[Mrtrix-discussion] Facial Nerve Tractography

[Dorian P.]

Hi all,

This is very interesting, the fact that you split the scan into 4. I think
each scan will have different calibration though. Do you acquire a B0 for
each of 15-orientation scans? So a question of principle is: doesn't this
splitting affect the results at all?

Would be really nice if DWIs can be split like this.

Dorian

On Fri, Sep 4, 2015 at 9:44 AM, Attye, Arnaud <aattye at chu-grenoble.fr>
wrote:

> Dear Mr Vanhoutte, Dear Dr Tournier,
> Firstly, I would acknowledge Mrtrix team and Dr Tournier for its wonderful
> software and this website.
> I’ve been working on peripheral nerves tractography for 3 years with
> Constrained Spherical Deconvolution model. We used the intraparotid facial
> nerve as a model to surgically validate CSD tractography data. I’m
> neuroradiologist so not expert in physics of MR diffusion imaging. However,
> I’m working with very good research engineers that help me applying CSD to
> peripheral nerves field. Our first tractography study will be soon
> published with methods details, but I'd be pleased to help Mr Vanhoutte
> with advices concerning facial nerve tractography:
>  -The facial nerve is more difficult to track into internal auditive canal
> than in parotid area, mainly due to susceptibility distorsion and the
> vicinity with the vestibulocochlear nerve. Thus, diffusion acquisition
> requires a strong correction of artifacts. As described in the last article
> of Dr Tournier’s team (http://www.ncbi.nlm.nih.gov/pubmed/26163802), we
> use topup and eddy tools in FSL5 to correct B0 field inhomogeneities, eddy
> currents and inter-volume motion.
> -Track-density imaging is a wonderful tool before performing tractography
> with inclusion ROIs, especially among patients with IAC tumors. I
> personally generate TDI maps with a 0.3 mm isotropic voxel size.
> -As Dr Tournier said, Tractography accuracy is better with 60 directions
> or more than with 32 directions. However, we obtained good results in the
> parotid area with 32 directions and acquisition time is more compatible
> with a clinical setting.
> -An alternative way to limit movements’ artifacts is to split MR diffusion
> acquisition (eg 4 scans of 15 directions for a total of 60 directions).
> Best regards, Arnaud
>
>
>
> Dr Arnaud ATTYE
>
> Department of Neuroradiology
>
> Grenoble University Hospital - France
>
> www.neuroradiologie-grenoble.fr<http://www.neuroradiologie-grenoble.fr/>
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