JPS63220857A - Phantom for mri - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an MRI phantom used as a pseudo object in a magnetic resonance imaging apparatus (MRII equipment).

(Prior art) An MHI device applies a uniform static magnetic field to a desired region of a subject, and uses a transmitting RF coil to form an RF field perpendicular to the static magnetic field to obtain a tomographic image in a specific slice. The magnetic resonance phenomenon is generated only in the atomic nucleus, and the magnetic resonance phenomenon generated from the atomic nucleus after the RFil field is released (hereinafter MR
This device is designed to detect the double signal) using a receiving RF coil, and applies a linear magnetic field gradient that has a linear gradient in the X'-axis direction (coordinate system rotated θ° from the X-axis) to the static magnetic field. A synthesized MR low signal is obtained, and an MR image can be formed by Fourier transforming this signal.

Incidentally, in such an MRI apparatus, a phantom is used for research and development or adjustment of the MRI apparatus.

Conventionally, a copper sulfate solution or an iron oxide solution has been used as the phantom contents.

However, with such phantom contents, the MR
Since T1 (longitudinal relaxation time), T2 (transverse relaxation time) and conductivity in the phenomenon differ from each tissue of the human body, the following drawbacks occur.

That is, T1. In a phantom whose T2 is different from that of a human body,
Differences in imaging conditions suitable for the human body and the phantom cause differences in the obtained MR signal values. Additionally, the difference in conductivity causes a difference in the Q of the receiving RF (radio frequency) coil, which causes a large difference between the S/N ratio of the phantom MR image and the S/N ratio of the human body MR image. .

Therefore, volunteers are often used for the final adjustment of the MRI apparatus.

However, when using volunteers, there are many inconveniences such as the labor cost of 2 hours, the fact that the effects of MR phenomena on the human body are unclear, and the time and effort required for imaging.

(Problem to be solved by the invention) As mentioned above, the conventional phantom is TI.

Since the T2 and conductivity are different from those of the human body, it is unsuitable as an MRI phantom, and there are various problems such as the labor cost of 2 hours for volunteers.

Therefore, the present invention aims to eliminate the above-mentioned drawbacks, and provides an MRI phantom which can obtain an MR multiplied signal close to that of human tissue and is suitable for research, development, and adjustment of MRI apparatuses.

[Structure of the Invention] (Means for Solving Problems) The present invention has a plurality of phantom parts arranged containing polyvinyl alcohol and physiological saline.

(Function) Polyvinyl alcohol can vary the relaxation times Tt and T2 independently, and by adding physiological saline, the conductivity of the phantom can be made equivalent to that of human tissue. Therefore, by arranging a plurality of the above-mentioned phantom parts, it is possible to obtain MRI@ that is close to human tissue, and it is possible to obtain an MRI@ that is suitable for research, development, and adjustment of MRI equipment.
We can provide phantoms for RI.

(Example) Hereinafter, the present invention will be specifically explained with reference to Examples.

1 and 2 show one embodiment of the present invention, with FIG. 1 being a front view of the apparatus of this embodiment, and FIG. 2 being a perspective view of the main parts of FIG. 1.

As shown in FIG. 1, this MRI phantom 1 includes a frame 2 formed in a substantially U-shape, and a plurality of phantom units 3a that are detachably attached to the frame 2.

3b, 3G, 3d, and 3e.

Each of the phantom units 3a to 3e includes five phantom parts 4 formed in a cylindrical shape, as shown in FIG.
are arranged in one direction at a predetermined interval, and each end of each phantom part 4 is supported by a first support member 9 and a second support member 10.

Each phantom part 4 is made of polyvinyl alcohol (hereinafter referred to as r
PVAJ (abbreviated as PVAJ) and physiological saline are housed in a cylindrical case body 11, and the sizes thereof are all the same in appearance. Therefore, the relaxation times T1 and T2 of each phantom section 4 are different between adjacent phantom sections.

