JPH0767441B2 - Magnetic resonance imaging device - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to magnetic resonance (MR: magnetic resonance)
"R") phenomenon, which is used for imaging with information based on the MR signal distribution of specific nuclear spins in a specific cross section of the subject, called a magnetic resonance imaging apparatus, especially the surface coil method. The present invention relates to a magnetic resonance imaging apparatus using the.

[Technical Background of the Invention and its Problems] For example, in a diagnostic MRI apparatus using the surface coil method, in order to obtain an image of a specific part of a subject, a magnetic pole surface is placed on the subject P as shown in FIG. A uniform static magnetic field H _o is made to act by the distorted magnets 11 (or coils) facing each other, and a linear magnetic field gradient is added to the static magnetic field H _o by the pair of gradient magnetic field coils 12 and 12, so that the subject P Placed on a local surface
An RF wave is transmitted by using the RF transmission / reception surface coil 13 to cause a rotating magnetic field to act.
The MR signal S received by 13 is imaged through the signal processing control means 14 mainly composed of a computer or the like and displayed on the display 15 (or recording means). Then, in the magnetic resonance imaging apparatus using the surface coil 13 as described above, an MR signal having an extension line substantially corresponding to the radius of the surface coil 13 is obtained as shown in FIG. Then, the area surrounded by this becomes the imaging area A.

By the way, the diagnosis by the surface coil method is performed on the local areas such as eyes, ears, cervix, and thyroid line, and as a device for knowing the positional relationship with various adjacent luminal organs and their surrounding structures. Use is desired.

The surface coil used for such an application needs to have a large diameter in order to widen the imaging area, but on the contrary, there is a problem that the resolution is lowered and it becomes difficult to clarify the local part. .

[Object of the Invention] The present invention has been made based on the above circumstances, and an object of the present invention is to provide a magnetic resonance imaging apparatus which has a wide imaging region and enables detailed elucidation of a local portion. Especially.

[Summary of the Invention] In order to achieve the above object, a magnetic resonance imaging apparatus according to the present invention comprises a static magnetic field generating means for generating a static magnetic field,
A gradient magnetic field generating means for generating a gradient magnetic field to be superimposed on the static magnetic field, a high-frequency generating means for applying an excitation magnetic field for causing a magnetic resonance phenomenon to the subject arranged in the magnetic field, and a body outside the subject. A surface coil arranged to receive a magnetic resonance signal generated from the subject and a magnetic resonance generated from the subject having a shape insertable into the body cavity of the subject and arranged in the receiving area of the surface coil. It has a coil for body cavity for receiving a signal, and an image generation means for generating a magnetic resonance image using the magnetic resonance signal received by the surface coil and the coil for body cavity.

Embodiments of the Invention Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view showing an embodiment of the present invention, in which a subject (for example, a living body) is placed in a static magnetic field H _o generated by a static magnetic field generating means (not shown) such as a permanent magnet or a coil. place as gradient coils 1,1 sandwiching the subject topical (including abdominal organs) P _1, arranged surface coils 2 having a large diameter as a transmitting and receiving coils on the surface of the object as surrounding the local P ₁ , A surface coil 3 for transmitting and receiving coils having a diameter smaller than that of the surface coil 2 is disposed in the vicinity of the local P ₁ inside the body located in or near the imaging area of the surface coil 2, and the surface coil 2 and the surface coil 3 are disposed. Each of the high frequency generation circuit 8
The surface coil 2,3 while sending the radio frequency (RF) signal from
A high-frequency bridge and a high-frequency amplifier circuit 5 for inputting a signal received by the high-frequency bridge, a phase detector circuit 6 for detecting the phase of the high-frequency signal from the high-frequency generator circuit 8 and a signal from the amplifier circuit 5, and the phase detector circuit. By the output from 6
It consists of a recorder 7 that records MR images in sequence.

The surface coil 3 is made of a shape memory alloy or the like so that it can be inserted into a body cavity and expanded in the body through warm water or the like. The diameter ratio with the surface coil 2 is a desired S / N ratio. It may be appropriately selected depending on the ratio or the sensitivity region.

Referring next to the operation of the device, linear magnetic field gradients are added by the gradient coils 1,1 in the uniform static magnetic field H _o by the static magnetic field generating means, and supplies the RF signal to each of the surface coils 2,3 the MR phenomenon occurs at the local P ₁ of the specimen. This MR phenomenon is received using the surface coils 2 and 3, captured as an MR signal, input to the phase detection circuit 6 via the high frequency bridge 4 and the high frequency amplification circuit 5, and based on the output of the phase detection circuit 6. Record the image on the recorder 7. In this way, the image obtained by the surface coil 2 represents a wide area which widely surrounds the local P _1, and the image obtained by the surface coil 3 clearly represents the localized area further defining the local P ₁ .

Therefore, local P ₁ is associated with the prostatic and seminal vesicles, the uterus and surrounding structures, the oral cavity and upper, the oropharynx, the stomach and surrounding structures, the luminal organs of the macrovascular valve, including the heart, and its associated organs. In this case, a wide area surrounding the local P ₁ can be confirmed, and at the same time, the position and situation of the local organ in that area can be analyzed, so that a high S / N ratio can be obtained for the target structure, and a wide angle and to a certain extent It is possible to secure a visual field with depth.

The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, the surface coil 3 is made of a shape memory alloy that can be expanded in the body through hot water or the like, but it is easy to place mercury or the like in the body. Various materials are also highly available, and their materials and structures can be selected as appropriate. The surface coils 2 and 3 may be provided separately for reception and transmission.

[Effects of the Invention] According to the present invention as described above, while observing the appearance of a wide area by the surface coil arranged on the surface of the subject,
The coil for body cavity placed inside the body enables simultaneous analysis of a target site with good resolution, and has an excellent effect of being able to analyze MR images of a luminal organ and surrounding structures with good image quality.

[Brief description of drawings]

FIG. 1 is a schematic view of a magnetic resonance imaging apparatus showing an embodiment of the present invention, FIG. 2 is a schematic view of a conventional apparatus, and FIG. 3 is an explanatory view showing an imaging area of a surface coil. 1 ...... gradient coil, 2,3 ...... surface coil, P ₁ ...... subject topical, H _o ...... static magnetic field.

Claims (1)

[Claims] 1. A static magnetic field generating means for generating a static magnetic field, a gradient magnetic field generating means for generating a gradient magnetic field superposed on the static magnetic field, and a magnetic resonance phenomenon for an object arranged in the magnetic field. A high-frequency generating means for applying an excitation magnetic field, a surface coil arranged outside the body of the subject to receive a magnetic resonance signal generated from the subject, and a surface coil having a shape insertable into the body cavity of the subject An image for generating a magnetic resonance image by using a coil for body cavity which is arranged in the receiving area of the body and receives a magnetic resonance signal generated from the subject, and a magnetic resonance signal which is received by the surface coil and the coil for body cavity. And a magnetic resonance imaging apparatus having a generating means.