Urethroscopic holmium:YAG laser epilation of urethral diverticular hair follicles following hypospadias repair.

Urethral hair and diverticula are well described long-term complications following urethroplasty or hypospadias repair. Endoscopic laser ablation is an uncommonly reported treatment option for a symptomatic hair-bearing urethra, and holmium laser hair epilation has not been previously reported in the literature. We report the first case of urethroscopic holmium laser ablation of urethral diverticular hair follicles and the outcome.

Dual-energy computed tomography with advanced postimage acquisition data processing: improved determination of urinary stone composition.

INTRODUCTION: The characterization of urinary calculi using noninvasive methods has the potential to affect clinical management. CT remains the gold standard for diagnosis of urinary calculi, but has not reliably differentiated varying stone compositions. Dual-energy CT (DECT) has emerged as a technology to improve CT characterization of anatomic structures. This study aims to assess the ability of DECT to accurately discriminate between different types of urinary calculi in an in vitro model using novel postimage acquisition data processing techniques. METHODS: Fifty urinary calculi were assessed, of which 44 had >or=60% composition of one component. DECT was performed utilizing 64-slice multidetector CT. The attenuation profiles of the lower-energy (DECT-Low) and higher-energy (DECT-High) datasets were used to investigate whether differences could be seen between different stone compositions. RESULTS: Postimage acquisition processing allowed for identification of the main different chemical compositions of urinary calculi: brushite, calcium oxalate-calcium phosphate, struvite, cystine, and uric acid. Statistical analysis demonstrated that this processing identified all stone compositions without obvious graphical overlap. CONCLUSION: Dual-energy multidetector CT with postprocessing techniques allows for accurate discrimination among the main different subtypes of urinary calculi in an in vitro model. The ability to better detect stone composition may have implications in determining the optimum clinical treatment modality for urinary calculi from noninvasive, preprocedure radiological assessment.

High definition laparoscopy: objective assessment of performance characteristics and comparison with standard laparoscopy.

INTRODUCTION: High definition (HD) digital imaging represents a major advance in endoscope technology. The development of the charge-coupled device chip and its location at the distal end of the endoscope allows for image capture and digitization, as well as specific light filtration and processing. We assessed the capability of HD technology combined with digital imaging to provide improved image quality and enhanced spatial three-dimensional positioning. METHODS: A HD digital laparoscope and a standard definition (SD) laparoscope were evaluated in the laboratory setting to assess and compare image resolution, brightness, contrast, and color reproducibility, using standard industry testing protocols. RESULTS: Compared with the SD laparoscope, the HD laparoscope had superior resolution at 50 mm distance (2.4 line pairs/mm v 2.0 line pairs/mm), increased image brightness (129 lumens v 112 lumens), increased depth of field, and decreased distortion. Color and grayscale reproduction were found to be similar for the two laparoscopes. CONCLUSION: HD laparoscopy has superior objective performance characteristics compared with standard laparoscopes. Further investigation is required to determine whether these objective findings translate into subjective improvements, and which characteristics can be adjusted to obtain the best possible results. These improved optics may lead to easier identification of anatomic structures, finer dissection, and enhanced three-dimensional spatial positioning during HD laparoscopic procedures.

Renal stone assessment with dual-energy multidetector CT and advanced postprocessing techniques: improved characterization of renal stone composition--pilot study.

