[Mristudio-users] recalculating means with two AIR series?

[Elizabeth Finger]

Thank you- that worked perfectly. My main mistake was not opening up the AIR files as .rec format.
Thanks,
Elizabeth Finger

>>> susumu <susumu at mri.jhu.edu> 05/16/08 11:48 AM >>>
I think you'd better run AIR, save the AIRed images, close the DtiStudio,
open the AIRed images, and run DTI calculation. 

When you save the AIRed image, save the first 3+33 images into one file as
the raw format. Then save the second 3+33 images is a separate files.

In this way, you end up with two 4D AIRed files. To read these raw 4D files,
please use "Philips REC" format. If you type in correct X, Y, and Z
dimensions, you should see there are 36 images in your file. 

For DTI calculation, you can load the two 4D files for simultaneous fitting.
Before the DTI calculation, it is good idea to calculate "mean and STD
(actually subtraction in your case)" to get an idea about the quality of
coregistration by AIR. However, this calculation would put extra burden to
memory. So, after the quality check, you may need to close the window and
load the data again before the tensor calculation.

As a reminder, you need a 64bit system to use RAM bigger than 1GB.

Hope this will help.

-----Original Message-----
From: mristudio-users-bounces at mristudio.org
[mailto:mristudio-users-bounces at mristudio.org] On Behalf Of Elizabeth Finger
Sent: Friday, May 16, 2008 10:52 AM
To: mristudio-users at mristudio.org
Subject: [Mristudio-users] recalculating means with two AIR series?

Hello-

I have a large DTI data from GE in dicom format set that contains 3 B0
images plus 33 gradients, 50 slices, and two separate runs per subject.  I
am able to pull up both runs  in DTI Mapping and to run the AIR. However,
when I try to then calculate the means and STD for multiple runs, I run out
of memory, as I do when trying to do the tensor calculation directly.  I am
able to proceed if I process just one run at a time. However, if possible, I
would like to use the mean from the two series (it was from children, with a
lot of movement and fair amount of scanner artifact).  I have tried to save
AIR files as raw and analyze format, but am only able to open up the analyze
format in MRI 3dview, and not in DTI mapping (for the raw formats in DTI
mapping, when I attempt to load them, it say "number of files in this fold
is less than expected".   Is there some way to load just the AIR files into
DTI mapping to use for the means recalculation and tensor calculations?  

Many thanks,
Elizabeth Finger
 
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