<div dir="ltr">The single fiber mask contains voxels out of brain, from skull etc. I will make some attempts to better refine the DWI mask up in the processing pipeline.<div><br></div><div>However, I still see good fiber tractography. What is the effect of low response function on CSD results?</div>
<div><br></div><div>Yes, this is a healthy control.</div><div><br></div><div>You help is appreciated.</div><div>Thank you</div><div>Dorian</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">2013/10/28 Donald Tournier <span dir="ltr"><<a href="mailto:jdtournier@gmail.com" target="_blank">jdtournier@gmail.com</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hi Dorian,<div><br></div><div>That's a bit lower than I'd expect, I typically see about 3/4 of the b=0 intensity (I think). That's for a b-value of ~3000, I would expect it to be lower than that for higher b-values. Basically, the first term in the response function multiplied by ~0.28 should correspond to the mean DW intensity averaged over all orientations. If that's not the case, I would have a good look at your single-fibre mask (the mask from which you estimate the response function), to make sure that all voxels included are in sensible, single-fibre, pure WM locations. I also assume this is a healthy volunteer? Otherwise T2 hyperintensity could explain this. If none of this helps, maybe you can post an image of the response function, its coefficients, and the b-value, SNR and number of directions of the data set, just in case we can spot anything obvious from them...</div>
<div><br></div><div>Cheers,</div><div><br></div><div>Donald.</div><div><br></div><div><br></div><div><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote"><div><div class="h5">On 25 October 2013 16:21, Dorian P. <span dir="ltr"><<a href="mailto:alb.net@gmail.com" target="_blank">alb.net@gmail.com</a>></span> wrote:<br>
</div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5"><div dir="ltr">Hi again MRtrix group,<div><br></div><div>My processing works fine and I see the doughnut shape of the response function. On checking some quality parameters I noticed that my response function starts from ~110 while white matter values on b0 are around 350-450. Is this normal or should I look at anything to improve?</div>
<div><br></div><div>This is not just a case as I have two HARDIs from the same subject, both around those values.</div><div><br></div><div>Thank you.</div><div><br></div><div>Dorian</div><div>TJU</div></div>
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<br></blockquote></div><span class="HOEnZb"><font color="#888888"><br><br clear="all"><div><br></div>-- <br><div dir="ltr"><b><font color="#990000">Dr J-Donald Tournier (PhD)</font></b><br><div><font color="#990000"><br>
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