PURPOSE: To prospectively evaluate the capability of noninvasive, simultaneous dual-energy (DE) multidetector computed tomography (CT) to improve characterization of human renal calculi in an anthropomorphic DE renal phantom by introducing advanced postprocessing techniques, with ex vivo renal stone spectroscopy as the reference standard. MATERIALS AND METHODS: Fifty renal calculi were assessed: Thirty stones were of pure crystalline composition (uric acid, cystine, struvite, calcium oxalate, calcium phosphate, brushite), and 20 were of polycrystalline composition. DE CT was performed with a 64-detector CT unit. A postprocessing algorithm (DECT(Slope)) was proposed as a pixel-by-pixel approach to generate Digital Imaging and Communications in Medicine dataset gray-scale-encoding ratios of relative differences in attenuation values of low- and high-energy DE CT. Graphic analysis, in which clusters of equal composition were identified, was performed by sorting attenuation values of color composition-encoded calculi in an ascending sequence. Multivariate general linear model analysis was used to determine level of significance to differentiate composition on native and postprocessed DE CT images. RESULTS: Graphic analysis of native DE CT images was used to identify clusters for uric acid (453-629 HU for low-energy CT, 443-615 HU for high-energy CT), cystine (725-832 HU for low-energy CT, 513-747 HU for high-energy CT), and struvite (1337-1530 HU for low-energy CT, 1007-1100 HU for high-energy CT) stones; high-energy clusters showed attenuation value overlap. Polycrystalline calcium oxalate and calcium phosphate calculi were found throughout the entire spectrum, and dense brushite had attenuation values of more than 1500 HU for low-energy CT and more than 1100 HU for high-energy CT. The DE CT algorithm was used to generate specific identifiers for uric acid (77-80 U(Slope), one outlier), cystine (70-71 U(Slope)), struvite (56-60 U(Slope)), calcium oxalate and calcium phosphate (17-59 U(Slope)), and brushite (4-15 U(Slope)) stones. Statistical analysis showed that all compositions were identified unambiguously with the DECT(Slope) algorithm. CONCLUSION: DE multidetector CT with advanced postprocessing techniques improves characterization of renal stone composition beyond that achieved with single-energy multidetector CT acquisitions with basic attenuation assessment.

Impact of long-term potassium citrate therapy on urinary profiles and recurrent stone formation.

PURPOSE: Potassium citrate therapy has become one of the cornerstones of medical stone management. We elucidated the long-term effects of potassium citrate on urinary metabolic profiles and its impact on stone formation rates. MATERIALS AND METHODS: We performed a retrospective cohort study in patients treated at the Comprehensive Kidney Stone Center at our institution between 2000 and 2006. Patients with pre-therapy and post-therapy 24-hour urinary profiles available who remained on potassium citrate for at least 6 months were included in the analysis. RESULTS: Of the 1,480 patients with 24-hour urinary profiles 503 met study inclusion criteria. Mean therapy duration was 41 months (range 6 to 168). Overall a significant and durable change in urinary metabolic profiles was noted as soon as 6 months after the onset of therapy. These changes included increased urinary pH (5.90 to 6.46, p <0.0001) and increased urinary citrate (470 to 700 mg a day, p <0.0001). The stone formation rate also significantly decreased after the initiation of potassium citrate from 1.89 to 0.46 stones per year (p <0.0001). There was a 68% remission rate and a 93% decrease in the stone formation rate. CONCLUSIONS: Potassium citrate provides a significant alkali and citraturic response during short-term and long-term therapy with the change in urinary metabolic profiles sustained as long as 14 years of treatment. Moreover, long-term potassium citrate significantly decreases the stone formation rate, confirming its usefulness in patients with recurrent nephrolithiasis.

Radiation exposure in the acute and short-term management of urolithiasis at 2 academic centers.

PURPOSE: Diagnostic imaging has a central role in the evaluation and management of urolithiasis. A variety of modalities are available, each with benefits and limitations. Without careful consideration of imaging modalities in quantity and type patients may receive excessive doses of radiation during initial diagnostic and followup evaluations. Therefore, we determined the effective radiation dose associated with an acute stone episode and short-term followup. MATERIALS AND METHODS: A multicenter retrospective study of all patients who presented with an acute stone episode was performed. The analysis included all imaging studies related to stone disease performed within 1 year of the acute event. Using accepted effective radiation dose standards for each of these examinations, the total radiation dose administered was calculated and compared by patient characteristics including stone location, stone number and intervention strategy. The primary outcome assessed was a total radiation dose greater than 50 mSv, the recommended yearly dose limit for occupational exposure by the International Commission on Radiological Protection. RESULTS: We identified 108 patients who presented to our respective institutions with a primary acute stone episode between 2000 and 2006. The mean age in our cohort was 48.6 years and 50% of the patients were men. Patients underwent an average of 4 radiographic examinations during the 1-year period. Studies performed included a mean of 1.2 plain abdominal films of the kidneys, ureters and bladder (range 0 to 7), 1.7 abdominopelvic computerized tomograms (range 0 to 6) and 1 excretory urogram (range 0 to 3) during the first year of followup. The median total effective radiation dose per patient was 29.7 mSv (IQR 24.2, 45.1). There were 22 (20%) patients who received greater than 50 mSv. Analysis of stone location, number of stones, stone composition, patient age, sex and surgical intervention indicated no statistically significant difference in the probability of receiving a total radiation dose greater than 50 mSv. CONCLUSIONS: A fifth of patients receive potentially significant radiation doses in the short-term followup of an acute stone event. Radiographic imaging remains an integral part of the diagnosis and management of symptomatic urolithiasis. While debate exists regarding the threshold level for radiation induced fatal malignancies, urologists must be cognizant of the radiation exposure to patients, and seek alternative imaging strategies to minimize radiation dose during acute and long-term stone management.

