Veneta Tountcheva1, Boris Keil2, Thomas Witzel1, Dylan Tisdall2, Philipp Hoecht3, Lawrence L. Wald1, 4
1A.A. Martinos Center for Biomedical Imaging, MGH, Harvard Medical School, Radiology, Charlsetown, MA, United States; 2A.A. Martinos Center for Biomedical Imaging,, MGH, Harvard Medical School, Radiology, Charlsetown, MA, United States; 3Siemens Medical Solutions USA Inc., Charlsetown, MA, United States; 4Harvard-MIT, Div. of Health Science and Technology, Cambridge, MA, United States
64ch receive-only field camera has been built to study the spatial and temporal evolution of the magnetic field in the presence of eddy currents and gradient trajectories. The field camera consists of 64 small solenoids in a 4 x 4 x 4 grid, each with a small (0.9mm diameter) water sample in a capillary plugged with susceptibility matched material. The camera was validated with field maps acquired after inducing eddy currents on the x-, y-, z-gradients at different time delays. The eddy currents frequency offsets have been mapped out as a function of position and time delay for each x-, y-, z-gradients allowing determination of the eddy current gradients and gradient cross terms time constants and amplitudes for either pre-emphasis adjustment or inclusion in image reconstruction methods.