Internal-Illumination Photoacoustic Tomography Enhanced by a Graded-Scattering Fiber Diffuser.

The penetration depth of photoacoustic imaging in biological tissues has been fundamentally limited by the strong optical attenuation when light is delivered externally through the tissue surface. To address this issue, we previously reported internal-illumination photoacoustic imaging using a customized radial-emission optical fiber diffuser, which, however, has complex fabrication, high cost, and non-uniform light emission. To overcome these shortcomings, we have developed a new type of low-cost fiber diffusers based on a graded-scattering method in which the optical scattering of the fiber diffuser is gradually increased as the light travels. The graded scattering can compensate for the optical attenuation and provide relatively uniform light emission along the diffuser. We performed Monte Carlo numerical simulations to optimize several key design parameters, including the number of scattering segments, scattering anisotropy factor, divergence angle of the optical fiber, and reflective index of the surrounding medium. These optimized parameters collectively result in uniform light emission along the fiber diffuser and can be flexibly adjusted to accommodate different applications. We fabricated and characterized the prototype fiber diffuser made of agarose gel and intralipid. Equipped with the new fiber diffuser, we performed thorough proof-of-concept studies on ex vivo tissue phantoms and an in vivo swine model to demonstrate the deep-imaging capability (~10 cm achieved ex vivo) of photoacoustic tomography. We believe that the internal light delivery via the optimized fiber diffuser is an effective strategy to image deep targets (e.g., kidney) in large animals or humans.

The Impact of Alternative Alkalinizing Agents on 24-Hour Urine Parameters.

OBJECTIVES: To determine if alternative alkalinizing agents lead to similar changes in 24-hour urine pH and citrate compared to potassium citrate (KCIT). Many stone formers cannot tolerate KCIT due to side effects or cost. In these patients, we have prescribed potassium bicarbonate or sodium bicarbonate as alternative alkali (AA), though their efficacy is unclear. METHODS: We performed a retrospective cohort study of adult stone formers seen from 2000 to 2018 with 24-hour urine analyses. Two analyses were performed. The first evaluated the alkalinizing and citraturic effects in patients with baseline low urine pH or hypocitraturia off of any alkalinizing medications, who were subsequently treated with either KCIT or AA. The second analysis compared the pH and citrate in patients changing from KCIT to an AA. Reasons for switching were abstracted by chart review and cost savings percentages were calculated using GoodRx medication prices. RESULTS: When starting alkali therapy, the median increase in pH from baseline was 0.64 for KCIT and 0.51 for AA (P = .077), and the median increase in citrate from baseline was 231 mg for KCIT and 171 mg for AA (P = .109). When switching alkali therapy, median pH and citrate did not significantly change. Hyperkalemia (24%), GI upset (19%), and cost (17%) were the most common reasons cited for switching to an AA. AA represented a savings of 86%-92% compared to KCIT. CONCLUSION: Alternative alkali appear to offer comparable improvements in 24-hour urine parameters and significant cost-savings compared to KCIT.

Assessment of conservative dietary management as a method for normalization of 24-h urine pH in stone formers.

Low urine pH is a metabolic risk factor for stone formation. While medical therapy is typically prescribed (as urinary alkalinization), patients typically prefer dietary modifications. We aimed to assess capacity to alter urine pH with dietary management alone. We analyzed a retrospective cohort of stone formers seen between 2000 and 2015 with multiple 24-h urine collections (24hUC). Patients ≥ 18 years old with low urine pH (< 6.0) were included; those prescribed alkalinizing agents or thiazides were excluded. Demographic data, 24hUC parameters, and medications were abstracted. 24hUC was utilized to calculate gastrointestinal alkali absorption (GIAA). The primary outcome was urine pH ≥ 6.0 on second 24hUC. Predictors were selected utilizing multivariable logistic regression. The database consisted of 2197 stone formers; 224 of these met inclusion criteria. On second 24hUC, 124 (55.4%) achieved a favorable pH ≥ 6.0. On univariable analysis, a second pH ≥ 6.0 was associated with high initial pH, low initial sulfate, younger age, increase in citrate/GIAA/urine volume, and decrease in ammonium (P < 0.02). On multivariable analysis, high initial pH (OR = 23.64, P < 0.001), high initial GIAA (OR = 1.03, P = 0.001), lower initial sulfate (OR = 0.95, P < 0.001), increase in urine volume (OR = 2.19, P = 0.001), increase in GIAA (OR = 8.6, P < 0.001), increase in citrate (OR = 2.7, P = 0.014), decrease in ammonium (OR = 0.18, P < 0.001), and younger age (OR = 0.97, P = 0.025) were associated with a second pH ≥ 6.0. The analysis demonstrated a corrected AUC of 0.853. These data suggest that certain dietary recommendations (increases in urine volume, citrate, GIAA, and decreased acid load) may normalize urine pH in a select group of patients. This may allow urologists to counsel patients with low urine pH on possibility of success with dietary modification alone.

