Sonochemically induced radicals generated by pulsed high-energy ultrasoundin vitro and in vivo

The aim of this study was to, evaluate the role of radicals as a mechanism of tissue damage induced by pulsed high-energy ultrasound. Transient cavita tion has proved to be an important mechanism for the generation of reactive radical species during pulsed high-energy ultrasound applications. The amo unt of radicals studied in in vitro experiments using a chemical dosimeter based on iodine release is proportional to the number of pulses. Sonication s of the R3327-AT1 subline of the Dunning prostate rat tumor transplanted i n the thigh of Copenhagen rats were performed applying 500 and 2000 pulses at a pulse repetition frequency of 1 Hz. Tumor growth after treatment was c ompared with sham-treated controls. We were able to assess a significant gr owth delay, but could not find a significant difference between the two gro ups treated. In conclusion, radical formation does not seem to be the major mechanism for tissue necrosis induced by pulsed high-energy ultrasound. (C ) 1999 World Federation for Ultrasound in Medicine & Biology.