RF receiving coil apparatus and magnetic resonance imaging apparatus

With a view to providing a receiving coil which permits a subject to assume a supine position when radiographing the breast of the subject, thereby improving the working efficiency, a receiving coil for receiving a magnetic resonance signal from the breast of a subject lying within a static magnetic field space is provided in each of a first cup and a second cup of a brassiere which cups receive the breast of the subject SU therein.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Application No. 2005-154369 filed May 26, 2005.

BACKGROUND OF THE INVENTION

The present invention relates to an RF receiving coil apparatus and a magnetic resonance imaging apparatus.

A magnetic resonance imaging (MRI) system is known as a system able to form a tomographic image of a subject by utilizing a nuclear magnetic resonance (NMR) phenomenon. In many cases the magnetic resonance imaging apparatus is utilized in medical and industrial fields.

For forming a tomographic image of a subject by using a magnetic resonance imaging apparatus, first the subject is placed within a radiographing space with a static magnetic field formed therein and then the direction of spin in proton within the subject is aligned with the direction of the static magnetic field to create a state of having obtained a magnetization vector. Thereafter, an electromagnetic wave having a resonance frequency is emitted from an RF coil, whereby a nuclear magnetic resonance phenomenon is generated to change the magnetization vector of proton. Then, the magnetic resonance imaging apparatus receives in the RF coil a magnetic resonance signal from proton which returns to the original magnetization vector, and forms a tomographic image of the subject in accordance with the received magnetic resonance signal.

In magnetic resonance imaging, MR mammography is utilized for early-stage detection and treatment of a cancer of the breast. In the MR mammography, a subject assumes a prone position so that his or her breast is received in an RF coil, and then scanning of the breast is carried out (see, for example, Patent Literature 1).

Thus, in MR mammography, since the scanning is carried out in a prone position of the subject, breathing may be difficult or arms may become numbed, resulting in that the subject cannot retain the prone position for a long time, thus making it difficult to improve the working efficiency in radiographing.

Generally, when a subject undergoes an operation on his or her breast, the subject is brought into a supine position, and thus the posture of the subject differs between during scan and during operation. Consequently, when observing a pre-radiographed breast image in an operation of a breast, there sometimes occurs a case where it is difficult to easily specify an operation site, thus making it difficult to improve the working efficiency in the operation.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide an RF receiving coil apparatus and a magnetic resonance imaging apparatus which permits a subject to assume a supine position at the time of radiographing a breast, thereby making it possible to improve the working efficiency.

According to the present invention, for achieving the above-mentioned object, there is provided an RF receiving coil apparatus comprising: a coil for receiving a magnetic resonance signal provided from a breast of a subject lying within a static magnetic field space; and a brassiere including a cup for receiving therein the breast of the subject and a cup fixing portion for fixing the cup to the subject, wherein the coil is provided in the cup portion.

According to the present invention, for achieving the above-mentioned object, there also is provided a magnetic resonance imaging apparatus wherein a magnetic resonance signal provided from a breast of a subject lying within a static magnetic field space is received by an RF receiving coil section and an image of the breast is formed on the basis of the magnetic resonance signal received by the RF coil, the RF receiving coil section comprising: a coil for receiving the magnetic resonance signal; and a brassiere including a cup for receiving therein the breast of the subject and a cup fixing portion for fixing the cup to the subject, the coil being provided in the cup portion.

According to the present invention it is possible to provide an RF receiving coil apparatus and a magnetic resonance imaging apparatus which permits a subject to assume a supine position when radiographing the breast of the subject, thereby making it possible to improve the working efficiency.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention will be described hereinunder.

FIG. 1illustrates the construction of a magnetic resonance imaging apparatus1embodying the present invention.

As shown inFIG. 1, the magnetic resonance imaging apparatus1includes a static magnetic field magnet section12, a gradient coil section13, an RF coil section14, an RF drive section22, a gradient drive section23, a data collecting section24, a control section25, a cradle26, a data processing section31, an operating section32, and a display section33. The magnetic resonance imaging apparatus1radiates an electromagnetic wave to a subject SU lying within a radiographing space B with a static magnetic field formed therein, performs scanning for obtaining a magnetic resonance signal from the subject SU, and forms an image of the subject SU on the basis of the magnetic resonance signal obtained by the scan.

