Rapid anatomical brain imaging using spiral acquisition and an expanded signal model

We report the deployment of spiral acquisition for high-resolution structural imaging at 7T. Long spiral readouts are rendered manageable by an expanded signal model including static off-resonance and B0 dynamics along with k-space trajectories and coil sensitivity maps. Image reconstruction is accomplished by inversion of the signal model using an extension of the iterative non-Cartesian SENSE algorithm. Spiral readouts up to 25 ms are shown to permit whole-brain 2D imaging at 0.5 mm in-plane resolution in less than a minute. A range of options is explored, including proton-density and T2* contrast, acceleration by parallel imaging, different readout orientations, and the extraction of phase images. Results are shown to exhibit competitive image quality along with high geometric consistency. [Display omitted] •Whole-brain high resolution T2* and PD images (0.5 x 0.5 x 2 mm3) are acquired at 7T in less than 1min using 2D spiral readouts.•This represents a 5–10x acceleration compared to spin-warp imaging, with competitive image quality and geometric accuracy.•An expanded signal model and iterative reconstruction proved essential to harness long spiral readout segments (25 ms).•The signal model accounts for static and dynamic off-resonance, actual gradient dynamics, and coil sensitivity encoding.•Accurate measurement of all model components was crucial, with field dynamics being concurrently monitored by NMR probes.