Hello all,
sorry, it took me a while to get some spare time on our TRIO. Here's what I did: I scanned a person using the standard Siemens MDDW-20direction-DTI-sequence with 19 slices (5 mm) and set the angulation to 0° (transverse). Images had been saved in mosaic format. As the sequence uses four averages, the dataset results in 84 (4*(B0 + 20 vectors)) mosaic images. The images are saved in the following order: B0, vector 1, vector 2, ..., vecotr 20, B0, vector 1, vector 2, ..., vector 20.
Then, I used dcm2nii and MRIconvert on a PC AND a MAC and compared the bvec files with the vector datasheet provided by Siemens.
MOST IMPORTANT: Both programs give you almost the exact vectors. dcm2nii seems to smooth a little more than MRIconvert.
I did notice one thing: MRIconvert sorts the data differently to the original one and the dcm2nii results. MRIconvert sorts it in: B0, B0, B0, B0, vector 1, vector 1, ..., vector 20, vector 20, vector 20, vector 20. But it uses this sorting ordern in all three files: bvec, bval and the 4D.nii-file. So in my point of view that does not seem to be a problem (can someonce with a lot more knowledge comment on that?).
I don't have the bvec-files with me right now, but if interesten I could also post the files (might be easier than reading the text).
Have a good weekend,
Martin
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