Eric K. Gibbons1, Samantha J. Holdsworth2, Melvyn B. Ooi2, Murat Aksoy2, Roland Bammer2
1Department of Bioengineering, Stanford University, Palo Alto, CA, United States; 2Center for Quantitative Neuroimaging Department of Radiology, Stanford University
Echo-Planar Imaging (EPI) is a fast acquisition technique that can reduce the effect of patient motion but it is still prone to motion that occurs between volumes. The real-time prospective approach can correct for head rotation by rotating the gradients. However, gradient hardware delays can result in different ghosting parameters for each rotation. Here we test whether the ghost correction parameters estimated from the first EPI scan can be applied to oblique angles that are limited to the expected extent of patient head motion, in order to test whether this extra reference scan is necessary for real-time prospective motion correction applications.We found that even in small rotations of 2.5 degrees ghosting artifacts appeared in the image and required a separate correction parameter to be calculated. Additionally, in the presence of gradient delays, such ghosting correction is equally unfeasible with or without the additional scans.
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