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Adiabatic RARE imaging
Author(s) -
de Graaf Robin A.,
Rothman Douglas L.,
Behar Kevin L.
Publication year - 2003
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.811
Subject(s) - adiabatic process , relaxation (psychology) , nuclear magnetic resonance , spurious relationship , k space , signal (programming language) , image quality , sensitivity (control systems) , physics , phase (matter) , materials science , image (mathematics) , computer science , electronic engineering , artificial intelligence , medicine , fourier transform , quantum mechanics , machine learning , engineering , thermodynamics , programming language
The practical implementation of ultra‐fast spin‐echo, or RARE imaging with adiabatic RF pulses and surface coil transmission at 7 T is described. Despite the large RF inhomogeneities, the adiabatic character of the 180° BIR‐4 refocusing pulses ensures optimal sensitivity and minimal image artifacts. An internal ‘phase‐cycle’ is used to remove spurious unwanted coherences. The short T 2 relaxation times in rat brain at 7 T demand a centric, rather than a linear coverage of k ‐space in order to avoid excessive signal loss. T 2 relaxation during k ‐space coverage also leads to image blurring, which can be counteracted by interleaved k ‐space sampling. The coverage of k ‐space in four acquisitions provides high‐quality anatomical images comparable to conventional spin‐echo images. A two‐scan RARE implementation provides sufficient spatial and temporal resolution for most applications. Quantitative mapping of T 1 relaxation and cerebral blood flow changes during forepaw stimulation in the rat are demonstrated. Copyright © 2003 John Wiley & Sons, Ltd.