Characterization of displacement forces and image artifacts in the presence of passive medical implants in low-field (<100 mT) permanent magnet-based MRI systems, and comparisons with clinical MRI systems

PurposeTo investigate the displacement forces and image artifacts associated with passive medical implants for recently-developed low-field (<100 mT) MRI systems, to compare these values from higher field strengths used clinical diagnosis.MethodsSetups were constructed measure in a permanent magnet-based Halbach array vivo at 50 mT, results compared measurements 7 T. Image assessed using turbo (fast) spin echo imaging sequences four different implants: septal occluder, iliac stent, pedicle screw (ferromagnetic) endoscopic clip. Comparisons made produced 1.5, 3 Finally, specific absorption rate (SAR) simulations performed determine under what operating conditions limits might be approached low-field.ResultsDisplacement mT on all but ferromagnetic implant between 1 10 mN. much less than devices, exception of SAR show that very long train (>128) can run short inter-pulse times (5–10 ms) within limits.ConclusionsThis work presents first evaluation effects 100 terms forces, SAR. The support previous claims such systems safely usefully challenging enviroments as intensive care unit.