Changes in ultrasound properties of porcine kidney tissue during heating

Changes in the ultrasound (US) attenuation and backscatter of fresh pig kid ney were measured as the tissue was heated. The objective was to use these changes to predict how an US image mould change in real-time with a view to its use as a monitoring tool for minimally invasive thermal therapy (MTTT) , Separate samples of fresh pig kidney were heated from 37 degreesC to temp eratures of 45 degrees, 50 degrees, 55 degrees, 60 degrees and 65 degrees w ith warm water. Measurements were made over the frequency range from 3.5 MH z to 7.0 MHz during 30-min heating experiments. A general increase in atten uation magnitude (dB/cm) and slope (dB/cm-MHz) was observed at temperatures of 55 degreesC or greater. Little change in backscatter power was observed during heating to 45 degreesC. At higher temperatures, the changes in back scatter showed a more complex pattern throughout the experiments, but still showed a trend of increase to a greater value at the end of heating than a t the start. This backscatter increase was greater at higher temperatures, The net effect of the changes in US properties suggests that it may be poss ible to use diagnostic US to monitor, in real-time, MITT in kidney. (E-mail : sherar@oci.utoronto.ca) (C) 2001 World Federation for Ultrasound in Medic ine & Biology.