磁共振成像SENSE 并行加速重建 g-factor计算方法（待更新）

MRI SENSE 并行图像加速重建 g-factor计算方法：

Matlab代码如下：

function g=gfactor_noise(map,LOSS,Rx,Ry)
% map -> sensitivity matrix
% LOSS -> noise-cov matrix
% Rx, Ry -> acc factor in x,y directions

[mm nn uu]=size(map);
cr=zeros(uu,Rx*Ry);
cf=zeros(uu,);
for ii=:mm
    for jj=:nn
            cf(:)=map(ii,jj,:);
            for xx=:Rx
                for yy=:Ry
            cr(:,Ry*(xx-)+yy)=map(cor_adjust(floor(mm/Rx)*(xx-)+ii,mm),cor_adjust(floor(nn/Ry)*(yy-)+jj,nn),:);
                end
            end
            LOSS_INV = inv(LOSS);
            cr11=pinv(cr'*LOSS_INV*cr);
            g(ii,jj)=sqrt((cf'*LOSS_INV*cf).*cr11(1,1));

    end
end

function [x_a] = cor_adjust(x,x_len)

if x<=x_len
    x_a = x;
else
    x_a = x - x_len;

end

end

参考文献：

K. P. Pruessmann et al., “SENSE: Sensitivity encoding for fast MRI,” Magn. Reson. Med., vol. 42, no. 5, pp. 952–962, 1999.