[Mrtrix-discussion] streamline numbers at two b-values

[Kerstin Pannek]

Hi Donald

thanks for your help.

I had a look at the length of the streamlines (see attached histograms).
I was expecting (maybe naively) to see more short streamlines for the 
low b-value data compared to the high b-value data. I found that the 
distributions look very similar (normalized using the number of accepted 
streamlines), with more short streamlines for the high b-value data.

Is this what you would expect?

Cheers
Kerstin


Donald Tournier wrote:
> Hi Kerstin,
>
> I have to admit, I'm not too sure about that. My best guess is that
> since the low b-value FODs are (presumably) smoother, more of them
> start in the 'right' direction, and a greater proportion of them
> manage to exceed the minimum length threshold. This is just a guess,
> I'd have to really dig down to give you a definitive answer though...
>
> Cheers,
>
> Donald.
>
>
> On Fri, Nov 13, 2009 at 3:10 PM, Kerstin Pannek <k.pannek1 at uq.edu.au> wrote:
>   
>> Hi all
>>
>> I have two DWI datasets acquired per participant, one with b-value 1000, and
>> another with b-value 3000. I performed whole brain tractography for both
>> datasets, seeding 1 streamline per mm3:
>>
>> $ streamtrack SD_PROB csd.mif -seed brain_mask.nii -number 103127 -maxnum
>> 103127 wb.tck
>>
>> The number of accepted streamlines is about 30% higher for the b1000 data
>> than for the b3000 data. This is consistent across all participants.
>>
>> I was just wondering why that is?
>>
>> Thanks
>> Kerstin
>> _______________________________________________
>> Mrtrix-discussion mailing list
>> Mrtrix-discussion at www.nitrc.org
>> http://www.nitrc.org/mailman/listinfo/mrtrix-discussion
>>
>>     
>
>
>
>   

-------------- next part --------------
A non-text attachment was scrubbed...
Name: length.normalized.png
Type: image/png
Size: 7141 bytes
Desc: not available
Url : http://www.nitrc.org/pipermail/mrtrix-discussion/attachments/20091116/8335af5f/length.normalized.png
-------------- next part --------------
A non-text attachment was scrubbed...
Name: length.png
Type: image/png
Size: 6739 bytes
Desc: not available
Url : http://www.nitrc.org/pipermail/mrtrix-discussion/attachments/20091116/8335af5f/length.png