¥ Besides the voxel numerical values, a
dataset also contains auxiliary information, including (some of which is
optional):
H xyz dimensions of each voxel (in
mm)
H Orientation of dataset axes;
ofor example, x-axis=R-L, y-axis=A-P,
z-axis=I-S
oÞ
axial slices (we call this
orientation ÒRAIÓ)
H Location of dataset in scanner
coordinates
o Needed to overlay one dataset onto another
o Very important to get right in FMRI, since we deal with many
datasets
H Time between sub-bricks, for 3D+time datasets
o Such datasets are the basic unit of FMRI data (one per
imaging run)
H Statistical parameters associated with
each sub-brick
o e.g., a t-statistic sub-brick has degrees-of-freedom
parameter stored
o e.g., an F-statistic sub-brick has 2 DOF parameters
stored