Astrid L.H.M.W. van Lier1, Johannes M.
Hoogduin2, Dennis J.W. Klomp2, Jan J.W. Lagendijk1,
Cornelis A.T. van den Berg1
1Radiotherapy, UMC Utrecht, Utrecht,
Netherlands; 2Radiology, UMC Utrecht, Utrecht, Netherlands
In
high-field MRI, phased-arrays are used to mitigate RF issues as excitation
field inhomogeneities. In order to design RF pulses that can produces a
desired excitation field, the B1+ field per coil must be mapped. We show that
it is possible to measure B1+ maps for phased arrays in the low flip angle
regime using phase-modulation (PMLF). This technique was validated by a
contemporary high-flip angle technique and electromagnetic simulations. The
advantages of the PMLF technique over the high-flip angle techniques are its
low SAR cost and higher speed.