T2* measurements in human brain at 1.5, 3 and 7 T.
Measurements have been carried out in six subjects at magnetic fields of 1.5, 3 and 7 T, with the aim of characterizing the variation of T2* with field strength in human brain. Accurate measurement of T2* in the presence of macroscopic magnetic field inhomogeneity is problematic due to signal decay resulting from through-slice dephasing. The approach employed here allowed the signal decay due to through-slice dephasing to be characterized and removed from data, thus facilitating an accurate measurement of T2* even at ultrahigh field. Using double inversion recovery turbo spin-echo images for tissue classification, an analysis of T2* relaxation times in cortical grey matter and white matter was carried out, along with an evaluation of the variation of T2* with field strength in the caudate nucleus and putamen. The results show an approximately linear increase in relaxation rate R2* with field strength for all tissues, leading to a greater range of relaxation times across tissue types at 7 T that can be exploited in high-resolution T2*-weighted imaging.
Peters
Andrew M
AM
Sir Peter Mansfield Magnetic Resonance Center, School of Physics and Astronomy, University of Nottingham, NG7 2RD Nottingham, UK.
Brookes
Matthew J
MJ
Hoogenraad
Frank G
FG
Gowland
Penny A
PA
Francis
Susan T
ST
Morris
Peter G
PG
Bowtell
Richard
R
D000328:Adult; D001921:Brain / Q000473:pathology*; D001927:Brain Diseases; D001931:Brain Mapping / Q000379:methods; D002421:Caudate Nucleus / Q000473:pathology; D002560:Cerebrovascular Circulation; D004574:Electromagnetic Fields; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015233:Models, Statistical; D011699:Putamen / Q000473:pathology; D012016:Reference Values; D012107:Research Design