Use of the Escape nitinol stone retrieval basket facilitates fragmentation and extraction of ureteral and renal calculi: a pilot study.

BACKGROUND AND PURPOSE: Advances in ureteroscope and stone basket design have catapulted ureteroscopy to the forefront of surgical stone management; however, persistent problems such as stone migration continue to challenge urologists. The Escape nitinol stone retrieval basket (Boston Scientific, Natick, MA) is a stone basket designed to capture calculi and facilitate simultaneous laser lithotripsy in situ. We report our initial experience with the Escape basket for the management of urinary calculi and compare the use of this device with other methods of optimizing ureteroscopic stone management. PATIENTS AND METHODS: A prospective evaluation of 23 patients undergoing ureteroscopic holmium:yttrium-aluminum-garnet laser lithotripsy of urinary calculi was performed at two institutions by two surgeons (R.M. and G.M.P). The Escape basket was used to prevent retrograde ureteral stone migration or to facilitate fragmentation and extraction of large renal calculi. Patient demographics and perioperative parameters were assessed. RESULTS: Twenty-three patients (16 men, 7 women), with a mean age of 55.5 years (range 33-74 yrs) were treated for renal (n = 9) or ureteral (n = 14) calculi. The mean stone diameter was 1.4 cm (range 0.4-2.5 cm), mean fragmentation time was 44.1 minutes (range 10-75 min), and mean energy used was 3.1 kJ (range 0.4-10.6 kJ). No complications were encountered. Eighty-seven percent (20/23) of patients were rendered completely stone free after ureteroscopic laser lithotripsy using the Escape basket. Of the three patients with residual calculi, one patient with a 2.5-cm renal calculus had residual fragments larger than 3 mm, and two patients with large renal calculi had residual fragments smaller than 3 mm. CONCLUSIONS: The Escape basket appears to be safe and effective in preventing stone migration and facilitating ureteroscopic laser lithotripsy and stone extraction.

Assessment of citrate concentrations in citrus fruit-based juices and beverages: implications for management of hypocitraturic nephrolithiasis.

BACKGROUND AND PURPOSE: Dietary intake of citrate in the form of citrus juices (eg, lemonade, orange juice) will enhance urinary citrate excretion, a valuable benefit for patients with hypocitraturic calcium oxalate nephrolithiasis. While information on citrate concentrations in select citrus juices is available, data on citrate concentrations of commercially available beverages (juice and otherwise) are limited. Using nuclear magnetic resonance spectroscopy (1H NMR), we report citrate concentrations of several beverages to help guide dietary recommendations aimed at increasing urinary citrate excretion and correcting hypocitraturia. METHODS: Citrate concentrations of a squeezed lemon, several fruit juices, and common beverages were measured using 1H NMR. Spectra for each sample were obtained in duplicate; citrate peak was identified, measured, and quantified and compared with the citrate concentration in the juice of 1 medium lemon. RESULTS: Quantitative analysis revealed the highest concentration of citrate was in grapefruit juice (64.7 mmol/L), followed in decreasing concentrations by lemon juice (47.66 mmol/L), orange juice (47.36 mmol/L), pineapple juice (41.57 mmol/L), reconstituted lemonade (38.65 mmol/L), lemonade flavored Crystal Light (38.39 mmol/L), ready to consume not from concentrate lemonade (38.24 mmol/L), cranberry juice (19.87 mmol/L), lemon-flavored Gatorade (19.82 mmol/L), homemade lemonade (17.42 mmol/L), Mountain Dew (8.84 mmol/L), and Diet 7Up (7.98 mmol/L), respectively. CONCLUSIONS: According to 1H NMR, all of the tested "natural" citrus juices have high concentrations of citrate (38.3-67.4 mmol/L), with grapefruit juice having the highest concentration of the beverages chosen. Lemonade flavored Crystal Light had the highest concentration of citrate in the nonjuice category of tested beverages. In patients with mild to moderate hypocitraturia, dietary supplementation with citrus-based juices may be an effective alternative to medical management while not requiring large serving sizes. Further prospective studies are warranted to evaluate the clinical significance of these findings.

