Reconstruction of 3D Stack of Stars in Cardiac MRI using a Combination of GRASP and TV

One of the most advanced non-invasive medical imaging methods is MRI that can make a good contrast between soft tissues. The main problem with this method is the time limitation in data acquisition, particularly in dynamic imaging. Radial sampling is an alternative for a faster data acquisition, and has several advantages compared to the Cartesian sampling. Among them, robustness to motion artifacts makes this acquisition useful in cardiac imaging. Recently, CS has been used in order to accelerate data acquisition in dynamic MRI. Cartesian acquisition uses irregular under-sampling patterns to create incoherent artifacts to meet the incoherent sampling requirement of CS. Radial acquisition, due to its incoherent artifact, even in regular sampling, has an inherent fitness to CS reconstruction. In this work, we reconstruct the (3D) stack of stars data in cardiac imaging using a combination of the TV penalty function and the GRASP algorithm. We reduce the number of spokes from 21 to 13, and then reduce to 8 to observe the performance of the algorithm at a high acceleration factor. We compare the output images of the proposed algorithm with both the GRASP and NUFFT algorithms. In all the three modes (21, 13, and 8 spokes), the average image similarity is increased by at least by 0.4, 0.1 compared to NUFFT and GRASP, respectively. Moreover, the streaking artifacts are significantly reduced. According to the results obtained, the proposed method can be used on a clinical study for a fast dynamic MRI such as cardiac imaging with a high image quality from low- rate sampling.