Development of a functional magnetic resonance imaging simulator for modeling realistic rigid‐body motion artifacts

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Abstract
Functional magnetic resonance imaging (FMRI) is a noninvasive method of imaging brain function in vivo. However, images produced in FMRI experiments are imperfect and contain several artifacts that contaminate the data. These artifacts include rigid‐body motion effects, B0‐field inhomogeneities, chemical shift, and eddy currents. To investigate these artifacts, with the eventual aim of minimizing or removing them completely, a computational model of the FMR image acquisition process was built that can simulate all of the above‐mentioned artifacts. This paper gives an overview of the development of the FMRI simulator. The simulator uses the Bloch equations together with a geometric definition of the object (brain) and a varying T model for the BOLD activations. Furthermore, it simulates rigid‐body motion of the object by solving Bloch equations for given motion parameters that are defined for an object moving continuously in time, including during the read‐out period, which is a novel approach in the area of MRI computer simulations. With this approach it is possible, in a controlled and precise way, to simulate the full effects of various rigid‐body motion artifacts in FMRI data (e.g. spin‐history effects, B0‐motion interaction, and within‐scan motion blurring) and therefore formulate and test algorithms for their reduction. Magn Reson Med, 2006.