<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:14px"><div id="yui_3_16_0_1_1440096297743_11928">Hi, Camino Users</div><div id="yui_3_16_0_1_1440096297743_12026"><br></div><div dir="ltr" id="yui_3_16_0_1_1440096297743_11929">I have obtained the whole brain tracts by seeding in every white matter voxel of the brain. Now, I want to get the tract length between each ROI pair in an atlas, say, AAL. What is the best way to get such a matrix of tract length?</div><div dir="ltr" id="yui_3_16_0_1_1440096297743_11930"><br></div><div dir="ltr" id="yui_3_16_0_1_1440096297743_11931">I asked because I may use random parcellation with >500 ROIs. Currently what I am doing are:</div><div dir="ltr" id="yui_3_16_0_1_1440096297743_11932"><br></div><div dir="ltr" id="yui_3_16_0_1_1440096297743_11933">(1) derive and separate two ROIs from the atlas</div><div dir="ltr" id="yui_3_16_0_1_1440096297743_11934">(2) combine them to form an endpoint file</div><div dir="ltr" id="yui_3_16_0_1_1440096297743_11934">(3) use procstreamline to separate the tracts connecting the ROI pair</div><div dir="ltr" id="yui_3_16_0_1_1440096297743_11934">(4) use tractstat to get the length, and put it in the cell of the matrix</div><div dir="ltr" id="yui_3_16_0_1_1440096297743_11934">(5) repeat (1)</div><div dir="ltr" id="yui_3_16_0_1_1440096297743_11934"><br></div><div dir="ltr" id="yui_3_16_0_1_1440096297743_11934">This method, although works, takes a while, especially when I have a high-resolution partitioning scheme. Is there any better way to do it? I am jealous that conmat can calculate the number of connected streamlines between two ROIs so fast, and wonder whether there is a similar command for calculating the length. </div><div dir="ltr" id="yui_3_16_0_1_1440096297743_11934"><br></div><div dir="ltr" id="yui_3_16_0_1_1440096297743_11934">Many thanks in advance!</div><div dir="ltr" id="yui_3_16_0_1_1440096297743_11934">Longchuan</div><div dir="ltr" id="yui_3_16_0_1_1440096297743_11934"><br></div></div></body></html>