About ReHo

Submitted by cherrychingju on

Dear all,

Is ReHo value equal to Kendall's W (KCC)?

And if we use a region to be a ROI and extract its value, then this value is ReHo value or KCC value? (Some values are more than 1, so KCC can be more than 1?) 

Your help will be greatly appreciated!

 

Best, 

Cherry

 

Dina Dajani

Mon, 10/06/2014 - 15:02

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ReHo values are KCC values (W), which range from 0 to 1.  I am wondering what the "m" prefix means for the Reho output, because these values range from 0 to above 1.  Also, the "s" prefixed images should also range from 0 to 1, these are just smoothed.  

mReHo is a standardized value by dividing the global mean ReHo, so, its value is no longer between 0 to 1.

 

Yufeng

 

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Commented by Dina Dajani (Dina Dajani)

ReHo values are KCC values (W), which range from 0 to 1.  I am wondering what the "m" prefix means for the Reho output, because these values range from 0 to above 1.  Also, the "s" prefixed images should also range from 0 to 1, these are just smoothed.  


Online version of this post: http://rfmri.org/comment/3322#comment-3322

 

m* is standardized by dividing the global mean ReHo, and z* is further standardized by z value (minus mean, then divided by SD). If do a two-sample t-test (between two groups) or paired t-test, the resultant t maps are almost identical for m* and z*.

 

Yufeng

 

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Commented by Dina Dajani (Dina Dajani)

Thank you for this information.  So what is the difference between the m* maps and the z* maps?

 

 


Online version of this post: http://rfmri.org/comment/3324#comment-3324

 

Hello Dr. Zang,

 

What would the difference be between performing a two sample t-test on the standardized maps versus using the original KCC-value maps?

 

Thank you for the information,

Dina Dajani

also to confirm, the global mean KCC value that is divided for these m* maps are gloabl means for each individual participant, correct? (not a global mean for the entire group)

The global mean value is used for standardization for many functional imaging techniques, e.g., PET. We do know the results will be different for standardization or not. But we do not know which is right. Either might be reasonable.

 

The global mean value here is at individual level.

 

Yufeng

 

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Commented by Dina Dajani (Dina Dajani)

Hello Dr. Zang,

 

What would the difference be between performing a two sample t-test on the standardized maps versus using the original KCC-value maps?

 

Thank you for the information,

Dina Dajani


Online version of this post: http://rfmri.org/comment/3330#comment-3330

 

ReHo uses KCC. So the raw ReHo value is from 0 – 1. But, of course, other algorithms can also be used to measure ReHo, e.g., coherence (Liu et al., 2009).

 

Ref: Liu D, Yan C, Ren J, Yao L, Kiviniemi VJ, Zang Y. Using coherence to measure regional homogeneity of resting-state fMRI signal. Front. Syst. Neurosci. 2010, 4:24.

 

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Commented by Ching-Ju Yang (cherrychingju)

Accroding to wiki, KCC values range from 0 to 1. Thus, KCC values seem not to be ReHo values! 


Online version of this post: http://rfmri.org/comment/3326#comment-3326

 

ReHo is just a general term for local synchronization here. KCC, coherence, or linear correlation are the algorithms.

 

The original value will never below 1. But after standardization, the value may be any big, depending on the standardization method.

 

Yufeng

 

From: RFMRI.ORG [mailto:rfmri.org-bounces@rnet.co] On Behalf Of The R-fMRI NetworkSent: Saturday, October 04, 2014 2:55 PM
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By Ching-Ju Yang (cherrychingju)

Hello, is ReHo value equal to Kendall's W (KCC)?

And if we use a region to be a ROI and extract its value, then this value is ReHo value or KCC value? (Some values are more than 1, so KCC can be more than 1?) 


Online version of this post: http://rfmri.org/content/about-reho

 

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