Characterization of Concomitant Gradient Fields and their effects on a 46 mT Halbach-Based point-of-care MRI system

Low field Halbach systems are susceptible to concomitant gradient effects. The associated fields are significantly different from clinical systems and are presented here for the first time. The corresponding equations and associated effects are verified using a spin echo sequence on a 46 mT Halbach system where a gradient strength of 10 mT/m on a phantom with maximum dimension of 200 mm is observed to create distortions. These are most evident in the transverse plane, where the phase encoding gradient causes blurring and overlapping the other transverse gradient lobe results in an additional warping effect.