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LMMSE filter for Rician MRI data

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LMMSE filter for Rician MRI data

by SANTIAGO AJA-FERNANDEZ

 

17 May 2012 (Updated 12 Jun 2012)

A filtering scheme for denoising MR data assuming an underlying Rician model.

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Description

The linear minimum mean square error (LMMSE) estimator estimates the signal out of a noisy MR adquisition. The method automatically estimates the noise level from background. It is based on a Rician noise assumption, which is valid for single coil adquisitions (and sometimes in SENSE).

The whole method is described in

S Aja-Fernández, M. Niethammer, M. Kubicki, M. E. Shenton, C.F. Westin, "Restoration of DWI data using a Rician LMMSE estimator". IEEE Tr. on Medical Imag. Vol. 27, No. 10, Oct. 2008, pp. 1389-1403.
MATLAB release MATLAB 5.3 (R11)
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denoising, image filtering, image processing, mri, noise
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Comments and Ratings (2)
12 Jun 2012 SANTIAGO AJA-FERNANDEZ

The method now requires to choose one of the existing noise estimation methods as an input: (See help)

I_est=MRI_lmmse(I,[7,7],'mode2N');

However, I have just realized that the function moda.m is not in the toolbox. I upload now a new version with this fixed, and a default option
11 Jun 2012 Alex

I get the error:

I_est = MRI_lmmse(img,[10, 10]);
Undefined function or variable "sigma2".

Error in MRI_lmmse (line 137)
K1=1+(4.*sigma2^2-4.*sigma2.*Squ)./(Qua-Squ.^2);

Did I input something incorrectly?

Updates
12 Jun 2012

Default method to estimate noise is added. Function moda.m was missing and it was added to the end to the file.

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