Holmium:Yttrium-Aluminum-Garnet Laser Pulse Type Affects Irrigation Temperatures in a Benchtop Ureteral Model.

Introduction: MOSES™ technology is a holmium:yttrium-aluminum-garnet laser pulse mode shown to minimize stone retropulsion. This may facilitate lithotripsy at higher power settings. However, power and heat production are proportional, and temperatures capable of tissue injury may occur during ureteroscopic lithotripsy. Although previous in vitro studies demonstrate the importance of irrigation and activation time on heat production, the impact of pulse type has not been evaluated. Methods: A flexible ureteroscope with a 365 µm laser fiber was placed in an 11/13 F access sheath inserted into a 50 mL saline bag to simulate a ureter, renal pelvis, and antegrade irrigant flow. A thermocouple was placed adjacent to the laser tip, and the laser fired for 30 seconds at 0.6 J/6 Hz, 0.8 J/8 Hz, 1 J/10 Hz, 1 J/20 Hz, and 0.2 J/70 Hz at irrigation pressure of 100 mmHg. Four runs were tested per setting using short pulse, long pulse (LP), MOSES-contact (MC), and MOSES-distance (MD) modes. The mean temperature changes (dT) were compared and thermal dose was calculated in cumulative equivalent minutes at 43°C (CEM43) using an adjusted baseline of 37°C. CEM43 ≥ 120 minutes was considered the tissue injury threshold. Results: At 0.8 J/8 Hz, LP produced the greatest dT, significantly higher than MC (p = 0.041). CEM43 did not exceed the injury threshold. At 1 J/10 Hz, dT was significantly higher for LP versus MC and MD (p = 0.024 and 0.045, respectively). Thermal dose remained below the injury threshold. No differences in dT were seen between pulse types at 0.6 J/6 Hz, 0.2 J/70 Hz, or 1 J/20 Hz. At 1 J/20 Hz, thermal dose exceeded the injury threshold for all pulse types within 3 seconds. Conclusions: Laser pulse type and length seemed to impact heat production in our ureteral model. LP produced significantly greater temperatures at 0.8 J/8 Hz and 1 J/10 Hz relative to MOSES settings. Fortunately, thermal dose remained safe at these settings. Both LP and MOSES technology have been shown to reduce stone retropulsion. At power ≤10 W, the latter may confer this advantage with decreased heat production.

The Rise and Fall of High Temperatures During Ureteroscopic Holmium Laser Lithotripsy.

