[Mristudio-users] How to answer this question?

[pengdoctor1]

Hello,everyone,
   I used ditstudio to produce FA,  and then used a VBA method to find a decreased FA brain region in my paper, but the referee asked a question, i don't know what it mean( the contents in yellow), who can tell me. thank you very much!
 

"Second, is it possible that the higher FA in the recovered scans is due to better quality of the scans? Maybe due to reduced movement artifact (coorelated with BDI)? Is it possible that simple filtering followed by VBA is more sensitive to such an artifact than TBSS would have been?Is this effect filter frequency dependent?"

 

 

在 2011-08-26 04:48:40，"susumu mori" <susumu at mri.jhu.edu> 写道：
I have to confirm Hangyi, but my understanding is;



Slice 
#_Of_Fibers: the number of reconstructed streamlines that penetrate the given slice
Max_Val: The maximum pixel value (if you chose FA, then the FA value) that contains the streamlines in the given slice
Min_Val
Mean_Val: The mean of the pixel values that contain the streamlines in the given slice
Std_Dev

Pixel#--: The number of pixels that contain the streamlines in the given slice
Max#--      : The maximum number of the streamlines a pixel holds in the given slice
Min#-- 
Mean#--     The mean number of the streamlines of the pixels that contain the streamlines in the given slice
Std_Dev-- (Fiber/Pixel)



Inorder to calculate a mean FA for a selected number of slices, would the following be correct?: (ie for slice 1, 2, 3...)



This number is already calculated in "Mean Val" column. 

((Pixel#)(Mean_val))1+((Pixel#)(Mean_val))2+((Pixel#)(Mean_val))3.......  / total # of pixels


Or....

((#_Of_Fibers)(Mean_val))1+((#_Of_Fibers)(Mean_val))2+((#_Of_Fibers)(Mean_val))3.......  / total #_Of_Fibers



Also, could you possibly explain what the rest of the values are? (especially beyond pixel #)

Thank you again, I really appreciate the help
Matt Gnirke




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