While human patients and healthy subjects are being imaged at 3T, 7T, and soon, 10.5T, more data and understanding of RF safety at these ultra-high field strengths are needed. The overall objective of this renewal proposal therefore is to extend the RF heating studies in the human head of our previous grant to the investigation of RF heating in the human body for ultra-high field MRI applications. Safety will be better assured and imaging performance improved by developing the means to accurately predict and measure RF temperature contours in human anatomy. Through development of new theory, technology, methodology, and experimental approach, these means will be achieved by accomplishing the following aims. First, a more fundamental understanding of the electrodynamics and thermodynamic nature of RF induced heating and heat transfer in anatomy will be furthered through mechanistic improvement of the empirical Pennes Bioheat Equation. Second, this new theoretical model will be validated at high field Larmor frequencies by invasive, direct measurement of RF heating in anesthetized porcine models, by fluoroptic 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 accurately and precisely calibrated by the invasive fluoroptic measurement. Once confidence is gained in predicting and noninvasively measuring temperatures in pigs, these methods will be applied or correlated 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.
While humans are being imaged at 3T, 7T, and soon, 10.5T, more data and understanding of RF safety at these ultra-high field strengths are needed. These RF safety issues were investigated for head imaging in the previous grant. The objective of this renewal proposal therefore is to continue the investigation of high frequency RF heating in the human body to improve RF safety and imaging performance for ultra-high field MRI. Safety will be better assured by developing means to accurately predict and image RF heating contours in human anatomy.
|Eryaman, Yi?itcan; Lagore, Russell L; Ertürk, M Arcan et al. (2018) Radiofrequency heating studies on anesthetized swine using fractionated dipole antennas at 10.5 T. Magn Reson Med 79:479-488|
|Wu, Xiaoping; Schmitter, Sebastian; Auerbach, Edward J et al. (2016) A generalized slab-wise framework for parallel transmit multiband RF pulse design. Magn Reson Med 75:1444-56|
|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|
|Liu, Jiaen; Zhang, Xiaotong; Schmitter, Sebastian et al. (2015) Gradient-based electrical properties tomography (gEPT): A robust method for mapping electrical properties of biological tissues in vivo using magnetic resonance imaging. Magn Reson Med 74:634-46|
|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|
|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|
|Sohn, Sung-Min; DelaBarre, Lance; Gopinath, Anand et al. (2015) Design of an Electrically Automated RF Transceiver Head Coil in MRI. IEEE Trans Biomed Circuits Syst 9:725-32|
|Rodgers, Christopher T; Clarke, William T; Snyder, Carl et al. (2014) Human cardiac 31P magnetic resonance spectroscopy at 7 Tesla. Magn Reson Med 72:304-15|
|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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