Sensitivity of Off-Resonance Susceptibility Separation with Superparamagnetic Iron Oxide
Faranesh A, Gold G, Grist T, Gard C, Reeder S
Superparamagnetic iron oxide (SPIO) particles have shown promise for labeling and tracking of cells. Using a positive contrast off-resonance separation method, we imaged a phantom with increasing concentrations of SPIO particles. This method acquires images at slightly different echo times to facilitate separation of spins in locally heterogeneous magnetic fields created by SPIO particles. Using a spherical magnetic perturbation model, on- and off-resonance signals were separated and used to measure the sensitivity of this method with free SPIO particles. This method demonstrated a linear increase in signal separation with increasing SPIO concentrations, and was sensitive to concentrations above 54 g/mL.