Hello,
I have SPECT and MR scans from controls and patients, and I want to run a
group comparison of the SPECT scans.
I am trying to perform some kind of atrophy correction on the SPECT scans
before running the statistics and think that the following method would be
the best way.
Coregister raw SPECT and raw MR images (with reslicing to bring them into line)
Segment coregistered MR images (without prior normalisation so that the
atrophied regions are not warped)
Take the GM image and make a binary mask
Take the WM image, and make all the WM pixels have an average WM value
(measured using an ROI)
Smooth the binarised GM and WM images to the point spread function of the
SPECT imaging system.
Subtract the WM image from the SPECT image (assuming no HMPAO is in the CSF)
Divide the SPECT image by the GM smoothed binary image
Normalise corrected SPECT scans to SPM5 SPECT template
I would appreciate any comments on the effectiveness or technicalities of
this process. I also have a couple of other questions,
Firstly, is there any problem with segmenting without prior normalisation?
(It seems that segmentation is possible without it, and I don’t want to warp
the MR at all before the atrophy is corrected for).
Secondly, should I mask the final resultant image with the unsmoothed GM image?
Thanks very much :-)
Emma
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