B-scan ultrasound imaging of thermal coagulation in bovine liver: Log envelope slope attenuation mapping

Thermal therapy is an experimental procedure to treat localised tumours in the prostate, liver, kidney or breast. Monitoring is important to ensure co mplete tumour destruction while sparing adjacent sensitive structures, Prev ious work demonstrated that, when biological tissues are heated above 65 de greesC, ultrasound (US) attenuation increases due to thermal coagulation of tissue. This study examined the feasibility of a B-scan, envelope-based at tenuation estimation method to monitor thermal therapy. The slope of the lo g of the signal envelope was used to estimate attenuation. It is shown that this method is able to demonstrate, from simulated and phantom data, a lim ited ability to differentiate attenuation levels that correspond to thermal ly coagulated and uncoagulated beef liver. In ex vivo bovine liver, however , issues due to signal-to-noise ratio (SNR) of the signal envelope prevente d the visulisation of a 2-cm diameter thermally coagulated inclusion. The l imitations of this method are extended to the multinarrow-band (MNB) techni que. (C) 2001 World Federation for Ultrasound in Medicine & Biology.