JPH0471536A - Ecg signal cable for mri device - Google Patents

Abstract

PURPOSE:To suppress the high-frequency induction current flowing in an ECG signal cable by providing a resistor suppressing the high-frequency induction current in part of the cable. CONSTITUTION:One end of an ECG signal cable 1 can be connected to a person under test via an ECG cable electrode 1A, and the other end is guided to a signal processing circuit. The cable 1 is made of a metal wires or carbon fibers, and a resistor element 2 for suppressing the high-frequency induction current is connected in the middle. The resistor element 2 is connected to the cable 1 via a connection section 3 by pressure connection or welding. The high-frequency induction current is suppressed, thus the heating of the ECG signal cable 1 or the ECG cable electrode 1A is suppressed. The person under test is prevented from being burnt.

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention (Industrial Application Field) The present invention relates to an ECG signal cable for an MHI device that is connected to a subject during MR imaging and detects an ECG signal.

(Prior Art) An MRI (Magnetic Resonance Imaging) device takes images in a magnetic field in which a gradient magnetic field for detecting position information formed by a gradient magnetic field coil is superimposed on a static magnetic field formed by a main magnet. A high-frequency magnetic field is applied to the subject by a transmitting coil to excite the target nuclide, and when the application of the high-frequency magnetic field is stopped, the MR multiplied signal (magnetic resonance signal) generated from the target nuclide is detected. This is detected by a receiving coil, and based on the detected image, an image of a desired region is reconstructed and displayed on a monitor for diagnosis.

When taking images of the chest, particularly the heart, with such an MRI apparatus, it is difficult to take accurate images due to the influence of heart beats. For this reason, the electrocardiogram (E 1 electro-C
A so-called ECG-synchronized imaging method has been implemented in which images are taken only from a certain phase of a heartbeat using a radio-gram.

Figure 5 explains the principle of such an ECG synchronized imaging method. Using the R wave, which is the steepest peak of the ECG signal that corresponds to the contraction of the ventricle, as a landmark, a certain period of time Δ is detected from this R wave. MR multiplied signal (echo signal) can be obtained by applying 900 pulses by the transmitting coil after delaying the signal, followed by a 180° pulse. By repeating the above operation every time an R wave is detected in the same way, it is possible to take images of the heart in synchronization with the systole and diastole of the ventricle, allowing for accurate imaging without being affected by the heartbeat. You will be able to take pictures. Note that t indicates the time for one heartbeat, and tR indicates the repetition time, and both are set equal.

FIG. 4 shows an outline of the case where ECG synchronized imaging is performed in this way, and a cable 1 for detecting ECG signals as shown in FIG. A plurality of, for example three, are connected via the electrode IA and guided to the signal processing circuit. As mentioned above, E from subject 6
MR imaging is performed by detecting a CG signal and applying a high frequency magnetic field at a predetermined timing.

(Problem to be Solved by the Invention) However, when a high-frequency magnetic field is applied to the conventional ECG signal cables used for such ECG synchronized imaging, the ECG signal cables are exposed to each other in a manner that is linked to the high-frequency magnetic field during MR imaging. Since the specimen may form a current loop for high-frequency current, there is a problem in that high-frequency current is induced and flows in this current loop. That is, as shown in FIG. 4, when a high frequency magnetic field H is applied, a high frequency current loop L is created interlinking with the high frequency magnetic field H, and a high frequency induced current flows through this loop L.

For this reason, the ECG signal cable or the ECG cable electrode generates heat, and in severe cases, the subject may be burned.

The present invention has been made in response to the above-mentioned problems.
EC for MRI equipment that suppresses high-frequency induced current
The purpose is to provide a G signal cable.

[Structure of the Invention] (Means for Solving the Problem) In order to achieve the above object, the present invention provides a cable for detecting an ECG signal by being connected to a subject during MR imaging, the cable comprising at least a portion of the cable. This is characterized by the provision of a resistor that suppresses high-frequency induced current.

