Simultaneous Multislice Excitation by Parallel Transmission

Benedikt A. Poser*, Robert James Anderson, Bastien Guerin, Kawin Setsompop, Weiran Deng, Azma Mareyam, Peter Serano, Lawrence L. Wald, V. Andrew Stenger

*Corresponding author for this work

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Abstract

Purpose A technique is described for simultaneous multislice (SMS) excitation using radiofrequency (RF) parallel transmission (pTX). MethodsSpatially distinct slices are simultaneously excited by applying different RF frequencies on groups of elements of a multichannel transmit array. The localized transmit sensitivities of the coil geometry are thereby exploited to reduce RF power. The method is capable of achieving SMS-excitation using single-slice RF pulses, or multiband pulses. SMS-pTX is demonstrated using eight-channel parallel RF transmission on a dual-ring pTX coil at 3 T. The effect on B-1(+) homogeneity and specific absorption rate (SAR) is evaluated experimentally and by simulations. Slice-GRAPPA reconstruction was used for separation of the collapsed slice signals. ResultsPhantom and in vivo brain data acquired with fast low-angle shot (FLASH) and blipped-controlled aliasing results in higher acceleration (CAIPIRINHA) echo-planar imaging are presented at SMS excitation factors of two, four, and six. We also show that with our pTX coil design, slice placement, and binary division of transmitters, SMS-pTX excitations can achieve the same mean flip angles excitations at approximate to 30% lower RF power than a conventional SMS approach with multiband RF pulses. ConclusionThe proposed SMS-pTX allows SMS excitations at reduced RF power by exploiting the local B-1(+) sensitivities of suitable multielement pTX arrays. Magn Reson Med 71:1416-1427, 2014.
Original languageEnglish
Pages (from-to)1416-1427
JournalMagnetic Resonance in Medicine
Volume71
Issue number4
DOIs
Publication statusPublished - Apr 2014

Keywords

  • parallel RF transmission
  • simultaneous multislice excitation
  • GRAPPA
  • SMS-pTX

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