In Vivo Experiments with Intraluminal Ultrasound Applicator Compatible with 'Real-Time' MR Temperature Mapping, designed for Oesophagus Tumour Ablation

摘要

High intensity ultrasound has shown considerable ability to produce precise and deep thermal coagulation necrosis. Focused, cylindrical, spherical or plane transducers have been used to induce high temperature elevation in tissues, in order to coagulate proteins and kill cells. Magnetic Resonance Imaging (MRI) has been used, with focused transducers and cylindrical interstitial applicators, to monitor temperature distribution and provide temperature feedback control during heating procedures. The active part of intraluminal applicators is positioned very close to the target region. It is therefore essential to provide accurate monitoring of heat deposition in the tissue layer near the transducer, in order to control the extension of coagulation necrosis. The purpose of this study was to develop a 10-mm diameter intraluminal ultrasound applicator, designed to treat oesophageal cancers and compatible with "real-time" MR temperature mapping. The ultrasound applicator was tested in vivo under real time, PRF based, fast MR temperature monitoring. Experiments were performed in vivo on pig oesophagus. Respiratory-gated, MR thermometry was performed with segmented EPI gradient echo sequences. Post treatment follow up was performed with MRI in oesophagus and liver. Excellent MR compatibility was demonstrated. Thermal lesions identified on post-treatment follow up showed good correlation with on line MR thermometry data. This study demonstrated the feasibility of oesophageal thermal ablation using intraluminal ultrasound and on line MR temperature monitoring.