Components of the magnetic resonance imaging apparatus1of this embodiment will be described below one by one.

The static magnetic field magnet section12includes, for example, a pair of permanent magnets in a sandwiching relation to the radiographing space B and forms a static magnetic field in the radiographing space B in which the subject SU is accommodated. For example, the static magnetic field magnet section12forms a static magnetic field in a vertical direction Z in which the pair of permanent magnets confront each other. The static magnetic field magnet section12may be constructed so as to include magnets such as superconducting magnets other than the permanent magnets.

The gradient coil section13forms gradient magnetic fields within the radiographing space B with a static magnetic field formed therein. The gradient coil section13includes three systems of gradient coils so as to generate gradient magnetic fields which are gradient in the direction of three axes orthogonal to one another. With the three systems of gradient coils, the gradient coil section13forms gradient magnetic fields in a frequency encoding direction, a phase encoding direction and a slice selecting direction according to radiographing conditions.

More specifically, the gradient coil section13applies a gradient magnetic field in a slice selecting direction of the subject SU and selects a slice of the subject SU which is excited by transmission of RF pulse from the RF coil section14.

Moreover, the gradient coil13applies a gradient magnetic field in a phase encoding direction of the subject SU and encodes the phase of a magnetic resonance signal provided from the RF pulse-excited slice. Further, the gradient coil section13applies a gradient magnetic field in a frequency encoding direction of the subject SU and encodes the frequency of a magnetic resonance signal provided from the RF pulse-excited slice.

Within the radiographing space B in which a static magnetic field is formed by the static magnetic field magnet section12, the RF coil section14transmits RF pulse from an RF transmitting coil portion14ato the subject SU to form a high frequency magnetic field, thereby exciting a spin of proton in a radiographing region of the subject SU. Then, in the RF coil section14, an electromagnetic wave generated from the excited proton in the subject SU is received as a magnetic resonance signal by an RF receiving coil portion14b. In this embodiment, a magnetic resonance signal provided from the breast of the subject SU is received. As to the details of the RF receiving coil portion14b, a description will be given later.

The RF drive section12drives the RF coil section14for the transmission of RF pulse into the radiographing space B to form a high-frequency magnetic field. In accordance with a control signal provided from the control section25and using a gate modulator, the RF drive section22modulates a signal provided from an RF oscillator into a signal having a predetermined timing and a predetermined envelope, thereafter, using an RF power amplifier, amplifies the signal having been modulated by the gate modulator, and outputs the amplified signal to the RF coil section14, allowing RF pulse to be transmitted.

In accordance with a control signal provided from the control section25, the gradient drive section23drives the gradient coil section13by applying a gradient pulse thereto, causing a gradient magnetic field to be developed within the radiographing space B with a static magnetic field formed therein. The gradient drive section23has three systems of drive circuits (not shown) correspondingly to the gradient coil section13of three systems.

In accordance with a control signal provided from the control section25the data collecting section24collects the magnetic resonance signal which the RF coil section14receives and then outputs the collected signal to the data processing section31. The data collecting section24collects the magnetic resonance signal having been subjected to phase encoding and frequency encoding so as to correspond to the k space. In the data collecting section24, the magnetic resonance signal which the RF coil section14receives is subjected to phase detection using the output of the RF oscillator in the RF drive section22as a reference signal. Thereafter, using an A/D converter, the data collecting section24converts the magnetic resonance signal as an analog signal into a digital signal. The data collecting section24stores this magnetic resonance signal in memory and then outputs it to the data processing section31.

The control section25has a computer and programs for allowing various portions to execute operations corresponding to a predetermined scan with use of the computer. In accordance with an operation signal inputted from the operating section32through the data processing section31, the control section25outputs a control signal for execution of the predetermined scan to each of the RF drive section22, gradient drive section23and data collecting section24and makes control.

As shown inFIG. 1, the cradle26has a table for placing the subject SU thereon. In accordance with a control signal provided from the control section25the cradle26moves the subject SU placed on the table over an area between the interior and the exterior of the radiographing space B. For example, the cradle26moves the subject SU in a central axis direction of the radiographing space B which is in the shape of a column.

