[Insight-users] itkHessian3DToVesselnessMeasureImageFilter false aura at the ends

[Oleksandr Dzyubak]

Hi Robert,

Junctions and intersections -- that is another story and another issue
which has to be solved.

At this point I am talking about the ends of the "vessels".
As you could see from the pictures I sent before, the filter generates 
highly undesirable
spherical "caps" at the ends.  Those "additional volumes" even do not
belong to the vessels. They are in "close premises". If you take a 
closer look,
you can find that there is a void volume between the vessel end and the 
spherical cap.

When you dig deeper, you can find that those "caps"
are actually generated by the RecursiveGaussian filter which is used to 
evaluate
the second order partial derivatives. And that filter works correctly 
since at the edges
there is a jump of intensities.

As itkHessian3DToVesselnessMeasureImageFilter manipulates with Hessian 
eigenvalues,
it should reflect the eigenvalue change along the principal major axis 
(along the vessel).
So when analyzing the object shape, the filter should catch these caps 
and reject them
as it does with minor axis (tangential). In fact, it does not.

In publications about Hessian-based shape analyzers, I have never seen 
this effect
"producing additional volumes around the vessel ends"... Did you?

Your suggestion to analyze original image in concert with the vesselness 
image
and based on this additional analysis ultimately generate a good final 
vesselnes image is good.

But correct me if I am wrong.
Isn't  the itkHessian3DToVesselnessMeasureImageFilter supposed to do that?

I am wondering, is it a bug or normal behavior?

If it is a bug, lets fix a bug. If it is normal, then go ahead and use 
your approach.


Still would like to know the ITK users' opinion.

Regards,

Alex


Atwood, Robert (DLSLtd,RAL,DIA) wrote:
> Hi, Alex:
> I used that filter and observed that sort of effect (actually a
> decreased value at intersections in my case)  but I understood it to be
> a consequence of the maths; these pixels satisfy the criteria, what I
> did was require a certain value in the original in combination with a
> certain value in the filtered result to accept pixels as belonging to my
> 'vessels', if the original value was quite high but 'vesselness' low
> then it could be a junction, if the original value too low then the
> pixel could be rejected even with a moderate "vessellness" value 
>
> But, if this is the wrong approach I should like to know !
>
> Thanks
>
>
> Robert
>
>
> -----Original Message-----
> From: insight-users-bounces at itk.org
> [mailto:insight-users-bounces at itk.org] On Behalf Of Oleksandr Dzyubak
> Sent: 18 August 2009 00:23
> To: insight-users at itk.org
> Subject: [Insight-users] itkHessian3DToVesselnessMeasureImageFilter
> falseaura at the ends
>
>
> Dear community,
>
> I played with the itkHessian3DToVesselnessMeasureImageFilter class using
> the example from the ITK distro "VesselnessMeasureImageFilter.cxx"
> and found some side-effect.
>
> The filter produces false broadenings ("spherical auras") at the ends of
> vessels.
> In attachment I am sending the pictures to demonstrate the effect.
>
> Has anybody experienced similar effect?
> Is there any recipe to avoid/reduce this?
>
> Thanks,
>
> Alex
>
>
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