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.