Urinary stone disease is a common urological condition with increasing incidence, particularly in developed countries. Laser lithotripsy (LL) has become a preferred minimally invasive treatment due to its high precision and low tissue damage. Recent studies suggest that cavitation plays a critical role in stone damage during LL, and three-dimensional passive cavitation mapping (3D-PCM) has emerged as a promising tool for detecting these events. However, clinical translation of 3D-PCM remains challenging due to limitations in imaging depth, field of view (FOV), and procedural compatibility. Here, we present a large-FOV dual-modality imaging system (3D-PCM and B-mode ultrasound) based on a large-aperture planar ultrasound array. Through array optimization and model-based reconstruction, our system achieves an expanded FOV of ~40 × 40 mm2 at a clinically relevant imaging depth of ~110 mm, while maintaining high spatial resolution of ~0.6 mm laterally and ~0.4 mm axially. In vivo experiments in a porcine model demonstrate that the reconstructed cavitation distribution correlates well with stone damage. Our technology has the potential to provide real-time treatment feedback during LL without disrupting the standard workflow.

To evaluate the risk of thermal injury and the treatment efficiency during thulium fiber laser (TFL) lithotripsy of renal and ureteral stone phantoms in an in vivo porcine model. BegoStone phantoms were sequentially implanted and treated in the kidneys and ureters of five live anesthetized pigs using ureteroscopy and a 200-µm TFL fiber. Room-temperature saline irrigation (20 mL/min) was used. Intraluminal temperatures were monitored using thermocouples. Nine kidney stone treatments were performed at 0.8 J/12 Hz, 0.2 J/100 Hz, and 1 J/20 Hz. Twelve ureteral stone treatments were performed at 0.8 J/12 Hz, 2 J/5 Hz, 0.2 J/100 Hz, and 1 J/20 Hz. Treatment efficiency was assessed by measuring residual stone mass. Histopathological examinations assessed for thermal injury. In kidney treatments, maximum temperatures were lower at 10 W settings (median 33.2˚C) than at 20 W (45.7˚C, p = 0.020). Histology revealed major thermal injury in 1/3 treatments at 10 W and 4/6 at 20 W (p = 0.524). In ureter treatments, temperatures did not differ significantly between 10 W (median 36.3˚C) and 20 W (44.6˚C, p = 0.109) settings. However, major histologic thermal injury occurred in 1/6 treatments at 10 W and 6/6 at 20 W (p = 0.015). Median treatment efficiency was 0.57 mg/sec (kidney) and 0.35 mg/sec (ureter), with no significant differences among settings. TFL lithotripsy at 20 W can exceed thermal safety thresholds, especially in the ureter. Treatment at 10 W appears safer without significantly compromising efficiency, supporting its use for minimizing thermal injury risk.

Purpose: Urine cultures are routinely used to inform preoperative antibiotic choice and duration prior to endourologic surgery. The presence of mixed flora in preoperative urine cultures holds unclear clinical significance. This study examines infectious outcomes after ureteroscopy in patients with preoperative mixed flora urine cultures. Materials and Methods: A retrospective cohort study was conducted on adult patients who underwent ureteroscopy with laser lithotripsy between January 2014 and June 2024 who had urine cultures performed within 60 days preoperatively. Patients were categorized into cohorts based on their preoperative urine culture: mixed flora, negative, or positive. Postoperative urinary tract infection rates within 30 days were compared between cohorts, and logistic regression was performed adjusting for demographic and clinical variables. Results: We identified 5166 patients who underwent ureteroscopy with laser lithotripsy (2139 mixed flora, 1525 negative, 1502 positive). Preoperative antibiotics were used more often in the mixed flora cohort (29%) than in the negative cohort (24%, p = 0.007) but less frequently than in the positive cohort (57%, p < 0.001). Postoperative infections were visualized in 165 patients (8%) in the mixed flora cohort, compared with 88 (6%) in the negative cohort (p = 0.067) and 237 (16%) in the positive cohort (p < 0.001). Multivariable logistic regression demonstrated that positive cultures were associated with an increased risk of infection (odds ratio [OR] = 1.95, 95% confidence interval [CI] = 1.49-2.55, p < 0.001), but negative cultures had a similar risk of infection compared with mixed flora (OR = 0.79, 95% CI = 0.56-1.11, p = 0.177). Within the mixed flora cohort, preoperative antibiotic treatment was not associated with decreased postoperative infection (OR = 0.99, 95% CI = 0.66-1.47, p = 0.964). Conclusions: While patients with preoperative mixed flora urine cultures received preoperative antibiotics more often than patients with negative urine cultures, they were not at higher risk for postoperative infection. Routine preoperative antibiotic use in patients with mixed flora cultures may not be effective in reducing infectious complications after ureteroscopy.

