Understanding the Effects of Oriented Susceptibility Inclusions on the Phase & Magnitude of Gradient Echo Signals

Anna Izabella Blazejewska¹, Samuel Wharton¹, Penny A. Gowland¹, Richard Bowtell¹

Magnetic susceptibility differences generate inhomogeneities in the local magnetic field which modulate the magnitude and phase of the signals acquired in MRI. With the advent of susceptibility mapping it has become particularly important to understand the relationship between microscopic structure in the distribution of susceptibility and the induced variation in the NMR frequency. We simulated the field perturbations generated in a uniform matrix containing oriented ellipsoidal inclusions of different susceptibility and used this information to explore the effect of the shape of the inclusions on the phase and magnitude of the MR signal in the "static dephasing" regime.