Mohammad Mehdi Khalighi1, Laura I. Sacolick2,
W Thomas Dixon3, Ron D. Watkins4, Sonal Josan4,
Brian K. Rutt4
1Applied Science Lab, GE Healthcare,
Menlo Park, CA, United States; 2Imaging Technologies Lab, General
Electric Global Research, Garching b. Munchen, Germany; 3General
Electric Global Research, Niskayuna, NY, United States; 4Department
of Radiology, Stanford University, Stanford, CA, United States
B1+
mapping is a critical step in the design of RF pulses for parallel transmit
systems. We used the Bloch-Siegert (BS) B1+ mapping
method and a 2-channel parallel transmit enabled 7T scanner to produce fast,
robust and accurate B1+ maps through the human brain.
Both B1+ magnitude and phase are obtained from a single
sequence, employing +/-4kHz off-resonance BS pulses. B1+
magnitude and phase maps acquired with a 26s BS scan are compared with those
acquired with a 640s classical double angle scan, showing that the BS method
is a very good candidate for efficient B1+ mapping at
7T.
Keywords