Probing the sparsity of the MPnRAGE sequence through subspace compression

Motivation: Acquiring multiple inversion contrasts in a single scan allows for comprehensive analysis of brain microstructure. However, the scan duration of a fully sampled MPnRAGE sequence is clinically infeasible. Goal(s): Proving the potential for a more efficient MPnRAGE acquisition. Approach: We assess the sparsity of MPnRAGE in the TI-space with data-driven subspace compression of a fully sampled Cartesian MPnRAGE acquisition with 10 TIs. We evaluate the feasibility of prospectively accelerated acquisitions using dictionary-based compressions. Results: Data-driven subspace compression with two temporal basis yields images comparable to reconstructed fully sampled MPnRAGE images. Dictionary-based subspace compression requires three temporal basis for a similar quality. Impact: We demonstrate the potential for an accelerated MPnRAGE acquisition by leveraging the sparsity in the TI-space. Rapid acquisition of different inversion contrasts will allow to analyze microstructure in a clinical context e.g. for the early detection of neurodegenerative diseases.