Histological study of normal and tumor-bearing liver treated with focused ultrasound

The purpose of this investigation was to study the tissue damage (including blood vessels) on both normal and tumor-bearing experimental livers and th e course of liver repair after focused ultrasound (FUS) treatment using his tological evaluation. A series of experiments were carried out ill vivo. Ti ssue was treated using arrays of ultrasound exposures with a frequency of 1 .7 MHz, in situ spatially averaged focal intensity (I-SAL in situ) of 212-2 66 W/cm(2) (corresponding to in situ spatial peak intensity of 382-479 W/cm 2), 5-10 s exposure duration and 1.5-3.0 mm exposure separation. Tissue spe cimens were examined using both light and electron microscopy, The damage t o the blood vessel walls was studied. The results showed the existence of i ndirect tissue damage in both normal and tumor tissue that is outside of th e treatment volume, due to disruption of the major blood vessels supplying the adjacent area, Evidence for liver regeneration was found 2 months after FUS treatment. (C) 1999 World Federation for Ultrasound in Medicine & Biol ogy.