That is, in FIG. 1, the longitudinal relaxation time T1 differs little by little in the vertical direction, and the lateral relaxation time T2 differs little by little in the horizontal direction. Tt and T2 can be adjusted by adding permanent ions (for example, N i 2+ ) or activated carbon (or graphite) to PVA. Since the relaxation times T1 and T2 of living bodies such as the human body differ depending on the tissue, the T1 and T2 of the phantom section 4 are taken into consideration. Perform T2 adjustment. Further, the saline solution is used to make the electrical conductivity of each phantom section 4 equivalent to that of the human body.

In addition, frame body 2. 1st. A non-magnetic material such as acrylic is applied to the second support members 9 and 10 and the case body 11 of each phantom part 4.

In this way, according to this MRI phantom 1, since PVA is applied to each phantom part 4, the relaxation time T1
．． By adjusting T2, T1 and T2 can be brought closer to human tissue, and by adding physiological saline, the conductivity can be made equivalent to that of human tissue, so the M of the human body can be adjusted.
It is possible to obtain an MR multiplied signal which is extremely close to the R multiplied signal. Therefore, this MRI phantom 1 is suitable for use in research and development of MRI apparatuses and for adjustment of MRI apparatuses.

Roughly speaking, since each phantom unit 3a to 3e is freely WIJR attached to the frame 2, each phantom unit 3
It also has the advantage that sensitivity unevenness can be prevented by appropriately replacing a to 3e for each image and averaging the MR information.

Note that the present invention is not limited to the above-mentioned embodiments, and various modifications can be made.

For example, as shown in FIG. 3A, four blocks are formed in the outer case body 12 with partition surfaces 13 and 14 that include the central axis of the outer case body 12 formed in a cylindrical shape and are orthogonal to each other. A plurality of phantom sections 5 having different sizes are arranged in each block. Each phantom section 5 is formed by storing PVA and physiological saline in a cylindrical case body (inner case body) 6 as in the above embodiment. The spaces between each phantom section 5 are also filled with PVA and physiological saline. Although the relaxation times Tt and T2 are the same in all phantom parts 5, the difference in solution concentration inside and outside the cylindrical case body 6 differs for each block.

Since such an MRI phantom has a plurality of phantom sections 5 which are responsible for the size, it is suitable for inspecting the resolution of an MRI apparatus.

In addition, a plurality of phantom parts 5 having different sizes are shown in FIG.
They may be arranged randomly within the outer case body 12, as shown in FIG.

Roughly speaking, in the configurations shown in FIGS. 3 and 4, if a uniform aqueous solution of PVA is converted into a highly elastic material (gelatinized) by freezing and thawing, the thickness of the cylindrical case body 6 in each phantom part 5 can be reduced. It is possible to maintain the predetermined shape of the phantom portion 6 even if the comb is extremely thin, and thereby it is possible to prevent the cylindrical case body 6 itself from appearing in the MR image. For example, considering the resolution of the MRI apparatus, the smallest phantom part 5 may have a diameter of about 0.1 mm. In this case, if the cylindrical case body 6 in the phantom part 6 is thick, this will become the outline. This may appear on the MR image and interfere with resolution testing. In order to avoid this, it is better to make the wall thickness of the cylindrical case body 6 as thin as possible by gelling the PVA.

In the above description, the phantom part is cylindrical, but the phantom part may have any shape (for example, the 5th column).
It may have a cubic shape as shown in the figure.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to provide an MRI phantom that can obtain an MR multiplied signal close to human tissue in an MRI apparatus and is suitable for research, development, and adjustment of an MRI apparatus. .

[Brief explanation of the drawing]

FIG. 1 is a front view of an apparatus according to an embodiment of the present invention, FIG. 2 is a perspective view of the main parts of FIG. 1, and FIGS. 3, 4, and 5 are front views and perspective views of other embodiments. It is. 1.1A, 1B... MRI phantom device, 3a to ff13e... phantom unit, 4.5... phantom section. Figure 1 Figure 5

Claims (3)

[Claims] (1) In an MRI phantom device used as a pseudo object in an MRI device that forms an MR image of the object,
A phantom for MRI, characterized in that a plurality of phantom parts each containing polyvinyl alcohol and physiological saline are arranged. (2) Relaxation time T_1, T_ between adjacent phantom parts
2. The MRI phantom according to claim 1, wherein the phantom is different from the above. (3) The MRI phantom according to claim 1, wherein adjacent phantom parts have different sizes.