Ablation rates with Holmium:YAG and Thulium Fiber Laser: Influence of the stone phantom homogeneity. An in vitro study.

OBJECTIVES: The lithotripsy efficiency (LE) in vitro study requires artificial or human stone samples (AS, HS). With the development of dusting lithotripsy, less ex vivo HS are available. We aimed to compare Thulium Fiber Laser (TFL) and Holmium:YAG (Ho:YAG)'s LE and define the most accurate LE parameter. METHODS: Hard and soft homogenous- and heterogenous-AS (Ho-AS, He-AS) were made to reproduce calcium-oxalate monohydrate and uric acid stones, respectively by a rapid or slow brewing of BegostonePlus (Bego) and distilled water. One hundred and fifty and 272µm-laser fibers, connected to 50W-TFL and 30W-HoYAG generators, compared three settings for TFL (FD: 0.15J/100Hz; D: 0.5J/30Hz; Fr: 1J/15Hz) and two for Ho:YAG (D-Fr). An experimental setup consisted in immerged 10mm cubic stone phantoms with a 20 seconds' lasing spiral, in contact mode, repeated four times. Stones were dried, weighted and µ-scanned (ablation weight and volume [AW and AV]). RESULTS: With He-AS, dusting AV were four- and three-fold higher with TFL compared to Ho:YAG against hard and soft (P<0.05). In fragmentation, AV were two-fold higher with TFL compared to Ho:YAG against hard (P<0.05) and soft (P<0.05). Experiments with Ho-AS were associated with non-significant differences when comparing TFL-150µm and TFL-272µm. The ablation weight-volume correlation coefficients was higher with Ho-AS than with He-AS (P<0.0001), and with hard than soft AS. If the LE can be estimated by the AW with hard AS, this approximation is not consistent for soft AS. CONCLUSION: TFL presented higher ablation rates than Ho:YAG, significant with He-AS. If the AW is acceptable and less expensive for hard Ho-AS, AV are more accurate for He-AS, which are suggested to imitate closely HS.

How to estimate stone volume and its use in stone surgery: a comprehensive review.

OBJECTIVE: Current interventional guidelines refer to the cumulative stone diameter to choose the appropriate surgical modality (ureteroscopy [URS], extracorporeal shockwave lithotripsy [ESWL] and percutaneous nephrolithotomy [PCNL]). The stone volume (SV) has been introduced recently, to better estimate the stone burden. This review aimed to summarize the available methods to evaluate the SV and its use in urolithiasis treatment. MATERIAL AND METHODS: A comprehensive review of the literature was performed in December 2022 by searching Embase, Cochrane and Pubmed databases. Articles were considered eligible if they described SV measurement or the stone free rate after different treatment modalities (SWL, URS, PCNL) or spontaneous passage, based on SV measurement. Two reviewers independently assessed the eligibility and the quality of the articles and performed the data extraction. RESULTS: In total, 28 studies were included. All studies used different measurement techniques for stone volume. The automated volume measurement appeared to be more precise than the calculated volume. In vitro studies showed that the automated volume measurement was closer to actual stone volume, with a lower inter-observer variability. Regarding URS, stone volume was found to be more predictive of stone free rates as compared to maximum stone diameter or cumulative diameter for stones >20 mm. This was not the case for PCNL and SWL. CONCLUSIONS: Stone volume estimation is feasible, manually or automatically and is likely a better representation of the actual stone burden. While for larger stones treated by retrograde intrarenal surgery, stone volume appears to be a better predictor of SFR, the superiority of stone volume throughout all stone burdens and for all stone treatments, remains to be proven. Automated volume acquisition is more precise and reproducible than calculated volume.

¿Cómo calcular el volumen litiásico y cuál es su aplicación quirúrgica? / How to estimate stone volume and its use in stone surgery: A comprehensive review?

Objetivo Las guías actuales para el tratamiento intervencionista sugieren el diámetro acumulativo de la litiasis (DAL) como factor decisivo en la elección del tratamiento quirúrgico óptimo (ureteroscopia [URS], litotricia extracorpórea por ondas de choque [LEOCh] y nefrolitotomía percutánea [NLPC]). El volumen litiásico (VL) se ha introducido recientemente para obtener una estimación más precisa de la carga litiásica. El objetivo de esta revisión es resumir los métodos disponibles para calcular el VL y su aplicación quirúrgica. Material y métodos En diciembre de 2022 se realizó una revisión sistemática de la literatura mediante búsquedas en las bases de datos Embase, Cochrane y Pubmed. Los artículos se consideraron elegibles si describían la medición del VL o la tasa libre de litiasis (TLL) tras diferentes modalidades de tratamiento (LEOCh, URS, NLPC) o la expulsión espontánea, basándose en la medición del VL. Dos revisores evaluaron de forma independiente la elegibilidad y la calidad de los artículos y realizaron la extracción de datos. Resultados En total se incluyeron 28 estudios. Todos los estudios utilizaron diferentes técnicas para calcular el VL. La medición automática del volumen pareció ser más precisa que la estimación del volumen. Los estudios in vitro mostraron que la medición automática del volumen se ajustaba más al volumen real de la litiasis, con una menor variabilidad interobservador. A diferencia de la NLPC y la LEOCh, en la URS se observó que el VL era un mejor predictor de mejor la TLL que el diámetro litiásico mayor o el diámetro acumulativo en litiasis >20mm. Conclusiones Calcular el VL —de forma manual o automática— es factible, y probablemente se ajuste más a la carga litiásica real. Aunque en el caso de las litiasis grandes tratadas mediante cirugía intrarrenal retrógrada el VL parece predecir mejor la TLL, la superioridad del VL en todas las cargas litiásicas y para todos los tipos de tratamiento está aún por demostrar. ... (AU)

Objective Current interventional guidelines refer to the cumulative stone diameter to choose the appropriate surgical modality (ureteroscopy (URS), extracorporeal shockwave lithotripsy (ESWL) and percutaneous nephrolithotomy (PCNL)). The stone volume (SV) has been introduced recently, to better estimate the stone burden. This review aimed to summarize the available methods to evaluate the SV and its use in urolithiasis treatment. Material and methods A comprehensive review of the literature was performed in December 2022 by searching Embase, Cochrane and Pubmed databases. Articles were considered eligible if they described SV measurement or the stone free rate after different treatment modalities (SWL, URS, PCNL) or spontaneous passage, based on SV measurement. Two reviewers independently assessed the eligibility and the quality of the articles and performed the data extraction. Results In total, 28 studies were included. All studies used different measurement techniques for stone volume. The automated volume measurement appeared to be more precise than the calculated volume. In vitro studies showed that the automated volume measurement was closer to actual stone volume, with a lower inter-observer variability. Regarding URS, stone volume was found to be more predictive of stone free rates as compared to maximum stone diameter or cumulative diameter for stones >20mm. This was not the case for PCNL and SWL. Conclusions Stone volume estimation is feasible, manually or automatically and is likely a better representation of the actual stone burden. While for larger stones treated by retrograde intrarenal surgery, stone volume appears to be a better predictor of SFR, the superiority of stone volume throughout all stone burdens and for all stone treatments, remains to be proven. Automated volume acquisition is more precise and reproducible than calculated volume. (AU)