JPH04102444A - Pulse wave detector for mri device - Google Patents

Abstract

PURPOSE:To enable stable pulse wave synchronization MR photography by arranging a light source to supply optically light-to a detecting section disposed outside a predetermined magnetic field and a photoelectric converter to receive optically an optical pulse wave signal outputted by the detecting section and convert it to an electric signal. CONSTITUTION:A detector 10 has a detecting part 11 provided with a luminescent end 1, light receiving end 2, etc., a light source unit 13 for supplying light S1 thorough an optical fiber cable 12 to the luminescent end 1 and a photoelectric converter 15 for receiving an optical pulse wave signal S2 received by the light receiving end 2 through an optical fiber cable 14 to convert the signal to an electric signal S3. The light source unit 13 and photoelectric converter 15 are disposed outside a predetermined magnetic field formed in the MR photography of an MRI system. Thus, since the light S1 supplied to the detecting section 11 and the optical pulse wave signal S2 outputted by the detecting section 11 are optically transmitted by the optical fiber cables 12, 14, induction noises are not generated even if the optical fiber cables 12, 14 are disposed in the predetermined magnetic field formed in the MR photography, so that the stable pulse wave synchronization MR photography can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention (Industrial Application Field) The present invention relates to a pulse wave detector for an MHI device used for pulse wave synchronized MR imaging of a living body (usually a subject).

(Prior Art) In MR imaging, pulse wave synchronized MR imaging is performed in order to prevent artifacts from occurring in MR images due to the flow of blood, cerebrospinal fluid, etc. through the brain due to heart beats. This imaging method detects the pulse wave from the subject using a pulse wave detector,
MR imaging is performed in synchronization with this pulse wave.

A conventional pulse wave detector uses a photoelectric sensor such as a photodiode as a pulse wave detecting section to be inserted into a finger or the like of a subject to detect a fingertip pulse wave or the like. Methods for detecting this pulse wave include a transmission method and a reflection method.

As shown in FIG. 2, the transmission method is a method in which the light emitted from the light emitting end 1 is transmitted to the finger F, and this transmitted light is detected by the light receiving end 2 placed opposite the light emitting end 1. . Taking advantage of the fact that when there is a lot of blood flow, more light is absorbed and the amount of transmitted light decreases, pulse waves are detected by detecting changes in transmitted light due to blood flow.

Although not shown in the drawings, the reflection method detects a pulse wave by detecting changes in reflected light emitted from blood flow.

The photoelectric sensor used in conventional pulse wave detectors receives an electrical signal from a power source through a cable led out from the sensor, emits light, converts the detected transmitted light into an electrical signal, and then transmits the light through the cable led out from the photoelectric sensor. The electric signal from the lever was output as a pulse signal.

(Problems to be Solved by the Invention) However, since MRI apparatuses generate high-frequency excitation pulses and gradient magnetic field pulses when performing MR imaging,
There is a problem in that these pulses generate induced noise in the cable, and this noise mixes into pulse signals, causing the MRI apparatus to malfunction.

The present invention has been made in view of the above circumstances, and provides an MRI system capable of performing stable pulse wave synchronized MR imaging.
The object of the present invention is to provide a pulse wave detector for a device.

[Configuration of the Invention (Means for Solving the Problems) In order to achieve the above object, the present invention provides an MRI system which places a living body in a predetermined magnetic field and subjects the living body to pulse wave synchronized MR imaging. The pulse wave detector for a device includes a detection unit that optically detects the pulse wave of the living body and outputs a pulse wave optical signal, and a light source that is disposed outside the predetermined magnetic field and optically supplies light to the detection unit. and a photoelectric converter that is disposed outside the predetermined magnetic field and optically receives the pulse wave optical signal output from the detection section and converts it into an electrical signal.

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

The light supplied to the detection section and the pulse wave optical signal output from the detection section are optically transmitted. This allows this transmission system to become MR.
Even when placed in a predetermined magnetic field formed during imaging, noise does not enter the transmission system, allowing stable pulse wave synchronized MR imaging.

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

FIG. 1 shows a schematic configuration of a detector 10 according to an embodiment of the present invention and M
FIG. 3 is a diagram showing an example of application to an RI device.

This detector 10 includes, as shown in FIG. Then, the light receiving end 2 receives the received pulse wave optical signal S2 via the optical fiber cable 14 and converts it into an electrical signal S.
3.

The synchronized imaging control unit 20 outputs a synchronizing signal S4 to the MHI system control unit 21 based on the electrical signal S3 outputted by the photoelectric converter 15, and the MR1 system control unit 21 outputs the synchronizing signal S4 as shown in the figure based on the transmitted synchronizing signal S4. Pulse wave synchronized MR imaging is performed by controlling the MRI system that does not operate.

The light source unit 13 and the photoelectric converter 15 are arranged outside a predetermined magnetic field formed by the MHI system during MR imaging, and the light source unit 13 and the photoelectric converter 15
MR imaging is made so that it does not affect or is not affected by the MR imaging.

Next, the operation of the detector 10 having the above configuration will be explained.

First, the detection unit 11 is inserted into the finger F of the subject, and pulse wave synchronized MR imaging is started for a desired imaging target region such as the head.

Light S□ output from the light source unit 13 is output from the light emitting end 1 of the detection section 11 via the optical fiber cable 12. This light S is partially absorbed by the blood flow of the finger F, passes through the finger F, is received by the light receiving end 2, and is received by the photoelectric converter 15 as a pulse wave optical signal S2 via the optical fiber cable 14.

The photoelectric converter 15 outputs an electric signal S depending on the strength of the pulse wave optical signal S2 to the synchronous imaging control unit 20. The synchronous imaging control unit 20 sends a synchronous signal S4 to the MRr system control unit 21 based on the sent electric signal S3.
Output to. The MRI system control unit 21 controls an MRI system (not shown) based on the sent synchronization signal S4, and performs MR imaging in synchronization with the pulse wave of the subject.

Through this MR imaging, an MR image with few artifacts of a desired imaging target region such as the head can be obtained.

According to the above embodiment detector 10 configured in this way,
The light S□ supplied to the detection unit 11 and the pulse wave optical signal S2 outputted from the detection unit 11 are optically transmitted by the optical fiber cable 12.14, so the optical fiber cable 1
Even if 2.14 is placed in a predetermined magnetic field formed during MR imaging, no induced noise is generated, so stable pulse wave synchronized MR imaging can be performed.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be variously modified without changing the gist thereof.

[Effects of the Invention] According to the present invention described in detail above, it is possible to provide a pulse wave detector for an MRI apparatus that can perform stable pulse wave synchronized MR imaging.

[Brief explanation of the drawing]

FIG. 1 shows a schematic configuration of a detector according to an embodiment of the present invention and an MRI
A diagram showing an example of application to the device, and FIG. 2 is a diagram showing the principle of pulse wave detection. 10... Pulse wave detector, 15... Photoelectric converter, F
...Finger, S-operation...Light, S2...Pulse wave optical signal,
S3...Electric signal. Diagram

Claims (1)

[Claims] A pulse wave detector for an MRI apparatus, which is used for pulse wave synchronized MR imaging of a living body placed in a predetermined magnetic field formed, optically detects the pulse wave of the living body and outputs a pulse wave optical signal. a light source disposed outside the predetermined magnetic field and optically supplies light to the detection section; and a light source disposed outside the predetermined magnetic field that optically receives the pulse wave optical signal outputted by the detection section and generates electricity. 1. A pulse wave detector for an MRI apparatus, comprising a photoelectric converter for converting into a signal.