JPH0565179B2 - - Google Patents

Description

[Detailed description of the invention] [Object of the invention] (Industrial application field) The present invention is directed to magnetic resonance (MR).
The present invention relates to a magnetic resonance imaging device that can generate images using the phenomenon of magnetic resonance.

(Prior art) Magnetic resonance is a phenomenon in which an atomic nucleus with non-zero spin and magnetic moment placed in a static magnetic field resonantly absorbs and emits only electromagnetic waves of a specific frequency. It resonates at the angular frequency ω ₀ (ω ₀ =2πν ₀ , ν ₀ ; Larmor frequency) shown in .

ω ₀ =γH ₀ where γ is the gyromagnetic ratio specific to the type of atomic nucleus, and H ₀ is the static magnetic field strength.

The device that performs biological diagnosis using the above principles is
Diagnosis that processes electromagnetic waves of the same frequency as above that are induced after the resonance absorption described above to reflect magnetic resonance parameters such as nuclear density, longitudinal relaxation time T ₁ , transverse relaxation time T ₂ , flow, and chemical shift. Information such as slice images of the subject can be obtained non-invasively.

Collecting diagnostic information using magnetic resonance can excite all parts of a subject placed in a static magnetic field and collect signals, but there are limitations in the equipment configuration and clinical aspects of imaging images. From the request,
The actual device excites a specific region and collects its signals.

In this case, the specific region to be imaged is generally a slice region with a certain thickness, and magnetic resonance signals (MR signals) such as echo signals and FID signals from this slice region are collected many times. A tomographic image (slice image) of the specific slice region is generated by collecting data by executing a data encoding process and subjecting the data group to image reconstruction processing using, for example, a two-dimensional Fourier transform method. In addition to tomographic images (slice images), it is also possible to obtain fluoroscopic images (Schiano images) and angio images suitable for use as positioning images.

In such a device, a whole-body coil built into the gantry excites a wide area of the subject and collects signals, thereby obtaining sagittal or coronal images or Schiyano images of a wide area. This enables positioning.

On the other hand, a method (multi-Surf Ace coil method) has been proposed in which a plurality of small, highly sensitive surface coils are embedded in the top plate of a bed to perform high-sensitivity imaging of localized areas. When this method is adopted, high-sensitivity imaging can be performed for the area near the selected surface coil, but it is not clear whether the area near the selected surface coil actually includes the region of interest to be diagnosed. , can only be confirmed after the photo is taken. That is, there is a problem in that it is difficult to accurately select a surface coil that includes a region of interest to be diagnosed.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a magnetic resonance imaging apparatus that can realize high-sensitivity imaging of a region of interest when employing a multi-Surface coil system.

[Structure of the Invention] (Means for Solving the Problems) The present invention has a structure in which the following means are taken to solve the above problems and achieve the objects.
In other words, the invention according to claim 1 includes a gantry capable of generating a magnetic field therein for causing a magnetic resonance phenomenon, and a gantry that is installed close to the gantry and moves back and forth into the gantry while placing a subject thereon. a bed having a top plate, and a plurality of RF coils, which are provided on the top plate of the bed and are involved in at least one of the generation of an excitation magnetic field related to a magnetic resonance phenomenon and the collection of magnetic resonance signals. A magnetic resonance imaging apparatus comprising: a setting means for setting a region of interest on a monitor displaying a reconstructed image based on the collected magnetic resonance signals, and a region corresponding to the region of interest on the image set by the setting means. calculation means for calculating position information in real space; and selection means for selecting one or more of the RF coils close to the region of interest in real space based on the position information calculated by the calculation means. It is characterized by having the following.

The invention according to claim 2 also provides a gantry capable of generating a magnetic field for causing a magnetic resonance phenomenon inside the gantry, and a gantry that is installed in close proximity to the gantry and that moves forward and backward into the gantry while placing a subject thereon. a bed having a top plate, and a plurality of RF coils, which are provided on the top plate of the bed and are involved in at least one of the generation of an excitation magnetic field related to a magnetic resonance phenomenon and the collection of magnetic resonance signals. A magnetic resonance imaging apparatus comprising: a setting means for setting a region of interest on a monitor displaying a reconstructed image based on the collected magnetic resonance signals, and a region corresponding to the region of interest on the image set by the setting means. calculation means for calculating position information in real space; and selection means for selecting one or more of the RF coils close to the region of interest in real space based on the position information calculated by the calculation means. and a moving means for moving the top plate so that the region of interest in real space is located at the center of the magnetic field in the gantry based on the position information calculated by the calculating means. do.

(Function) According to the invention according to claim 1, simply by setting a region of interest in an image displayed on a monitor, one or more of the RF coils close to the region are selected. High-sensitivity imaging is possible using the one or more selected RF coils.

Further, according to the invention according to claim 2, by simply setting a region of interest in an image displayed on a monitor, one or more of the RF coils in the vicinity of the region are selected; The selected one or more under favorable magnetic field conditions will be located at the center of the magnetic field within the gantry.
The RF coil enables high-sensitivity imaging.

