Self‐navigated 4D cartesian imaging of periodic motion in the body trunk using partial k‐space compressed sensing

Purpose To enable fast and flexible high‐resolution four‐dimensional (4D) MRI of periodic thoracic/abdominal motion for motion visualization or motion‐corrected imaging. Methods We proposed a Cartesian three‐dimensional k‐space sampling scheme that acquires a random combination of k‐space lines in thek y / k zplane. A partial Fourier–like constraint compacts the sampling space to one half of k‐space. The central k‐space line is periodically acquired to allow an extraction of a self‐navigated respiration signal used to populate a k‐space of multiple breathing positions. The randomness of the acquisition (induced by periodic breathing pattern) yields a subsampled k‐space that is reconstructed using compressed sensing. Local image evaluations (coefficient of variation and slope steepness through organs) reveal information about motion resolvability. Image quality is inspected by a blinded reading. Sequence and reconstruction method are made publicly available. Results The method is able to capture and reconstruct 4D images with high image quality and motion resolution within a short scan time of less than 2 min. These findings are supported by restricted‐isometry‐property analysis, local image evaluation, and blinded reading. Conclusion The proposed method provides a clinical feasible setup to capture periodic respiratory motion with a fast acquisition protocol and can be extended by further surrogate signals to capture additional periodic motions. Retrospective parametrization allows for flexible tuning toward the targeted applications. Magn Reson Med 78:632–644, 2017. © 2016 International Society for Magnetic Resonance in Medicine