In vitro comparison of stone retropulsion between the new holmium:yttrium aluminium garnet laser generator with a very low peak power pulse modulation mode (Magneto technology) and the thulium fibre laser.

Abstract

To compare the stone retropulsion of an artificial model of urinary stones in vitro using the new holmium:yttrium aluminium garnet (Ho:YAG) laser generator with a very low peak power pulse modulation mode (Quanta Magneto Technology™; Quanta System, Samarate, Italy) and thulium fibre laser (TFL). The following laser energy settings were used: 0.2 J-50 Hz, 0.4 J-25 Hz, 0.8 J-12 Hz, 1.5 J-6 Hz, and 2 J-5 Hz. A 5 × 5 × 5 mm cubic artificial stone was placed on two perpendicularly aligned metal rulers to create a V-shaped cross-sectional rail submerged in a tank filled with 0.9% saline solution, with the laser fibre in contact with the stone. The laser was activated for 5 s. Stone retropulsion was captured by a camera and assessed using video tracking software. Five repetitions were performed for each setting. Descriptive statistics investigated differences between the two lasers in stone retropulsion distance and speed at selected time points (0.35, 1, 3, and 5 s) and over the first second following laser activation. Comparable stone retropulsion distance and speed were observed between 'Magneto' and TFL according to tested high-energy settings. Magneto exhibited lower mean stone displacement at selected time points (all P < 0.02) and lower mean retropulsion speed over the first second following laser activation (all P < 0.01), when compared to TFL at low-energy settings (0.2 and 0.4 J). Although Ho:YAG lasers are generally associated with greater stone retropulsion compared to TFL, Magneto exhibited a retropulsion performance similar to TFL. Further research is needed to clarify the retropulsion dynamics observed with Magneto at low-energy settings.