JPH0467861B2 - - Google Patents

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention produces a magnetic resonance phenomenon in a specific part of a subject placed in a static magnetic field, and detects the induced magnetic resonance signal. The magnetic resonance imaging apparatus is configured to obtain morphological information and functional information of the specific area by reconstructing slice images of the specific area using a magnetic resonance imaging apparatus, and is particularly applicable to intracranial, cervical, and thoracic vertebral areas for treating diseases of the spinal cord and vertebrae. , spinal fluid (CSF:
This invention relates to a magnetic resonance imaging device capable of depicting the flow of Cerebro Spinal Fluid.

(Prior Art) In order to diagnose hydrocephalus, which is a disease associated with outflow of spinal fluid into the skull, a method of depicting the flow of spinal fluid has been conventionally used. This is a method called X-ray micro-efficiency, and will be explained below. That is, this is a method in which an iodine contrast agent is injected using a syringe into a region where spinal fluid is expected to leak, and the region is contrasted with the iodine contrast agent and then X-ray photography is performed. In images taken using this method, the spinal fluid is highlighted in white using an iodinated contrast agent, making it possible to clearly see where the flow of spinal fluid is blocked, which is effective in diagnosing spinal disc herniation. It is true. There is also an X-ray myelography CT in which a CT image is obtained by injecting a contrast medium as described above.

However, the above-mentioned X-ray myelography
This method involves injecting an iodinated contrast agent using a syringe into a site where spinal fluid is expected to leak, which is a painful and dangerous method for the subject, and is not an easy diagnostic method.

(Problems to be Solved by the Invention) As described above, the conventional technique of X-ray myelography has been problematic because it is a painful and dangerous method for the subject.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a magnetic resonance imaging apparatus that can visualize the flow of spinal fluid without causing pain or danger to a subject.

[Structure of the Invention] (Means for Solving the Problems) The present invention has a structure in which the following measures are taken to solve the above problems and achieve the object. That is, the present invention provides a magnetic resonance system that generates a magnetic resonance phenomenon in a specific region of a subject placed in a static magnetic field, and detects the induced magnetic resonance signal to obtain morphological information and functional information about the specific region. The resonance imaging apparatus includes: a sequencer that executes a pulse sequence with short repetition intervals of excitation high-frequency pulses in order to magnetically excite a specific plane in the specific region; a probe for collecting magnetic resonance signals from the specific surface, the probe being disposed close to the specific surface with the specific surface being disposed approximately at the center of the uniform space of the static magnetic field; an electrocardiographic waveform detecting means for detecting an electrocardiographic waveform of a specimen; and repeatedly activating the sequencer in synchronization with a plurality of time phases set for the electrocardiographic waveform detected by the electrocardiographic waveform detecting means. The present invention includes means for obtaining a large number of slice images of different time phases through a probe, and display means for displaying the large number of slice images of different time phases obtained by this means in a high-speed cyclic manner.

(Effect) By taking such measures, it is possible to collect signals from the visualized region with high sensitivity and high speed, and by displaying a large number of slice images in a high-speed cyclic manner, a change in signal intensity appears, and this change is caused by the increase in spinal fluid. It depicts the flow, and is non-invasive and does not cause pain or danger to the subject.

(Example) The magnetic resonance imaging apparatus for depicting the flow of spinal fluid according to the present invention will be described below as an example of application to depicting the flow of spinal fluid within the skull.

FIG. 1 shows a magnetic resonance imaging apparatus used in this example.

As shown in Fig. 1, a magnet assembly capable of accommodating a subject P therein is equipped with a static magnetic field generated by a permanent magnet, a normal conducting magnet, a superconducting magnet, or a combination thereof. A magnet (sometimes a shim coil for static magnetic field correction is added) 1, a gradient magnetic field generating coil 2 that generates a gradient magnetic field for providing positional information of the induced site of the magnetic resonance signal, and a high-frequency magnetic field for excitation. It has a probe 3 consisting of a coil, which is a transmitting/receiving system for transmitting and detecting the induced magnetic resonance signals.

Here, the subject P places the head HP approximately at the center of the static magnetic field uniform space of the static magnetic field magnet 1 in order to slice the head median sagittal plane, and the probe 3 Use a head coil or head and neck coil that can cover the area.