Introduction: Temperatures over 43°C-the threshold for cellular injury-may be achieved during ureteroscopic holmium laser lithotripsy. The time to reach and subsequently clear high temperatures at variable laser power settings and irrigation pressures has not been studied. Methods: A flexible or semirigid ureteroscope was placed within an 11/13 F ureteral access sheath inserted into a 250-mL saline bag simulating a normal-caliber ureter, renal pelvis reservoir, and antegrade irrigation flow. A thermocouple was placed adjacent to a 365 µm fiber fired for 45 seconds at 0.6 J/6 Hz, 0.8 J/8 Hz, 1 J/10 Hz, 1 J/20 Hz, and 0.2 J/80 Hz. Irrigation pressures of 200, 100, and 0 mm Hg were tested. Mean temperature changes were recorded with 6°C increase as a threshold for injury (as body temperature is 6°C below 43°C). Results: Semirigid scope: At 200 mm Hg no temperature changes >6°C were observed. At 100 mm Hg, changes >6°C occurred with 1 J/20 Hz within 1 second of activation and returned to ≤6°C within 1 second of cessation. At 0 mm Hg, changes >6°C occurred with all settings; within 1 second at power ≥10 W. Temperatures returned to ≤6°C within 5-10 seconds. Flexible scope: At 200 mm Hg, changes >6°C occurred at 1 J/10 Hz (15 seconds), 0.2 J/80 Hz (3 seconds), and 1 J/20 Hz (2 seconds). Temperatures returned within 6°C of baseline within 2 seconds. At 100 mm Hg, changes >6°C occurred in all but 0.6 J/6 Hz. Temperatures returned to ≤6°C in 5-10 seconds. At 0 mm Hg, all settings produced changes >6°C within 3 seconds, except 0.6 J/6 Hz (35 seconds). Temperatures returned to ≤6°C in under 10 seconds. Conclusions: High temperatures were achieved in our in vitro model in as little as 1 second at common irrigation pressures and laser settings, particularly with a flexible ureteroscope and power ≥10 W. However, with laser cessation, temperatures quickly returned to a safe level at each irrigation pressure.

Avoiding a Lemon: Performance Consistency of Single-Use Ureteroscopes.

INTRODUCTION AND OBJECTIVES: Single-use flexible ureteroscopes are increasingly popular because of high repair costs of reusable ureteroscopes. As new single-use ureteroscopes enter the market, the consistency of performance of these devices has been questioned. Our objective was to compare two single-use ureteroscopes: the Pusen PU3022a (Zhuhai Pusen) and the LithoVue (Boston Scientific) with emphasis on physical and optical performance consistency. METHODS: Ten LithoVue and 10 Pusen ureteroscopes were evaluated in never-used condition. The following parameters were recorded: maximal tip deflection with an empty working channel, 200 µm laser fiber, and 1.9F basket; image resolution at 10, 20, and 50 mm; and irrigation flow rate; all ureteroscopes were then fully deflected for 200 cycles. Maximum deflection was remeasured. Mean values for each parameter were compared. To examine within-manufacturer consistency, the variance was calculated and an F-test performed to evaluate for equivalence. RESULTS: Both ureteroscopes provided max deflection over 270°. The Pusen flexed to a greater degree than LithoVue. The Pusen lost more deflection with a laser fiber in the working channel. LithoVue had higher resolution at 10 mm, but the ureteroscopes were similar at 20 and 50 mm. Although the working channel diameter is identical, irrigation flow was higher with the Pusen. However, its working channel was 7 cm shorter than LithoVue. After 200 cycles of deflections, LithoVue had less deflection loss, although one ureteroscope was excluded from analysis because of mechanical failure. Variability was minimal and not significant between manufacturers at all measured parameters. CONCLUSIONS: LithoVue and the newer PU3022a have similar "out-of-the-box" performance characteristics and seem durable. These two single-use flexible ureteroscopes performed consistently regardless of the manufacturer.

Psychiatric Diagnoses and Other Factors Associated with Emergency Department Return within 30 Days of Ureteroscopy.

