Figure 1.

The process used to reconstruct the free-breathing 3D MRI data set. (a) Golden-angle radial SOS trajectory. (b) Projection profiles of the 3D volume derived from the K-space centre [central line in (a)]. (c) Respiratory signal is binned into three bins. (d) According to the respiratory position, the corresponding K-spaces are obtained for each bin. Each of them is reconstructed separately. (e) The CNN Net estimates the spatially corresponding image patches from the moving (Bin2/Bin3) and fixed images (Bin1). (f) The spatial transformer generates the DVF which will be used to warp the moving image to the fixed image. (g) The network is trained by back propagating a similarity metric as a cost function.3D, three-dimensional; CNN, convolutional neural network; DVF, displacement vector field; SOS, stack-of-star.