In the case of the superconducting system, there is a static magnetic field control system 4 that includes a refrigerant supply control system and mainly controls the energization of the static magnetic field power source, and X-axis, Y-axis, and Z-axis gradient magnetic field power sources 5, 6, and 7. It is equipped with

Furthermore, the transmitter 8 provides power for generating a high-frequency magnetic field for excitation to the probe 3, and the signal from the receiving coil of the probe 3 is amplified to the extent that it can be applied to subsequent processing, and the output is divided into a real part and an imaginary part, respectively. The receiver 9 performs phase detection, converts the phase detection output into a digital signal, and outputs an A/D conversion output.

It also includes a sequencer 10 that executes a data collection sequence (gradient field echo method in which the angle of magnetization (flip angle) is smaller than 90°) as shown in FIG. 2 regarding protons, for example. This gradient fill echo method is widely known as a high-speed sequence in which the repetition interval T _R of excitation high-frequency pulses (90° pulses) is short. The raw data from the receiver 9 is sent to the computer system 1.
Here, the slice image is reconstructed using, for example, a two-dimensional Fourier transform method, and then displayed on the display system 1.
It is now displayed at 2. This display system 1
2 is configured to be able to hold a large number of images and to display the large number of held images in high-speed cyclic display, that is, in cine display.

The present embodiment also includes an electrocardiograph 13 that generates a signal synchronized with an electrocardiogram waveform. This electrocardiograph 1
3 consists of an induction electrode 13a that is applied to the subject P and a synchronization signal generation section 13b, and from this synchronization signal generation section 13b, the R wave-R wave is multi-divided (for example, the R wave-R wave interval is 800 msec). In the case of subject P, if the division is divided into 16, the division interval is 50 msec.) The synchronization signals S1, S2, S3, S4, S are sent at each division time.
5, S6~ is generated and given to the computer system 11 to be used as a photographing start signal.

With the apparatus configuration as described above, the method of this embodiment is performed as follows. That is, as shown in FIG. 3a, the electrocardiograph 13 sends synchronization signals S1, S2, S3, S4, S5,
S6~ is given to the computer system 11,
The computer system 11 receives this synchronization signal S1,
S2, S3, S4, S5, S6 and so on are given to the sequencer 10 as photographing start signals.

As a result, the sequencer 10 first executes the data collection sequence of the gradient field echo method shown in FIG. 7 to drive the probe 3 and the gradient magnetic field generating coil 2.
A predetermined magnetic field is generated to excite the slice site SI, and the induced magnetic resonance signal (echo signal)
is detected by the probe 3 and the receiver 9, and the temporal image at S1 is detected by the computer system 11.
IM1 is generated and the temporal image IM1 at S1 is held in the display system 12.

Next, in S2, use the same gradient as above.
The field echo method data collection sequence is executed and the computer system 11
A temporal image IM2 at S2 is generated, and the temporal image IM2 at S2 is held in the display system 12. This is carried out at S3, S4, S5, S6 ~ and the display system 1
Temporal images at S3, S4, S5, S6 ~ in 2
IM3, IM4, IM5, IM6~ are retained.

Through the above procedure, S1, S
2. Temporal images at S3, S4, S5, S6~
IM1, IM2, IM3, IM4, IM5, IM6~ are retained, and then the next phase image is created as shown in Figure 3b.
IM1, IM2, IM3, IM4, IM5, IM6 and so on are displayed in high-speed cyclic display, that is, cine display.

As described above, according to this embodiment, the temporal images IM1, IM2, IM3, IM4, IM5,
By displaying IM6~ in cine mode, the observer can visually follow the change in signal intensity (pixel value) between time-phase images. Therefore, since the signal strength changes depending on the flow velocity in a part where there is a flow, by displaying the cine, it is possible to know the degree of flow velocity of the spinal fluid CSF gushing out from the cerebral aqueduct.

In addition, in this embodiment, although image acquisition is performed within each division interval of electrocardiographic synchronization, the sequence of image acquisition is S/2 even if the echo time te is short.
A gradient field echo method with a high N is applied, and the flip angle is set to an angle smaller than 90°. Therefore, the changes in the temporal image within each division interval are emphasized only by the changes in signal intensity (pixel value) between the temporal images with respect to the flow velocity of the spinal fluid moving in response to the heartbeat. By displaying multiple temporal images in cine, only the flow of spinal fluid can be clearly shown.

