Dear All,

I want to use 3dFourier to filter (bandpass: 0.01Hz - 0.08Hz) a
3D+time fMRI data, but I met with a problem: the resulted filtered
time series looked not right. Could anyone help me? The details are as
follows:

step1: the fMRI data were first preprocessed in SPM2 (slice timing,
realign, normalise and smooth).

step2: then the preprocessed fMRI data (170 analyze image files) were
converted from SPM2 to AFNI by the following command:
to3d -prefix nor008 -view orig -xFOV 91.5R-91.5L -yFOV 127.5P-91.5A
-zFOV 73.5I-109.5S -time:zt 61 170 2s altplus 3D:-1:0:61:73:61:sw*.img
and then I got the nor008+orig.BRIK/HEAD file. I have checked this
BRIK file and it is exatly same as those analyze image files (I ploted
the time series of some voxels in matlab, and found that the two time
series from the BRIK file and those analyze files are exactly same).

step3: the obtained nor008+orig.BRIK was bandpass filtered by using 3dFourier:
3dFourier -prefix LPnor008 -lowpass 0.08 -highpass 0.01 -ignore 1
-retrend nor008+orig.
I found that the filtered time series of some voxels(not all voxels)
looked a little weird (the whole time series is not very smoothing and
there exist some short horizontal lines in the time series). The time
series of some voxels before and after filtering are in the attached
file TS.pnm and filteredTS.pnm respectively.

Any mistake did I make in the above steps?
And any help and advices are appreciated. Thanks!

Meng

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