Technical Program

Paper Detail

Paper:	SA-PM-PS2.4
Session:	Ultrasound Imaging and Analysis
Time:	Saturday, April 8, 13:30 - 14:50
Presentation:	Poster
Title:	Noninvasive Two-Dimensional Temperature Imaging for Guidance of Thermal Therapy
Authors:	Emad Ebbini; University of Minnesota
Abstract:	Two-dimensional temperature estimation using pulse-echo diagnostic ultrasound has been previously described. Measurement models in both time and frequency domains have been proposed. spectral shifts in the echo data have been shown to be proportional to changes in the local tissue temperature. Echo shifts were also shown to be proportional to local change in tissue temperature. For both the spectral and echo shift methods, the roportionality was shown to be proportional to the local changes in the speed of sound and local tissue expansion. However, temperature images suffer from some artifacts due to the distortion of the imaging beam as it traverses the heated region. In particular, temperature imaging artifacts due to the thermoacoustic lens effects have been reported. In addition, tissue inhomogeneity leads to nonuniform speckle patterns which also lead to errors in the estimated temperature profiles. A reconstructive imaging method employing a physics-based 2D filter and a projection method is presented. The method of projection onto convex sets (POCS) is used. Experimental data was obtained during controlled temperature heating of \textit{in vitro} bovine muscle using a helical RF ablation probe. Reconstructions using the POCS-based iterative algorithm are shown to produce artifact-free temperature fields.

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