JPH031842A - Apparatus for magnetic resonance imaging - Google Patents

Abstract

PURPOSE:To obtain a good magnetic resonance image by supporting lead wires so that loops are not formed by the lead wires in an irradiation zone of inclined magnetic field pulses. CONSTITUTION:Inclined magnetic field pulses, which are synchronized with an R-wave signal sent from a heartbeat information detector 8, are irradiated to a patient P by a system controller 7. Lead wires 13a to 13c from electrodes 12a to 12c are connected to a connector 22, which is arranged at the tip of a cylindrical flexible arm 23, a supporting member for the lead wires, and further connected to a transmitter 24 through the inside of the flexible arm 23. The connector 22 has its position adjusted by bending the flexible arm 23 as a whole in accordance with setting positions of the electrodes 12a to 12c, and can be kept at that position after the adjustment. The lead wires 13a to 13c are kept not in contact with the body surface Pa of patient P by supporting the connector 22 above the patient P with the flexible arm 23.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a magnetic resonance imaging apparatus that obtains a magnetic resonance image of a living body (usually a patient). The present invention relates to a magnetic resonance imaging apparatus that is used to obtain magnetic resonance images synchronized with heartbeat information, which is periodic activity information from a living body.

(Prior art) A patient placed on a bed is placed in a uniform static magnetic field, electrodes are attached to the surface of the patient's body, synchronized with the patient's heartbeat information obtained from the electrodes, and the static magnetic field is 2. Description of the Related Art Magnetic resonance imaging apparatuses are known that emit gradient magnetic field pulses in a direction perpendicular to a magnetic field to cause a magnetic resonance phenomenon in a specific region of a patient and obtain a magnetic resonance image of the specific region.

FIG. 5 is a diagram showing a method of obtaining heartbeat information from a patient using a conventional device.

The patient P is placed on the top plate 16 in the shield room 11 with the upper body naked, and three electrodes 12a to 12c are attached to the naked upper body. These electrodes 12a to 12c are connected to the transmitter 1 by lead wires 13a to 13c.
Connected to 4. The signals obtained from the electrodes 12a to 12c are transmitted by the transmitter 14 via the lead wire 13c from the electrode 12c to the antenna 15 provided in the shield room 11, and are detected by the heartbeat information detecting means 8.
The R-wave signal is sent to the system controller 7, and the system controller 7 irradiates the patient P with gradient magnetic field pulses in synchronization with the R-wave signal.

By the way, since the transmitter 14 is simply placed on the patient P or the top plate 16, as shown in FIG. Intersection 13d.

A loop may be formed by the lead wires 13a and 13.

Other examples in which the lead wires 13a to 13c are formed in a loop shape are shown in FIGS. 6(a) and 6(b).

FIG. 6(a) shows a case where the negative lead wires 13c intersect at the intersection 13e to form a loop and form a surface F2 that generates a local magnetic field.

FIG. 6(b) shows that the lead wire 13b and the lead wire 13c come into contact at a point 13f, forming a loop with the transmitter 141 point 13f and the lead wires 13b and 13c, forming a surface F3 that generates a local magnetic field. This shows the case where

Therefore, the electrodes 12a are connected to the lead wires 13a to 13c.
When a current flows due to the potential difference between 12a and 12a, an unnecessary local magnetic field is generated in a direction perpendicular to the planes F to F3 in the shaded portions of FIGS. 5 and 6.

(Problem to be Solved by the Invention) Since the conventional device is configured as described above, the lead wires from the electrodes are formed in a loop shape within the irradiation area of the gradient magnetic field pulse, generating an unnecessary local magnetic field. However, there was a problem in that this adversely affected magnetic resonance images.

Furthermore, since the lead wires are in contact with the body surface, there is a problem in that the heat generated by the current flowing through the lead wires may cause burns.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a magnetic resonance imaging apparatus that eliminates the above problems and is capable of obtaining good magnetic resonance images.

[Configuration of the Invention (Means for Solving the Problems) The present invention includes a method in which a detection section is attached to the body surface of a living body placed in a static magnetic field, and a current is detected from a lead wire led out from the detection section. In a magnetic resonance imaging apparatus that obtains a magnetic resonance image of the living body by irradiating gradient magnetic field pulses toward the living body in synchronization with periodic activity information of the living body obtained by The present invention is characterized by having a lead wire holding member that holds the lead wire so as not to form a loop.

