Comparison of the ablation rates, fissures and fragments produced with 150 µm and 272 µm laser fibers with superpulsed thulium fiber laser: an in vitro study.

Holmium:YAG(Ho:YAG) is currently the standard for lithotripsy. Superpulsed Thulium Fiber Laser(TFL) has been evaluated as an alternative for lithotripsy, using laser fibers with core-diameters(CDF) down to 50 µm and additional available settings suitable for "dusting" technique. This in-vitro study compared ablation rates, fissures and fragments' size with 150µmCDF or 272µmCDF with different laser settings using TFL and Ho:YAG.

150CDF and 272CDF were compared using three settings for TFL "fine dusting"(FD:0.15 J/100 Hz); "dusting"(D:0.5 J/30 Hz); "fragmentation"(Fr:1 J/15 Hz) and Ho:YAG(D and Fr). An experimental setup consisting of immerged 10 mm cubes of artificial hard(H) or soft(S) stone phantoms was used with a 20 s' lasing time and a spiral trajectory, in contact mode. Fragments (acquired through sieves) and stones were observed under optical microscopy before three-dimensional scanning to measure fragments and fissures(DOF) mean diameters and ablation volumes.

Ablation volumes in with 150CDF-TFL and 272CDF-TFL were higher than those for 272CDF-Ho:YAG in both "dusting" (twofold and threefold) and "fragmentation"(1,5-fold and twofold). "Fine dusting" ablation rates with 150CDF-TFL and 272CDF-TFL were respectively at least 1,5-fold and twofold higher than those for 272CDF-Ho:YAG in "dusting". 150CDF produced significantly smaller DOF than 272CDF in all settings against S and H except in fragmentation. 150CDF produced lower fragments' diameter than 272CDF in all settings except dusting.

These preliminary studies demonstrate that at equal settings and CDF, TFL ablation rates are at least two-fold higher than those with Ho:YAG. 150CDF produces smaller fissures and fragments (that meets the definition of "dusting" lithotripsy) than 272CDF and higher ablation volumes than Ho:YAG.

World journal of urology. 2020 Apr 06 [Epub ahead of print]

Frédéric Panthier, Steeve Doizi, Pierre Lapouge, Catherine Chaussain, Nicolas Kogane, Laurent Berthe, Olivier Traxer

GRC no. 20, Groupe de Recherche Clinique sur la Lithiase Urinaire, Hôpital Tenon, Sorbonne Université, 75020, Paris, France., PIMM, UMR 8006 CNRS-Arts et Métiers ParisTech, 151 bd de l'ôpital, 75013, Paris, France., Plateforme d'imagerie du Vivant, EA 2496 Orofacial Pathologies, Imagery and Biotherapies, Dental School Faculty, University Paris Descartes and Life Imaging Plateform (PIV), Montrouge, France., École Nationale Supérieure de Techniques Avancées Paris, 828 Boulevard des Maréchaux, 91120, Palaiseau, France., GRC no. 20, Groupe de Recherche Clinique sur la Lithiase Urinaire, Hôpital Tenon, Sorbonne Université, 75020, Paris, France. .