Three-Dimensional Late Gadolinium Enhancement Imaging of the Left Atrium With a Hybrid Radial Acquisition and Compressed Sensing

Purpose: To develop and test a hybrid radial (stack of stars) acquisition and compressed sensing reconstruction for efficient late gadolinium enhancement (LGE) imaging of the left atrium. Materials and Methods: Two hybrid radial acquisition schemes, kx-ky-first and kz-first, are tested using the signal equation for an inversion recovery sequence with simulated data. Undersampled data reconstructions are then performed using a compressed sensing approach with a three-dimensional total variation constraint. The data acquisition and reconstruction framework is tested on five atrial fibrillation patients after treatment by radio-frequency ablation. The hybrid radial data are acquired with free breathing without respiratory navigation. Results: The kz-first radial acquisition gave improved image quality as compared to a kx-ky-first scheme. Compressed sensing reconstructions improved the overall quality of undersampled radial LGE images. An image quality metric that takes into account the signal, noise, artifact, and blur for the radial images was 35% (+/- 17%) higher than the corresponding Cartesian acquisitions. Total acquisition time for 36 slices with 1.25 x 1.25 x 2.5 mm(3) resolution was under 3 min for the proposed scheme. Conclusion: Hybrid radial LGE imaging of the LA with compressed sensing is a promising approach for obtaining images efficiently and offers more robust image quality than Cartesian acquisitions that were acquired without a respiratory navigator signal.