CN213934172U

CN213934172U - Magnetic resonance system with elliptical body coil

Info

Publication number: CN213934172U
Application number: CN202022126612.9U
Authority: CN
Inventors: S.比伯; J.尼斯特勒
Original assignee: Siemens Healthcare GmbH
Current assignee: Siemens Medical Ag
Priority date: 2019-09-27
Filing date: 2020-09-24
Publication date: 2021-08-10
Anticipated expiration: 2030-09-24
Also published as: DE202019105368U1

Abstract

The utility model relates to a magnetic resonance equipment with body coil. The body coil has a horizontal extent and a vertical extent in a cross section perpendicular to a central axis of the body coil. The body coil surrounds, in particular encloses, the patient receiving region in the circumferential direction around the central axis. The body coil has at least one opening in the direction of the central axis, which is suitable for moving a patient through the opening into the patient receiving region. Here, the horizontal extension is greater than the vertical extension, wherein the horizontal extension is at least 75cm and the vertical extension is at least 70 cm.

Description

Magnetic resonance system with elliptical body coil

Technical Field

The utility model relates to a magnetic resonance equipment with body coil.

Background

Magnetic resonance tomography is now a frequently used method for medical imaging. In this case, nuclear spins in the object, for example in a patient, are excited by means of a magnetic resonance system by means of a high-frequency signal (HF signal, english RF signal), and the emitted magnetic resonance signal is received and evaluated for imaging when the excitation is reduced. The high-frequency excitation signals can be emitted, in particular, by means of body coils (body coils) which are fixedly installed in the magnetic resonance apparatus, in particular, whole-body coils. Furthermore, the body coil usually comprises one or more antennas designed for transmitting high-frequency signals. The body coil can also be designed for receiving magnetic resonance signals.

The body coil usually surrounds a patient receiving region in which the patient is positioned during the magnetic resonance examination. The body coil generally defines a tunnel-shaped patient receiving area.

If the patient is in a narrow tunnel during the magnetic resonance examination, the patient may feel frustrated.

SUMMERY OF THE UTILITY MODEL

The to-be-solved technical problem of the utility model is to provide a magnetic resonance device, this magnetic resonance device provides comfort level as far as possible for the patient.

The above technical problem is solved by the features of the present invention. Advantageous embodiments are also described in the present application.

Therefore, a magnetic resonance apparatus with a body coil for transmitting high-frequency signals for generating magnetic resonance signals in a patient is proposed. The body coil has a horizontal extent and a vertical extent in a cross section perpendicular to a central axis of the body coil. The body coil surrounds, in particular encloses, the patient receiving region in the circumferential direction around the central axis. The body coil has at least one opening in the direction of the central axis, which is suitable for moving a patient through the opening into the patient receiving region. Here, the horizontal extension is greater than the vertical extension, wherein the horizontal extension is at least 75cm and the vertical extension is at least 70 cm. Preferably, the horizontal extension is at least 80cm and the horizontal extension is at least 75 cm.

In particular, horizontal extension may be understood as the clear width of the body coil in the horizontal direction. In particular, vertical extension can be understood as the clear width of the body coil in the vertical direction.

Preferably, the horizontal extension extends in the x-direction, the vertical extension extends in the y-direction, and the central axis of the body coil extends in the z-direction, wherein the x-, y-, and z-directions form an orthogonal coordinate system.

The different extensions in the horizontal and vertical directions provide that the body coil does not have a circular shape in cross section, but rather an oval and/or a round convex shape and/or a round shape with one side flattened.

In particular, the body coil may have an elliptical shape in cross section. Here, the horizontal extension preferably extends along the major axis of the ellipse and the vertical extension along the minor axis of the ellipse.

In particular, the body coil may comprise one or more electrically conductive antenna elements, which are arranged along an ellipse, for example an ellipse, perpendicular to the central axis.

The particularly large extension of the body coil provides a particularly large space for the patient, advantageously so that the patient does not feel cramped during the magnetic resonance examination.

