Borjan Gagoski1, Himanshu Bhat2,
Philipp Hoecht2, Khaldoun Makhoul3,4, Ulrich Fontius5,
Josef Pfeuffer5, Franz Schmitt5, Michael Hamm2,
Joonsung Lee1, Kawin Setsompop3,4, Lawrence L. Wald3,6,
Elfar Adalsteinsson1,6
1Electrical Engineering
& Computer Science, Massachusetts Institute of Technology, Cambridge, MA,
United States; 2Siemens Healthcare, Charlestown, MA, United
States; 3A.A. Martinos Center for Biomedical Imaging, Department
of Radiology, Massachusetts General Hospital, Charlestown, MA, United States;
4Harvard Medical School, Boston, MA, United States; 5Siemens
Healthcare, Erlangen, Germany; 6Harvard-MIT Division of Health
Sciences & Technology, MIT, Cambridge, MA, United States
To guard against run-time deviations in parallel transmission RF waveforms that may result in violation of SAR limits, real-time RF waveform monitoring serves an important role. In this work we investigated subject-to-subject variation in excitation coil array monitoring parameters and use these findings to propose threshold criteria to detect a mismatch between ideal and observed RF signals. Calibration of the cut-off values needed in the threshold algorithm was done empirically by monitoring the RF signals in 15 in-vivo acqisitions. The performance of the proposed algorithm was then tested for different types of RF pulses in undisturbed and purposely disturbed acquisitions.
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