UEPS: Robust and Efficient MRI Reconstruction

Deep unrolled models (DUM) have become the state-of-the-art for accelerated MRI reconstruction, yet their robustness under domain shift remains a critical barrier to clinical adoption. In this work, we identify coil sensitivity map (CSM) estimation as the primary bottleneck limiting generalization. To address this, we propose UEPS, a novel DUM architecture featuring three key designs: (i) an Un-rolled Expanded (UE) design that eliminates CSM dependency by reconstructing each coil independently; (ii) progressive resolution, which leverages k-space-to- image mapping for efficient coarse-to-fine refinement; and (iii) sparse attention tailored to MRI’s 1D undersampling nature. These physics-grounded designs en- able gains in robustness and computational efficiency. We construct a large-scale zero-shot transfer benchmark comprising 10 out-of-distribution (OOD) test sets spanning diverse clinical shifts—anatomy, view, contrast, vendor, field strength, and coil configurations. Extensive experiments demonstrate that UEPS consis- tently and substantially outperforms existing DUM, end-to-end, diffusion, and un- trained methods across all OOD tests, achieving state-of-the-art robustness with low-latency inference suitable for real-time deployment.