Multi-channel transmit MR imaging

摘要

The invention relates to a multi-channel (e.g. quadrature) MRI transmit system in which RF power amplifiers having different power capabilities are used in different transmit channels. This results in reduced system costs, due to the avoidance of an unused excess of RF power capability when the power demand for obtaining a homogeneous B1-field (RF shimming) is asymmetric and the asymmetry is qualitatively the same for different imaging applications. The multi-channel transmit unit may also comprise a commutator which enables to selectively connect each RF power amplifier to each drive port of transmit coil arrangement (e.g. a birdcage coil).

主权项

1. A method of magnetic resonance (MR) imaging of at least a portion of a body of a patient placed in an examination volume of a MR device, the method comprising the steps of:
subjecting the portion of the body to an imaging sequence comprising RF pulses and switched magnetic field gradients, the RF pulses being transmitted toward the portion of the body via a RF coil arrangement surrounding the examination volume, wherein RF signals are supplied to the RF coil arrangement via two or more transmit channels in an asymmetric fashion relative to a horizontal and/or vertical axis of the cross section of the portion of the body; acquiring MR signals from the portion of the body; and reconstructing a MR image from the acquired MR signals, wherein the RF pulses are transmitted by supplying RF signals in parallel via the two or more transmit channels at different power levels by way of a transmit unit for transmitting the RF signal to the RF coil arrangement, which transmit unit has two or more transmit channels, each transmit channel being connected to one RF drive port of the RF coil arrangement and wherein each transmit channel comprises a RF power amplifier, and wherein the RF power amplifiers of the different transmit channels have different power capabilities.