Focussed extracorporeal pyrotherapy: experimental results

Area of Science:

• Medical Devices
• Oncology
• Biophysics

Background:

• Deep tissue ablation often requires invasive procedures.
• Non-invasive methods for precise thermal tissue destruction are needed.
• Current treatments may cause collateral damage to surrounding healthy tissues.

Purpose of the Study:

• To develop and evaluate a new device for focused extracorporeal pyrotherapy.
• To assess the efficacy of focused ultrasound-induced heat and cavitation for tissue ablation.
• To explore potential clinical applications in treating solid tumors.

Main Methods:

• A piezoelectric ceramic device in a semispherical dish was designed for focused ultrasound generation (3.5 MHz).
• In vitro studies used polyurethane phantoms and tissue samples (prostate cancer, BPH) to assess thermal effects and cavitation.
• In vivo studies in pigs involved surgically implanted plastic spheres in the bladder, kidney, and liver to evaluate tissue ablation and healing response.

Main Results:

• In vitro, the device melted 2 x 12 mm surfaces in 1 s on phantoms, reaching 270°C at the focus.
• Tissue samples reached 85°C in vitro, showing hyperechoic zones.
• In vivo, plastic spheres were melted without damaging surrounding tissues; histological analysis showed necrosis and subsequent fibrosis at the treated sites.

Conclusions:

• Focused extracorporeal pyrotherapy effectively ablates deep tissues through combined heat and cavitation.
• The technique demonstrated safety and efficacy in preclinical models, with minimal damage to adjacent tissues.
• Potential indications include prostate, bladder, kidney tumors, and liver metastases.