Deep Generalization of Structured Low-Rank Algorithms (Deep-SLR)
This work addresses computational bottlenecks in MRI reconstruction for medical imaging, offering a more efficient and motion-insensitive method, though it is incremental as it builds on existing SLR frameworks with deep learning enhancements.
The authors tackled the high computational complexity of structured low-rank (SLR) algorithms in MRI reconstruction by introducing a deep learning approach using a CNN-based filterbank, which reduced runtime by around three orders of magnitude while maintaining similar performance and enabling calibration-less parallel MRI.
Structured low-rank (SLR) algorithms, which exploit annihilation relations between the Fourier samples of a signal resulting from different properties, is a powerful image reconstruction framework in several applications. This scheme relies on low-rank matrix completion to estimate the annihilation relations from the measurements. The main challenge with this strategy is the high computational complexity of matrix completion. We introduce a deep learning (DL) approach to significantly reduce the computational complexity. Specifically, we use a convolutional neural network (CNN)-based filterbank that is trained to estimate the annihilation relations from imperfect (under-sampled and noisy) k-space measurements of Magnetic Resonance Imaging (MRI). The main reason for the computational efficiency is the pre-learning of the parameters of the non-linear CNN from exemplar data, compared to SLR schemes that learn the linear filterbank parameters from the dataset itself. Experimental comparisons show that the proposed scheme can enable calibration-less parallel MRI; it can offer performance similar to SLR schemes while reducing the runtime by around three orders of magnitude. Unlike pre-calibrated and self-calibrated approaches, the proposed uncalibrated approach is insensitive to motion errors and affords higher acceleration. The proposed scheme also incorporates image domain priors that are complementary, thus significantly improving the performance over that of SLR schemes.