Combining two DTI scans for tractography

Dear MRtric community,

We have identified a limitation in our scanner regarding the utilization of different directions for different b values. Specifically, we are currently unable to independently acquire images with b=1000 and b=2000 while using varying directions and gradient tables.

To overcome this limitation, we propose a solution: acquiring the b=1000 images with 30 directions and the b=2000 images with 45 directions separately, all on the same subject, while keeping all parameters constant except for the gradient directions. We are wondering if MRtrix offers any commands that could facilitate the process of combining these separate scans. Additionally, we have concerns about the potential impact on tractography performance when combining these datasets. I would appreciate your input


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Hi @pabbasian,

This is not uncommon, and the solution you’ve come up with is how many centres will also be doing it. There is a command in MRtrix called dwicat, which is designed to merge these kinds of datasets and avoid the most common issues you might encounter in the process.

All the best,

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Thank you, Donald.