The data processing section31has a computer and programs for the execution of predetermined data processings with use of the computer. The data processing section31is connected to the operating section32and an operation signal provided from the operating section32is inputted to the data processing section31. The data processing section31is connected also to the control section25and outputs an operation signal to the control section25which signal is inputted to the operating section32by an operator. The data processing section31is further connected to the data collecting section24and acquires a magnetic resonance signal collected by the data collecting section24, then performs an image processing on the magnetic resonance signal thus acquired and forms an image on a slice of the subject SU. For example, the data processing section31performs a Fourier transform processing on a magnetic resonance signal which has been converted to a digital signal to form an image of the subject SU. Then, the data processing section31outputs the thus-formed image to the display section33.

The operating section32is composed of operating devices, including a keyboard and a mouse. The operating section32, which is operated by the operator, outputs an operation signal corresponding to operation performed by the operator to the data processing section31. In this embodiment, the operating section32is constructed so that the operator can select and input a scan over plural pulse sequences according to radiographing purposes.

The display section33is constituted by a display device such as CRT. The display section33displays an image on the slice of the subject SU which is generated on the basis of the magnetic resonance signal provided from the subject SU.

A detailed description will be given below about the RF receiving coil portion14bin the RF coil section14.

FIG. 2illustrates the RF receiving coil portion14b, in whichFIG. 2(a) is a front view of the RF receiving coil portion14bandFIG. 2(b) is an enlarged perspective view of a first cup401ain the RF receiving coil portion14b.

As shown inFIG. 2, the RF receiving coil portion14bhas a brassiere141and receiving coils241. These components will be described below one by one.

The brassiere141will be described first.

As shown inFIG. 2(a), the brassiere141includes a first cup401a, a second cup401b, and a cup fixing portion402, and encloses the breast B of the subject SU as a human body in good shape.

The first cup401aand the second cup401bin the brassiere141are formed in the same shape. In this embodiment, as shown inFIG. 2(b), the first cup401aand the second cup401bare each formed so as to have a semispherical space, and breasts of the subject SU are accommodated within the semispherical spaces respectively. More particularly, the first cup401a receives therein the right breast of the subject SU, while the second cup401breceives therein the left breast of the subject SU.

As shown inFIG. 2(b), the first cup401aand the second cup401beach include a first cover member412, a cover connecting member413, and a second cover member414.

The first cover member412is formed in a semispherical shape using cloth of both nylon and urethane fibers knitted therein for example so as to cover a top side T of the breast of the subject SU. The first cover member412is sewed to the cover connecting member413. In the first cover412, as shown inFIG. 2(b), a saddle-shaped coil241ain the receiving coil241is provided on the top side T so as to cover the top side T of the breast B of the subject SU.

As shown inFIG. 2(b), the cover connecting member413is provided so as to be sandwiched between the first cover member412and the second cover member414. The cover connecting member413is sewed to each of the first cover member412and the second cover member414, connecting both cover members with each other. The cover connecting member413is formed as a ring-shaped bellows mechanism using a plastic material for example and is adapted to expand and contract so that it can be fixed at any of plural different lengths between the top side T and an under side U of the breast of the subject SU.

FIG. 3is a sectional view showing the first cup401a, in whichFIG. 3(a) shows a contracted state of the bellows mechanism of the cover connecting member413in the first cup401aandFIG. 3(b) shows an expanded state of the bellows mechanism of the cover connecting member413in the first cup401a.

In case of the breast B of the subject SU being small in volume, as shown inFIG. 3(a), the cover connecting member413is used in a contracted state of the bellows mechanism. In case of the breast B of the subject SU being large in volume, as shown inFIG. 3(b), the cover connecting member413is used in an expanded state of the bellows mechanism.

The second cover414is formed in a ring shape using cloth of both nylon and urethane fibers knitted therein so as to cover the under side U of the subject SU. The second cover member414is sewed to the cover connecting member413. In the second cover member414, as shown inFIG. 2(b), a loop shaped coil241bis provided on the under side U of the breast of the subject Su so as to surround the under side U.

The cup fixing portion402of the brassiere141is provided for fixing the first cup401aand the second cup401bto the subject SU.

As shown inFIG. 2, the cup fixing portion402includes a trunk belt421, a first shoulder belt422a, a second shoulder belt422b, and trunk belt connecting portions423.

