ULTRASOUND-INDUCED TISSUE ABLATION - STUDIES ON ISOLATED, PERFUSED PORCINE LIVER

Minimally invasive methods for the treatment of cancers, such as high- intensity focused ultrasound (HIFU) and high-energy shock waves (SW), have been proposed recently. Their feasibility for treatment of human cancer needs to be confirmed. A simplified model of isolated perfused pig liver that is close to the human liver in vivo has been proposed. The objective was to study the feasibility of deep focused tissue abla tion with HIFU and SW in large organs approaching the size of the huma n liver, The model was demonstrated to be physiologically valid during the first 2 h of anoxic perfusion with a composite saline solution; a rterial and portal pressure, enzymes, urea levels and bile secretion r emained stable, lit can simulate the major effects of perfusion and ph ysical phenomena that occur in vivo during treatment, Histological ana lysis revealed no major changes, Previous results obtained ill vivo in animal models at a depth of 2-3 cm were successfully reproduced and d eeper lesion arrays at 4, 6, 8 and 9 cm from the surface were produced using the same principles. The depth of 9 cm from the liver surface i s consistent with an extracorporeal treatment of most of the liver seg ments in man. Other applications of the model are proposed, particular ly for the study of the role of interferences such as ribs and intesti nal gas, blood perfusion and respiratory movements. (C) 1998 World Fed eration for Ultrasound in Medicine & Biology.