Multi Nuclear Sense/Synergy RF Coil Array For MRI
Publication Date: 2002-Jul-04
The IP.com Prior Art Database
ID201832: MULTI NUCLEAR SENSE/SYNERGY RF COIL ARRAY FOR MRI
Author: Christoph Leussler, Philips Research Hamburg
A surface coil array is proposed where the individual elements of the array are tuned to more than one frequency. Each individual coil element can be used simultaneously at different frequencies. The high SNR benefit of the coil array is preserved for all nuclei to be imaged with spectroscopic or standard imaging techniques. It is guaranteed that the imaging information originates from the same spatial region. Image information is received simultaneously or in a time sharing mode.
The advent of high performance 3 Tesla whole body MR systems might require functionality for multi-nuclear MR of such a coil array. Especially advanced imaging techniques for functional imaging (break-through in molecular imaging, gene imaging) will demand the simultaneous or sequential information of different nuclei. When each individual coil element of the array is provided for multi-resonance functionality, then the required image information can be acquired without moving the patient and without the exchange of RF-coils.
The individual multi-resonant coils are arranged around the body [see Fig.1]. Each element is multi-resonant or can be electronically switched between the different frequencies. The spectrometer has multi-channel and multi-frequency functionality. A body or local transmit coil, driven by the transmit path, can handle the required frequencies. The multi-resonant transmit coil can also work as a multi element transmit/receive coil (Transmit Sense, lower RF power, RF shim-homogeneity, k-space coding and encoding), where each element is fed by a separate transmitter.
The individual synergy coils have electronic impedance matching for simultaneous acquisition using impedance networks for the individual frequencies. Rejection filters are made of parallel resonant L-C circuits or quarter wavelength transmission lines [Fig.2].
Multi-resonant synergy coil preamplifier circuits give optimal noise impedance transformation at the desired frequencies. Here the individual center resonance frequencies can electronically be switched using PIN diodes [Fig.3]. The application of high Q varactor tuning diodes for tuning of arbitrary frequencies is also possible. A diplexer circuit directly mounted on the preamplifier reduces the required number of coax cables. All signals are simultaneously fed by one coax cable [Fig.4]. Decoupling of the multi-resonant synergy...