[Mristudio-users] new option save fiber density

[Seongjin]

Dr. Mory,

One of Ventat's question was about the normalization condition for the
normalized fiber density map.

Could you explain the difference between them?
Conceptually, I can understand the normalization, but would like to have
more detailed explanation on the difference.

-Seongjin

On Sat, Jul 24, 2010 at 8:56 AM, susumu mori <susumu at mri.jhu.edu> wrote:

> Hi Venkat,
>
> After fiber tracking, it is a common practice to quantify the results. For
> the quantification, the streamline information of the tractography needs to
> be converted to pixel information. For this conversion, the simplest way is
> to use 1/0 binarilzation. If a pixel contains a streamline, it becomes 1 and
> if not, remains 0. This is basically a masking, which can be applied to, for
> example, a FA map and get a FA value of the tract. You can also count the
> number of pixels with "1" and use it as the tract volume.
>
> One problem of this simple approach is that even if a pixel contains 10
> streamlines, the pixel becomes "1", which is the same as another pixel that
> contains only 1 streamline. Namely, during the binalization, information
> about the density of the streamline is lost. I believe (Hangyi, please
> correct me if I'm wrong) "fiber density map" tells how many streamlines were
> there in each pixel. You can potentially use it to get, for example,
> density-weighted FA value, in which pixels that contain more streamlines are
> more weighted than those contain only 1 streamline.
>
> On Fri, Jul 23, 2010 at 6:19 PM, Rajagopalan, Venkateswaran <
> rajagov2 at ccf.org> wrote:
>
>>
>> Dear All,
>>
>> I am using DTIstudio_latest_x86.exe after fiber tractography I notices a
>> new option named "save fiber density map" (normalized and non normalized). I
>> am wondering what information does this fiber density map convey and how
>> this information can be used for instance to compare between two groups. How
>> the map is normalized.
>>
>> Thanks
>>
>> Venkat
>>
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