[Camino-users] the best way to get the tract length of a connectivity matrix

[Longchuan Li]

Hi, Camino Users
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?
I asked because I may use random parcellation with >500 ROIs. Currently what I am doing are:
(1) derive and separate two ROIs from the atlas(2) combine them to form an endpoint file(3) use procstreamline to separate the tracts connecting the ROI pair(4) use tractstat to get the length, and put it in the cell of the matrix(5) repeat (1)
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. 
Many thanks in advance!Longchuan
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