Hi Gabriel - The eddy-current correction method that's appropriate depends on the b-value. For a moderate b-value, the DWIs have enough features to be registered to the b=0 image. If you have something like b=2000, this won't work so well.
The reorientation of tensors is just applied to the gradient table, it doesn't do anythign to the images themselves, so nothing special there that would change with the protocol. The intra-subject registration is from the b=0 image to the T1, so as long as there is b=0 image, the rest of the protocol doesn't have any effect. To check the gradient vectors, you have to fit some kind of model of orientation (like the tensor) to the image data and check if the estimated orientations are correct (following the big tracts, like going left-right in the corpus callosum, inferior-superior in the corticospinal tract, etc). Hope this helps, a.y On Thu, 18 Sep 2014, Gabriel Gonzalez Escamilla wrote: > Dear Freesurfer and DTI experts, > > I will start some analyses with DWI data, but I have some doubts about it: > > 1) I have data with 5 different acquisition protocols, so, I'm not sure if > the standard pre-processing protocol (like eddy-current compensations the > reorientation of the vectors and the intra-subject registration) can be > applied to all images equally or if I do need to set any specific parameters > for each acquisition protocol? > > 2) Does your method have any tool to check that the vectors are good, before > or after fitting the tensors? > > Many thanks in advanced, > Gabriel > > _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer The information in this e-mail is intended only for the person to whom it is addressed. If you believe this e-mail was sent to you in error and the e-mail contains patient information, please contact the Partners Compliance HelpLine at http://www.partners.org/complianceline . If the e-mail was sent to you in error but does not contain patient information, please contact the sender and properly dispose of the e-mail.