(for production) The operation of the apparatus having the above configuration will be explained below.

The detection section of this device obtains electrical signals as periodic activity information of the living body. Since the lead wire is held by the lead wire holding member so as not to form a loop, no unnecessary magnetic field is generated from the lead wire even if current flows through the lead wire within the irradiation region of the gradient magnetic field pulse.

(Example) Examples of the present invention will be described in detail below.

FIG. 1 shows a block diagram of an embodiment of the present invention.

The device of this embodiment includes a static magnetic field generating section 1 that generates a static magnetic field,
A gradient magnetic field generator 3 irradiates gradient magnetic field pulses to the patient P placed in this static magnetic field, and transmits an RF pulse, which is an excitation pulse, to the patient P, and generates an FI as a magnetic resonance signal from the patient P. D (free induction d
RF that receives the eca7) signal (hereinafter referred to as MR double signal)
A pulse transmitting/receiving unit 2, a signal processing system 40 that performs predetermined processing on MR signals obtained from the patient P, a heartbeat information detection means 8 that detects heartbeat information obtained from the patient P, and a heartbeat information detection means 8 that detects heartbeat information obtained from the patient P. The signal processing system 40 is synchronized with the R wave signal sent from the means 8. It has a system controller 7 that controls the gradient magnetic field generator 3.

An electrode 12 as a detection part is attached to the patient P, and this electrode 1
2, heartbeat information as periodic activity information of the patient P is sent to the heartbeat information detection means 8.

The heartbeat information detection means 8 includes an electrocardiograph (ECG) 9 that detects cardiac electromotive force, and an electrocardiogram synchronization circuit 10 that transmits an electrocardiogram waveform output from the ECG 9, particularly an R wave signal generated by ventricular excitement. have.

The signal processing system 40 includes a signal collecting unit 4 that collects MR multiplied signals from the patient P, and a unit that Fourier transforms the data collected from the signal collecting unit 4 to identify the patient P irradiated with gradient magnetic field pulses. It has an image creation section 5 that creates a tomographic image, and an image display section 6 that displays the tomographic image created by the image creation section 5.

The static magnetic field generating section 1. The RF pulse transmitting/receiving unit 2° gradient magnetic field generating unit 3 is arranged in the shield room 11 so that the electromagnetic waves generated therefrom do not adversely affect external electronic equipment and the like.

FIG. 2 is a diagram showing a method for obtaining heartbeat information from a patient P in the apparatus of this embodiment.

The patient P is placed on the top plate 16 in the shield room 11 with the upper body naked, and three electrodes 12a to 12c are attached to the naked upper body. The electrodes 12a to 12c are attached to the body surface Pa of the patient P via paste, and among the electrodes 12a to 12c, electrode 12b
is attached to the body surface Pa above the heart H. In addition, lead wires 13a from these electrodes 12a to 12c
13c to 13c are connected to a connector 22 provided at the tip of a cylindrical flexible arm 23 serving as a lead wire holding member. Furthermore, the lead wires 13a to 13c are connected to a transmitter 24 via the inside of the flexible arm 23.

The signals obtained from the electrodes 12a to 12c are sent to a transmitter 24.
Thus, the wave is transmitted from the electrode 12c to the antenna 15 provided in the shield room 11 via the lead wire 13c. Then, in response to the signal received from the antenna 15, the heartbeat information detection means 8 sends an R wave signal to the system controller 7, and the system controller 7 applies a gradient magnetic field to the patient P in synchronization with the R wave signal. I'm trying to irradiate pulses.

The flexible arm 23 has electrodes 12a to 12c.
This flexible arm 2
By bending the entire connector 3, the position of the connector 22 can be adjusted, and the position can be maintained after adjustment.

FIG. 3 shows a view taken in the direction of arrow A in FIG. 2, and the lead wires 13a to 13c are supported by a flexible arm 23 so that the connector 22 is positioned above the patient P, as shown in FIG. By doing so, the lead wires 13a to 13c are prevented from coming into contact with the patient's P's body surface Pa.