PURPOSE: Emergency department visits after ureteroscopy are costly and inconvenient. To better understand those at risk we aimed to identify patient demographic, medical and surgical factors associated with 30-day emergency department presentation following ureteroscopy for urolithiasis with particular attention to those with a history of a psychiatric diagnosis. MATERIALS AND METHODS: We retrospectively reviewed 1,576 cases (1,395 adults) who underwent stone related ureteroscopy during 3 years at a total of 2 hospitals. We collected patient demographics, medical history and operative details. The primary outcome was return to the emergency department within 30 days of ureteroscopy. Logistic regression was performed to examine factors associated with emergency department presentation. RESULTS: Of the patients 613 (43.9%) had a history of psychiatric diagnosis. Of those with ureteroscopy encounters 12.6% returned to the emergency department within 30 days of ureteroscopy, including 58.8% with a history of psychiatric diagnosis. On multivariable analysis variables associated with emergency department return included a history of psychiatric diagnosis (OR 1.57, p = 0.012), uninsured status (OR 2.46, p = 0.001) and a stone only in the kidney (OR 1.76, p = 0.022). Patients who returned to the emergency department had had more emergency department visits in the year prior to surgery (OR 1.40, p <0.001). On univariable analysis older patients and those with longer operative time were more frequently admitted from the emergency department (OR 1.03, p = 0.002 and OR 1.96, p = 0.03. respectively) while uninsured patients were admitted less frequently (OR 0.19, p = 0.013). No difference was noted in admissions between those with a psychiatric diagnosis and all others (60.7% vs 55.8%, p = 0.48). CONCLUSIONS: We identified factors associated with emergency department return after ureteroscopy, including a history of psychiatric diagnosis, uninsured status and emergency department visits in the year before surgery. These patients may benefit from targeted interventions to help avoid unnecessary emergency department visits.

Let's Get to the Point: Comparing Insertion Characteristics and Scope Damage of Flat-Tip and Ball-Tip Holmium Laser Fibers.

INTRODUCTION: A ball-tip holmium laser fiber (TracTip; Boston Scientific) has been developed to theoretically reduce damaging friction forces generated within a ureteroscope working channel. We compared the insertional forces and damage with a ureteroscope inner lining when inserting standard flat-tip and ball-tip laser fibers. MATERIALS AND METHODS: A standard ureteroscope channel liner was placed in a 3D-printed plastic mold. Molds were created at four angles of deflection (30°, 45°, 90°, and 180°) with a 1 cm radius of curvature. New 200 µm ball-tip (TracTip; Boston Scientific) and 200 µm flat-tip (Flexiva; Boston Scientific) laser fibers were advanced through the liner using a stage controller. A strain gauge was used to measure force required for insertion. Each fiber was passed 600 times at each angle of deflection. The ureteroscope liner was changed every 150 passes. Leak testing was performed every 50 passes or when the insertional force increased significantly to assess damage to the liner. RESULTS: At all deflection angles, the average insertional force was significantly lower with the ball-tip laser fibers compared with flat-tip laser fibers (p < 0.001). All trials with the ball-tip lasers were completed at each angle without any leaks. Two of four trials using flat-tip fibers at 45° deflection caused liner leaks (at 91 and 114 passes). At 90° deflection, all flat-tip trials caused liner leaks on first pass. The 180° trials could not physically be completed with the flat-tip laser fiber. Within the flat- and ball-tip groups, an increasing amount of force was needed to pass the fiber as the degree of deflection increased (p < 0.001). CONCLUSIONS: The ball-tip holmium laser fiber can be safely passed through a deflected ureteroscope without causing liner perforation. The standard flat-tip fiber requires greater insertion force at all angles and can cause the ureteroscope liner to leak if it is deflected 45° or more.

Dusting Efficiency of the Moses Holmium Laser: An Automated In Vitro Assessment.

INTRODUCTION: Moses technology is a novel Holmium:YAG laser system designed to minimize stone retropulsion and improve stone ablation when the laser is not in direct contact with the stone. Our aim was to assess the efficiency of Moses technology relative to short- and long-pulse lithotripsy using an automated in vitro "dusting model" of stone comminution. METHODS: All tests were conducted using a Lumenis Pulse 120H Holmium:YAG laser with a 365 µm Moses D/F/L fiber. "Hard" (15:3) and "soft" (15:6) Begostones mimicking calcium oxalate monohydrate and uric acid stones, respectively, were used. To assess ablation efficiency and fiber tip degradation, a dusting model was employed: the laser was moved by a three-dimensional positioning system in a spiral motion across a flat Begostone surface submerged in water. Ablation efficiency was measured as stone mass loss after 4 kJ of energy delivery. Fiber tip degradation was measured at 1 kJ intervals. Comparative trials with short pulse, long pulse, Moses contact, and Moses distance settings were completed with the laser tip positioned at 0, 1, and 2 mm distances from the stone at energy settings of 0.4 J delivered at 70 Hz. RESULTS: In our dusting model, stone ablation was significantly greater the closer the laser was to the stone. On hard stones, pulse type did not have a significant impact on ablation at any distance. On soft stones at 0 mm, Moses contact produced the greatest ablation, significantly greater than long pulse (p < 0.05). At 1 mm, Moses distance produced significantly greater ablation than all other settings (p = 0.025) and was as effective as long or short pulse at 0 mm. At 2 mm distance, no pulse type demonstrated significantly different ablation. Fiber tip degradation was minimal and not significant between settings. CONCLUSIONS: Moses technology delivers greater ablation of soft stones when in contact and 1mm from the stone surface.

