To increase HIFU throughput, a HIFU transducer (diameter of 7 cm, focal length of 6 cm, operating frequency of 3.4 MHz), coupled to an imaging probe (ICT 7-4, Sonosite), was driven by 100 W driving unit with 500 W amplifier. A water pillow connected to a circulation pump with degassed water provided transducer coupling and cooling. Input electrical power was 400 W, corresponding to focal intensity of 51<th>300 W/cm2 (in water). HIFU was applied transcutaneously in porcine thigh muscle in vivo, and intraoperatively in liver hilum, for 30–60 s. After 30 s of treatment, muscle lesions had diameter of 2.1±0.4 cm and length of 2.0±0.4 cm. After 60 s of treatment, muscle lesions had diameter of 3.1±0.9 cm and length of 3.1±1.0 cm. In few cases of severe skin burns, the lesions were formed immediately under the skin and were shallow (∼1 cm). Liver lesions had diameter of 2.1±0.3 cm and length of 2.3±0.6 cm. In comparison, after the 30 s treatment with our standard HIFU device (focal intensity of 27<th>000 W/cm2, in water) the muscle lesions had diameter of 1.3±0.6 cm and length of 1.1±0.6 cm. High power HIFU device can quickly coagulate large tissue volumes.
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