[elastix] volume preservation

M.Staring at lumc.nl M.Staring at lumc.nl
Fri Mar 5 10:56:51 CET 2010


Hi Xi Liang, 

> In one of my case, I have the following result. By turning 
> off the rigid constraint, the ROI in the resulting image has 
> 74.61% percent of its volume segmented in moving image. By 
> using the rigid constraint, it increases the volume to 
> 86.30%, but still lost of 13.90%. Is this normal? What should 
> I do to improve this?
>

I got the best results when I used all terms, so including the PropernessCondition, so you could enable that one:
(UsePropernessCondition "true")
The properness condition is a volume preserving condition, so enabling that should help you.

I think the next step would be to set the weights of the different terms such that they contribute more evenly, as indicated by the gradient magnitude of each term during the registration. I think you are using the orthonormality condition quite strongly, if I compare your weights with the ones I used in the paper. I used them more like:
(LinearityConditionWeight 100.0)
(OrthonormalityConditionWeight 1.0)
(PropernessConditionWeight 10.0)
or in the ratio 250.0, 2.0, 10.0 or in the ratio 100.0, 1.0, 2.0,  but never 1 10 1.

Other settings are hard to recommend like this, I would have to take a look at your elastix.log or the data.

Regards,

Marius
 
> I use the following parameters. I tried to increase the 
> (RigidityPenaltyWeight 0.1) from 0.1 to 0.2, but the 
> registration explodes. Those conditional weights are roughly 
> the highest I can give without getting exploded. 
> 
> 
> 
> (FixedLimitRangeRatio 0.001)
> (MovingLimitRangeRatio  0.001)
> (RigidityPenaltyWeight 0.1 0.1 0.1 0.1)
> (LinearityConditionWeight 1.0)
> (OrthonormalityConditionWeight 10.0)
> (PropernessConditionWeight 1.0)
> (UseLinearityCondition "true")
> (UseOrthonormalityCondition "true")
> (UsePropernessCondition "false")
> (CalculateLinearityCondition "true")
> (CalculateOrthonormalityCondition "true") 
> (CalculatePropernessCondition "false") (DilateRigidityImages 
> "false" "false" "false" "true") (DilationRadiusMultiplier 
> 2.0) (UseMovingRigidityImage "true") (MovingRigidityImageName 
> "MHD\motion_coarse_mask.mhd")
> 
> 
> --------------------------------
> Xi Liang
> 
> 梁茜
> --------------------------------
> 
> 
> 
> 
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