stone analysis using X-ray diffraction: results from a tertiary referral centre in northern India.

BACKGROUND: The spectrum of urinary stone disease has changed considerably in India from the common childhood bladder stone to the more frequent upper tract calculi. We analysed the gravel retrieved from the upper urinary tract using X-ray diffraction analysis in an attempt to evaluate the composition of the stones. METHODS: We analysed 434 upper urinary tract calculi from May 1993 to June 1994 obtained endourologically, as well as by extracorporeal shock wave lithotripsy and open surgery. The stones were analysed using a Phillips compact X-ray diffractometer (PW1840). The PC-APD software was used for data collection and peak search. The phase matching was done by the software using the JCPDS reference database. RESULTS: Oxalate stones comprised 97% of the total stones with calcium oxalate monohydrate forming 90% and calcium oxalate dihydrate and mixed stones forming the remainder. Struvite stones were found in 1.4%, while uric acid and apatite stones were less than 1%. There were no cystine calculi. Seventy per cent of calcium oxalate monohydrate and 40% of calcium oxalate dihydrate stones were pure. All the struvite and apatite calculi were almost pure. Only 15% of staghorns did not consist of oxalate. Nine of the ten stones in children were of the calcium oxalate monohydrate variety. The stone composition in females was similar to that in males. CONCLUSIONS: X-ray diffraction data indicate that urinary stone disease in north India is different from that in the western world. Calcium oxalate monohydrate stones predominate. These stones are hard to break and have a different metabolic origin from those consisting of calcium oxalate dihydrate. These findings might help in selecting the most appropriate method of treatment in north India and they indicate directions in which further metabolic studies might be planned.