Determining the composition of urinary tract calculi using stone-targeted dual-energy CT: evaluation of a low-dose scanning protocol in a clinical environment.

OBJECTIVE: This study will evaluate the accuracy of dual-energy CT (DECT) in characterizing urinary tract stone composition on patients presenting to a UK hospital with renal colic. The study will also assess the additional radiation dose burden of DECT over standard protocol. METHODS: Data from 106 DECTs between October 2011 and October 2015 were retrospectively analyzed. Patients were imaged using a Toshiba Aquilion ONE™ CT scanner (Toshiba Medical Systems, Otawara-shi, Japan). All patients received a low-dose non-contrast CT of the abdomen and pelvis prior to stone-targeted DECT at 80 and 135 kVp and 40-mm field of view. Radiation dose output was evaluated using dose-length product (DLP). 19 stones were recovered and their compositions were analyzed using Fourier transform infrared spectroscopy. RESULTS: 137 stones were characterized. Mean stone diameter was 8.8 mm (range 3-48 mm). There was an 18.7% increase in mean DLP for DECT over standard CT protocol (319.4 vs 269.1 mGy cm; p < 0.001). Infrared spectroscopy analysis of 19 recovered stones identified 15 stones as calcium, 2 stones as cystine and 2 stones as mixed composition. Dual energy correctly predicted 11 (78.6%) of 14 calcium stones, 2 (100%) of 2 mixed composition stones and 0 (0%) of 2 cystine stones, resulting in a fair agreement (Cohen's κ = 0.374, p = 0.009). CONCLUSION: DECT is able to determine the composition of urinary tract stones with fair accuracy. Its utility is offset by a small but significant supplementary radiation exposure. Advances in knowledge: DECT can provide urological surgeons with useful diagnostic stone material information prior to planning optimal management of stone disease.

Estimation of urinary stone composition by automated processing of CT images.

The objective of this article was developing an automated tool for routine clinical practice to estimate urinary stone composition from CT images based on the density of all constituent voxels. A total of 118 stones for which the composition had been determined by infrared spectroscopy were placed in a helical CT scanner. A standard acquisition, low-dose and high-dose acquisitions were performed. All voxels constituting each stone were automatically selected. A dissimilarity index evaluating variations of density around each voxel was created in order to minimize partial volume effects: stone composition was established on the basis of voxel density of homogeneous zones. Stone composition was determined in 52% of cases. Sensitivities for each compound were: uric acid: 65%, struvite: 19%, cystine: 78%, carbapatite: 33.5%, calcium oxalate dihydrate: 57%, calcium oxalate monohydrate: 66.5%, brushite: 75%. Low-dose acquisition did not lower the performances (P < 0.05). This entirely automated approach eliminates manual intervention on the images by the radiologist while providing identical performances including for low-dose protocols.

[Diuress for the treatment of early stages of urolithiasis]. / Diuress dlia lecheniia rannikh stadii urolitiaza.

The efficacy of the plant diuretic Diuress is evaluated by using the rapid diagnosis program including renal ultrasonography, Lithos system, and urinary sediment microscopy.

Tips and tricks for the management of retained ureteral stents.

BACKGROUND AND PURPOSE: Retained ureteral stents, especially those that are encrusted and associated with a stone burden, can be a difficult management problem. We review our experience and the different options employed for treating this complication. PATIENTS AND METHODS: From July 1998 to February 2002, 26 retained ureteral stents were managed in our department. The average patient age was 45.9 years (range 8-77 years). The average time the stent had been in place was 10.7 months (range 3-28 months). Prior to planning definitive therapy, a plain radiograph with tomographic views was reviewed. RESULTS: A guidewire or Glidewire was often placed adjacent to the stent in order to maintain ureteral access and in some cases was able to facilitate removal of the retained stent. The patients required an average of 2.7 endourologic procedures (range 1-4) performed at one or more sessions to remove the stent and all associated stone burden. If the stone burden could not be entirely removed then stent extraction and subsequent sessions were performed until stone-free status was achieved. Cystolitholapaxy was required to treat the distal component of stent encrustation in 20 cases. Percutaneous nephrolithotomy was performed in four patients, antegrade ureteroscopy with or without intracorporeal lithotripsy in four patients, retrograde ureteroscopy with or without laser lithotripsy in five patients, and extracorporeal shockwave lithotripsy in seven patients to treat the proximal component of stent encrustation. The stent could be removed in a single anesthetic session in 23 of 26 cases (88.5%). Analysis revealed that the major component of the encrustations was a combination of calcium oxalate and phosphate. CONCLUSION: Successful management of retained ureteral stents requires careful planning and may entail a combination of endourologic approaches. It is imperative to avoid using significant force, which can result in severe ureteral injury or breakage of the stent. If encrustations are present along the stent, we believe in treating the distal component prior to managing any proximal or ureteral components.

Magnesium, citrate, magnesium citrate and magnesium-alkali citrate as modulators of calcium oxalate crystallization in urine: observations in patients with recurrent idiopathic calcium urolithiasis.

