Complementary time‐frequency domain networks for dynamic parallel MR image reconstruction

Purpose To introduce a novel deep learning‐based approach for fast and high‐quality dynamic multicoil MR reconstruction by learning a complementary time‐frequency domain network that exploits spatiotemporal correlations simultaneously from complementary domains. Theory and Methods Dynamic parallel MR image reconstruction is formulated as a multivariable minimization problem, where the data are regularized in combined temporal Fourier and spatial (x‐f) domain as well as in spatiotemporal image (x‐t) domain. An iterative algorithm based on variable splitting technique is derived, which alternates among signal de‐aliasing steps in x‐f and x‐t spaces, a closed‐form point‐wise data consistency step and a weighted coupling step. The iterative model is embedded into a deep recurrent neural network which learns to recover the image via exploiting spatiotemporal redundancies in complementary domains. Results Experiments were performed on two datasets of highly undersampled multicoil short‐axis cardiac cine MRI scans. Results demonstrate that our proposed method outperforms the current state‐of‐the‐art approaches both quantitatively and qualitatively. The proposed model can also generalize well to data acquired from a different scanner and data with pathologies that were not seen in the training set. Conclusion The work shows the benefit of reconstructing dynamic parallel MRI in complementary time‐frequency domains with deep neural networks. The method can effectively and robustly reconstruct high‐quality images from highly undersampled dynamic multicoil data (16× and 24× yielding 15 s and 10 s scan times respectively) with fast reconstruction speed (2.8 seconds). This could potentially facilitate achieving fast single‐breath‐hold clinical 2D cardiac cine imaging.