DRF-GRAPPA: A Parallel MRI Method with a Direct Reconstruction Filter

A novel multi-channel image reconstruction algorithm for parallel MRI is proposed to reconstruct a complex-valued image with both magnitude and phase information in a reduced computation time, so called the DRF-GRAPPA. The DRF-GRAPPA combines multichannel images by separately obtaining magnitude information and phase information. The method is applied to parallel MRI to reconstruct an image from under-sampled k-space data by using a direct reconstruction filter that can simultaneously estimate full k-space signals and combine multi-channel images. To obtain both magnitude and phase information, the DRF-GRAPPA provides two different direct reconstruction filters. The accuracy of the magnitude and phase information is validated through simulations. In addition, the experiment results of spherical water phantom imaging and in-vivo imaging demonstrate that the DRF-GRAPPA can successfully reconstruct images with both magnitude and phase information within a reduced reconstruction time.