Feasibility of intercostal high intensity focused ultrasound ablation of clinically relevant volumes under the application of beam shaping

Martijn De Greef,Mario Ries,Chrit Moonen,Julius Koskela,Lambertus W Bartels,Gerald Schubert,Joost Wijlemans

doi:10.1186/2050-5736-3-s1-o86

Abstract

Obstruction by the thoracic cage of the high intensity focused ultrasound (HIFU) beam is one of the major challenges in the ablation of abdominal lesions. Several beam shaping methods have been proposed to reduce exposure of the ribs to acoustic energy and to recover focal point intensity. The feasibility of HIFU ablation of a clinically relevant volume applying beam shaping remains however unaddressed. In this study, feasibility was evaluated based on exposure of both the ribs as well as the near-field to acoustic energy. In addition, the volumetric ablation rate was estimated to evaluate whether clinically relevant ablation speeds can be achieved.

Highlights

Background/introduction Obstruction by the thoracic cage of the high intensity focused ultrasound (HIFU) beam is one of the major challenges in the ablation of abdominal lesions
Based on the time required to achieve 65 °C in a defined ROI according to simulation, acoustic energy density at the ribs and the fat – muscle interface was estimated based on ray tracer and ASPW simulations of the acoustic intensity, respectively
Based on MR thermometry, rib temperature increases of 20 – 34 °C were observed at simulated acoustic energy densities of 5.4 – 6.6 J/mm[2]

Summary

Introduction

Background/introduction Obstruction by the thoracic cage of the high intensity focused ultrasound (HIFU) beam is one of the major challenges in the ablation of abdominal lesions. Methods To establish a safety limit for the exposure of the ribs to acoustic energy, rib heating was studied in an in vivo porcine model using MR thermometry (Achieva, Philips Healthcare, Best, the Netherlands). The animals (n = 2) were installed on the Sonalleve V2 HIFU platform (Philips Healthcare, Vantaa, Finland) and sonications (n = 3) were performed for transducer positions where rib obstruction occurred.

Results

Conclusion