A further embodiment of the magnetic resonance apparatus provides that the body coil comprises two electrically conductive end rings and a plurality of electrically conductive rods, wherein the end rings are connected by the rods.

The patient receiving area is preferably limited in cross section by two end rings. Preferably, the rod extends parallel to the central axis of the body coil.

Preferably, the body coil is designed as a birdcage coil. Birdcage coils are particularly well suited for transmitting high frequency excitation signals.

In a further embodiment of the magnetic resonance apparatus, the width of at least one end ring varies in the circumferential direction and/or the width of the rod varies.

The variation of the width of the at least one end ring and/or the rods may enable a better tuning of the body coil and/or an improved, in particular more uniform distribution of the HF magnetic field (also referred to as B1 field) generated by the body coil.

A further embodiment of the magnetic resonance apparatus provides that the magnetic resonance apparatus has a high-frequency shield (HF shield) arranged around the body coil, wherein the width of the end ring and/or the width of the rods is designed such that an equal inductance is present in the circumferential direction with respect to the HF shield. Preferably, a more uniform distribution of the HF magnetic field generated by the body coil can thereby be achieved.

A further embodiment of the magnetic resonance apparatus provides that the HF shield has a greater distance from the body coil in the vertical direction than in the horizontal direction.

In particular, the distance from the HF shield, i.e. the return flow space, can be selected small, for example 2cm, in the horizontal direction, since a larger return flow space in the vertical direction ensures still sufficient efficiency of the body coil as a transmitting antenna.

A further embodiment of the magnetic resonance apparatus provides that the magnetic resonance apparatus comprises a patient bed with a patient support surface, wherein the patient support surface is arranged at a vertical distance of between 12cm and 20cm from a vertically extending center point of the body coil.

In particular, the patient support surface is arranged below the vertically extending midpoint of the body coil, so that the patient support surface rests low in the patient tunnel. Thereby providing a relatively large space for the patient. At the same time, the imaging volume, which is usually determined by the magnet and the gradient coils of the magnetic resonance apparatus, can be optimally utilized.

A further embodiment of the magnetic resonance apparatus provides that the body coil is designed to be excited by means of an elliptical excitation. The distribution of the HF magnetic field generated by the body coil can thereby be improved. In particular, the homogeneity of the HF magnetic field can be improved. Preferably, the elliptical excitations have unequal amplitudes and/or a phase shift different from 90 °.

Drawings

Further advantages, features and details of the invention can be derived from the embodiments described below and with reference to the drawings. In all the drawings, parts corresponding to each other have the same reference numerals.

In the drawings:

figure 1 shows a magnetic resonance apparatus in a schematic view,

figure 2 shows a cross-sectional view of the body coil and the HF shield,

fig. 3 shows a body coil with two end rings of varying width in an expanded view.

Detailed Description

A magnetic resonance apparatus 10 is schematically shown in figure 1. The magnetic resonance apparatus 10 comprises a magnet unit 11 having a main magnet 12 for generating a strong and in particular temporally constant main magnetic field 13. Furthermore, the magnetic resonance apparatus 10 comprises a patient receiving region 14 for receiving a patient 15. In this exemplary embodiment, the patient receiving region 14 is designed in the form of a tunnel, the central axis z of which extends along the tunnel center. The vertical axis y is oriented perpendicular to the central axis z. In the circumferential direction, the patient receiving area 14 is surrounded by the magnet unit 11. The patient 15 can be moved into the patient accommodation region 14 by means of the patient support 16 of the magnetic resonance apparatus 10. Furthermore, the patient support device 16 has a patient bed 17 which is designed to be movable within the patient receiving region 14. The patient 15 lies on a patient support surface of a patient bed 17.

