If the scans are not co-registered (the subject went out and came back to the scanner), I suggest you to calculate the tensor first and register the tensor using DiffeoMap and linear registration (AIR or MI).<div><br></div>
<div>If you register the raw DWI data, you may get a bit better SNR (this is my guess), but you have to make sure to use the b-table re-orientation scheme in the AIR. I would recommend to use AIR or MI (MI may take a lot of time), although I don't have much experience in the cross-scan registration.</div>
<div><br></div><div>I think the first method (calculate tensor and then register) is the easiest.<br><br><div class="gmail_quote">On Thu, Aug 11, 2011 at 6:35 PM, Min Liu <span dir="ltr"><<a href="mailto:mliu4@ualberta.ca">mliu4@ualberta.ca</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Dear MRIStudio users,<br>
<br>
I have four human brain datasets that are scanned sequentially (back<br>
to back) of a single subject using the same DTI protocol. I want to<br>
get an averaged dataset out of the four. Before doing that,<br>
motion/eddy current correction is definitely needed. I am wondering<br>
among the three methods provided by DTIStudio, i.e. AIR/MI?theory AIR.<br>
By visual inspection, there is rotation/shifting between the very<br>
first dataset and the very last by about 2 voxels. For this subtle<br>
movement, is there a conclusion so far regarding which coregistration<br>
is the best (without introducing errors! Sometimes AIR does more harm<br>
than good by misalignment.) Thank you for your thoughts!!<br>
<br>
Min<br>
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