Simultaneous acquisition of spatial harmonics (SMASH): Fast imaging with radiofrequency coil arrays

TLDR

SMASH is a fast‑imaging technique that increases MR acquisition speed by an integer factor over existing methods without significant loss of spatial resolution or SNR, and larger time savings are possible with suitable coil designs. SMASH reduces acquisition time by using the spatial information from a surface coil array to replace part of the phase encoding, enabling partially parallel acquisitions with existing fast‑imaging sequences and employing a small set of MR signal combinations before Fourier transformation for easier artifact handling. Using commercial phased‑array coils on two MR systems, SMASH achieved a two‑fold reduction in image acquisition time.

Abstract

Abstract SiMultaneous Acquisition of Spatial Harmonics (SMASH) is a new fast‐imaging technique that increases MR image acquisition speed by an integer factor over existing fast‐imaging methods, without significant sacrifices in spatial resolution or signal‐to‐noise ratio. Image acquisition time is reduced by exploiting spatial information inherent in the geometry of a surface coil array to substitute for some of the phase encoding usually produced by magnetic field gradients. This allows for partially parallel image acquisitions using many of the existing fast‐imaging sequences. Unlike the data combination algorithms of prior proposals for parallel imaging, SMASH reconstruction involves a small set of MR signal combinations prior to Fourier transformation, which can be advantageous for artifact handling and practical implementation. A twofold savings in image acquisition time is demonstrated here using commercial phased array coils on two different MR‐imaging systems. Larger time savings factors can be expected for appropriate coil designs.