(Example) A magnetic resonance imaging apparatus according to the present invention will be described below with reference to the drawings. That is, as shown in FIG. 1, this device uses a static magnetic field coil or a permanent magnet using a normal conduction or superconductivity method as a magnetic assembly MA that can accommodate a subject P therein. (Shim coils for static magnetic field correction may be added.) 1 and X, Y, and Z-axis gradient magnetic field generating coils for generating gradient magnetic fields for providing positional information of magnetic resonance signal induction sites. 2, and a whole-body RF coil 3 comprising a transmitting coil and a receiving coil, which is a transmitting/receiving system for transmitting a rotating high-frequency magnetic field and detecting an induced magnetic resonance signal (MR signal). have. This gantry 4
In the test subject introduction space, the coils 1, 2, 3 are installed.
A magnetic field for causing a magnetic resonance phenomenon is generated, and a uniform magnetic field region DSV is generated particularly at a portion located in the center of the figure.

On the other hand, a bed 5 is installed adjacent to the gantry 4. This bed 5 has a top plate 6 that moves forward and backward into the gantry 4 while placing the subject P thereon. Further, as shown in FIG. 2, a multi-Surf Ace coil 7 is embedded in the top plate 6.

Furthermore, as shown in FIG. 3, the multi-Surf Ace coil 7 can be selectively switched between a single coil or a plurality of coils by means of a switching circuit 8. That is, as shown in FIG. 3, when terminals a and b are selected by switching circuit 8, a single coil with terminals a and b at both ends is formed, and similarly when terminals a and c are selected by switching circuit 8, a single coil is formed with terminals a and b at both ends. A single coil is formed with ends a and c. That is, by selecting two or more terminals, it is possible to select a single coil or a plurality of coils in any position and size. Furthermore, an encoder 9 is provided on the bed 5 to measure the position of the top 6, and feedback control regarding the movement of the top 6 is performed based on the output of the encoder 9.

On the other hand, this device includes a transmitter 10 that controls the transmission of RF pulses, and a receiver 11 that controls the reception of induced MR signals. The transmitter 10 is configured to transmit excitation RF pulses to the whole body RF coil 3,
Moreover, the receiver 11 has a multi-surf ace coil 7.
It is designed to receive magnetic resonance signals collected by the Of course, the transmitter 10 transmits excitation RF pulses to the multi-surf ace coil 7, and the receiver 11 transmits whole-body RF pulses.
In the case where the magnetic resonance signals collected by the coil 3 are to be received, the transmitter 10 and the receiver 11
Both include Multi Surf Ace Coil 7 and whole body.
It is also possible to use any of the RF coils 3 as transmitting/receiving coils.

Furthermore, this device includes a gradient magnetic field power source 12 that performs excitation control of each of the gradient magnetic field generating coils 2 on the X, Y, and Z axes, and a pulse sequence for generating slice images and pulse sequences for generating spectroscopy. Sequencer 1 that can
3. A computer system 14 that controls these and performs signal processing of the detection signal and display thereof;
It has a monitor 15 and a console 16.

Next, the operation of this embodiment configured as described above will be explained with reference to the flowchart shown in FIG. Note that, prior to executing the process shown in FIG.
5 on the screen 15A. The illustrated display example is a sagittal image of the upper body of the subject P. Processing steps are started for this positioning image SI, and in step S1, for example, an ROI related to a line segment is specified. In this case, an axial image including the line segment ROI will finally be photographed, and step S2 is executed to set the photographing area of the axial image. That is, step
Set the field of view (FOV) in S2.

Next, in step S3, by determining the coordinates of the line segment ROI on the screen, the line segment ROI is
Calculate the coordinates of in real space. Note that there is a correspondence between the coordinates in real space and the coordinates on the image, and this relationship is established by the computer system 1.
4 is known in advance, and image reconstruction is performed using this correspondence. Therefore,
The computer system 14 calculates the magnetic field center of the line segment ROI based on the coordinate information of the line segment ROI in real space.
Find the distance from FC. This distance is the distance that the top plate 6 should move.

Next, in step S4, calculations for selecting a coil in the multi-Surface coil 7 are performed. That is, since the position of the line segment ROI in real space is already known, the single coil located directly below the line segment ROI is recognized.

Next, in step S5, computer system 1
The bed 5 receiving the command No. 4 moves the top plate 6 by the distance of the top plate movement. As a result, the position corresponding to the line segment ROI in real space is the center of the magnetic field.
It will match FC.

Next, in step S6, the switching circuit 8 receives a command from the computer system 14 and performs terminal switching in order to select the single coil directly below the line segment ROI recognized by the above-described operation.

Through the above series of operations, the axial cross section including the line segment ROI set on the positioning image shown in FIG.
The positioning setting for FC is made, and the operation of the switching circuit 8 selects a coil whose data collection area is an area corresponding to the line segment ROI of the subject P. As a result, an environment has been created in which highly sensitive data collection under a highly uniform magnetic field can be achieved for the axial cross section that includes the line segment ROI. In this case, the line segment ROI is a region arbitrarily designated by the operator on the screen, and this region is automatically set to the optimal imaging conditions.

