[Mristudio-users] Gradient table

[eric Q]

Hello Dear DTIstudio users:

I am new to DTIstudio, I was hoping someone could give me some much needed advises for beginners.


I was trying to obtain the FA values for my brain phantom (PHILIP 3T scanner). When I clicked on "DTI mapping", it prompted me to enter the "gradient table", how do I calculate the "gradient table"?

Thanks in advanced

Best regards

Eric



Date: Thu, 9 Apr 2009 11:04:09 -0400
From: susumu at mri.jhu.edu
To: mristudio-users at mristudio.org
Subject: Re: [Mristudio-users] MriView3D application close








Hi Hugh,
 
When you got this error, please suspect one of the 
following two reasons;
 
1) Memory shortage:
 
Even if you have many GB of memories, 32-bit Windows system 
can allocate only 1 - 1.5 GB to each program. To check if you have the memory 
problem, please restrict the slices to be calculated. In the 
initial data parameter window, there is a section called "Slices to be 
processed". Here you can specify only a portion of slices to be processed. 
Please limit the slices to, for example, 0-9 and see how it goes. If you can 
calculate tensors without errors, then you have the memory problem. The solution 
is; a) upgrade to the 64-bit system or b) devide the calculation to 2 batches 
(e.g. slice 0-29 for the first batch and 30-59 for the second batch), calculate 
all maps (e.g. FA), and later combine them.
 
2) Mismatch between the gradient table and the number of 
images:
 
For example, if you specify 12-orientation table and 30 
volume images, then you get the error. After loading the data and before you go 
to the Dti Map tab, make sure that you have 1 b0 + 64 DWIs in the pull-down menu 
in the right column of the Image tab. If you have the correct number of the 
images, then you might have an error in your gradient table. Small mistakes such 
as missing "," are often difficult to detect. The best way is; a) load the data 
using DtiMapping under the "File" button on the top left, b) close the window, 
c) open the image paremater window again by clicking "DtiMapping" in the "File" 
button again, d) the window still remembers the gradient table you entered last 
time. This remembered window tells how DtiStudio interpreted your gradient 
table. If there is any syntax errors, you may find them much easier. For 
example, if you enter, "4: 1 0.5 0", instead of "4: 1, 0.5, 0", then you would 
find, "4: 1, 0, 0".
 
If any of these do not solve the issue, please let us 
know.
 
Susumu



From: mristudio-users-bounces at mristudio.org 
[mailto:mristudio-users-bounces at mristudio.org] On Behalf Of Hugh 
Wang
Sent: Wednesday, April 08, 2009 6:30 PM
To: 
mristudio-users at mristudio.org
Subject: [Mristudio-users] MriView3D 
application close


Hi, 

I was using the dtistudio (ver. 2.4)  to look at the 
Siemens DICOM diffusion images (1baseline,64 gradients). After successfully 
loading the images, I click the "dti map" option at lower right corner. Whatever 
calculation I choose, it always gives me an error: 

"MriView3D MFC 
Application has encountered a problem and needs to close.  We are sorry for 
the inconvenience."

I tried several PCs, and the problem keeped the same. 
I would appreciate that if there's anyone having any idea on how to solve it. 
Thanks.
Best,
Hugh

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