Laser-guided real-time automatic target identification for endoscopic stone lithotripsy: a two-arm in vivo porcine comparison study

Abstract

Introduction and objective Thermal injuries associated with Holmium laser lithotripsy of the urinary tract are an underestimated problem in stone therapy. Surgical precision relies exclusively on visual target identification when applying laser energy for stone disintegration. This study evaluates a laser system that enables target identification automatically during bladder stone lithotripsy, URS, and PCNL in a porcine animal model. Methods Holmium laser lithotripsy was performed on two domestic pigs by an experienced endourology surgeon in vivo. Human stone fragments (4–6 mm) were inserted in both ureters, renal pelvises, and bladders. Ho:YAG laser lithotripsy was conducted as a two-arm comparison study, evaluating the target identification system against common lithotripsy. We assessed the ureters’ lesions according to PULS and the other locations descriptively. Post-mortem nephroureterectomy and cystectomy specimens were examined by a pathologist. Results The sufficient disintegration of stone samples was achieved in both setups. Endoscopic examination revealed numerous lesions in the urinary tract after the commercial Holmium laser system. The extent of lesions with the feedback system was semi-quantitatively and qualitatively lower. The energy applied was significantly less, with a mean reduction of more than 30% (URS 27.1%, PCNL 52.2%, bladder stone lithotripsy 17.1%). Pathology examination revealed only superficial lesions in both animals. There was no evidence of organ perforation in either study arm. Conclusions Our study provides proof-of-concept for a laser system enabling automatic real-time target identification during lithotripsy on human urinary stones. Further studies in humans are necessary, and to objectively quantify this new system’s advantages, investigations involving a large number of cases are mandatory.

A novel laser lithotripsy system with automatic target recognition: from bench to bedside

“…During the procedure, the emission of energy was monitored independently by the feedback system, emitting laser energy only when it "recognized" stone material. The safety and efficiency of the present setup was successfully proven in animal models [10]. Our observations have also been confirmed histologically.…”

“…The experimental setup is descripted in Figures 1 and 2. Finally, the performance was assessed performing conventional Ho:YAG laser lithotripsy with and without target recognition in an in vivo setting in an animal study on domestic pigs [10]. Laser lithotripsy procedures were performed in the porcine collecting system of the kidney, in the ureter and bladder after retrograde placement of human stone material in the porcine urinary tract under general anesthesia.…”

Fluorescence‐guided laser lithotripsy: Estimation of the potential effectiveness and safety increase based on first clinical data

“…The autofluorescence of urinary stones and the possibility of using it for automatic stone detection during laser lithotripsy has been studied by various groups for several years [28][29][30][31][32][33]. In the surgical field, only stones show an autofluorescence signal when excited with green light.…”

“…With the latter, a laser system with a feedback loop has already been realized, that allows laser pulses only to be fired when the fluorescence signal is above a set threshold [32]. This system has been tested in an animal study [33]. However, in this study an investigation on if and how the fluorescence detection is affected by the lithotripsy process and which laser pulses were blocked or should have been blocked is missing.…”

Lasers for stone lithotripsy: advantages/disadvantages of each laser source

“…Ho:YAG has proved to be safe during lithotripsy pediatric population using low and HP for all surgical approaches [30][31][32]. As for the future, the possibility to apply artificial intelligence could decease lesions to surrounding tissues keeping adequate speed and precision [33]. Also Ho:YAG with micro-pulse packets have provided significantly greater stone ablation in comparison to thulium laser fiber (TFL) [34].…”