[Mrtrix-discussion] nan in response function

[Zhuang Song]

Dear Group,

In the output response functions produced by estimate_response, there are
several cases in my data that have nan in the response functions while
others look fine. These image were all acquired and processed with the same
methods. I was wondering what might be the reason to get nan in the
results. Does it indicate there are some problems in the DWI data? The DTI
construction all looks fine for all these data.

Some examples of response functions in my data:

378.369 nan nan nan nan

374.228 nan nan nan nan

410.525 nan nan nan nan

364.583 -32.2504 0.4034 -0.0136654 -0.0424694

427.235 -48.645 0.795029 0.0733941 -0.0156282

334.129 -36.3756 0.0756312 0.0734365 -0.0178463

413.255 -43.6258 0.441787 -0.0159834 0.0150817

385.935 -39.2011 0.477614 0.0651567 0.00753772

433.311 nan nan nan nan

405.377 nan nan nan nan

In order to generate a group mean response function, I do simple averaging
of each coefficient of those individual without any nan's. Does this sound
reasonable?

Thanks,
Zhuang
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