LMMSE filter for Rician MRI data
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.
Cite As
SANTIAGO AJA-FERNANDEZ (2020). LMMSE filter for Rician MRI data (https://www.mathworks.com/matlabcentral/fileexchange/36741-lmmse-filter-for-rician-mri-data), MATLAB Central File Exchange. Retrieved .
Comments and Ratings (10)
Updates
| 1.2.0.0 | 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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MATLAB Version: 9.2.0.556344 (R2017a)
Array dimensions must match for binary array op.
Error in MRI_lmmse (line 149)
I_est=sqrt(Squ-2.*sigma2+K1.*(Im.^2-Squ));
Not enough input arguments.
Error in mean (line 12)
a=find(image>thr);%m0
How to fix this error?
Error in MRI_lmmse>moda (line 238)
M1=mean(u(:));
Error in MRI_lmmse (line 103)
sigma2=(prod(Ws)/(prod(Ws)-1)).*(moda(En,1000)./2);
I would like to know whether this method can be successfully deal with the T1 weighted MRI data
thanks
Thanks
very good stuff
very useful! thank you!
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
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?