In order to obtain a stable magnetic resonance image, the system controller 7 performs signal processing to ignore signals sent from the electrocardiogram gated circuit 10 for more than a predetermined time period or signals sent consecutively within a predetermined time period. I am trying to do this.

The operation of the device of this embodiment will be explained using FIG. 4 as well.

A potential difference between the electrodes 12a and 12b is obtained as shown by Wl, and a potential difference between the electrodes 12b and 12c is obtained as shown by W2.

The transmitter 24 receives these potential difference signals W1. The signal W3 converted into a frequency from W2 is sent backward through the lead wire 13c to the electrode 1.
The wave is transmitted from 2c toward the antenna 15.

The ECG 9 inversely converts this signal W3 into a voltage, and sends a pulse signal W4 to the system controller 7 in synchronization with the sudden change in this voltage by the electrocardiogram synchronization circuit 10.

Therefore, the system controller 7 uses this pulse signal W.
4, the gradient magnetic field generator 3 emits gradient magnetic field pulses toward the patient P, and the RF pulse transmitter/receiver 2
By transmitting the excitation pulse toward the patient P,
The MR multiplied signal from the RF pulse is detected by the RF pulse transmitting/receiving section 2. The MR multiplied signal detected by the RF pulse transmitting/receiving section 2 is received by the signal collecting section 4, an image is created by the image creating section 5, and the created image is further displayed on the image display section 6.

Since the device of this embodiment is configured as detailed above, the lead wires from the electrodes are not formed in a loop shape, so there is no generation of unnecessary local magnetic fields that adversely affect magnetic resonance images. Therefore, a good magnetic resonance image can be obtained.

Furthermore, since the lead wires do not come into contact with the body surface, there is no risk of burns caused by the heat generated by the current flowing through the lead wires.

Although one embodiment has been described above, the present invention is not limited to this, and various modifications can be made without changing the gist thereof.

For example, although a flexible arm is used as the lead wire holding member, a structure in which the arms are fastened and connected using a screw may also be used. Alternatively, the connector may be supported using an elastic member to apply tension to the lead wire.

Moreover, although the case where three electrodes are used is shown, the case where four or more electrodes are used may be sufficient, or the case where one electrode is used.

As periodic activity information of a living body, a magnetic resonance image synchronized with not only heartbeat information but also other information such as brain wave information and breathing information may be obtained. When detecting mechanical signals such as respiratory information, a converter that converts mechanical signals into electrical signals may be used as the detection section.

[Effects of the Invention] According to the present invention described in detail above, since the lead wire is held by the lead wire holding member so as not to form a loop, no unnecessary local magnetic field is generated by the lead wire. , it is possible to provide a magnetic resonance imaging apparatus that can obtain good magnetic resonance images.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing a method for obtaining heartbeat information from a patient in the device shown in FIG. 1, and FIG. 3 is an arrow A shown in FIG. View, 4th
Figure 5 is an explanatory diagram of signals, Figure 5 is an explanatory diagram showing a method of obtaining heartbeat information from a patient in a conventional device, and Figures 6(a) and 6(b) are lead wires formed in a loop shape. FIG. 2 is an explanatory diagram showing a surface on which a local magnetic field is generated by. 12a to 12c... electrodes (detection section), 13a to 1
3c... Lead wire, 23... Flexible arm (lead wire holding member),
P...Patient (living body). Diagram

Claims (2)

[Claims] (1) A detection unit is attached to the body surface of a living body placed in a static magnetic field, and a gradient magnetic field is generated in synchronization with the periodic activity information of the living body obtained by detecting current from a lead wire led out from this detection unit. In a magnetic resonance imaging apparatus that irradiates a pulse toward the living body and obtains a magnetic resonance image of the living body, a lead wire holder that holds the lead wire so that a loop is not formed by the lead wire within the irradiation area of the gradient magnetic field pulse. A magnetic resonance imaging apparatus comprising: a member. (2) The lead wire is suspended by the lead wire holding member so that the lead wire within the irradiation area of the gradient magnetic field pulse does not form a loop and so that the lead wire does not come into contact with the surface of the living body. 1. The magnetic resonance imaging apparatus according to 1.