J. W. Trobaugh, W. L. Straube, R. M. Arthur, E. G. Moros, S. Sangkatumvong, "Apparent Motion And Temperature Dependence Of Backscattered Energy In Ultrasonic Images," Proceedings of the 21st Annual Meeting of the North American Hyperthermia Society (NAHS)/1st Annual Meeting of the Cell Stress Society International (CSSI), Quebec City, Canada, September 10-14, 2003.

Abstract

Previously, we have investigated techniques for measuring temperature-dependent change in backscattered energy (CBE) in 1D ultrasonic signals. Extension of those techniques to 2D images is limited by apparent non-rigid motion of tissue as temperature changes. Our recent experimental data comes from a Terason 2000 laptop-based ultrasound system equipped with a 7MHz linear array probe, model 10L5. Typical image sets cover 37 to 50^oC with 0.5^oC  steps, with apparent movement between 0.5 and 1 mm laterally and axially. This movement was estimated by maximizing the cross-correlation of image regions at adjacent temperatures. After compensation for movement, image data was squared and averaged to form backscattered energy at each pixel. Two measures were computed to characterize the CBE over an image region, the standard deviation over the whole region and the means of all positive- and all negative-going pixels in the region. These results are consistent with theoretical expectations and continue support the possibility of using CBE in ultrasound as a tool for noninvasive thermometry. (Supported by NIH grant R21-CA90531 from the National Cancer Institute and the Wilkinson Trust at Washington University in St. Louis.)