Hi.
I am trying to run probabilistic fiber tractography in FSL in parallel. My first approach was to take my seed volume mask and divide this into a set of seed volume masks, running tractography from these masks to the whole brain.
I thought that adding these fdt_paths outputs would be equal to running tractography from the whole seed volume mask. However this is not the case (large percent differences between the methods)
I thought it might be due to the probabilistic nature of this method, so I re-ran the tractography using the full volume mask, and got the same result (running the same script twice using the full mask got the same result)
I am now trying to use the --rseed flag. My thoughts, as I've seen in this page, is to:
Rather than run probtrackx using a -P 1000 value, to use a -P 10 value 100 times. This would require me to use the --rseed flag since I have observed that running the same script yields the same result.
However, I am not sure how to use the --rseed flag. Should I run:
"probtrackx2 ........ -P 10 ..... --rseed=i ....."
For i 0:100?
What exactly is --rseed, and why shouldn't I iterate --rseed from 0 to 10, or 0 to 1000?
Thank you!