High-intensity focused ultrasound in the treatment of experimental liver tumour.

This project aimed to determine the adequacy and accuracy of high-intensity focused ultrasound (HIFU) for ablating experimental liver tumour, and to assess imaging methods for monitoring the therapeutic results. The rabbit liver pseudotumour model was established by injection of Freund's complete adjuvant into the liver; the animals then received HIFU therapy via laparotomy at the focal point of the beam (1.1 MHz, 500 W/cm2, 20 s). The rabbits were sacrificed at scheduled times after treatment and liver tumours were examined histologically. Sequential imaging of the liver tumour was performed before and after HIFU treatment. HIFU accurately destroyed the rabbit liver tumour and induced coagulation necrosis 24 h later. Sonographic imaging studies revealed that characteristic changes occurred. A hyperechoic mass turned to a hypoechoic lesion with no Doppler signal, and a high echogenic rim appeared 24 h after HIFU treatment, correlating well with the pathological changes of a sonoablated lesion. These results verify that HIFU has the power to ablate liver tumour quite adequately and accurately, and that sonography is useful for monitoring sonoablated liver tumour.