In Vitro Comparison of a Novel Single Probe Dual-Energy Lithotripter to Current Devices.

PURPOSE: The LithoClast Trilogy is a novel single probe, dual-energy lithotripter with ultrasonic (US) vibration and electromagnetic impact forces. ShockPulse and LithoClast Select are existing lithotripters that also use a combination of US and mechanical impact energies. We compared the efficacy and tip motion of these devices in an in vitro setting. MATERIALS AND METHODS: Begostones, in the ratio 15:3, were used in all trials. Test groups were Trilogy, ShockPulse, Select ultrasound (US) only, and Select ultrasound with pneumatic (USP). For clearance testing, a single investigator facile with each lithotripter fragmented 10 stones per device. For drill testing, a hands-free apparatus with a submerged balance was used to apply 1 or 2 lbs of pressure on a stone in contact with the device tip. High-speed photography was used to assess Trilogy and ShockPulse's probe tip motion. RESULTS: Select-USP was slowest and Trilogy fastest on clearance testing (p < 0.01). On 1 lbs drill testing, Select-US was slowest (p = 0.001). At 2 lbs, ShockPulse was faster than Select US (p = 0.027), but did not significantly outpace Trilogy nor Select-USP. At either weight, there was no significant difference between Trilogy and ShockPulse. During its US function, Trilogy's maximum downward tip displacement was 0.041 mm relative to 0.0025 mm with ShockPulse. Trilogy had 0.25 mm of maximum downward displacement during its impactor function while ShockPulse had 0.01 mm. CONCLUSIONS: Single probe dual-energy devices, such as Trilogy and ShockPulse, represent the next generation of lithotripters. Trilogy more efficiently cleared stone than currently available devices, which could be explained by its larger probe diameter and greater downward tip displacement during both US and impactor functions.

In pursuit of the perfect penis: Hypospadias repair outcomes.

Hypospadias is commonly assessed and repaired by pediatric urologists. Mild, distal hypospadias is generally more a cosmetic problem than a functional one and is more frequently encountered than severe, proximal hypospadias. Outcomes following repair, especially of mild phenotypes, are important to understand, but range widely in timing and measurability. Surgical complications, postoperative satisfaction of parents, patients, surgeons and even lay observers, urinary function, sexual function, and quality of life all may be considered as relevant outcomes of hypospadias repair. Existing studies examining these outcomes are diverse in their conclusions, but are important to understand when counseling parents and patients prior to any surgical intervention.

Safety of perioperative subcutaneous heparin for partial nephrectomy.

INTRODUCTION: The development of deep venous thrombosis (DVT) or pulmonary embolism (PE) following urologic surgery is a life threatening, but largely preventable complication. Patients undergoing partial nephrectomy are at increased risk for the development of DVT or PE as they often possess multiple risk factors including malignancy, advanced age, and prolonged surgical time. This risk can be significantly reduced by administration of perioperative subcutaneous heparin (SQH), however many surgeons feel this is contraindicated due to potential blood loss and related complications. MATERIALS AND METHODS: The medical records of 293 consecutive patients undergoing planned open, laparoscopic, or robotic assisted partial nephrectomy by a single surgeon over a 7 year period were reviewed. Approximately halfway through the period, the standard DVT prevention practice was changed from sequential compression stockings and early ambulation to include 5000 units of SQH administered 30-60 minutes prior to incision and continuing every 8 hours until discharge. RESULTS: A total of 158 patients received perioperative SQH. There was no significant difference in surgical blood loss, transfusions, operative time, change in pre to postoperative hemoglobin or creatinine, conversion to radical nephrectomy, or duration of stay between the groups. There were no DVTs in either group. There was one PE in the group receiving SQH which was incidentally discovered. CONCLUSIONS: Patients undergoing renal surgery for cancer are at increased risk for the development of DVT and PE. Prophylaxis against this serious complication with perioperative SQH is safe in patients undergoing partial nephrectomy despite common surgeon concerns regarding blood loss and related complications.

