Hi,
I recently acquired an old Varian dataset and am trying to import the data into TORTOISE for preprocessing. The Import works without error, however it seems the b-matrix is not being calculated correctly. The original bvecs are:
0.00 0.00 0.00
1.00 1.00 0.00
1.00 0.00 1.00
0.00 1.00 1.00
-1.00 1.00 0.00
-1.00 0.00 1.00
0.00 -1.00 1.00
0.00 0.00 0.00
-1.00 -1.00 0.00
-1.00 0.00 -1.00
0.00 -1.00 -1.00
1.00 -1.00 0.00
1.00 0.00 -1.00
0.00 1.00 -1.00
And bvals are:
0.00
605.46
605.46
605.46
605.46
605.46
605.46
0.00
605.46
605.46
605.46
605.46
605.46
605.46
After importing the data and using TORTOISEBmatrixToFSLBVecs, I get the following bvecs:
0.000000 0.000000 0.000000
0.000000 0.707107 0.707107
0.000000 0.000000 0.000000
-0.577350 0.577350 -0.577350
0.707107 0.000000 0.707107
-0.000000 0.707107 0.707107
-0.577350 0.577350 -0.577350
0.000000 0.000000 0.000000
0.707107 -0.000000 0.707107
0.000000 0.000000 0.000000
0.577350 0.577350 0.577350
0.707107 0.707107 0.000000
0.707107 0.000000 0.707107
0.577350 0.577350 0.577350
And the bvals are:
0.000
1210.920
0.000
1816.380
1210.920
1210.920
1816.380
0.000
1210.920
0.000
1816.380
1210.920
1210.920
1816.380
The only command I am running other than the b matrix conversion is:
ImportNIFTI -i 3204_dwi.nii -p vertical -v ../../bvecs.txt -b ../../bvals.txt
Is there a way to correctly import the bvecs and bvals? Any suggestion is greatly appreciated. I am using TORTOISE 3.1.4 on MacOS 11.5.
Thanks
Hello,
Apologies for the late reply. We have had issues with our web server for a while so we didnt receive the question.
Unlike some of the other softwares, we do not scale the bvectors to unity internally. That is because we want to have another form of control over the Bmatrix.
Your bvecs are not unit vectors. Therefore, internally, these would have an effect on the bvalues. If you are sure your bvals are correct, for instance, instead of:
1.00 1.00 0.00
you should have
1./sqrt(2) 1./sqrt(2) 0
I mean each vector as unit.
That should do it.