JPS6259845A - Tuning device for receiving coil of magnetic resonance imaging device - Google Patents

Abstract

PURPOSE:To increase the variation width of the electrostatic capacity of the receiving coil of a magnetic resonance imaging (MRI) device by varying the capacity of the variable capacitor connected to the receiving coil by an external driving source. CONSTITUTION:The variable capacitor 2 is connected to a surface coil 1 provided to the probe head side of the MRI device in parallel to a power source and a main gear 3 is fixed on its rotary operation shaft 2a. Then, the main gear 3 is coupled with the output shaft 5 of a rotor 6 projecting into a driving head 7 through a driving gear 4. Then, the driving head 7 is coupled with an air pump through an intermediate member, a connector, etc. Then, compressed air is sent in the driving head 7 from the air pump according to the indication of the computer of the MRI device body, and then the rotor 6 rotates to vary the electrostatic capacity of the variable capacitor 2 through the driving gear 4 and main gear 3.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a magnetic resonance imaging apparatus () lagnet
1c Resonance Imaging: MRI
The present invention relates to a probe head of 1999, and in particular to a tuning device for its receiving coil.

[Technical background of the invention and its problems] Generally, in an MRI apparatus, the subject (
For example, since it is necessary to tune the receiving coil according to the human body, the capacitance of the capacitor component on the probe head side can be changed.

In this case, priority has been given to ease of tuning or operation, or to automation, so conventional devices have used a variable capacitance diode (for example, VARICAP: registered trademark) as a means for changing the capacitance. However, since the capacitance variable width (range) of this type of diode is not very wide, this type of device inevitably runs out of range and is forced to use it in a region other than the resonant frequency. As a result, there is an inherent problem that sufficient reception sensitivity cannot be obtained and the S/N ratio of the image deteriorates.

[Object of the Invention] The present invention has been made in view of this situation, and an object of the present invention is to provide a tuning device for a receiving coil for a magnetic resonance imaging apparatus, which allows a sufficiently large variable range of capacitance when tuning the receiving coil. The purpose is to

[Summary of the Invention] The outline of the present invention for achieving the above object is that a variable capacitor is connected to a receiving coil of a magnetic resonance imaging apparatus, and the capacitance of the capacitor is configured to be variably controlled by an external drive source. It is in.

[Embodiments of the Invention] The present invention will be described in detail below based on the embodiments shown in FIGS. 1 to 4.

In Fig. 1, 1 is a surface coil installed on the probe head side, 2 is a mechanical variable capacitor (hereinafter referred to as a variable capacitor) connected in parallel with the coil 1 to the power supply, and 3 is an electrostatic capacitor of the variable capacitor 2. A main gear is fixed to the rotary operation shaft 2a for changing the capacity, 4 is a drive gear meshing with the main gear 3 in a decelerating manner, and 5 is an output shaft integrally constructed with the drive gear 4. , passes through a wall 7a of the drive head section 7, which will be described later, and is rotatably supported by the wall 7a. The output shaft 5 and the wall 7a are configured to be air-tightly held using, for example, an O-ring or the like. Reference numeral 6 denotes a rotor having a plurality of blades fixed to the tip of the output shaft 5 protruding into the rotor chamber 7b in the drive head section 7.

Now, the drive head section 7 forms a part of the fluid drive power device, and is composed of a wall body 7a, a rotor chamber 7b, a normal rotation passage 7C, and a reverse rotation passage 7d. The rotor 6 is rotated in the forward direction by the compressed air flowing into the rotor chamber 7a from the normal rotation flow path 7C and flowing out into the reverse rotation flow path 7d, and the compressed air flowing in from the reverse rotation flow path 7d and flowing out into the reverse rotation flow path 7C.
The rotor 6 is configured so that the rotor 6 can be rotated in the opposite direction by the compressed air flowing out.

