David Zsolt Balla1, Hannes M. Wiesner1,
Gunamony Shajan1, Rolf Pohmann1
1High Field Magnetic Resonance Center,
Max Planck Insitute for Biological Cybernetics, Tbingen, Baden-Wrttemberg,
Germany
Functional
MRI (fMRI) in animals at high magnetic fields keeps expanding our knowledge
about the basics of neural processing but the specificity of the fMRI-signal
is still under ongoing investigation. Yet, as the signal to noise ratio in
MRI depends linearly on the magnetic field strength and calls for even
stronger magnets for the detection of even smaller anatomical details, the
relation between the functional MR-response and field strength can only be
approximated with complex models. In this study the blood oxygenation
dependent (BOLD) effect was measured and compared at 9.4 T and 16.4 T in the
same animal with segmented gradient-echo (GE) and spin-echo (SE) echo planar
imaging (EPI) sequence using optimal echo times for the respective field.
Furthermore, high resolution fMRI acquisition at 16.4 T was performed up to a
50 m in-plane accuracy and for an 8 s temporal resolution without the use of
cryo-coils or coil-arrays.