The effects of magnesium (Mg) and citrate on the metastable limit of calcium oxalate (CaOx) solubility (synonym: tolerable oxalate TO) were examined in artificial urine and in postprandial urine of male patients with idiopathic calcium urolithiasis (ICU). In artificial urine increasing pH, Mg and citrate elevate TO, decrease CaOx supersaturation only marginally, but elevate considerably free citrate; the effect of Mg alone was small in comparison with citrate alone, and the effects of both substances appeared additive. In ICU patients, matched for sex, age and CaOx supersaturation to non-stone-forming controls, TO was decreased (mean values 0.33 vs. 0.52 mM/l in controls, P < 0.05). Additional significant (P < 0.05) differences were found between ICU and controls: the former exhibited increased CaOx crystal growth, decreased crystal agglomeration time, a more acidic urinary pH, increased concentrations of free calcium and free Mg, and decreased free oxalate and free citrate. After ingestion of a urine-acidifying test meal, or this meal supplemented with either neutral Mg citrate or Mg-alkali citrate, by three groups of male ICU patients, matched for age and CaOx supersaturation, only the last-named preparation evoked an increase in TO and a decrease in crystal diameter, while the normally occurring pH decline from fasting urine was virtually abolished, and the ratios urinary Mg/citrate and calcium/citrate tended towards low values. In contrast, Mg citrate increased crystal agglomeration time, while changes in the other parameters were only insignificant. The crystals formed in urine were CaOx di- and monohydrate (by electron microscopy), and energy dispersive X-ray analysis showed calcium peaks exclusively. However, chemical analysis of crystals verified the presence not only of oxalate and calcium, but also of Mg, phosphate, citrate, and urate; moreover, these crystal constituents seemed to be influenced by Mg citrate and Mg-alkali citrate in different ways. It was concluded that (1) Mg and citrate are effectors of TO in artificial and natural urine; (2) in ICU, low TO and other disturbed CaOx crystallization parameters appear related to the prevailing low urinary pH and low free citrate; (3) Mg-alkali citrate inhibits CaOx crystallization, probably via actions of the citrate, but not the Mg. Because of the eminent role of Mg in human health and ICU, further studies on crystallization after oral intake of Mg in the form of citrate are warranted.

[The use of sinusoidal modulated currents and iodobromine baths in treating patients with the "stone pathway" of the upper urinary tract]. / Primenenie sinusoidal'nykh modulirovannykh tokov i iodobromnykh vann v lechenii bol'nykh s "kamennoi dorozhkoi" verkhnikh mochevykh putei.

After exposure to sinusoidal modulated currents and iodinebromine baths there was a decrease in serum levels of calcium, alanin aminotransferase, lactate dehydrogenase and urinary calcium, oxalates, leukocytes, red cells, acceleration of radiopharmaceutical accumulation (Tmax) and elimination from the kidneys (T1/2), urolith fragments (1-5 mm in size) elimination from the upper urinary tract in 21 (48.9%) out of 43 patients. The above physiotherapeutic complex is indicated for urolithiasis patients with associated diseases (hyperesthesia, causalgia).

[The usefulness of dual-energy radiographic densitometry (DO) in establishing the composition of calculi]. / Utilidad de la densitometría radiográfica de energía dual (DO) en el establecimiento de la composición litiásica.

Dual-energy radiographic bone densitometry is utilized to determine the bone mineral content in patients with osteoporosis. The present in vitro experimental study investigated the usefulness of densitometry in determining stone composition and in evaluating the mineral and non mineral phases of the calculus. For the study we analyzed 114 calculi of 6 different chemical composition (calcium oxalate monohydrate, calcium oxalate dihydrate, magnesium ammonium phosphate, phosphate carbonate, uric acid and phosphate oxalate). The phosphate carbonate calculi had the highest mineral density, whereas the uric acid calculi had the lowest and contained more water. Although densitometry appears to be of little value in determining stone composition, it provides information on the mineral and non mineral phases of the calculus.

Plain radiography, renography, and 99mTc-DMSA renal scintigraphy before and after extracorporeal shock wave lithotripsy for urolithiasis.

Eighteen patients were evaluated before and 5 weeks after the first treatment with extracorporeal shock wave lithotripsy (ESWL) using abdominal plain radiography, 131I-hippuran probe renography, and 99mTc-dimercaptosuccinic acid scintigraphy. In 6 patients no urolithiasis was present on the post ESWL plain radiograph, in 7 the size had decreased, and in 5 the stone mass was unchanged. The renograms were within normal range in the 6 patients who were cured by ESWL, whereas this was the case for only 4 of the 12 who still had renal calculi. In 2 patients pelvic stones had descended into the ureter after ESWL, and the renograms indicated obstruction. Another 3 patients had ureteral stones, whereas in the remaining 7 patients only pelvic stones were found on the plain radiographs. In no patient did the scintigrams reveal scars. It is concluded that abdominal plain radiography of the urinary tract and probe renography are complementary and sufficient in the monitoring of patients with urolithiasis post ESWL.

Urological complications in Crohn's disease.

We report the radiographic appearances of urinary tract complications in 11 patients with Crohn's disease, which included ureteric obstruction, displacement of ureters, renal calculi, bladder involvement with a pseudotumor appearance, and enterovesical fistulae.

[Ectopic calcifications in adult hypophosphatasia]. / Calcificazioni ectopiche in corso di ipofosfatasia dell'adulto.

The first case of hypophosphatasia in adults reported in Italy (20th in the world) is described with remarks on the epidemiology, pathogenesis and therapeutic possibilities. The formation of renal and cholecystic calculi after long-term, intensive vitamin D and Calcium therapy indicates the limited capacity of pyrophosphate (PPi), even in large doses, to prevent the precipitation in man of calcium and phosphorus and the subsequent formation of ectopic calcifications.

[Therapeutic effects of Quercus extract in urolithiasis]. / Efectos terapeuticos del extracto de "quercus" en la urolitiasis.

97 patients suffering from urolithiasis were treated with Litiax. 82 of them presented ureteral stones and the other 15 kidney stones. The product was administered in doses of 1350 mg. a day. The treatment lasted between 8 and 225 days, the average duration being 58 days. It was revealed from the results obtained that the product tested has an inhibiting effect on the growth of the stone, antiinflammatory and diuretic. It also seems to inhibit the bacteria proliferation to a certain extent. The excellent tolerance of the product is stressed.