Reference numeral 8 shown in FIG. 2 is an intermediate member that connects the drive head section 7 and a connector 11, which will be described later, which has a flexible structure as a whole and has a cross-sectional view shown in FIG. 3 inside. Two water conductive cables 9a, 9b and two intermediate channels 10a, 1Qb are provided as shown in FIG. On the other hand, one end of each of the conductive cables 9a and 9b is connected to the terminals of the coil 1 and the bicon 2, and the other end of each of the conductive cables 9a and 9b is connected to a connecting terminal (
(not shown), and on the other hand, one end of the intermediate flow path 10a is connected to the forward flow path 7C of the drive head section 7, and one end of the other intermediate flow path 10b is connected to the reverse flow path 7d.
Each is bonded with an airtight structure. Moreover, the other end portions of each of the intermediate flow paths 10a and 1Qb are connected to a flow path connecting portion (not shown) appropriately constructed within the connector 11, also with an airtight structure. It is assumed that each of the materials or members 1 to 10 disposed closer to the probe head is made of a non-magnetic material (for example, plastic or rubber).

The connector 11 has respective transmission means 12a, 12b and 13a which are themselves removable as shown in the fourth figure.
, 13b to the MRI apparatus main body 14 and the air pump 15, which is a fluid driving force generating device, in the same manner as in the above case. The air pump 15 is configured to be appropriately controlled by a computer 16 within the MRI apparatus main body 14. For example, it is configured so that compressed air can be supplied from one transmission means 13a or from the other transmission means 13b in accordance with instructions of a forward flow signal and a reverse flow signal from the computer 16.

With the above configuration, when changing the capacity of the variable capacitor 2, compressed air from the air pump 15 is transmitted to the drive head section 7 via the transmission means 13a, b and the intermediate flow paths 10a, b according to a command from the computer 16. Normal flow path 7
C or reverse flow path 7d, the drive gear 4 and main gear 3 can be rotated by rotating the rotor 6 by an arbitrary amount, and the capacitance of the variable capacitor 2 can be changed smoothly and accurately. . Therefore, it becomes possible to easily apply a variable capacitor with a wide variable capacitance region to the probe head of an MRI apparatus. In this case, if the length of the intermediate member 8 is appropriately selected and the MRI apparatus main body 14 and air pump 15 are installed at a position appropriately distant from the subject, remote control is also possible.

Although the illustrated embodiment shows an example in which compressed air is used as the fluid, the present invention is not limited to the illustrated embodiment, and various modifications can be made without changing the gist of the invention. is possible. For example, the fluid may be a hydraulic drive means using liquid (oil etc.);
The transmission method may also be such that the fluid is pressurized only in the forward rotation direction of the variable capacitor, and the biasing force of a return spring or the like is used in the reverse rotation direction of the variable capacitor. Further, although the illustrated embodiment uses an intermediate member in which the conductive cable and the intermediate flow path are integrated, they may be constructed separately.

[Effects of the Invention] As described above, when the present invention is used, a mechanical variable capacitor with a wide capacitance variable range can be applied to an MRI device, so that an MRI device with sufficiently high receiving sensitivity can be obtained.
It is possible to obtain a tuning device for a receiving coil for a device, and furthermore, it is possible to expect effects such as enabling remote control if necessary.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of main parts of an embodiment according to the present invention. FIG. 2 is a schematic external view thereof, FIG. 3 is a sectional view taken along line AA in FIG. 2, and FIG. 4 is a diagram showing the relationship between the MRI apparatus main body and an air pump. 1... Surface coil 2... Variable capacitor 6.
... Rotor 7 ... Drive head part 8 ... Intermediate member 11 ... Connector 14 ... MRI apparatus main body 15 ... Air pump representative Patent attorney Nori Chika I also Nori Ogo
Mistake 2

Claims (2)

[Claims] (1) A tuning device for a receiving coil for a magnetic resonance imaging apparatus, characterized in that a variable capacitor is connected to the receiving coil of the magnetic resonance imaging apparatus, and the capacitance of the capacitor is variably controlled by an external drive source. (2) The tuning device for a receiving coil for a magnetic resonance imaging apparatus according to claim 1, wherein the external drive source uses a fluid, and the fluid conduction pipe for driving the fluid is a flexible pipe.