Question
Question Posted 09/20/22:
I have a problem about preprocessed DTI data.
I can download the Eddy_current_corrected_image from the data collections, however, the downloaded data do not contain the bvec and bval files. I took efforts to find those files, but cannot find them.
More specifically, my problem here is about the pre-processed DTI data, which are already .nii files. And I cannot find the .bvec and .bval files along with the pre-processed DTI data, Eddy_current_corrected_image or EPI current corrected image.
From my understanding, the Eddy_current_corrected_image has been rotated, hereby, the bvec vector should be rotated accordingly. If I hope to use the Eddy_current_corrected_image for saving time and for a fair comparison, I have to employ the corresponding .bvec and .bval files. Could you please tell me where I can obtain the bvec and bval files?
I have a problem about preprocessed DTI data.
I can download the Eddy_current_corrected_image from the data collections, however, the downloaded data do not contain the bvec and bval files. I took efforts to find those files, but cannot find them.
More specifically, my problem here is about the pre-processed DTI data, which are already .nii files. And I cannot find the .bvec and .bval files along with the pre-processed DTI data, Eddy_current_corrected_image or EPI current corrected image.
From my understanding, the Eddy_current_corrected_image has been rotated, hereby, the bvec vector should be rotated accordingly. If I hope to use the Eddy_current_corrected_image for saving time and for a fair comparison, I have to employ the corresponding .bvec and .bval files. Could you please tell me where I can obtain the bvec and bval files?
Response posted 09/21/22 by Rob Reid:
Hi, I have forwarded your question to Paul Thompson's lab, who pre-process the DTI data, and Karen Crawford, since this might just be a case of there not being a good spot on the website for serving weird little files like these.
In the meantime, the DICOM is available, and has the diffusion gradients in its headers; you can extract them with a program like dcm2niix. That will yield the pre-rotated .bvec, but the rotations are typically very small.
In the meantime, the DICOM is available, and has the diffusion gradients in its headers; you can extract them with a program like dcm2niix. That will yield the pre-rotated .bvec, but the rotations are typically very small.
