Acquisition and Reconstruction of Magnetic Resonance Imaging
Some basic concepts about MRI acquisition are reviewed. The foundations here described will be necessary to understand the different assumptions about signal and noise used along the book; the statistical models defined in following chapters are based on the premises here set. We especially focus on modeling the k-space and x-space from a signal processing point of view. Sequences and specifics on acquisition modalities will be left aside to confine us to an upper level modeling of the acquired signal. First, we review the formation process in single-coil systems and then we extrapolate the results to multiple-coil systems. For the sake of illustration, two methods are considered in order to fuse the information from the different antennae into one single magnitude image: the sum of squares (SoS) and the spatial matched filter (SMF). The chapter concludes with the analysis of some parallel MRI methods, focusing on two of the most used ones, SENSE and GRAPPA.