The magnet unit 11 also has a gradient coil unit 18 for generating magnetic field gradients, which are used for spatial encoding during imaging. The gradient coil unit 18 is controlled by means of a gradient control unit 19 of the magnetic resonance apparatus 10. Further, the magnet unit 11 includes a high-frequency antenna unit 20. The high-frequency antenna unit 20 comprises, in particular, a body coil 26, as is shown, for example, in fig. 2 and 3. The body coil 26 surrounds the patient accommodation region 14 in a circumferential direction around the central axis z. Furthermore, the body coil 26 has at least one opening in the direction of the central axis z, which opening is suitable for the patient 15 to pass through into the patient receiving region 14.

The body coil 26 is designed for transmitting high-frequency signals for generating magnetic resonance signals in the patient 15. In particular, an HF magnetic field can thereby be generated in the patient receiving region 14. The nuclei in the patient can be excited by the high-frequency signal, which then relax and emit magnetic resonance signals. The radio-frequency antenna unit 20 is controlled by a radio-frequency antenna control unit 21 of the magnetic resonance apparatus 10. The body coil 26 is also designed for receiving magnetic resonance signals.

For controlling the main magnet 12, the gradient control unit 19 and for controlling the high-frequency antenna control unit 21, the magnetic resonance apparatus 10 has a system control unit 22. The system control unit 22 centrally controls the magnetic resonance apparatus 10, such as for example, to execute a predetermined imaging gradient echo sequence. Furthermore, the system control unit 22 comprises an analysis unit, not shown in detail, for analyzing the medical image data acquired during the magnetic resonance examination. Furthermore, the magnetic resonance apparatus 10 comprises a user interface 23 connected to the system control unit 22. The control information (e.g. imaging parameters) as well as the reconstructed magnetic resonance image may be displayed for the medical operator on a display unit 24 of the user interface 23, e.g. on at least one monitor. Furthermore, the user interface 23 has an input unit 25, by means of which the medical operator can input information and/or parameters during the measurement process.

Fig. 2 shows the body coil 26 in a cross section perpendicular to the central axis z. The body coil 26 has a horizontal extension Δ x and a vertical extension Δ y, wherein the horizontal extension Δ x is larger than the vertical extension Δ y. The horizontal extension Δ x is at least 75cm, preferably at least 80 cm. The vertical extension deltay is at least 70cm, preferably at least 75 cm. A HF shield 27 is arranged around the body coil 26.

For large tunnel openings, the body coil 26 formed here in an elliptical shape, in particular in an elliptical shape, can better meet the requirements for the transmission power for generating the HF magnetic field. By means of the oval design, the return flow space Rx, i.e. the horizontal distance from the HF shield 27, can be selected to be smaller laterally, since a larger return flow space Ry, i.e. the vertical distance from the HF shield 27, above and below ensures sufficient efficiency of the body coil 26 as a transmitting antenna. For example, it is possible to achieve that the required HF transmit power is not increased even with an increased tunnel opening or an increased patient accommodation region 14. Furthermore, for magnetic resonance systems 10 with large tunnel openings or large patient receiving regions 14, the gradient coil units 18 and the main magnet 12 can be constructed as small as possible.

The patient support surface of the patient bed 17 is preferably arranged at a vertical distance of between 12 and 20cm, for example 15cm, from the center point M of the vertical extent Δ y of the body coil 26. In particular, the patient support surface is arranged below the center point M of the vertical extension Δ y of the body coil 26 in cross section.

The patient couch 17 is thus positioned lower in the patient accommodation region 14, so that as much space as possible is provided for the patient 15 and at the same time the imaging volume V, which is mainly defined by the main magnet 12 and the gradient coil unit 18, is optimally utilized.

Preferably, the patient bed is vertically adjustable, i.e., height adjustable, so that the patient 15 can be optimally positioned in the vertical direction in the patient receiving area 14. This embodiment is particularly advantageous here because of the large vertical extent Δ y of the body coil 26.

The body coil 26 is shown in an expanded view in fig. 3. The body coil comprises two electrically conductive end rings 28 and a plurality of electrically conductive rods 29, wherein the end rings 28 are connected by the rods 29.

