Hi Purbasha,

It's tricky to do these kinds of things on a grid, but you can get a uniform layer around a segmented region by using the dilate and erode filter to dilate the volume the desired thickness, then subtracting the original volume.  this is dependent on the grid and if it not isotropically spaced, the new layer will not be uniform.   You can use the resampling tool to change the spacing to whatever you'd like.  the resampling would also allow you achieve a dilated distance closer to your target distance.  However, there will always be problems on the diagonal regions because of the grid sampling.

If you wanted a more precise outer surface, you could do some manipulation of the surfaces instead of the segmentation.  You would need to generate good surfaces with cleaver or biomesh, then you can scale the surface to create two concentric surfaces.  If you plan on making tet meshes, this is probably the better way to do it as most meshing software has trouble with thin regions like that layer would be.

cheers,
Jess

On Dec 17, 2014, at 8:35 AM, Purbasha Garai <pg0222@gmail.com> wrote:

> Hello,
>
> I want to segment out the perineurium, surrounding each fascicle. Is there a way I could have a mask layer around the fascicle with 0.03mm thickness. Right now, I am doing it manually, which isnt very consistent. Moreover, I need to add perineurium in around 60 MRI nerve slices. I am afraid by doing manually may lead to inconsistency.
>
> Any suggestions will be highly appreciated.
>
> Regards
> Purbasha

> <unequal_perineurium.JPG><t2w_50.dcm>