<div> </div><div>Hello DTI experts!</div><div> </div><div>I'm Jeongpyo Son.</div><div> </div><div>I have some questions regarding<strong> how to acquire tractography data using homemade calculated images</strong>.</div>
<div>For tensor calculations, DTI studio cannot calculate my DTI data (rat DTI data acquired by using Bruker 7T scanner) correctly.</div><div>Hangyi gave me some advice about calculating tensor using DTI studio but unfortunately it didn't help. (Regardless of the results, I sincerely appreciate your help Hangyi ^^)</div>
<div>So, I made MATLAB M-files and acquired the FA, tensor (Dxx, Dyy, Dzz, .....) and directional diffusivity maps and I saved all the calculated data in the nii format. </div><div> </div><div>Now, here are some questions that I have about fiber tracking methods:</div>
<div> </div><div>1. As far as I know, fiber tracking is available<u> by tensor images (Dxx, Dyy, Dzz, .....).</u></div><div><strong>How can I create fiber tracts using tensor images?</strong></div><div>My tensor images are 3D so the number of tensor images is 6(Dxx, Dyy, Dzz, Dxy, Dxz, Dyz). </div>
<div>In the fiber tracking menu, only 1 image can be chosen in the "Tensor Image" tab. </div><div>Should I convert my Tensor images to 4D? If so, then how should I arrange the Tensor images?</div><div> </div><div>
2. Another method, <u><font color="#000000">using principal vector and FA map</font>.</u></div><div>I made the FA map using my own M-files but I don't know how to create the principal vector map.</div><div>The calculation method of the M-file are same as following.</div>
<div>----------------------------------------------------------------------------------------------------------------------------------------------------</div><div> for z = 1:dz<br> for y = 1:dy<br> for x = 1:dx <br>
y_temp = [log(S1(x,y,z)); log(S2(x,y,z)); log(S3(x,y,z)); log(S4(x,y,z)); log(S5(x,y,z)); log(S6(x,y,z))]; <br> D = inv(b_matrix)*y_temp;<br> Dxx(x,y,z) = D(1,1);<br> Dyy(x,y,z) = D(2,1);<br>
Dzz(x,y,z) = D(3,1);<br> Dxy(x,y,z) = D(4,1);<br> Dxz(x,y,z) = D(5,1);<br> Dyz(x,y,z) = D(6,1);<br> end<br> end<br> end</div><div>
-------------------------------------------------------------------------------------------------------------------------------------------------------</div><div>This M-file is made for calculating the data acquired using 6 diffusion encoding gradients scheme, and S# means "signal of the original DWI/signals of the b0 image".</div>
<div>So, y_temp means ln(S/S0).</div><div> </div><div>After the Tensor calculations, the eigen values and eigen vectors are acquired.</div><div><strong>The eigen vectors are formed as 3x3 matrix and by them, how can I acquire principal eigen vectors?</strong></div>
<div>Please let me know the formula for calculating principal eigen vector. </div><div> </div><div> </div><div> </div><div>Best Wishes. </div><div> </div><div> </div>