Accurate multislice gradient echo T(1) measurement in the presence of non-ideal RF pulse shape and RF field nonuniformity.
A methodology is presented for estimating T(1) using a two-point technique with a standard multislice gradient echo sequence. The method explicitly corrects for the shape of the RF pulse and for spatial variations in transmitted RF field intensity. Including these factors in the calculation of T(1) gives a substantial improvement in accuracy and precision of two-point gradient echo T(1) measurements in the presence of RF nonuniformity and non-ideal pulse profiles. The mean accuracy of the technique was found to be 1.4%. The mean precision was found to be 3.0%. The mean variation along the axis of a head coil was found to be 2.3%.
Parker
G J
GJ
NMR Research Unit, Department of Clinical Neurology, Institute of Neurology, University College London, Queen Square, London, UK. g.parker@ion.ucl.ac.uk
Barker
G J
GJ
Tofts
P S
PS
D001921:Brain / Q000033:anatomy & histology*; D001931:Brain Mapping; D017352:Echo-Planar Imaging / Q000379:methods*; D006801:Humans; D019047:Phantoms, Imaging; D011846:Radio Waves