To verify output files

[Hyungyou Park]

Dear NODDI experts,

Hello, I am getting outputs from NODDI toolbox and have some questions as follows:

1. Is it very long to process the whole NODDI matlab toolbox? In my case, it was about 2 hours for each subject (working on 56 cores).

2. I am wondering if I have correct NODDI outputs. Particularly for the FICVF image, there may be some problems. Could you check the images? We use b-value 1000 (singe-shell) and 65-direction (b0 for first volume) data.

Thank you all in advance,

Hyungyou

[Hui Zhang]

Hi Hyungyou,

I’m afraid that you can not use single-shell data for NODDI.  The problem you see is reported in the original NODDI paper.

Gary

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[Pratik Mukherjee]

Has anyone looked at how accurate and precise the FISO measurements are for single-shell vs multi-shell data?  Is there a theoretical reason it wouldn't work for single shell data?

Thanks,

- Pratik

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Pratik Mukherjee
pratik.m...@gmail.com

[Hui Zhang]

Hi Pratik,

I’ve looked at this in the original NODDI paper as well.  FISO is also less accurate with single-shell data, but it is much less inaccurate compared to FICVF.

The reason is theoretical.  With single-shell data alone, the same data may be explained equally well with many possible combinations of FISO and FICVF, an issue known as degeneracy.  This degeneracy is resolved by the inclusion of another shell with a suitable choice of b-value, providing the complementary information required.

Gary

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