<div dir="ltr">Hi all, <div>I would like to obtain tensor components computed with using modelfit and nldt_pos as algorithm. Everything seems to work properly, as I can also correctly visualize results using e.g. pdview.</div>
<div>But when I want to split this file to obtain single components I eot stuck: here is my code</div><div><br></div><div><div>for ((i=0;i<8;i=i+1));do</div><div>#splitting tensor into its components</div><div>shredder $((i*8)) 8 56 < dti.Bdouble > DT_comp${i}.img</div>
<div>#creating proper header</div><div>analyzeheader -voxeldims 1.75 1.75 2 -datadims 128 128 74 -datatype double > DT_comp${i}.hdr</div><div>done<br></div></div><div><br></div><div>If I have correclty understood,my output should be</div>
<div><br></div><div>DT_comp0.img which contains exitcode</div><div>DT_comp1.img which contains log of unweighted signal</div><div>DT_comp2.img which is DT_xx</div><div>DT_comp3.img which is DT_xy<br></div><div>DT_comp4.img which is DT_xz<br>
</div><div>DT_comp5.img which is DT_yy<br></div><div>DT_comp6.img which is DT_yz<br></div><div>DT_comp7.img which is DT_zz<br></div><div><br></div><div>Now, to check if my assumptions are correct I go back to tensor by means of nii2dt function (before doing that I merge volumes using fslmerge)</div>
<div><br></div><div>fslmerge -t tensor DT_xx.nii DT_xy.nii DT_xz.nii DT_yy.nii DT_yz.nii DT_zz.nii<br></div><div><br></div><div>so </div><div><br></div><div>nii2dt -inputfile tensor.nii.gz > dt.Bdouble<br></div><div><br>
</div><div>eventually I calculate fa </div><div><br></div><div>cat dt.Bdouble | fa | voxel2image -outputroot my_fa -header tensor.nii.gz<br></div><div><br></div><div>But when I look at the results fa map is totally wrong as the fa values are in the range [.9 1.2], which is impossible of course.</div>
<div><br></div><div>I also tried using linear option and addingo lns0 and mask (inverting endianness as described for mask output of bet2 function) as well .In this last case the code was</div><div><br></div><div>nii2dt -inputfile tensore.nii.gz -bgmask mask.img -lns0 DT_comp1.img > dt.Bdouble</div>
<div><br></div><div>but with no amelioration at all. </div><div><br></div><div>Where am I wrong? Is the position of tensor components wrong?</div><div>Is the reconstruction back to camino tensor wrong? </div><div>Is shredder badly used? </div>
<div>Is it a problem of mask endianness?</div><div><br></div><div><br></div><div>Hope you can help me,</div><div><br></div><div>Best,</div><div>Alessandro</div></div>