RU191437U1 - RF coil for magnetic resonance imaging of the brain - Google Patents

Abstract

The radio frequency coil is designed to transmit and receive pulse signals in magnetic resonance imaging of the brain. The coil is made in the form of a ring of metal, twelve conductors connected through a balancing device to the transmitter-receiver device of the tomograph. The coil is excited using a meandered conductor, and the conductors are bent in this way and connected at one point in the upper part of the coil in order to repeat the shape of the human head. The field of the excited coil is localized in the area of the coil corresponding to the cerebral cortex. Features of the proposed technical solution allow the use of this device for receiving and transmitting radio frequency MRI signals in the study of the human cerebral cortex.

Description

The utility model relates to medical equipment and can be used as a receiving coil of a magnetic resonance imager with a constant magnetic field level of 1.5 T (corresponding to an operating frequency of the tomograph of 63.8 MHz) used in medical studies of the human body using magnetic resonance imaging and spectroscopy .

Known receiving radio frequency coil for use in MRI, designed to obtain images of the human brain. This coil is a “birdcage” type resonator (application number US No. 54474069, IPC A61B 5/055, priority date 6/10/1994, publication date 12/12/1995), made in the form of two rings of metal, electrically interconnected by twelve conductors . Between the contact points of the rings with the conductors, cuts are made in the ring, in which the capacitors are included, which are necessary to tune the coil to the resonant frequency. The disadvantage of this technical solution is that this radio frequency coil creates a uniform magnetic radio frequency field in the entire brain, but does not localize the radio frequency magnetic field near the cerebral cortex. The magnitude of the radio frequency magnetic field is related to the signal-to-noise ratio of the resulting image, which in turn is directly related to the quality of the resulting image, which limits the use of the birdcage coil described above.

The closest solution in technical essence to the claimed technical solution is a quadrature magnetic resonance coil type "birdcage" with two degenerate modes (degenerate are the modes whose eigenfrequencies coincide) (Application WO No. 2004/048987 A2, IPC A61B 5/055, date Priority 04/26/2003, publication date 11/25/2004), made in the form of two rings of conductive material, electrically interconnected by twelve conductors. Between the contact points of the rings with the conductors of the ring are broken. Capacitors needed to tune one of the coil modes to the resonant frequency are included in the ring breaks. The centers of the conductors connecting the rings also include capacitors necessary to tune another mode to the resonant frequency. At the moment of transmission, the coil mode is excited, which has maximum uniformity, and at the time of reception, another coil mode is used, which has the maximum level of radio frequency magnetic field in the area near the surface of the coil, which corresponds to the cortex of the human brain. The disadvantage of this coil is that at the time of transmission it works in a fashion that creates a radio frequency field in the entire volume of the coil, and not locally in the cortex. Using a mode with a radio frequency field localized near the surface of the coil is impossible due to additional devices necessary for its excitation, which cannot be used when transmitting signals. Also, the above-described coil, having a cylindrical shape, does not repeat the shape of the scalp of the human head, which in turn leads to a decrease in the received signal from the cerebral cortex.

The task to which the proposed technical solution is directed is to improve the quality of the resulting image in the region of the cerebral cortex by increasing the MP signal at the time of transmission and reception through the use of a higher coil mode.

The essence of the useful one is that as a radiofrequency coil for magnetic resonance imaging of the brain, a coil is used that contains a ring of conductive material, capacitors in its ruptures and to which twelve conductors are connected, bent and interconnected electrically at one point located in the upper part of the coil in accordance with the shape of the head, a device for exciting the coil mode, made in the form of a conductor in the shape of a meander, connected through its input and symme the tracking device to the coaxial cable, made with the possibility of communication with the transceiver device of the tomograph.

The combination of the above features allows you to create a radio frequency coil that allows you to get the level of the radio frequency field in the cortex of the human brain is 2-3 times larger than the prototype, which allows to increase the signal-to-noise ratio of the resulting image.

The essence of the utility model is illustrated by a figure, which shows a diagram of the proposed device.

The device consists of 12 conductors 1, at a point 2 electrically interconnected, on the other hand, conductors 1 are connected to a ring 3 of conductive material, the breakers of which include capacitors 4, devices for exciting the coil mode in the form of a conductor in the form of a meander 5, which through its input 6 and a balancing device 7 connected to the coaxial cable 8.

The device operates as follows.

At the time of transmission, the radio-frequency sounding signals from the transceiver of the tomograph through a coaxial cable 8 and a balancing device 7 to the input 6 of the conductor in the form of a meander 5.

The conductor in the form of a meander 5 excites in the coil, consisting of conductors 1, ring 3 and capacitors 4, the higher mode of the coil due to

near-field interaction. The higher mode of the coil excites the spins of hydrogen atoms in the region adjacent to the coil (i.e., in the cortex of the patient’s brain). At the time of reception, the spin relaxation signals excite a voltage in the coil, which is transmitted through the near-field interaction to the meander-shaped conductor 5. A voltage-shaped signal is fed to the input 6 of the meander-shaped conductor and through the balancing device 7 and coaxial cable 8 is transmitted to the transceiver tomograph device.

Claims (1)

 Radio-frequency coil for magnetic resonance imaging of the brain, containing a ring of conductive material, in the breaks of which are connected capacitors and to which are connected twelve conductors, bent and interconnected electrically at one point located in the upper part of the coil in accordance with the shape of the head, device for exciting the coil mode, made in the form of a conductor in the form of a meander, connected through its input and a balancing device to a coaxial cable, made with the possibility of Due to the TRD imager.

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