====== Correction of B1 inhomogeneity artifacts in CEST images ======
{{ :b1_corr.png?direct&200|}}
Here you find a B1-correction algorithm as published in **Windschuh et al. (2015), NMR Biomed., 28(5):529-37.  [[http://onlinelibrary.wiley.com/doi/10.1002/nbm.3283/abstract|doi: 10.1002/nbm.3283]]**. 
 
Dowload zipped Matlab implementations [[https://github.com/cest-sources/B1_correction/archive/master.zip|here]] or find the package on [[https://github.com/cest-sources/B1_correction/]]

======  Tutorial ======
There are two functions, **Z_B1_correction** and **contrast_B1_correction**, which both require data of several CEST acquisitions with different B1. Both reconstruct either Z-spectrum stacks or contrast stacks at the B1 values given by **B1_output**.

<code matlab>
function [Z_stack_corr] = Z_B1_correction(Z_stack,rel_B1map,B1_input,B1_output,SEGMENT,fit_type,B1_input_index)
% [Z_stack_corr] = Z_B1_correction(Z_stack,rel_B1map,SEGMENT_2D,B1_input,fit_type,B1_input_index,B1_output)
% output: B1 corrected Z-stack (5D-stack)
% input:    Z_stack = 5D-stack of Z-spectra (y,x,z,offset,B1)
%           rel_B1map = relative B1map
%           B1_output = output B1 (scalar or vector)
%           SEGMENT = voxel/pixel mask for evaluation
%           fit_type = fit or interpolation type
%           B1_input_index = index vector of B1 samples that should be used
%           for correction
%
</code>

<code matlab>
function [corr_img]=contrast_B1_correction(img,rel_B1map,B1_input,B1_output,SEGMENT_2D,fit_type,B1_input_index)
% [corr_img]=contrast_B1_correction(img,rel_B1map,B1_input,B1_output,SEGMENT_2D,fit_type,B1_input_index)
% output: B1 corrected images (2D or 3D-stack) (x,y,B1)
% input:    img = 3D-stack of images (x,y,B1) which are used for B1-correciton
%           rel_B1map = relative B1map
%           B1_output = output B1 (scalar or vector)
%           SEGMENT_2D = pixel mask for evaluation
%           fit_type = fit or interpolation type
%           B1_input_index = index vector of B1 samples that should be used
%           for correction
</code>
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