Holmium: YAG Popcorn Lithotripsy-In Vitro Comparison of Settings and MOSES Across Stone Densities

To compare Holmium: YAG laser settings for popcorn lithotripsy and evaluate the impact of MOSES modulation across stone-density groups.

An in vitro bench model was used with synthetic gypsum stones prepared at three density levels (low, intermediate, and high: mean attenuation was 574, 945, and 2067 HU, respectively). For each trial, five fragments (2.8-3.3 mm) were treated using popcorn technique with Holmium: YAG laser and 272 µm fiber during a 2 min run under standardized irrigation. Five laser settings (0.3 J/80 Hz, 0.5 J/40 Hz, 1.0 J/20 Hz, 1.0 J/30 Hz, and 1.5 J/20 Hz) were tested with and without MOSES mode: each setting-by-modulation condition was repeated six times. The primary endpoint was percent mass reduction; secondary endpoints were residual fragment counts 1-2 and > 2 mm. Results are presented as mean ± SD, and ANOVA was used for comparison.

In the low-density group, percent mass reduction was highest overall (65%-86%), with 1.0 J/30 Hz achieving the greatest reduction, MOSES provided no additional benefit (p = 0.6). In the intermediate-density group, the greatest mass reduction was achieved with 1.0 J/30 Hz with MOSES (51% ± 5.9%), and MOSES effects were setting-dependent, and at 1.0 J/30 Hz MOSES reduced total residual fragments (5.3 vs 8.0, p = 0.04). In the high-density group, 1.0 J/30 Hz with MOSES achieved the highest mass reduction (71.5% ± 12.1%) and was associated with improved outcomes (p = 0.037). Secondary analyses of residual fragments generally paralleled these findings.

In this in vitro popcorn lithotripsy model, 1.0 J/30 Hz provided the most consistent performance across density groups. MOSES modulation did not improve outcomes in low-density stones but was associated with improved efficiency in intermediate- and high-density stones.