Hi all,<div><br></div><div>A general question about motion correction in diffusion imaging. In fmri this is a commonly practiced preprocessing step where the new signal, say, F' is obtained by a spatial shift of F, signal acquired when movement occurred:</div>
<div><br></div><div>F' = F*m</div><div><br></div><div>where m = m(x,y,z), the motion matrix.</div><div><br></div><div>But in diffusion this is clearly not the case as the signal in each direction is a function not only of the position of the brain but also of individual brain geometry. Therefore, new signal D' will be a <u>transform</u> (not shift) of signal D, acquired when movement occurred:</div>
<div><br></div><div>D' = D*t</div><div><br></div><div>where t = t(x,y,z,brain_geometry), the transform factor. </div><div><br></div><div>So unless there is an estimate of t, I don't think any motion correction is going to be useful in diffusion, certainly not a simple rigid body adjustment. Am I wrong?</div>
<div><br></div><div>Thanks</div><div>Durai</div><div><br></div><div><br></div>