Application Study of Using Ultrasonic Integral Backscatter to Monitor Microwave Coagulation Therapy

Microwave (MW) ablation is a minimally invasive therapeutic strategy for the local treatment of solid malignancies that has received much attention over the past few years. It is very important to detect and evaluate lesions generated by MW during treatment procedures. This study describes one new ultrasonic imaging technique to characterize lesions based on estimation of relative changes in tissue properties derived from backscattered RF data. A single microwave heating antenna was used to produce coagulation in vitro pig liver tissues. The RF signals were recorded as outputs from a modified diagnostic ultrasound system. The integrated backscatter values, which can be used as an indicator of the microstructure and backscattering property of tissues, were calculated in water-bath experiment and MW treatment. The rule of change in integrated backscatter values with temperature has been analyzed by statistics through water-bath experiment. The integrated backscatter ratio values were subsequently used to form images revealing the lesion areas. It is possible using ultrasonic integral backscatter to monitor microwave coagulation. The result shows that this approach can be used to identify the normal and coagulated tissue caused by temperature rise and provide the information of tissue damage.