Dear Bin-Ke,
ASL works by adding an inversion pulse at the neck every second image.
You can compute your normalization parameters on the (averaged) native
image after realignment, i.e. before computing the CBF estimate, and
then apply them to the CBF images. In the common case, you use EPI
images to compute the normalization parameters to the EPI template.
Best wishes,
Roberto Viviani
Dept. of Psychiatry and Psychotherapy III
University of Ulm, Germany
Quoting Bin-Ke YUAN <[log in to unmask]>:
> Dear Karsten,
>
> Thanks for quick reply. The processing procedure of CBF data are: Firstly,
> the CBF image were corregistered with the corresponding T1
> image;Secondly,the T1 image were normalized using the unified segmentation
> method in SPM;Finally,the CBF images were spatially normalized and
> re-sampled (2x2x2 mm) using the normalization parameters estimated during
> unified segmentation.
>
>
> The 3D ASL sequence I used constructed images of two types: one is
> perfusion-weighted image and the other is PD image.Thanks for you
> suggestion and I will try a normalization on the PD image.
>
> Best,
> Bin-Ke
>
> 2013/3/4 Karsten Specht <[log in to unmask]>
>
>> Dear Bin-Ke,
>>
>> Which template have you used? You wrote you did a coregistration before.
>> Did you coregister the ASL images with an T1 image and segmented this one
>> or what exactly was your procedure?
>>
>> You could also try to normalize the CBF maps to a PET template and create
>> your own population based template out of that and re-normalize your scans.
>> Some ASL sequences are providing also a PD image. You may want to try out a
>> normalization on that one, as well.
>>
>> Good luck,
>>
>> Karsten
>>
>>
>> Fra: Bin-Ke YUAN <[log in to unmask]>
>> Svar til: Bin-Ke YUAN <[log in to unmask]>
>> Dato: 10Montag, 4. März 2013 11:51
>> Til: <[log in to unmask]>
>> Emne: [SPM] Normalization of ASL images
>>
>> Dear all:
>> I used unified segmentation to perform normalization of my CBF images and
>> found the normalization effect was bad (images of unnormalized and
>> normalized were attached). I have done the corregister before normalization.
>> The pulse sequence of ASL are 3DASL (no contrast,GE healthcare MR-750 3.0
>> T scanner) and the CBF images were got using the 3DASL functiontool of the
>> scanner.
>> Any suggestion / advice will be very welcome.
>>
>> Many thanks in advance,
>> Bin-Ke
>>
>
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