Objective: To optimize thulium fiber laser (TFL) settings for effective stone fragmentation although minimizing thermal injury in confined ureteral spaces using a three-dimensional ureter model. Materials and Methods: A hydrogel-based ureter model was maintained at 37.2 ± 0.5°C, with a cylindrical BegoStone (10 × 10 mm, 1.00 ± 0.07 gm) occluding the ureter. Ureteroscopy was performed using a 150 µm TFL fiber for 3 minutes with room temperature irrigation and differing rates (0, 20, 40 mL/min) and power settings (6.4 to 20 W). Maximum sustained temperature (MST) and cumulative thermal dose (cumulative equivalent minutes at 43°C) were assessed against a 120-minute safety threshold. We also evaluated the effects of ureter volume and irrigation temperature. Stone mass treated was calculated by subtracting the mass of residual fragments >3 mm from the initial mass. Results: At 6.4 and 10 W, MSTs were below body temperature, and thermal doses were under 1 minute, indicating minimal thermal risk. At 20 W with 20 mL/min irrigation, MST exceeded 43°C within seconds, and thermal doses surpassed 120 minutes. Treatment efficiency was highest at 20 W (1.58 mg/s), followed by 10 W (1.15 mg/s) and 6.4 W (0.78 mg/s). Among 10 W settings, 1.0 J/10 Hz was more efficient than 2.0 J/5 Hz and 3.0 J/3 Hz. Safe settings produced 95.5% fine dust, whereas high-energy pulses 2-3 J produced significantly more fragments (1-3 mm) compared with settings with pulse energy 0.5-1.0 J. Increasing irrigation to 40 mL/min or using 15°C irrigation effectively reduced MST and improved efficiency, particularly at 20 W. Conclusion: Our study demonstrates the risk of thermal injury with 20 W TFL treatment. Conversely, 10 W settings at 2.0 J/5 Hz are safe and effective for fragmentation. Future research will focus on validating these optimal settings for human stone treatment.

Urinary stone disease, characterized by the hard mineral deposits in the urinary tract, has seen a rising prevalence globally. This condition often leads to severe pain and requires medical intervention. Laser lithotripsy, a minimally invasive treatment, uses laser to fragment urinary stones to facilitate removal or natural passage. Among available laser technologies, Ho:YAG laser has established itself as the gold standard for three decades. Efforts to improve ablation efficiency have focused on laser parameters such as pulse energy and frequency. This study introduces an ablation enhancement strategy that incorporates nanoparticles with strong near-infrared absorption into the surrounding fluid to enhance light-matter interaction. Using 0.03 wt.% PEDOT:PSS nanofluid improves stone ablation efficiency by 38-727% in spot treatment and 26-75% in scanning treatment with a clinical Ho:YAG laser lithotripter. The highly absorbing nanofluid accelerates vapor tunnel formation, boosts laser energy transmission, and permeates stone pores to enhance damage, without increasing thermal tissue injury. Cytotoxicity tests also confirmed minimal toxicity at appropriate concentrations. This nanofluid-based approach offers a promising advancement for more efficient and safer laser lithotripsy. Further work should address the remaining challenges for clinical translation, including aggregation in saline, efficacy in real human kidney stones, and comprehensive animal studies.

Laser technology has rapidly propelled surgical techniques in urinary tract calculus removal. The thulium fiber laser (TFL) is a relatively new tool that can be used for laser lithotripsy, as an alternative to the holmium: yttrium-aluminum-garnet (Ho:YAG) laser. TFL differs from Ho:YAG in several important ways including longer pulse width, lower peak power, and higher absorption in water. Surgically, this translates to less retropulsion, improved visibility, and improved stone dusting capability. The clinical literature to date supports comparable efficacy and safety between TFL and Ho:YAG. Each laser serves an important role in the treatment of urinary calculi.

