Christina Graf1, Martin Soellradl1, Armin Rund2, Christoph Stefan Aigner3, and Rudolf Stollberger1
1Graz University of Technology, Institute of Medical Engineering, Graz, Austria, 2Institute of Mathematics and Scientific Computing, University of Graz, Graz, Austria, 3Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Berlin, Germany
1Graz University of Technology, Institute of Medical Engineering, Graz, Austria, 2Institute of Mathematics and Scientific Computing, University of Graz, Graz, Austria, 3Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Berlin, Germany
We optimize short and B0- and
B1-robust RF pulses by time-optimal control. The optimized pulse
shows a good efficiency over a broad set of B0- and B1-variations in
numerical experiments as well as extensive phantom measurements on a
3T MRI system.
Absolute value and angle of the oil-water phantom image measured with a B1-scaling of 100% (a-b). The red line shows the position of the line plots depicted in (c) and (d). The signal intensity profile without and with inversion pulse $$$\textbf{optim}$$$ with different B1-scalings are shown in (c). In (d), the measured normalized signal intensity after application of the $$$\textbf{optim}$$$ inversion pulse by a measurement without inversion is plotted. Thus, the influence of the coil sensitivity distribution and the varying excitation flip angle is eliminated.
Absolute value and angle of the cylindrical MR phantom image measured with a B1-scaling of 100% (a-b) and the nominal B1-map (c). The red line shows the position of the line plots depicted in (d) and (e). The signal intensity profile without and with inversion pulse $$$\textbf{optim}$$$ with different B1-scalings are shown in (d). In (e), the measured normalized signal intensity after application of the inversion pulse by a measurement without inversion is plotted. Thus, the influence of the coil sensitivity distribution and the varying excitation flip angle is eliminated.
