TIME DIVISION MULTIPLEXING SYSTEM FOR RF CHANNELS IN MRI
Publication Date: 2005-Apr-11
The IP.com Prior Art Database
In one embodiment of this invention, time-division multiplexing of RF-receive channels for MRI during image acquisition includes sharing the RF-receive channel analog-conducting and data acquisition system inputs by selecting different RF inputs to be sampled in different time slots. The selection of the RF inputs connected to the data acquisition system is altered while the RF signal is being acquired for an image.
FIELD OF THE INVENTION
 This invention relates generally, to RF receive channels and more particularly to, a time division multiplexing system for RF channels in MRI.
BACKGROUND OF THE INVENTION
 MRI depends on the use of RF-receive channels to acquire analog RF signals that are sampled and converted to digital data to create an image. Typically, an individual RF-receive channel requires a dedicated analog-conducting path, such as a coaxial cable, to the inputs of the data acquisition system where the analog RF signal is converted into digital data. As the number of RF-receive channels increases so does the number of physical analog connections and the number of inputs to the data acquisition system. Therefore, currently for a system to support 8 RF-receive channels 8 dedicated analog signal paths must exist and the data acquisition system must include 8 corresponding inputs.
 Also, during image acquisition an MRI system is sensitive to electronic noise emissions, such as the digital clock signals commonly used in communication systems and microprocessors. Interference in the acquisition frequencies will result in image artifacts. Therefore, electrical systems near the RF-receive coils of an MRI system must have very low electro-magnetic emissions. Many common communication interfaces, which depend upon digital synchronous data transfers and microprocessors, radiate unacceptable emissions during image acquisition.
 Presently, an RF switch or multiplexer may be used in a MRI system to connect multiple RF coils to a single set of RF-receive channels. For example, an MRI system could have two 8-channel coils, for 16 RF inputs total, attached to an RF switch that connects to only one set of 8 RF-receive channels. Before image acquisition the RF switch could be configured to connect one set of the 8-input channels on the coils to the 8 RF-receive channels of the data acquisition system. The RF switch is configured before image acquisition and connects the RF inputs to the RF-receive channels of the data acquisition system for the duration of a scan.
BRIEF DESCRIPTION OF THE DRAWINGS
 FIG. 1 shows a system level diagram of time division multiplexing according to one embodiment of this invention.
 FIG. 2 shows a schematic diagram of an RF switch according to this invention.
DETAILED DESCRIPTION OF THE INVENTION
 Various embodiments of this invention provide a time division multiplexing system for RF channels in MRI.
 In one embodiment of this invention, time-division multiplexing of RF-receive channels for MRI during image acquisition includes sharing the RF-receive channel analog-conducting and data acquisition system inputs by selecting different RF inputs to be sampled in different time slots. The selection of the RF inputs connected to the data acquisition system is altered while the RF signal...