You have accessJournal of UrologyStone Disease: Surgical Therapy (Including ESWL) V (MP78)1 May 2024MP78-04 EVALUATION OF CHAR FORMATION USING THE THULIUM FIBER LASER: THE STANDOFF BETWEEN HIGH VERSUS LOW PULSE ENERGY David L. Barquin, Junqin Chen, Arpit Mishra, Robert A. Medairos, Ezra J. Margolin, Jodi Antonelli, Glenn M. Preminger, Charles D. Scales, Gary J. Faerber, Pei Zhong, and Michael E. Lipkin David L. BarquinDavid L. Barquin , Junqin ChenJunqin Chen , Arpit MishraArpit Mishra , Robert A. MedairosRobert A. Medairos , Ezra J. MargolinEzra J. Margolin , Jodi AntonelliJodi Antonelli , Glenn M. PremingerGlenn M. Preminger , Charles D. ScalesCharles D. Scales , Gary J. FaerberGary J. Faerber , Pei ZhongPei Zhong , and Michael E. LipkinMichael E. Lipkin View All Author Informationhttps://doi.org/10.1097/01.JU.0001008856.05210.73.04AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Char formation on stones during laser lithotripsy with the Thulium Fiber Laser (TFL) can significantly impede treatment efficacy, especially in cases involving calcium phosphate (CaP) stones. The current understanding the reasons for char formation during TFL is limited. Our aim was to assess how char formation and treatment efficiency in a CaP stone may vary under various TFL settings. METHODS: A 6 x 6 x 4 cm 100% CaP stone was cold-mounted, bisected, and polished using 1200-grit sandpapers to create a flat surface (Figure 1a). The stone sample was fixed in a water tank filled with degassed water at room temperature and treated by the TFL at two different pulse energy/frequency settings with a power of 10 W: 0.2 J/50 Hz and 0.8 J/12 Hz. A 200 µm fiber was placed perpendicularly to the stone surface. Laser spot treatments were delivered at three different standoff distances (SD) (0.2 mm, 0.5 mm, 1 mm) and three different treatment times (TT) (1 sec, 2 sec, 3 sec). Each combination of SD and TT was repeated three times at a different localized area of the stone. The resultant stone crater volume was then quantified by optical coherence tomography. Charring was defined as the carbonization of stone materials (Figure 1b). Crater volumes were compared using Student's t-tests, and charring rates were compared using chi squared tests. The effects of SD and TT on crater volume were assessed using multivariable linear regression. RESULTS: Charring, was observed more frequently using the low pulse energy 0.2 J setting at all SDs compared to 0.8 J (all p<0.05). At the 0.2 J setting, charring was observed in 7/9 tests at SD 0.2 mm, 5/9 tests at 0.5 mm, and 4/9 tests at 1 mm. At the 0.8 J setting, charring was not observed in any tests at any SD. Crater volume was significantly greater at the 0.8 J setting at all SD and TT (all p<0.01, Figure 1c). At the 0.8 J setting, crater volume increased with higher TT (coef 0.18, p<0.001) and decreased with higher SD (coef -0.60, p<0.001). At the 0.2 J setting, crater volume only increased slightly with higher TT (coef 0.04, p<0.001) and did not change with higher SD (coef 0.01, p=0.564). CONCLUSIONS: At a low pulse energy and high frequency, TFL treatment efficiency of CaP stone may significantly decrease due to the charring. A high pulse energy level may help to avoid the charring and improve the treatment efficiency. Download PPT Source of Funding: This project is supported by the National Institutes of Health (NIH) through grants 1P20DK135107-02 and 2R01DK052985-26 © 2024 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 211Issue 5SMay 2024Page: e1264 Advertisement Copyright & Permissions© 2024 by American Urological Association Education and Research, Inc.Metrics Author Information David L. Barquin More articles by this author Junqin Chen More articles by this author Arpit Mishra More articles by this author Robert A. Medairos More articles by this author Ezra J. Margolin More articles by this author Jodi Antonelli More articles by this author Glenn M. Preminger More articles by this author Charles D. Scales More articles by this author Gary J. Faerber More articles by this author Pei Zhong More articles by this author Michael E. Lipkin More articles by this author Expand All Advertisement PDF downloadLoading ...

Introduction Patients with ureteral stones are often managed with a spontaneous trial of passage. While cost effective, the current literature has not examined the effects of a trial of passage on patients’ work productivity. In this study, we aim to characterize work absence and productivity losses in a cohort of patients undergoing a trial of passage for ureteral stones. Materials and Methods Actively employed patients aged 18 to 64 and discharged from Duke emergency departments without surgical intervention for ureteral stones ≤ 10mm were contacted by phone four weeks after their presentation. Participants completed the Institute for Medical Technology Assessment Productivity Cost Questionnaire which assesses three domains: absenteeism — missed work; presenteeism —productivity when returning to work; and unpaid work — assistance with household work. Linear regression associated demographic and stone factors with productivity losses. Results 109 patients completed the survey. In total, 67% of patients missed work, 46% had decreased productivity when returning to work, and 55% required assistance with unpaid work. 59% of patients with stones ≤ 5mm missed work versus 84% with stones > 5mm (p = 0.009). African American race (coefficient 23.68, 95% confidence interval 2.24–45.11, p = 0.031), first-time stone formers (coefficient 20.28, 95% confidence interval 2.50-38.07, p = 0.026), and patients with stones > 5mm (coefficient 25.34, 95% CI 5.25–45.44, p = 0.014) were associated with increased productivity losses. Conclusions The majority of patients miss work while undergoing a trial of passage and many have decreased productivity when returning to work. This information may help counsel patients in emergency departments, especially first-time stone formers, and prevent return visits.