AFNI Message Board

Dear AFNI users-

We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:

https://discuss.afni.nimh.nih.gov

Existing user accounts have been migrated, so returning users can login by requesting a password reset. New users can create accounts, as well, through a standard account creation process. Please note that these setup emails might initially go to spam folders (esp. for NIH users!), so please check those locations in the beginning.

The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.

Sincerely, AFNI HQ

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isades
January 16, 2017 03:57PM
Dear AFNI experts,

I am trying to calculate the frame displacement (FD) according to the formula given in Power et al. 2012. The goal is to compare FD values between two groups. However, I have some doubts regarding how I can implement this with the output I have access to (the data is already analyzed). If I understand correctly, frame displacement represents the absolute value of displacement changes in the x, y, z directions as well as rotational changes (roll, pitch and yaw--once converted to mm) between adjacent volumes.

I only have access to the motion files (2 runs) and the .1D matrix from 3dVolreg. The base for registration was the 10th volume of the 2nd run. With the output that I have, can I calculate an FD value per participant? If I understand correctly, the motion parameters in the motion file represent the displacement between the volume and the base volume used for registration, which are not adjacent.

Thank you in advance for your help,

Sincerely,


Isabelle



Edited 1 time(s). Last edit at 01/16/2017 03:58PM by isades.
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Subject Author Posted

Frame displacement

isades January 16, 2017 03:57PM

Re: Frame displacement

rick reynolds January 17, 2017 10:58AM