Ultrasound monitored laser-induced local hyperthermia in the liver. An experimental study on pigs

Ultrasound (US) was used to monitor the size of tissue necrosis generated by Nd-YAG laser-induced local interstitial hyperthermia and tissue coagulation in 8 normal pig livers. Four treatments were done in each liver with 4 different energy settings. The size of the tissue necrosis measured on specimens was compared to the size measured on US. The laser energy caused a round tissue necrosis with some charring in the centre surrounded by a zone of white necrosis and a thin border of hyperaemia. A good correlation was found between the true and US-measured size of the necrosis diameters. It therefore seems possible to safely guide and monitor local laser hyperthermia in the liver with real-time US. The water-cooled quartz fibre used in this study has, however, some limitations.