Gradient Pre-Emphasis Calibration

Abstract

A common problem since the early development of MRI systems, which persists to this day, is the induction of eddy currents (EC) in the conductive parts of the MR scanner during the rise and decay of gradient pulses. The magnitude of the eddy currents, among other factors, is proportional to the magnitude of the gradient pulses and the magnitude of change in the gradient field over time. These eddy currents cause several problems, ranging from heating of the cryostat to undesirable time-varying gradient fields that produce various artefacts in the acquired images or undesirable effects on tissue structures in patients. There are several ways to suppress the eddy current effect. In this article, we focus on eddy current compensation by modulating gradient pre-emphasis.