Question about ALFF analysis

Submitted by jjtormur on Wed, 05/24/2017 - 14:15

Dear all,

I am trying to do some of ALFF and fALFF analysis in resting -state, but I don't know if I am proceeding well. I just want to compare the activity in resting-state beteween two groups. Similar to this paper from Wang, Human Brain Mapping 32:1720–1740 (2011).

I did all the pre-processing in SPM and now I want to use this images for ALFF. 

After the preprocessing, I do detrend and apply a filter of 0.01 - 0.08 to my images with DPARSFA. And then I do ALFF+fALFF clicking in this buttom of DPARSFA. Doing this I get three images for each subject: ALFFmap, mALFF and zALFF.

After this, I do a two sample t-test using the statistical analysis of dpabi. But here I don't know which image of above I should use to perform the analysis.

And the other question maybe is basic, but I don't know how to do this: How can I set the Z threshold and P in dpabi viewer?

Thank you very much in advance,

Best,

Juan.

 

Forums:

puyunfashi

Thu, 05/25/2017 - 01:20

Hi Juan,

I'm afraid you cannot adapt bandpass filtering to metrics like ALFF or fALFF, since these two are based on calculating the amplitude across different bands. 
You may use the zALFF map to perform the two-sample t-test, because zALFF map has been transformed by the Fisher' z transformation. This map will obey normal distribution better.
You may find answers to your last question at http://rfmri.org/Course, where Prof. Yan gives an outstanding and comprehensive tutorial to the usage of dpabi and DPABI_VIEWER.

Best!

Xiao.


-----原始邮件-----

发件人: "The R-fMRI Network" <rfmri.org@gmail.com>

发送时间: 2017年5月24日 星期三

收件人: rfmri.org@rnet.co

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主题: [RFMRI] Question about ALFF analysis

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By Juan JJesús Toro (jjtormur)

Dear all,

I am trying to do some of ALFF and fALFF analysis in resting -state, but I don't know if I am proceeding well. I just want to compare the activity in resting-state beteween two groups. Similar to this paper from Wang, Human Brain Mapping 32:1720–1740 (2011).

I did all the pre-processing in SPM and now I want to use this images for ALFF. 

After the preprocessing, I do detrend and apply a filter of 0.01 - 0.08 to my images with DPARSFA. And then I do ALFF+fALFF clicking in this buttom of DPARSFA. Doing this I get three images for each subject: ALFFmap, mALFF and zALFF.

After this, I do a two sample t-test using the statistical analysis of dpabi. But here I don't know which image of above I should use to perform the analysis.

And the other question maybe is basic, but I don't know how to do this: How can I set the Z threshold and P in dpabi viewer?

Thank you very much in advance,

Best,

Juan.

 


Online version of this post: http://rfmri.org/content/question-about-alff-analysis








jjtormur

Thu, 05/25/2017 - 09:40

Dear Xiao,

Thank you for your answer. I understand know why I should use the zALFF map!

Just for clarify me, so, Have I to do the ALFF+fALFF option in DPARSFA just after apply the linear trend to the images?

Thank you very much again,

Best,

Juan

YAN Chao-Gan

Tue, 06/13/2017 - 08:46

If you included linear regressor in nuisance regression, you don't have to.