Magnetic resonance imaging unit; has field magnet to form background field gradient that is smaller than time-varying field gradient produced by gradient coils

摘要

The unit has a background field magnet is designed without taking into account the absolute field homogeneity, so that it has a field gradient in the scan volume, which is smaller in the slice selection direction and in the read-out direction, than a field gradient switched with gradient coils in the appropriate directions. The unit has gradient coils that generate time-varying field gradients, as well as a control and evaluation circuit.