JPH04200530A - Head and neck part coil for mri - Google Patents

Abstract

PURPOSE:To obtain images of a required range with good quality by one time of image pickup by providing a deformed 8-shaped loop coil formed by coupling two deformed loops consisting of two loops, large and small, which are coupled to one, to an 8 shape and a deformed saddle-shaped loop coil facing the large loop. CONSTITUTION:The deformed saddle-shaped loop coil 2 is not oppositely disposed in the parts of the small loops 15, 16 of the 8-shaped loop coil 1 and, therefore, a sensitivity region is formed by the small loops 15, 16 alone and the shallow sensitivity region of a small effective relative sensitivity is obtd. Orthogonal magnetic fields are formed of the deformed saddle shaped loop coil 2 in the parts of the large loops 13, 14 and the entire part enclosed by the coil is the sensitivity region. The deep and large sensitivity region is thus obtd. The small loops are applied to the back from behind the neck of the person to be inspected. Since the neck from the head is inserted into the space of the large loop and the deformed saddle-shaped loop coil is inserted, the images of the backbone part up to about T6 over the entire part of the neck from the head are obtd. by one time of image pickup. Since the signals from the heart to entail the deterioration of image quality are not received, the image quality is improved.

Description

[Detailed description of the invention] [Industrial application field]

This invention relates to the transmission of excitation signals or NMR in an MRI apparatus that performs imaging using nuclear magnetic resonance (NMR).
The present invention relates to an RF coil used for receiving MR signals, and particularly to a head and neck coil suitable for imaging the head and neck.

[Conventional technology]

When diagnosing the head and neck, images from the first cervical vertebra (C1) to the sixth thoracic vertebra (T6) are required. Conventionally, as RF coils, a saddle-shaped coil for the neck and a coil for the chest are often used to separately image the neck and chest. This is because due to the presence of the human body's shoulders, it is difficult to insert the human body all the way into the saddle-shaped coil for the neck2, and as a result, the field of view up to T6 cannot be secured with only this saddle-shaped coil for the neck. It is from. Additionally, a planar coil (surface coil) with shallow sensitivity depth is used as the thoracic coil to avoid blood flow artifacts from the heart due to the thoracic vertebrae being in the same position as the heart.

[Invention or problem to be solved]

However, there is a problem in that the conventional method of separately capturing images using two RF coils to obtain an image of the required range is time-consuming and extremely inefficient. In view of the above, an object of the present invention is to provide a condylar head and neck coil for MRI, which can obtain images of a necessary range of the head and neck with good image quality in one imaging session.

[Means to solve the problem]

In order to achieve the above object, the MRI head and neck coil according to the present invention has a modified figure-8 loop in which two modified loops each formed by combining two large and small loops into one are combined in a figure-8 shape. It is characterized by being provided with a coil and a modified saddle-shaped loop coil disposed opposite to the large loop portion.

[For production]

In the small loop portion of the figure-eight loop coil, the modified saddle-shaped loop coil is not disposed facing each other, so a sensitivity region is formed only by this small loop. Therefore, a shallow and small sensitivity region with high effective relative sensitivity is obtained. On the other hand, in the large loop portion of the figure-eight loop coil, the modified saddle-shaped loop coils are arranged facing each other, so each of them forms an orthogonal magnetic field, and the entire area surrounded by these loop coils becomes a sensitive area. Therefore, a deep and large sensitivity region can be obtained. The small loop part is applied from the back of the subject's neck to the back, and the subject's neck is inserted from the head into the space surrounded by the large loop part and the modified saddle-shaped loop coil part. Therefore, the entire male part from the head to the neck and around T6 becomes the visual field, and an image of the entire visual field can be obtained by -degree imaging. In addition, since the small loop section provides a shallow, small sensitivity region with high effective relative sensitivity, it is possible to avoid receiving signals from areas that cause image quality deterioration, such as the heart, and improve the overall image quality. .

