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Abstract #4902

Calculation of 10g average SAR via inversion of the heat equation using MRI Thermometry and Thermal Property Measurements

Leeor Alon 1,2 , Gene Cho 1,2 , Leslie F. Greengard 3 , Ricardo Otazo 1,2 , Daniel K. Sodickson 1,2 , and Cem M. Deniz 1,2

1 Department of Radiology, Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, NY, United States, 2 Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, United States, 3 Courant Institute of Mathematical Sciences, New York University, NY, United States

RF safety of MRI coils is often evaluated by conducting RF heating experiments on tissue mimicking phantoms inside the scanner room. Because of power delivery capabilities of RF amplifiers, long RF heating durations (>6 minutes) are required to create a temperature change that can be accurately detected by MR thermometry measurements. In such cases when the heating duration is long, conversion from temperature-change to SAR is nontrivial, since the heat-diffusion effect is prominent and direct scaling of the temperature change with heat capacity yields large 10g average SAR errors (~55% , shown as in this abstract ). In this work, a method for 3D calculation of 10g average SAR is presented via inversion of the heat equation using high-resolution 3D temperature maps and measured thermal properties of the phantom. The algorithm can be used to calculate 10g average SAR experimentally for limiting RF energy deposition from physical coils in the scanner room with small errors, %3.1.

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