I intend after scanning. Can I consider only the 16 directions that are
shared by the two groups?
Thank you
>
> The technician, or physicist at your scanner can probably best answer this
> question.Christine
> > Date: Tue, 24 Jan 2012 17:16:32 +0100
>> From: [log in to unmask]
>> Subject: Re: [FSL] TBSS some questions
>> To: [log in to unmask]
>>
>> Is there a way to 'reduce' the number of directions from 32 to 16 (same
>> scanner) to be able to compare groups?
>>
>> thank you!
>> Angela
>>
>>
>> > the answer is no..... especiallu if group one was scanned with low
>> > directions and group two was scanned with more directoons
>> > On Jan 24, 2012 10:32 AM, "Angela Favaro" <[log in to unmask]>
>> wrote:
>> >
>> >> Thank you
>> >> But my question is: can I (after performing TBSS scripts) compare
>> >> subjects
>> >> with a different number of directions in their DTI? If the quality is
>> >> different - as you are saying - I think the answer is no.
>> >>
>> >> Angela
>> >>
>> >>
>> >> >
>> >> > I can provide the following insight:1. The more diffusion
>> directions,
>> >> the
>> >> > better the dependent measure will be.2. You will have perform
>> >> across-group
>> >> > analyses with FEAT.3. You should probably resample your original
>> image
>> >> to
>> >> > 1x1x1mm resolution before spatially normailizing to the MNI
>> >> templae.Hope
>> >> > this helps.Christine
>> >> > > Date: Tue, 24 Jan 2012 12:40:50 +0100
>> >> >> From: [log in to unmask]
>> >> >> Subject: [FSL] TBSS some questions
>> >> >> To: [log in to unmask]
>> >> >>
>> >> >> Dear FSL experts,
>> >> >> I have some questions about TBSS for which I have not found
>> answers
>> >> in
>> >> >> the
>> >> >> mailing list.
>> >> >>
>> >> >> 1. Which is the influence of the number of directions on the
>> quality
>> >> of
>> >> >> TBSS?
>> >> >>
>> >> >> I have a set of DTI images with B0=800 and number of directions=16
>> >> and
>> >> >> another set with the same B0 and 32 directions.
>> >> >> I guess that probabilistic tracking is not reliable with only 16
>> >> >> directions, but what about TBSS? Can images of the two groups be
>> >> >> compared
>> >> >> with TBSS in some way?
>> >> >>
>> >> >> 2. During the TBSS procedure there is a registration to the
>> standard
>> >> >> image
>> >> >> with resultion 1mm*1mm*1mm. This result in a very long time when
>> >> >> performing statistics with randomise. My original scanning
>> resolution
>> >> is
>> >> >> 2mm. Do you think that registration of the skeletonised images and
>> >> mask
>> >> >> to
>> >> >> a 2mm resolution would impair the statistical analyses? Or is it a
>> >> >> feasable approach?
>> >> >>
>> >> >> Thank you for your help!
>> >> >>
>> >> >> Angela
>> >> >
>> >>
>> >
>
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