[Insight-users] Selecting the sigma for the vesselness

[Chris McIntosh]

Hello Rashed,

It appears I misunderstood your goal. It seems you are trying to 
determine the vessel radius
at each voxel, and not filter the image. Or perhaps segment the entire 
vessel...

Yes your interpretation of the VED filter is correct. As is your 
interpretation of Frangi's approach.
I thought there was a multi-scale version of that filter in ITK already, 
but perhaps I was wrong.

The Hessian3DToVesselnessMeasuerImageFilter, however, is not Frangi's 
filter.
http://www.itk.org/Doxygen34/html/classitk_1_1Hessian3DToVesselnessMeasureImageFilter.html

"3D Multi-scale line filter for segmentation and visualization of 
curvilinear structures in medical images", Yoshinobu Sato, Shin 
Nakajima, Hideki Atsumi, Thomas Koller, Guido Gerig, Shigeyuki Yoshida, 
Ron Kikinis.

is the filter that is used there.

Cheers,

Chris



rashedk wrote:
> Hi Chris, 
>
> Doesn't Manniseng's VED filter *enhance* the vessels rather than detecting
> them? It does do multi-scale analysis, but goes one step further by applying
> the appropriate diffusion (iso- or aniso-) process. So the output of the VED
> filter should be the same image with the vessels enhanced and not the
> vesselness. Please, correct me if I am wrong. 
>
> What I also don't understand is why Hessian3DToVesselnessMeasureImageFilter
> does not implement a multiscale approach? If it is Frangi's vesselness which
> is implemented here, then his paper did suggest returning the highest
> response by varying the sigma. 
>
> Regards, 
> Rashed
>
>
>
> Chris McIntosh-2 wrote:
>   
>> Hello,
>>
>> I'm not sure if this helps, but just in case.
>>
>> In general, using a constant sigma for an image is troublesome because 
>> the ideal scale for each vessel
>> is the actual radius of that vessel (in voxels). So you need a different 
>> scale at each voxel.
>>
>> I would suggest looking at:
>> http://hdl.handle.net/1926/558
>>
>> They implement a powerful multi-scale technique for vessel filtering, 
>> where each pixel's response
>> is tested under a range of scales and the maximal response is taken.
>>
>>
>> Cheers,
>>
>> Chris
>>
>> rashedk wrote:
>>     
>>> Hi everyone, 
>>>
>>> I am currently using the vesselness filters to detect vessels. I use a
>>> pipeline with HessianRecursiveGaussianImageFilter and
>>> Hessian3DToVesselnessMeasureImageFilter filters which works fine.
>>> However, I
>>> am using a trial and error approach for selecting the sigma. In a
>>> previous
>>> post I came across an approach whereby sigma selection can be done
>>> effectively by observing the responses of a single pixel that is known to
>>> be
>>> part of a vessel (a.k.a multi-scale analysis). How do I constraint the
>>> above
>>> filters to only process a single pixel and not the entire image? 
>>>
>>> Thanks, 
>>>
>>> Rashed Karim
>>>   
>>>       
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>>     
>
>