High resolution SE-fMRI in humans at 3 and 7 T using a motor task.
OBJECTIVE
The sensitivity of spin echo (SE) experiments to blood oxygenation level dependent (BOLD) contrast was explored in a study of the same six subjects carried out at 3 and 7 T.


METHODS
Multi-slice, single shot, spin echo, echo planar images with a voxel size of 1 x 1 x 3 mm3 were acquired at three different echo times, during execution of a simple motor task.


RESULTS
Significant activation was observed at all echo times at both field strengths. Analysis of the fractional signal change as a function of echo time indicated that the change in relaxation rate, Delta R2, at 7 T was -0.51 +/- 0.14 s (-1), which was 1.3 times larger than the value found at 3 T. Measurements of the percentage signal change on activation and temporal signal to noise ratio showed that there was an increase in the BOLD contrast to noise ratio (CNR) at 7 versus 3 T by a factor of 1.9. There was no overlap of areas of significant activation in the SE data acquired at either field strength with the site of large veins.


CONCLUSIONS
SE-BOLD CNR in motor cortex was found to increase significantly at 7 T compared with 3 T.
Schäfer
Andreas
A
Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, UK. andreas.schaefer@nottingham.ac.uk
van der Zwaag
Wietske
W
Francis
Susan T
ST
Head
Kay E
KE
Gowland
Penny A
PA
Bowtell
Richard W
RW
D000328:Adult; D001931:Brain Mapping / Q000379:methods; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008280:Magnetics; D008297:Male; D015233:Models, Statistical; D009044:Motor Cortex / Q000473:pathology*; D009048:Motor Skills; D010100:Oxygen / Q000097:blood; D010364:Pattern Recognition, Visual; D012680:Sensitivity and Specificity; D013997:Time Factors
D010100:Oxygen