Furthermore, the head HP, which is the object of depicting the flow of spinal fluid, is placed approximately at the center of the static magnetic field uniform space of the static magnetic field magnet 1, and a head coil or a head and neck coil capable of covering the head HP is installed. Therefore, the receiving sensitivity is high and a good image can be generated.

The above-mentioned movements are non-invasive movements for the subject P, so they do not cause any pain to the subject P, and
It is a diagnostic method that is not dangerous and can be easily performed.

The present invention has other embodiments as follows. In other words, the slice site for depicting the flow of spinal fluid is not limited to the midsagittal plane of the head mentioned above, but also the axial plane at the lateral ventricle level, the third ventricle level, the fourth ventricle level, and the midsagittal plane of the neck. Can be set.

In addition, in the above example, the flow of cerebrospinal fluid in the skull and neck was described.
It is also possible to visualize the flow of spinal fluid in the spinal cord in areas such as the lumbar vertebrae. That is, the desired diagnostic region of the lower back is placed approximately at the center of the static magnetic field uniform space of the static magnetic field magnet 1, and the spinal cord surface coil is applied to the diagnostic region, and a large number of It obtains a temporal image and displays it as a cine. This cine display allows you to clearly see that the flow of spinal fluid is obstructed.

Furthermore, the image acquisition sequence is not limited to the gradient field echo method, and various sequences, particularly high-speed sequences, can be implemented. In the spin echo method, each magnetic field is adjusted so that flowing protons are focused.

Furthermore, it does not specify each element of the magnetic resonance imaging device or the configuration of the electrocardiograph.

In addition, various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] As described above, in the present invention, a magnetic resonance phenomenon is caused in a specific region of a subject placed in a static magnetic field,
In a magnetic resonance imaging apparatus that detects induced magnetic resonance signals to obtain morphological information and functional information about the specific region, the repetition interval of the excitation high-frequency pulse is adjusted to magnetically excite a specific surface in the specific region. a sequencer that executes a short pulse sequence; a probe disposed close to the specific surface while being disposed approximately at the center of the body; an electrocardiographic waveform detecting means for detecting an electrocardiographic waveform of the subject; and an electrocardiographic waveform detected by the electrocardiographic waveform detecting means. means for obtaining a large number of slice images at different time phases through the probe by repeatedly activating the sequencer in synchronization with a plurality of time phases set in an electrocardiographic waveform; By being equipped with a display means for displaying a large number of slice images of a phase in a high-speed cyclical manner, it is possible to collect signals from the imaged region with high sensitivity and at high speed, and by displaying a large number of slice images in a high-speed cyclical manner, changes in signal intensity can be prevented. This change is a depiction of the flow of spinal fluid, which has the effect of being non-invasive, causing no pain to the subject, and without any danger.

[Brief explanation of drawings]

1 is a diagram showing the configuration of an apparatus capable of carrying out an embodiment of the method for depicting the flow of spinal fluid according to the present invention; FIG. 2 is a diagram showing an image acquisition sequence used in the configuration of FIG. 1; FIG. 3 is a diagram showing an example of image collection and display in the same embodiment. 1... Static magnetic field magnet, 2... Gradient magnetic field generating coil, 3... Probe, 4... Static magnetic field control system, 5.
6, 7...X-axis, Y-axis, Z-axis gradient magnetic field power supply, 8...
...Transmitter, 9...Receiver, 10...Sequencer,
11...computer system, 12...display system, 13...electrocardiograph.

Claims (1)

[Claims] 1. A magnetic resonance phenomenon is caused in a specific region of a subject placed in a static magnetic field, and the induced magnetic resonance signal is detected to obtain morphological information and functional information about the specific region. The magnetic resonance imaging apparatus includes: a sequencer that executes a pulse sequence with a short repetition interval of high-frequency excitation pulses in order to magnetically excite a specific plane in the specific region; and a sequencer that applies the high-frequency excitation pulses to the subject. and a probe for collecting magnetic resonance signals from the specific surface, the probe being disposed close to the specific surface with the specific surface being disposed approximately at the center of the uniform space of the static magnetic field; an electrocardiographic waveform detecting means for detecting an electrocardiographic waveform of the subject; and repeatedly activating the sequencer in synchronization with a plurality of time phases set to the electrocardiographic waveform detected by the electrocardiographic waveform detecting means, A magnetic resonance imaging apparatus comprising: means for obtaining a large number of slice images in different time phases through the probe; and a display means for displaying the large number of slice images in different time phases obtained by the means in a high-speed cyclic manner.