Figure 1.

Constructing a data matrix from a multi-channel k-space dataset (H) and vice versa (H^†). A single data block in the k-space is vectorized into a column in the data matrix. Note that the data matrix will have a block-wise Hankel matrix structure. When reversely forming a k-space dataset from a data matrix, multiple anti-diagonal entries are averaged and stored at appropriate k-space locations.