In the example shown, the width of the two end rings 28 varies in the circumferential direction U. It is also conceivable, for example, that the width of the bar 29 also changes at the same time.

The tuning of the body coil 26 can be simplified by the variation of the width. In particular, the capacitance values can be set to the same size, resulting in a more uniform HF magnetic field distribution. Preferably, the width of the end rings 28 and/or the width of the rods 29 can be chosen such that there is an equal inductance in the circumferential direction U with respect to the HF shield 27.

The high-frequency antenna unit 20 can control the body coil 26 such that a circularly polarized HF magnetic field is generated, for example, with the same amplitude and a phase offset of 90 °. Furthermore, it is also conceivable to design the body coil such that it is excited by means of an elliptical excitation. The HF magnetic field homogeneity can be further improved by elliptical excitation, for example by identical amplitudes and/or a phase shift different from 90 °. This is particularly suitable, for example, in the case of a prone patient 15, when it is desired to optimize the compensation of the body coil 26 to a specific load situation.

Finally, it is pointed out again that the magnetic resonance apparatus shown is an example only, which can be modified in different ways by a person skilled in the art without departing from the scope of the invention. Furthermore, the use of the indefinite article "a" or "an" does not exclude that a feature referred to may also be present several times. Likewise, the terms "unit" and "element" do not exclude that the element in question consists of a plurality of co-acting sub-elements, which may also be spatially distributed, if desired.

Claims

1. A magnetic resonance apparatus having a body coil for transmitting high frequency signals to generate magnetic resonance signals in a patient,

characterized in that the body coil has a horizontal extension and a vertical extension in a cross section perpendicular to a central axis of the body coil,

wherein the body coil surrounds the patient receiving area in a circumferential direction around the central axis,

wherein the body coil has at least one opening in the direction of the central axis, which opening is adapted to move a patient through the opening into the patient receiving area,

wherein the horizontal extension is larger than the vertical extension,

wherein the horizontal extension is at least 75cm,

wherein the vertical extension is at least 70 cm.

2. The magnetic resonance apparatus of claim 1, wherein the horizontal extension is at least 80cm, wherein the horizontal extension is at least 75 cm.

3. The magnetic resonance apparatus of claim 1, wherein the body coil includes two electrically conductive end rings and a plurality of electrically conductive rods, wherein the end rings are connected by the rods.

4. The MR apparatus of claim 3, wherein the width of the at least one end ring varies in a circumferential direction and/or the width of the rods varies.

5. The magnetic resonance apparatus according to claim 4, characterized in that the magnetic resonance apparatus has an HF shield arranged around the body coil, wherein the width of the end ring and/or the width of the rods is designed such that there is an equal inductance in the circumferential direction with respect to the HF shield.

6. The magnetic resonance apparatus of claim 5, characterized in that the HF shield has a greater distance from the body coil in the vertical direction than in the horizontal direction.

7. The magnetic resonance apparatus of any one of claims 1 to 4, characterized in that the magnetic resonance apparatus has an HF shield arranged around the body coil, wherein the HF shield has a greater distance from the body coil in the vertical direction than in the horizontal direction.

8. The magnetic resonance apparatus of one of claims 1 to 6, characterized in that the magnetic resonance apparatus comprises a patient couch with a patient support surface, wherein the patient support surface is arranged in a vertical distance of between 12cm and 20cm from a vertically extending midpoint of the body coil.

9. The magnetic resonance apparatus of claim 8, wherein the patient support surface is arranged in cross section below a vertically extending midpoint of the body coil.

10. The magnetic resonance apparatus of any one of claims 1 to 6, characterized in that the magnetic resonance apparatus comprises a patient couch with a patient support surface, wherein the patient support surface is adjustable in a vertical direction.

11. The magnetic resonance apparatus of any one of claims 1 to 6, characterized in that the body coil is designed to be excited by means of an elliptical excitation.

12. The mr apparatus of claim 11 wherein the elliptical excitations have unequal amplitudes and/or a phase shift other than 90 °.