The trunk belt421is formed of cloth for example and is sewed so that the first and second cups401a,401bare arranged side by side in the extending direction of the belt. By being wound round the trunk portion of the subject SU, the trunk belt421fixes the first and second cups401a,401bto the subject SU.

The first shoulder belt422ais formed of cloth for example and one end thereof is connected by sewing to the first cup401aso as to extend in direction nearly perpendicular to the extending direction of the trunk belt421. To the portion of the trunk belt421extending in the direction opposite to the direction extending from the first cup401ato the second cup401b, an opposite end of the shoulder belt422ais connected by sewing so as to extend in a direction nearly perpendicular to the extending direction of the trunk belt421. That is, the first shoulder belt422ais connected to both first cup401aand trunk belt421so as to describe a loop and, by being wound round a shoulder portion of the subject Su, fixes the breast B in the first cup401ain a suspended manner to the subject SU.

The second shoulder belt422bis formed of cloth for example and one end thereof is connected by sewing to the second cup401bso as to extend in a direction nearly perpendicular to the extending direction of the trunk belt421. To the portion of the trunk belt421extending in the direction opposite to the direction extending from the second cup401bto the first cup401a, an opposite end of the second shoulder belt422bis connected by sewing so as to extend in a direction nearly perpendicular to the extending direction of the trunk belt421. That is, the second shoulder belt422bis connected to both second cup401band trunk belt421so as to describe a loop and, by being wound round a shoulder portion of the subject SU, fixes the breast B in the second cup401bin a suspended manner to the subject SU.

The trunk belt connecting portion423includes a hook423afixed by sewing to one end of the trunk belt421and a ring423bfixed by sewing to an opposite end of the trunk belt421. The hook423ais engaged with the ring423bto connect both ends of the trunk belt421with each other. In this embodiment, the ring423bis installed in plural positions at the opposite end of the trunk belt421and the hook423ais brought into engagement with any of the rings423blocated at plural different positions, whereby the trunk belt421can be fixed at any of plural different lengths.

The following description is now provided about the receiving coil241.

The receiving coil241receives a magnetic resonance signal from the breast B of the subject SU lying in a static magnetic field space11. As shown inFIG. 2, the receiving coil241includes the saddle-shaped coil241aand the loop-shaped coil241bso as to permit two-channel reception.

The saddle-shaped coil241ais provided on the top side T of each of the first cup401aand the second cup401bso as to cover the top side T of the breast B of the subject SU. More specifically, as shown inFIG. 2(b), the saddle-shaped coil241ais provided in the first cover member412of each of the first cup401aand the second cup401b.

On the other hand, the loop-shaped coil241bis provided on the under side U of each of the first cup401aand the second cup401bso as to surround the under side U of the breast of the subject SU. More specifically, as shown inFIG. 2(b), the loop-shaped coil241bis provided in the second cover member414of each of the first cup401aand the second cup401b. As the loop-shaped coil241bit is preferable to use, for example, a copper wire for retaining the shape of the breast B of the subject SU.

The saddle-shaped coil241aand the loop-shaped coil241bare geometrically decoupled and, by expansion and contraction of the cover connecting members413of the first cup401aand the second cup401brespectively, both coils move in parallel with each other so that there is little interference caused by mutual inductance.

Thus, in the magnetic resonance imaging apparatus1of this embodiment, the receiving coils241for receiving magnetic resonance signals from the breast of the subject SU lying within a static magnetic field space are provided respectively in the first cup401aand the second cup401bin the brassiere which cups accommodate the breast of the subject SU. Therefore, when the subject SU assumes a supine position for radiographing the breast, the breast B of the subject SU is enclosed by the first and second cups401a,401bof the brassiere141and assumes an orderly state, so that the receiving coils241can receive magnetic resonance signals from the breast B of the subject SU. Consequently, in this embodiment, not only the subject SU can perform the breathing action easily, but also his or her arms can be prevented from becoming numbed, thus making it possible to effect radiographing over a long time and permitting the operator to improve the working efficiency in radiographing. Besides, since the posture of the subject SU in radiographing and that in operation become the same, it is possible to easily specify an operation site at the time of operation of the breast B and hence possible to improve the working efficiency during operation. Thus, according to this embodiment, the subject SU can be brought into a supine position at the time of radiographing the breast, whereby the working efficiency can be improved.

