Simultaneous multislice excitation by parallel transmission.
Magn Reson Med
; 71(4): 1416-27, 2014 Apr.
Article
in En
| MEDLINE
| ID: mdl-23716365
ABSTRACT
PURPOSE:
A technique is described for simultaneous multislice (SMS) excitation using radiofrequency (RF) parallel transmission (pTX).METHODS:
Spatially 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.RESULTS:
Phantom 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 â¼30% lower RF power than a conventional SMS approach with multiband RF pulses.CONCLUSION:
The proposed SMS-pTX allows SMS excitations at reduced RF power by exploiting the local B(1)(+) sensitivities of suitable multielement pTX arrays.Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Brain
/
Magnetic Resonance Imaging
/
Image Interpretation, Computer-Assisted
/
Image Enhancement
/
Imaging, Three-Dimensional
Type of study:
Diagnostic_studies
Limits:
Humans
Language:
En
Journal:
Magn Reson Med
Journal subject:
DIAGNOSTICO POR IMAGEM
Year:
2014
Document type:
Article
Affiliation country:
United States