【Example】

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. 3. Figures 1, 2, 3, and 4 show an MRI head condylar neck according to an embodiment of the present invention. Fig. 1 is a view from an oblique direction, Fig. 2 is a view from a side, Fig. 3 is a sectional view taken along the line A-A in Fig. 2, and Fig. 4 is a view from a side view. It is a sectional view taken along the line BB in the figure. As shown in these figures, an MRI head condylar neck coil 8-shaped loop coil 1 and a modified saddle-shaped loop coil 2 are arranged to face each other. The figure-of-eight loop coil 1 has two deformed loops 11.12
are connected in a figure-eight shape. Transformation loop] 1.12
are each a large loop 13.14 and a small loop] 5.16
It becomes by combining. The entire structure is curved along the cylindrical surface (see FIGS. 1, 3, and 4). The modified saddle-shaped loop coil 2 is a modified version of a normal saddle-shaped loop coil that is curved along the cylindrical surface, and is shown on the front left side in FIG. 1 and on the left side in FIG. The curved part of is made oblique. Several capacitors 3 are inserted into each of these loop coils 1.2 (see Figures 2, 3, and 4).
(omitted in the figure). These two loop coils 1.2
is integrally embedded in a dielectric cylindrical retaining member (not shown). This cylindrical holding member has an area large enough for each loop coil 1.2 to be embedded, so that the large loop 13.14 and the modified saddle-shaped loop coil 2 are
In the part of , it covers the entire circumference of the cylinder side surface, but in the part of 5.16, it does not cover the entire circumference of the cylinder, but only a part of the cylinder side surface. When actually attached to the subject, it will look like the one shown in Figure 5.6 The head of the subject 6 is a cylinder containing the large loop of the figure-8 loop coil 1]3.14 and the modified saddle-shaped loop coil 2. A small loop 15.16 of the figure-8 loop coil will be inserted into the shape-retaining member, or from the neck to the back.
It's just a part of it. Therefore, the area of sensitivity can be set from the head and neck to the back without getting in the way of the part of the waste to which the R and F coils are attached. The loop coil 2 is connected to a signal synthesizer 5 via a 90" phase shifter 4 on either side. That is, the phase of either one is shifted by 90 degrees and then synthesized, and the signal is sent to the transmitter of the MHI device. With this refinement, if a current flows through each of the loop coils 1.2 as shown by the arrows in FIG. 1, then the small loop 15.
At the portion 16, a magnetic flux as shown by the dotted line in FIG. 3 is formed. That is, a small shallow area from the neck to the back becomes the sensitive area. Therefore, areas that cause image quality deterioration, such as the heart, fall outside the sensitivity area. Furthermore, since the sensitivity depth is shallow, the effective relative sensitivity can be improved. Therefore, the male part from the neck to the back can be used as the viewing area. On the other hand, magnetic flux as shown by the dotted line in FIG. 4 is formed in the large loop] 3.14 and the modified saddle-shaped loop coil 2. That is, the entire inside of the cylinder becomes a sensitive area, and the entire area from the head to the neck can be covered. Since the sensitivity region is thus wide, the effective relative sensitivity is reduced. Therefore, the magnetic field formed by the modified saddle-shaped loop coil 2 and the large loop 113, 14 of the figure-8-shaped loop coil 1
Noting that the magnetic fields formed by the two are orthogonal to each other, they are synthesized through a 90° phase shifter 4 to form a quadrature and prevent a decrease in the S/'N ratio. In the modified saddle-shaped loop coil 2, since one curved portion is made oblique, it is possible to avoid hitting the chest part of the subject 6. In addition, although the shape of the 8-shaped loop coil 1 and the modified saddle-shaped loop coil 2 are curved so as to be embedded in one cylindrical holding member in the above, the curved shape is not necessarily limited to a cylindrical shape. The shape of No. 2 can take various shapes to fit the human body. That is, for example, the figure-8 loop coil 1 can be made flatter to match the shape of the human body.

【Effect of the invention】

According to the head and neck coil for MRI of the present invention, it is possible to obtain images of the necessary range of the head and neck in one imaging session, and since the field of view is limited to the necessary range, the S/N ratio is high.
It is possible to take an image with an N ratio and obtain a good image quality. Further, it is easy to form a shape that fits the shape of the human body and is easily worn.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of the present invention, FIG. 2 is a side view of the embodiment, and FIG. 3 is taken along the line AA of FIG. 4 is a cross-sectional view taken along the line B--B in FIG. 2, and FIG. 5 is a schematic diagram of the device in use. 1... Figure-8 loop coil, 11.12... Deformed loop, 13.14... Large loop, 15.16... Small loop, 2... Deformed saddle-shaped loop coil, 3...
Capacitor, 4... 90° phase shifter, 5... Combiner, 6... Subject.

Claims (1)

[Claims] (1) A modified figure-8 loop coil in which two modified loops, each made by combining two large and two small loops, are combined into a figure-8 shape, and a modified saddle placed opposite the large loop part. A head and neck coil for MRI characterized by comprising a shaped loop coil.