Trainees do not negatively impact the institutional learning curve for robotic prostatectomy as characterized by operative time, estimated blood loss, and positive surgical margin rate.

OBJECTIVES: We evaluated the learning curves and perioperative outcomes of an experienced laparoscopic surgeon and his trainees to assess our structured teaching program. METHODS: We retrieved 383 patients undergoing robot-assisted laparoscopic prostatectomy (RALP) from our database. Trainees completed a structured teaching program and were categorized as early (days 0 to 232), mid (days 566 to 797), and late (days 825 to 1218) according to the time period in which they were working with the mentor. We compared operative times, estimated blood loss (EBL), and positive surgical margin (PSM) rates between the trainees and the mentor (Mann-Whitney and Chi-square test). Association of EBL, body mass index (BMI), and prostate weight with operative time was evaluated in multivariate linear regression analysis. RESULTS: Median operative times of the early, mid, and late trainees (258, 220, and 200 minutes) significantly decreased and were similar to the corresponding senior surgeon's (254, 242, and 180 minutes). Operative times decreased with lower BMI, EBL, and prostate weight (P = 0.006, P <0.001, and P <0.001, respectively). Overall, EBL (150 mL vs. 150 mL, P = 0.215) and PSM rates (20% vs. 18.6%, P = 0.741) did not differ between the mentor and the trainees. CONCLUSIONS: A structured teaching program for RALP is effective and trainees are able to adopt the increased efficiency and skills of their mentor. Lower BMI, EBL, and prostate weight were associated with shorter operative times. Trainees performing the procedure did not negatively affect EBL and positive surgical margin rate.

Evaluation of a new multi-basket load-release ureteral stent.

INTRODUCTION: A multi-basket ureteral stent was tested and modified to assess feasibility of load-release features intended to release stone(s) if resistance is encountered during stent removal. METHODS: Three versions of the stent were evaluated: (1) unaltered stent, (2) one strand of each basket partially cut to 50%, or 75% (3) tube between baskets longitudinally slit. One of the baskets was filled with multiple 3-4-mm stones or a single large 6-mm stone to 20Fr diameter. The force required to release the device through a tube with an 8Fr narrowing was determined. In a separate assessment, urologists used a string attached to the force gauge to exert the maximum force they would be comfortable using in ureteral stent removal. RESULTS: The unaltered stent was associated with higher release forces or inability to remove the stent: 18.67 +/- 8.35 N when a single large stone was present, compared to 8.46 +/- 2.75 N for multiple small stones. Modified devices with 50% and 75% cut basket strands released at 15.19 +/- 1.54 N, and 10.65 +/- 2.09 N, respectively. The longitudinal slit device released at 3.11 +/- 1.57 N. The maximum force exerted by urologists in simulated stent removal was 7.3 +/- 0.4 N. CONCLUSION: Modifications to the multi-basket ureteral stent allow for stent removal in an in vitro model with a narrowing present with stone(s) in the stent baskets. The longitudinal slit modification appears to allow for stent removal with forces low enough to prevent significant ureteral injury, even if ureteral strictures are present.

The future of lasers in urology.

The use of laser applications in urology has undergone significant advances over the past 20 years. Laser technology is now used in a wide variety of procedures, and has become the primary treatment modality or standard of care for many urologic conditions. Despite these advances, a number of challenges still face laser utilization in urologic practice. Recent work has illuminated the potential improvement and further optimization of this field. Improvements in types of lasers, the wavelength of energy used, optical fiber delivery systems, precision of laser application and cost reduction have served to further improve laser technology and extend the potential applications.