[Insight-users] A question about MRIBiasCorrection

[Jonathan Lok-Chuen Lo]

Hi Song,

Basically, the MRIBiasCorrection estimates the bias field by a set of
parametric set of Legendre polynomials.  The degree refers to the largest
degree used in those polynomials, and therefore results are very different
between degree=1 (i.e. a linear varying field) and degree=3.

For more information, you could have a look at this paper: Styner, M., C.
Brechbuhler, et al. (2000). "Parametric estimate of intensity
inhomogeneities applied to MRI." IEEE Transactions on Medical Imaging 19(3):
153-165.

Cheers,
Jonathan 

*************************************
Jonathan Lok-Chuen Lo

Medical Vision Labortory
Department of Engineering Science
Oxford University
Parks Road
Oxford OX1 3PJ
 
Phone: (44) 1865 280940
Fax:   (44) 1865 280922
*************************************


-----Original Message-----
From: insight-users-bounces at itk.org [mailto:insight-users-bounces at itk.org]
On Behalf Of Song Ting
Sent: 21 June 2004 20:02
To: insight-users at itk.org
Subject: [Insight-users] A question about MRIBiasCorrection


Dear group,

I have a question when I use the 'MRIBiasCorrection'.
I am not sure about the parameters that I used.

./BiasFieldEstimator --input esulla_input.mhd --class-mean 106.150716 
75.854006 38.056458 0 
--class-sigma 8.412902 13.128059 13.299162 0 --use-log yes --input-mask 
esulla_output_mask.mhd --degree 3 --grow 1.05 --shrink 0.9 max-iteration 
2000 --init-step-size 1.02

I am more concerned about the degree number, since degree=1 and degree=3 
gave very different results. I attached two images which are the histogram 
before and after the correction and a slice of the 3D volume image and its 
bias field image.

Thanks,
Ting

_________________________________________________________________
享用世界上最大的电子邮件系统― MSN Hotmail。  http://www.hotmail.com