EXEC-MRI: Gradient Execution Deviations Reverse MRI Reconstruction Rankings

MRI reconstruction relies on knowing where signals were sampled in Fourier space. Hardware response can shift these locations, making the actual acquisition differ from the reconstruction model. We ask whether method rankings remain reliable under this mismatch. EXEC-MRI provides a controlled evaluation protocol for MRI with non-Cartesian sampling paths, such as spirals. It pairs simulated gradient execution errors with tests of trajectory knowledge, numerical settings, and training. On fastMRI Brain, 22/28 method pairs change mean-score order from matched acquisition to moderate mismatch; reversals also occur on two external datasets. Numerical choices and model adaptation can themselves change the ordering, showing that robustness comparisons depend on the complete reconstruction pipeline rather than architecture alone. These retrospective simulations show why nominal performance alone does not establish relative performance under acquisition error. EXEC-MRI makes the conditions of such comparisons explicit and reproducible.