Improved temporal resolution in cardiac imaging using through-time spiral GRAPPA.

Previous work has shown that the use of radial GRAPPA for the reconstruction of undersampled real-time free-breathing cardiac data allows for frame rates of up to 30 images/s. It is well known that the spiral trajectory offers a higher scan efficiency compared to radial trajectories. For this reason, we have developed a novel through-time spiral GRAPPA method and demonstrate its application to real-time cardiac imaging. By moving from the radial trajectory to the spiral trajectory, the temporal resolution can be further improved at lower acceleration factors compared to radial GRAPPA. In addition, the image quality is improved compared to those generated using the radial trajectory due to the lower acceleration factor. Here, we show that 2D frame rates of up to 56 images/s can be achieved using this parallel imaging method with the spiral trajectory.