Figure 1
a) k-t SPIRiT (1) and k-t ESPIRiT (2) minimization problems with PI operators G and S x,f . While (1) solves for a multi-channel x-f object, (2) reconstructs a coil-combined image (d: k-t space data, F x,f : Fourier transform from x-f to k-t space, I u : undersampling matrix, λ's: regularization parameters). (3) shows the relation between S x,f and the temporally resolved coil sensitivities S x,t . b) L1 k-t ESPIRiT POCS reconstruction algorithm. Soft denotes the element-wise soft-thresholding operation.