Mise au point et expérimentation d'un applicateur interstitiel à ultrasons pour le traitement des cancers primitifs et métastatiques du foie

Un applicateur interstitiel à ultrasons est développé pour le traitement des cancers primitifs et métastatiques du foie. L expérimentation sur le foie de porc in vitro et in vivo a permis d étudier la capacité de l applicateur à induire une zone de coagulation de taille et de forme satisfaisantes. Deux types de lésions sont étudiés : la lésion élémentaire obtenue par un seul tir et la lésion cylindrique obtenue par activation du transducteur sur 360. Un dispositif opératoire est développé et la rotation de la sonde est guidée par un logiciel informatique afin d assurer un traitement précis. Les paramètres physiques du traitement sont déterminés pour avoir un meilleur rendement au niveau du transducteur et obtenir des zones de coagulation de plus en plus larges avec, en parallèle, une analyse de l effet de la perfusion sanguine hépatique. Une reconstruction 3D des lésions cylindriques à partir d une analyse par IRM a permis, avec l étude macroscopique des lésions, d analyser la reproductibilité de leurs taille et forme. L applicateur testée a l avantage d assurer un traitement au pas à pas de la zone cible, hautement directionnel avec une grande précision escomptée. L applicateur à ultrasons génère des zones de coagulation de forme très régulière avec des contours toujours bien définis. La simulation du traitement sur le porc in vivo a démontré la bonne tolérance du traitement malgré le risque de complications notamment biliairesAn interstitial ultrasound applicator was developed for the treatment of primary and metastatic tumours of the liver. Experiments on porcine liver in vitro and in vivo were conduced to check the capability of the applicator to induce a thermal ablation area with a satisfactory size and shape. Two types of lesions were studied: the elementary lesion corresponding to an ultrasonic lesion as a result of a single shot and cylindrical lesions obtained over a 360-deployment. An operative device was developed and the rotation of the applicator was computer-controlled to ensure precision in the treatment. The physical parameters of the treatment were determined to have the best output of the transducer and to obtain larger and larger areas of tissue coagulation with analysis of the effect of hepatic blood perfusion. A 3D reconstruction of the cylindrical lesions was made using MR images of the thermal ablation areas to assess, together with the gross examination, their size and shape reproducibility. The tested applicator has the advantage to provide a step-by-step and highly directional treatment in the target zone with an expected higher precision. The ultrasonic applicator enabled an effective ablation which has a regular shape, always with sharply defined borders. The simulation of the treatment on pigs in vivo demonstrated quite good tolerance despite the risk of complications such as biliary complicationsLYON1-BU.Sciences (692662101) / SudocPARIS-Académie Médecine (751065201) / SudocSudocFranceF

Developing an interstitial ultrasound applicator for thermal ablation in liver: results of animal experiments.

International audienceBACKGROUND: In this project, an interstitial ultrasound applicator was developed for the treatment of primary and secondary cancers of the liver. Experiments on animals were used to check the destructive capabilities of this probe within the hepatic parenchyma of the pig in vivo, with a study of the physical parameters of the ultrasound treatment. In parallel, the possibility of visualizing the lesions induced by means of ultrasound imaging was also studied. MATERIALS AND METHODS: Thirteen pigs were used in this project, which had received the prior approval of the ethics committee of Lyon Veterinary School. Ultrasound lesions were performed by varying the physical parameters of the treatment (acoustic intensity and shot time) with the aim of obtaining larger and larger areas of destruction. An operative device was developed to ensure precision in treatments. Two types of lesions were performed: elementary lesions corresponding to single shots at 40 degrees to 50 degrees rotation intervals, and cylindrical lesions obtained by a continuous rotary deployment of the probe. The effect of hepatic pedicle clamping on the size of ultrasound lesions was studied. The aspect and dimension of the lesions were analyzed by means of operative ultrasound imaging and macroscopic examination. Histological analysis showed the impact of the treatment on the hepatic parenchyma. RESULTS: This work made it possible to study the elementary ultrasound lesions produced by our probe. Seventy elementary ultrasound lesions were analyzed. Treatments could be performed on all pigs without any difficulty. There were no operative incidents. The ultrasound-induced elementary lesions showed complete necrosis, with lesion length of up to 37 mm obtained without resort to pedicle clamping; this must be considered as a radius of the final lesion obtained over a complete rotary deployment (360 degrees ), then a diameter of 7 cm of thermal ablation can theoretically be obtained. The effect of pedicle clamping was studied and showed improvement of the lesion length. Results of continuous rotary deployment of the probe were encouraging. Operative ultrasound imaging proved to be a simple tool for directing and positioning the applicator in the target zone on the one hand and which, on the other hand, enabled accurate, real-time visualization of the ultrasound lesions. On histological analysis, the ultrasound-induced necrosis was complete and well defined. CONCLUSION: This work shows that it is feasible to treat cancers of the liver using interstitial ultrasound probe. Thermal damage obtained on the hepatic parenchyma of pigs in vivo is complete and can be monitored using simple diagnostic ultrasound. The ultrasound parameters can be adapted to obtain destruction of variable size