PARENT SESSION
1:30 PM to 3:30 PM
Saturday, April 20, 2002
Poster Session 1 Noninvasive Treatment Monitoring and Treatment Planning
Room: Nevada 1-2

(MP01-3) MRI Based Technique for Measuring Ultrasound SAR Distributions.

Allen, Blake^*,1, Parker, Dennis², Christensen, Douglas³, Roemer, Robert¹, ¹ University of Utah - Mechanical Engineering, Salt Lake City, Utah² University of Utah - School of Medicine, Salt Lake City, Utah³ University of Utah - Bioengineering, Salt Lake City, Utah

ABSTRACT-
Hyperthermia and HIFU treatment planning rely on accurate power deposition models to accurately predict tissue temperatures. Predicting such SAR fields in actual patients is difficult at present due to the patients' complicated anatomies and inhomogeneous properties. It is clear from previous investigators that MRI can be used to non-invasively measure the temperature rises due to power step functions, and to thereby determine the SAR field. However, the use of MRI temperature measuring techniques involves a trade off between speed of measurement and spatial accuracy, a trade off that can affect the accuracy of the SAR field calculations. The purpose of this investigation is to determine how accurately such MRI based approaches can measure such fields for both homogeneous and inhomogeneous absorbers. Experimental MRI results will be presented and compared to thermocouple measurements and numerical simulation results. Studies will be performed to determine how much the accuracy of the MRI temperature measurements can be improved by using inverse techniques and power deposition models. This paper will report the accuracy of the technique for consideration of future applications.

KEYWORDS: focused ultrasound, temperature mapping, power deposition, US absorption