[Insight-users] help in registration

[hariharan ganesh lalgudi]

Hii,

   I am a new user of ITK and was wondering if someone could help me in 
some of the basic problems that I am facing. My goal is to register 
3D cardiac CT/MR images across time using some of the registration 
algorithms in ITK. To get started, I tried to run the "RatLungSlice" 
example with different deformable registration algorithms (FEM, Bspline, 
Demons..).

Problem 1:

When I use Bsline (DeformableRegistration4) it gives me the error:

"IFLAG= -1. LINE SEARCH FAILED. SEE DOCUMENTATION OF ROUTINE MCSRCH ERROR 
RETURN  OF LINE SEARCH: INFO=3 POSSIBLE CAUSES: FUNCTION OR GRADIENT
ARE  INCORRECT OR INCORRECT TOLERANCES"

Based on some previous discussion in the list I guess that it has got to 
do with parameters of the optimization:

"  optimizer->SetGradientConvergenceTolerance( 0.05 );
   optimizer->SetLineSearchAccuracy( 0.9 );
   optimizer->SetDefaultStepLength( 1.5 );
   optimizer->TraceOn();
   optimizer->SetMaximumNumberOfFunctionEvaluations( 1000 ); "

But I guess these should be correct for the given example.

I got confused as to whether my building process was right. I compiled the 
examples again. I tried both in windows and Linux. It gives me the same 
error.

Problem 2:

   When I try to use the Demons algorithm (DeformableRegistration2) with 
"RatSlice" example it simply "aborts" after some iterations

Prob 3:

   I also tried FEM ( DeformableRegistration1). This works. But the Mean 
absolute error only reduces only by 20% after registration. The difference 
image before and after registration doesn't look much different.

Question:

    I looked at some papers in cardiac Image registraion to know which 
registration algorithm I should use. It is very inconclusive and people 
claim different methods for different applications. I was wondering if 
B-spline registration would work well for cardiac CT/MR. I actually tried 
registering 2 cardiac cubes in the time cycle (with Bspline for 3D). But 
it kept running for 50 mins. Does it generally take that long?


I am sure some of the questions that I am posting would be very basic. I 
am in the process of learning and hope someone could clarify the issues 
that I have.

Thanks
Hari