Acoustic Power Measurement and Thermal Bioeffect Evaluation of Therapeutic Langevin Transducers

We recently proposed an analytical design method of Langevin transducers for therapeutic ultrasound treatment by conducting parametric study to estimate the effect of compression force on resonance characteristics. In this study, experimental investigations were further performed under various electrical conditions to observe the acoustic power of the fully equipped transducer and to assess its heat-related bioeffect. Thermal index (TI) tests were carried out to examine temperature rise and thermal damage induced by the acoustic energy in fatty porcine tissue. Acoustic power emission, TI values, temperature characteristics, and depth/size of thermal ablation were measured as a function of transducer’s driving voltage. By exciting the transducer with 300 Vpp sinusoidal continuous waveform, for instance, the average power was 23.1 W and its corresponding TI was 4.1, less than the 6 specified by the Food and Drug Administration (FDA) guideline. The maximum temperature and the depth of the affected site were 74.5 °C and 19 mm, respectively. It is shown that thermal ablation is likely to be more affected by steep heat surge for a short duration rather than by slow temperature rise over time. Hence, the results demonstrate the capability of our ultrasonic transducer intended for therapeutic procedures by safely interrogating soft tissue and yet delivering enough energy to thermally stimulate the tissue in depth.

Ultrasound-Guided Percutaneous Thermal Ablation of Hepatic Focal Nodular Hyperplasia——A Multicenter Retrospective Study

Background and Aim: To evaluate the clinical effect of ultrasound (US)-guided percutaneous thermal ablation of hepatic focal nodular hyperplasia (FNH).Methods: A retrospective analysis of the clinical data of patients undergoing US-guided percutaneous thermal ablation of FNH from November 2008 to August 2021 at five medical centers in China was conducted.Results: A total of 53 patients were included (26 males and 27 females). The mean age was 35.1 ± 10.8 years. Sixty-five lesions (46 solitary cases and 7 cases with multiple lesions) were included, 70.8% (46/65) of which were located in the right liver lobe. The mean tumor length was 2.9 ± 1.5 cm. All patients successfully completed the ablation treatment. Immediate postoperative imaging showed that the primary technical success rate was 94.3% (50/53). Two patients underwent ablation 3 and 6 months after the primary ablation, and the secondary technical success rate was 100% (2/2). The incidence of complications was 3.8% (2/53). Imaging follow-up was conducted regularly after ablation, and no residual lesion enlargement or tumor recurrence was observed during the follow-up period. The technique efficacy rate was 98.1% (52/53).Conclusion: US-guided percutaneous thermal ablation is a safe and effective treatment for FNH of the liver.

Bio-engineered Nano-vesicles for IR820 Delivery: A Therapy Platform for Cancer by Surgery and Photothermal Therapy

Long-term unsolved health problems from pre-/Intra-/postoperative complications and thermal ablation complications pose threats to liver cancer patients. To reduce the threats, we propose a multimodal-imaging guided surgical navigation system...