After completion of the above settings, pre-scanning and photographing are performed in step S7, and the axial image shown in FIG. 6 is displayed on the screen of the monitor 16.

As described above, according to this embodiment, a desired area set on a positioning image can be imaged with high sensitivity using a surface coil selected in accordance with the area under highly uniform magnetic field conditions. becomes.

The present invention is not limited to the above-mentioned embodiments. For example, the present invention may be configured to perform at least one of moving the top plate 6 and switching the coil.
The present invention can be modified and implemented in various ways without departing from the spirit of the present invention.

[Effects of the Invention] As described above, the invention according to claim 1 includes a setting means for setting a region of interest on a monitor that displays a reconstructed image based on collected magnetic resonance signals, and a region of interest set by the setting means. a calculation means for calculating positional information in real space corresponding to the region of interest on an image; and an RF coil located close to the region of interest in real space based on the positional information calculated by the calculation means. By having a selection means for selecting one or more of the RF coils, simply by setting a region of interest on the image displayed on the monitor, one or more of the RF coils that are close to the region can be selected. Therefore, high-sensitivity imaging is possible using the one or more selected RF coils.

In the invention according to claim 2, there is provided a setting means for setting a region of interest on a monitor displaying a reconstructed image based on the collected magnetic resonance signals, and a setting means for setting a region of interest on the image set by the setting means. a calculation means for calculating position information in real space corresponding to the area of interest, and selecting one or more RF coils close to the region of interest in real space based on the position information calculated by the calculation means. By comprising a selection means and a moving means for moving the top plate so that the region of interest in real space is located at the center of the magnetic field in the gantry based on the position information calculated by the calculation means. ,
By simply setting a region of interest on the image displayed on the monitor, one or more of the RF coils near the region will be selected, and the region will be located at the center of the magnetic field within the gantry. , High-sensitivity imaging using the selected one or more RF coils is possible under favorable magnetic field conditions.

Therefore, according to the present invention, it is possible to provide a magnetic resonance imaging apparatus that can realize high-sensitivity imaging of a region of interest when employing the multi-Surface coil method.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of the magnetic resonance imaging apparatus according to the present invention, FIG. 2 is a perspective view showing the configuration of a bed in the embodiment, and FIG. 3 is a multi-Surf Ace coil in the embodiment. FIG. 4 is a flowchart showing the operation of the same embodiment, FIG. 5 is a diagram showing a positioning image in the same embodiment, and FIG. 6 is a diagram showing a final photographed image. MA...Magnetic assembly, 1...Static magnetic field coil, 2...Gradient magnetic field coil, 3...For whole body
RF coil, 4...gantry, 5...bed, 6...
...Top plate, 7...Multi Surf Ace coil, 8...
...Switching circuit, 9...Encoder, 10...Transmitter, 11...Receiver, 12...Gradient magnetic field power supply, 1
3...Sequencer, 14...Computer system, 15...Monitor, 16...Console.

Claims (1)

[Scope of Claims] 1. A gantry capable of generating a magnetic field therein to cause a magnetic resonance phenomenon, and a top plate that is installed in close proximity to this gantry and that advances and retreats into the gantry while placing a subject thereon. and a plurality of RF coils that are provided on the top plate of the bed and that are involved in at least one of the generation of an excitation magnetic field and the collection of magnetic resonance signals related to magnetic resonance phenomena. In the imaging apparatus, a setting means for setting a region of interest on a monitor that displays a reconstructed image based on the collected magnetic resonance signals;
a calculating means for calculating positional information in real space corresponding to the region of interest on the image set by the setting means; and calculating means for calculating positional information in real space corresponding to the region of interest on the image set by the setting means; 1. A magnetic resonance imaging apparatus, comprising: selection means for selecting one or more of the RF coils close to a region. 2. A gantry capable of generating a magnetic field for causing a magnetic resonance phenomenon inside the gantry, a bed installed close to the gantry and having a top plate that moves forward and backward into the gantry while placing the subject thereon; In a magnetic resonance imaging apparatus that is provided on a top plate of a bed and includes a plurality of RF coils that are involved in at least one of the generation of an excitation magnetic field related to a magnetic resonance phenomenon and the collection of magnetic resonance signals, said collection a setting means for setting a region of interest on a monitor displaying a reconstructed image based on the magnetic resonance signals;
a calculation means for calculating position information in real space corresponding to the region of interest on the image set by the setting means; and a calculation means for calculating position information in real space corresponding to the region of interest on the image set by the setting means; selection means for selecting one or more of the RF coils close to the region, the region of interest in real space is located at the center of the magnetic field in the gantry based on the position information calculated by the calculation means; A magnetic resonance imaging apparatus comprising: a moving means for moving the top plate as shown in FIG.