Non-invasive thermotherapy of abdominal organs

Abstract

Objective. -Thermal therapies are rapidly gaining importance in oncology as an alternative to radiotherapy and surgery. The possibility to locally deposit thermal energy in a non-invasive way opens a path towards new therapeutic strategies with improved reliability and reduced associated trauma leading to improved efficacy, reduced hospitalisation and costs. Liver and kidney tumors represent a major health problem because not all patients are suitable for curative treatment with surgery. Currently, radiofrequency is the most used method for percutaneous ablation and the development of a completely non-invasive method based on MR-guided high intensity focused ultrasound (HIFU) treatments is of particular interest, since the energy source is located outside the body. This project addressed technological challenges for the treatment of liver and kidney, related to their motion and their location within the thoracic cage. Material and methods. -This project proposed safe and non-invasive methods for MR-guided thermal ablation of malignant tumors of liver and kidney with HIFU. Real-time MRI was used to precisely control heat deposition with HIFU within the targeted pathological area despite the motion of these organs, in order to provide an effective treatment with a reduced duration and an increased level of safety for the patient. New technologies were studied for the development of matrix transducers able to generate high acoustic power. Discussion. -3D Real-Time MRI guidance of a HIFU intervention as well as intercostal firing were realized in vivo in pig liver during breathing under real-time MR-thermometry over sustained periods of several minutes. The ability to generate acoustic power as high as up to five time the usual level was demonstrated in vitro thanks to the development of the new transducer technology proposed in this project. Conclusion. -A fully MR-integrated HIFU treatment platform dedicated to the treatment of cancer in mobile abdominal organs was developed. RésuméObjectifs. -Les thermothérapies gagnent rapidement en importance dans le domaine de l'oncologie comme alternative à la radiothérapie et à la chirurgie. La possibilité de déposer localement l'énergie thermique de manière non invasive ouvre une nouvelle voie vers des stratégies thérapeutiques plus fiables et moins agressives pour les patients, et permettront une réduction des temps et des coûts d'hospitalisation. Les tumeurs du foie et du rein représentent une problématique majeure, la chirurgie ne convenant pas à tous les patients. À l'heure actuelle, la méthode d'ablation par radiofréquences est la plus utilisée. Le développement d'une méthode non invasive basée sur les ultrasons focalisés guidés par IRM s'avère particulièrement intéressante, car la source d'énergie est extracorporelle. Ce projet adresse des challenges technologiques pour le traitement du foie et du rein, associés à leur mouvement et à leur localisation en dessous de la cage thoracique. Matériel et méthodes. -Ce projet propose des méthodes non invasives destinées au guid...