Parallel imaging methods, such as SENSE 6 and GRAPPA 7 can be employed to reduce the number of phase-encoding steps through the use of coil sensitivity encoding from multichannel receiver arrays. The speed of conventional Cartesian imaging is mainly limited by contrast preparation and the encoding of a large number of k-space lines. This poses several problems for the clinical use of MP-RAGE where long scans increase susceptibility to patient motion, reduce patient comfort and compliance, and may necessitate sedation of pediatric patients. These sequence features lead to long scan times of over 10 min without acceleration for whole-brain coverage at 1-mm isotropic resolution. To achieve T1-weighted contrast, MP-RAGE uses a magnetization preparation period followed by a gradient echo readout train and a recovery period 1. This has enabled measures such as cortical thickness to be obtained accurately 5. It has proven to be a powerful tool to investigate psychiatric and neurodegenerative disorders by applying brain volumetry 3, segmentation, and cortical surface reconstruction 4. ![]() MP-RAGE serves as a precise anatomical reference for T2*-weighted functional MRI data 2. Numerous applications of MP-RAGE, mainly in neuroimaging, have been introduced. In 1990, Mugler and Brookeman 1 demonstrated that magnetization-prepared rapid gradient echo (MP-RAGE) provides high-resolution structural images with detailed contrast between gray matter, white matter, and cerebrospinal fluid. © 2017 International Society for Magnetic Resonance in Medicine. Wave encoding overcomes the g-factor noise amplification penalty and allows for an order of magnitude acceleration of MP-RAGE acquisitions. This acquisition has a g-factor performance of g max = 1.15 and g avg = 1.04. In addition, we demonstrate a 57 s acquisition at 7T with 12-fold acceleration. Compared with the state-of-the-art method controlled aliasing in parallel imaging results in higher acceleration (2D-CAIPIRINHA), this is a factor of 4.6/1.4 improvement in g max/g avg. The 9-fold accelerated MP-RAGE acquisition can be performed in 71 s, with a maximum and average g-factor of g max = 1.27 and g avg = 1.06 at 3T. Combined with a rapid (2 s) coil sensitivity acquisition and data-driven trajectory calibration, we propose an online integrated acquisition-reconstruction pipeline for highly efficient MP-RAGE imaging. Here, sinusoidal waveforms are used to spread aliasing in all three directions to improve the g-factor. Significant acceleration of the MP-RAGE sequence is demonstrated using the wave-CAIPI technique. To introduce a highly accelerated T1-weighted magnetization-prepared rapid gradient echo (MP-RAGE) acquisition that uses wave-controlled aliasing in parallel imaging (wave-CAIPI) encoding to retain high image quality.
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