While human patients and healthy subjects are being imaged at 3T, 7T, 8T, 9.4T and soon, 11.74T, more data and understanding of RF safety at these ultra-high field strengths is needed. The overall objective of this proposal therefore is to investigate high frequency RF heating in order to improve RF safety for high field MRI. Safety will be better assured by developing the means to accurately predict and measure RF heating contours in human anatomy. These means will be achieved by accomplishing the following aims. First, a more fundamental understanding of the electrodynamic and thermodynamic nature of RF induced heating and heat transfer in anatomy will be furthered through mechanistic derivation and modification of the empirical Pennes Bioheat Equation. Second, this new theoretical model will be tested at high field Larmor frequencies by invasive, direct measurement of RF heating in anesthetized porcine models, by fluroptic thermometry. The porcine model is required as an intermediate step toward understanding and measuring RF heating in humans. Toward this end, the third aim is to develop a noninvasive NMR thermometer that is calibrated to an absolute temperature scale by the invasive fluroptic measurement. Once confidence is gained in predicting and noninvasively measuring temperature in pigs, these methods will be applied to monitoring RF heating in humans and so accomplishing the final aim of this study. With new understanding, data, and thermal measurement methods, high field human MRI will become safer. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Biomedical Imaging and Bioengineering (NIBIB)
Type
Research Project (R01)
Project #
5R01EB007327-02
Application #
7494061
Study Section
Biomedical Imaging Technology Study Section (BMIT)
Program Officer
Liu, Guoying
Project Start
2007-09-15
Project End
2011-06-30
Budget Start
2008-07-01
Budget End
2009-06-30
Support Year
2
Fiscal Year
2008
Total Cost
$404,436
Indirect Cost
Name
University of Minnesota Twin Cities
Department
Radiation-Diagnostic/Oncology
Type
Schools of Medicine
DUNS #
555917996
City
Minneapolis
State
MN
Country
United States
Zip Code
55455
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Wu, Xiaoping; Tian, Jinfeng; Schmitter, Sebastian et al. (2016) Distributing coil elements in three dimensions enhances parallel transmission multiband RF performance: A simulation study in the human brain at 7 Tesla. Magn Reson Med 75:2464-72
Schmitter, Sebastian; Wu, Xiaoping; U?urbil, Kâmil et al. (2015) Design of parallel transmission radiofrequency pulses robust against respiration in cardiac MRI at 7 Tesla. Magn Reson Med 74:1291-305
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Keith, Graeme A; Rodgers, Christopher T; Hess, Aaron T et al. (2015) Automated tuning of an eight-channel cardiac transceive array at 7 tesla using piezoelectric actuators. Magn Reson Med 73:2390-7
Wu, Xiaoping; Zhang, Xiaotong; Tian, Jinfeng et al. (2015) Comparison of RF body coils for MRI at 3??T: a simulation study using parallel transmission on various anatomical targets. NMR Biomed 28:1332-44
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Akgun, Can E; DelaBarre, Lance; Yoo, Hyoungsuk et al. (2014) Stepped impedance resonators for high-field magnetic resonance imaging. IEEE Trans Biomed Eng 61:327-33

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