Reconstruction of MRI signal losses in EPI images

This paper derives and implements a method for recovering MRI signal losses caused by susceptibility-induced magnetic field gradients (SFGs) in regions with large static field inhomogeneities in echo-planar imaging (EPI). Factor to account for SFGs was added in a traditional EPI equation, which was a simple Fourier transform (FT) for expressing the actual k-space data of an EPI scan. The inverse calculation of this "distorted EPI" equation was used as a kernel to correct reduction in intensity during reconstruction. A step-by-step EPI reconstruction method is proposed to avoid complicated phase unwrapping problems