Kesa Spiral

Application of K-Space Energy Spectrum Analysis for Inherent and Dynamic B0 Mapping and Deblurring in Spiral Imaging Trong-Kha Truong, Nan-kuei Chen, Allen W. Song Submitted to Magnetic Resonance in Medicine (2009) Abstract: Spiral imaging is vulnerable to static magnetic field (B0) inhomogeneities caused by susceptibility effects, eddy currents, and chemical shifts, as well as temporal B0 variations due to subject motion, physiological noise, and system instabilities, resulting in image blurring. Here, a novel off-resonance correction method is proposed to address these issues. This method integrates (i) a k-space energy spectrum analysis algorithm, which can inherently and dynamically generate a full-resolution B0 map from the k-space data at each time point, without requiring any additional data acquisition or pulse sequence modification, as well as (ii) a multichannel modulation algorithm and (iii) an automatic residual deblurring algorithm, which use these B0 maps to correct for the blurring caused by both spatial and temporal B0 variations, thereby resulting in a high spatial fidelity and temporal stability. The proposed method is validated in a phantom and in healthy volunteers against conventional multiecho B0 mapping and conjugate phase deblurring methods, and its advantages for dynamic MRI applications are demonstrated in a functional MRI experiment.