Predicting Pileup Artifacts Around Magnetized Spheres in SWIFT Images

Robert O'Connell¹, Steen Moeller, Curt Corum, Djaudat Idiyatullin, Michael Garwood

Magnetic materials cause T2* shortening and frequency shifts in MRI. With conventional techniques, magnetized objects give rise to signal voids, whereas with SWIFT the signal voids are surrounded by pileup artifacts. The pileup artifacts arise from the displaced signals from off-resonance spins. By knowing how the signals are displaced, it should be possible to return them to their correct positions in image space, correcting the image distortion. This work used an analytic method to derive a predictive equation for the pileup artifact. The equation was then verified through simulation and experimental measurement of titanium balls.