Magnetic Resonance Imaging Radiofrequency Research Articles

Magnetically induced surface charges on samples in magnetic resonance imaging radio-frequency coils: Effect on electric fields, sample losses, and coil resonance

We present a solution to Maxwell's equations which describe the inductive interaction between an irregularly shaped sample in a magnetic resonance imaging rf coil. It is demonstrated that the inductive interaction between the coil and sample can induce charge densities on the sample surface and that these charge densities lead to observable changes in coil Q, resonant frequency offset and sample power dissipation.

Analysis of capacitive coupling and associated loss for a solenoidal magnetic resonance imaging radio-frequency coil.

Presented is an analysis of the capacitive coupling between a magnetic resonance imaging radio-frequency (rf) coil and a dielectric sample. Calculated is the coil self-capacitance and power loss in the medium. The capacitively coupled power loss is compared with the more familiar inductively coupled eddy current loss and the predicted dependence of self-capacitance on coil and sample size is studied experimentally in a series of single-turn slotted solenoids of various sizes.