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
>> >
>>
>
|