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Abstract #4940

Contrast Agents: the Effect of Relaxation on Magnetic Particle Imaging

Yong Wu1, Zhen Yao1, Gareth Kafka1, David Farrell1, Mark Griswold2, Robert Brown1

1Department of Physics, Case Western Reserve University, Cleveland, OH, United States; 2Department of Radiology, Case Western Reserve University, Cleveland, OH, United States

Magnetic particle imaging (MPI) is a new tomographic technique that allows fast, inexpensive imaging of MRI contrast ferrofluid agents with submillimeter resolution. Selection fields combined with oscillating driving fields can move unsaturated field-free-points so as to cover the field of view. In previous studies, the average magnetization is assumed to respond instantaneously to changes in the applied field. Realistically, however, a finite relaxation time slows the magnetic response. The present simulation demonstrates that, for contrast agents of interest, the choice of an optimal particle size is strongly dependent on this effect. A trade-off thus exists between sensitivity and resolution.