The quality of pediatric orthopaedic information on the internet.

BACKGROUND: Many patients use the Internet for health information. However, there are few guarantees to the reliability and accuracy of this information. This study examined the quality and content of the Internet Web pages for 10 common pediatric orthopaedic diagnoses. METHODS: We identified 10 common diagnoses in pediatric orthopaedics: brachial plexus injury, cerebral palsy, clubfoot, developmental dysplasia of the hip, leg length discrepancy, osteochondroma, polydactyly, scoliosis, spina bifida, and syndactyly. We used 2 of the most popular search engines to identify the top 10 Web sites for each disease. We evaluated the Web sites utilizing both the quality-based Health On the Net (HON) Foundation criteria and our own content-based grading sheets. The custom grading sheets focused on essential information about disease summary, pathogenesis, diagnosis, treatment, and prognosis. RESULTS: Three orthopaedic surgeons graded 98 academic, commercial, nonprofit, and physicians' Web sites for 10 diseases. Academic Web sites scored the highest in content (mean, 60.8% ± 15.5%), whereas commercial Web sites scored the lowest (mean, 46.7% ± 22.2%). Among the diagnoses, osteochondroma Web sites had the highest content scores (mean, 75.8% ± 11.8%), whereas polydactyly Web sites had the lowest content scores (mean, 39.3% ± 15.7%). In contrast, Web sites about developmental dysplasia of the hip had the highest HON scores (65.0 ± 11.1), whereas those about brachial plexus birth palsy scored the lowest (42.6% ± 16.9%). Among the content subgroups, scores were generally higher for disease summary and diagnostics and lower for prognosis. CONCLUSIONS: The Internet Web sites reviewed demonstrated a wide range of content and information. We found that nonprofit and academic Web sites were the most reliable sources, whereas commercial and, surprisingly, physician-run Web sites were the least reliable. We advise physicians to talk to their patients about the information they get on the Internet and how it dictates their expectations. We hope this study, combined with further understanding of how our patients use this information, can help improve the Internet content. CLINICAL RELEVANCE: Physicians should know that their patients may be receiving misleading information from the Internet and be able to discuss this with their patients.

A single-center analysis of abdominal imaging in the evaluation of kidney transplant recipients.

Many transplantation programs utilize noninvasive abdominal and pelvic imaging in the pre-operative evaluation of recipient candidates. Practice patterns vary, and consensus guidelines addressing the risks and benefits of computed tomography (CT) and magnetic resonance imaging (MRI) in the pre-transplant evaluation process do not currently exist. In this single-center study, we examined the frequency, clinical significance, and associated costs of CT and MRI findings during the pre-transplant evaluation of renal transplant recipients. A retrospective chart review of 3041 adult patients who underwent a CT/CTA or MRI/MRA of the abdomen and pelvis for pre-transplant evaluation between 2005 and 2010 was performed. Pre-transplant imaging with MRI offered a more sensitive evaluation in comparison with CT, with the notable exception of abnormalities in which calcium was detected. Patients imaged with CT had a significantly greater proportion of subsequent clinical actions arising from imaging findings. The total financial cost of MRI was greater than that of CT. No cases of nephrogenic systemic fibrosis (NSF) in patients who received MultiHance gadolinium contrast were reported. In conclusion, the risks, benefits, and costs of CT/CTA and MRI/MRA must be carefully considered to optimize the pre-operative evaluation of renal transplant recipients.