In this embodiment, moreover, each of the first and second cups401a,401bis allowed to expand and contract between the top side T and the under side U of the breast B of the subject SU by the cover connecting member413which includes a bellows mechanism. Therefore, by expanding and contracting the bellows mechanism of each cover connecting member413, the volume of the space in which the breast B of the subject SU is received in each of the first and second cups401a,401bcan be changed to match the volume of the breast B. Therefore, in this embodiment, the receiving coils241provided respectively in the first cup401aand the second cup401bcan be made closer to the breast B of the subject SU to match the volume of the breast B, whereby it is possible to obtain an image of high quality and easily specify an operation site at the time of operation of the breast B. Thus, in this embodiment, the subject SU can be brought into a supine position at the time of radiographing the breast and it is thereby possible to improve the working efficiency.

Further, in this embodiment, the trunk belt connecting members423for connecting both ends of the trunk belt421of the cup fixing portion402are formed in such a manner that they can fix the trunk belt421at any of plural different lengths. Therefore, in this embodiment, the cup fixing portion402can fix each of the first cup401aand the second cup401bto the subject SU to match the length of the trunk portion of the subject SU. Consequently, when the subject SU is brought into a supine position, the shape of the breast B of the subject SU can be maintained in an orderly state by the first and second cups401aand401b. Thus, in this embodiment the subject SU can be brought into a supine position at the time of radiographing the breast and hence it is possible to improve the working efficiency.

In the above embodiment, the magnetic resonance imaging apparatus1corresponds to the magnetic resonance imaging apparatus of the present invention. The radiographing space B in the above embodiment corresponds to the static magnetic field space in the present invention. The RF receiving coil portion14bin the above embodiment corresponds to the RF receiving coil section and the RF receiving coil apparatus in the present invention. The brassiere141in the above embodiment corresponds to the brassiere in the present invention. The receiving coil241in the above embodiment corresponds to the coil in the present invention. The saddle-shaped coil241ain the above embodiment corresponds to the first coil in the present invention. The loop-shaped coil241bin the above embodiment corresponds to the second coil in the present invention. The first cup401ain the above embodiment corresponds to the cup in the present invention. The second cup401bin the above embodiment corresponds to the cup in the present invention. The cup fixing portion402in the above embodiment corresponds to the cup fixing portion in the present invention. The first cover member412in the above embodiment corresponds to the first cover member in the present invention. The cover connecting member413in the above embodiment corresponds to the cover connecting member in the present invention. The second cover member414in the above embodiment corresponds to the second cover member in the present invention. The trunk belt421in the above embodiment corresponds to the trunk belt in the present invention. The first shoulder belt422ain the above embodiment corresponds to the shoulder belt in the present invention. The second shoulder belt422bin the above embodiment corresponds to the shoulder belt in the present invention. Further, the trunk belt connecting portion423in the above embodiment corresponds to the trunk belt connecting member in the present invention.

In practicing the present invention, no limitation is made to the above embodiment, but various modifications may be adopted.

FIG. 4is a sectional view showing a first cup401aaccording to a modification.

For example, as shown inFIG. 4, as the cover connecting member413there may be used a face zipper comprising a pair of a hook portion413aand a loop portion413b, such as Magic Tale (trademark). As shown inFIG. 4(a), in case of the breast B of the subject SU being small in volume, the loop portion413bof the face zipper is engaged with the hook portion413aso as to shorten the distance between the first cover member412and the second cover member414. In case of the breast B of the subject SU being large in volume, as shown inFIG. 4(b), the loop portion413bof the face zipper is engaged with the hook portion413aso as to lengthen the distance between the first cover member412and the second cover member414.

For example, the trunk belt connecting portion423may be provided so as to be what is called a front hook type. That is, the hook423aand the ring423bof the trunk belt connecting portion423may be provided in the trunk belt421located between the first cup401aand the second cup401b, thereby making possible the engaging motion between the hook423aand the ring423bon the chest side of the subject SU and making the brassiere removable on the chest side of the subject SU. In this portion, as in the above embodiment, the trunk belt421may be formed so as to be adjustable among plural different lengths.