(Function) By providing a resistor for suppressing high-frequency induced current in at least a portion of the cable, high-frequency induced current is suppressed, and therefore heat generation of the ECG signal cable or ECG cable electrode is suppressed. Therefore, there is no risk of the subject getting burned.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a configuration diagram showing an embodiment of the ECG signal cable for MRr device of the present invention, in which one end of the ECG signal cable 1 is
The CG cable is configured to be connectable to the subject via the electrode IA, and the other end is led to a signal processing circuit. The cable 1 is made of metal wire, carbon fiber, etc., and a resistance element 2 for suppressing high-frequency induced current is connected along the cable. This resistive element 2 is connected to the cable 1 via a connecting portion 3 by crimping, soldering, or the like.

Figure 2 shows an M in which the ECG signal cable 1 shown in Figure 1 is incorporated.
This shows an RI device, in which numeral 4 denotes a static magnetic field generator, which is constructed of a superconducting magnet using a superconducting coil 5, for example. Reference numeral 8 denotes a space that guides the subject 6 to be imaged in a dome, and in this dome 8, a high frequency coil 9 and a gradient magnetic field forming coil 10 necessary for imaging are arranged. 1
Reference numeral 1 designates a radio frequency (RF) pulse transmitting unit that applies an excitation pulse to the subject 6 to a high frequency coil 9, and reference numeral 12 designates a gradient magnetic field generating unit that generates a gradient magnetic field superimposed on a static magnetic field in a gradient magnetic field forming coil 10. The gradient magnetic field generating section 12 is designed to generate a slicing gradient magnetic field, a one-phase encoding gradient magnetic field, and a read gradient magnetic field, respectively, which are necessary for imaging.

13 is a signal collection unit that receives the MR multiplied signal from the subject 6;
Reference numeral 14 denotes an image creation unit that takes in the MR multiplied signals received by the signal collection unit 13 and reconstructs an MR image (magnetic resonance image) of the subject 6, and 15 visualizes the MR image formed by the image creation unit 14. This is an image display section. 16 is an imaging controller which connects the RF pulse transmitter 11. Gradient magnetic field generator 12. This is for controlling the signal collecting section 13 and the like. 17 is a part of the cover.

The body surface of the subject 6 guided by the dome 8 is marked E in Figure 1.
A plurality of CG signal cables 1 are connected via electrodes IA. The other end of the ECG signal cable 1 is connected to an imaging controller 16 for signal processing.

If MR imaging is performed using such an MRI apparatus as shown in FIG. 2, when a high-frequency magnetic field is applied to the subject 6 from the RF pulse transmitter 11 during MR imaging, it interlinks with this high-frequency magnetic field as shown in FIG. Even if the ECG signal cable 1 and the subject 6 create a current loop for high-frequency current, the high-frequency induced current flowing through the cable 1 due to this is suppressed by the provision of the resistive element 2. become. Therefore, the heat generation of the ECG signal cable 1 or the ECG cable electrode IA can be suppressed, so that there is no risk of burning the subject 6.

FIG. 3 shows the configuration of an ECG signal cable according to another embodiment of the present invention, in which a resistance region 2A is provided in the middle of the cable 1. This can be easily formed by mixing impurities into a specific region of a lead made of metal wire, carbon fiber, etc. to increase the resistivity of this region compared to other parts. That is, by changing the impurity concentration in a specific region of the lead 1, the resistivity can be increased.

[Effects of the Invention] As described above, according to the present invention, since a resistor for suppressing high-frequency induced current is provided in a part of the ECG signal cable, the high-frequency induced current flowing in the ECG signal cable can be suppressed. Can ECG signal cable or ECG
Heat generation of the cable electrode can be suppressed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of an ECG signal cable for an MRI apparatus according to the present invention, FIG. 2 is a block diagram showing an MRI apparatus in which the cable of this embodiment is incorporated, and FIG. 3 is a block diagram showing another embodiment of the present invention. FIG. 4 is a diagram illustrating the conventional problem, and FIG. 5 is a timing chart illustrating the ECG synchronized imaging method. 1...ECG signal cable for MRI device, 1A...
ECG cable electrode, 2... Resistance element, 2A... Resistance region, 4... Static magnetic field generating section, 6... Subject, 9...
...High frequency coil, 10... Coil for forming gradient magnetic field, 16... Imaging controller. Figure 1 Agent Patent Attorney Masayoshi Misawa 6th Nucleus A Book Figure 1

Claims (1)

[Claims] An ECG signal cable for an MRI apparatus, which is connected to a subject during MR imaging to detect an ECG signal, and is characterized in that at least a portion thereof is provided with a resistor for suppressing high-frequency induced current.