Peter Jan Koopmans1, Markus Barth1,2,
David Gordon Norris1,2
1Radboud University Nijmegen, Donders
Institute for Brain, Cognition and Behaviour, Nijmegen, Netherlands; 2Erwin
L. Hahn Institute for Magnetic Resonance Imaging, Essen, Germany
We
present a multi-echo fMRI study at 7 T with 0.75 mm isotropic voxels and TEs
ranging from 4.8 to 56 ms. Layer dependent T2* values are reported for human
V1 showing a gradient from lower T2* near white matter and higher near the cortical
surface with a superimposed dip in the granular layer. We show that the
intravascular contribution to GE-BOLD at 7 T is dominated by the pial
compartment and that laminar activation profiles are TE dependent. The
optimal TE to detect BOLD changes in parenchyma is ~28 ms considerably longer
than previously thought as previous estimates have included venous blood.