A z-gradient array for simultaneous multi-slice excitation with a single-band RF pulse

作者：Ertan Koray; Taraghinia Soheil; Sadeghi Alireza; Atalar Ergin^*

来源：Magnetic Resonance in Medicine, 2018, 80(1): 400-412.

DOI：10.1002/mrm.27031

• multi-slice excitation
• simultaneous multi-slice (SMS)
• gradient array
• RF pulse design

PurposeMulti-slice radiofrequency (RF) pulses have higher specific absorption rates, more peak RF power, and longer pulse durations than single-slice RF pulses. Gradient field design techniques using a z-gradient array are investigated for exciting multiple slices with a single-band RF pulse.
Theory and MethodsTwo different field design methods are formulated to solve for the required current values of the gradient array elements for the given slice locations. The method requirements are specified, optimization problems are formulated for the minimum current norm and an analytical solution is provided. A 9-channel z-gradient coil array driven by independent, custom-designed gradient amplifiers is used to validate the theory.
ResultsPerformance measures such as normalized slice thickness error, gradient strength per unit norm current, power dissipation, and maximum amplitude of the magnetic field are provided for various slice locations and numbers of slices. Two and 3 slices are excited by a single-band RF pulse in simulations and phantom experiments.
ConclusionThe possibility of multi-slice excitation with a single-band RF pulse using a z-gradient array is validated in simulations and phantom experiments. Magn Reson Med 80:400-412, 2018.

• 出版日期2018-7