MAGNETIC FIELD PROBE, PRODUCTION OF SAME, AND METHOD FOR OPERATING A MAGNETIC FIELD PROBE

Abstract

A magnetic field probe (1) having a capsule (3), in which an MR-active substance (5) is encapsulated. Two coils (7, 9) are preferably arranged in the capsule (3). Advantageous production methods for magnetic field probes (1) are also described, as well as advantageous uses of the magnetic field probe (1) and methods in which magnetic field probes (1) of this kind and arrangements of magnetic field probes (1) are used.

Claims

1. A magnetic field probe (1), comprising: a capsule (3) encapsulating an MR-active substance (5); a first coil (7) disposed within the capsule; and a second coil (9) disposed within the capsule (3).

2. The magnetic field probe (1) as claimed in claim 1, wherein the MR-active substance (5) fills a cavity (11) formed by the capsule (3).

3. The magnetic field probe (1) as claimed in claim 1, wherein the capsule (3) is in spherical form.

4. The magnetic field probe (1) as claimed in claim 1, wherein the capsule (3) is formed from a material (19) of homogeneous composition.

5. The magnetic field probe (1) as claimed in claim 1, wherein a winding (13) of the first coil (7) is disposed within a winding (15) of the second coil (9).

6. The magnetic field probe (1) as claimed in claim 1, wherein the second coil (9) is configured to generate a homogeneous magnetic field within a volume (17) formed by the MR-active substance (5).

7. The magnetic field probe (1) as claimed in claim 1, wherein the second coil (9) is configured to generate a spatially varying magnetic field within a volume (17) formed by the MR-active substance (5).

8. A magnetic field probe (1), comprising: a capsule (3) encapsulating an MR-active substance (5); a first coil (7) disposed within the capsule; and the MR-active substance (5) fills a cavity (11) formed by the capsule (3).

9. The magnetic field probe (1) as claimed in claim 8, wherein the MR-active substance forms direct contact with the capsule.

10. An arrangement of magnetic field probes (1), comprising: a plurality of the magnetic field probes (1) according to claim 1, wherein for each of the magnetic field probes (1): the first coil (7) is connectable or is connected to receiving electronics set up to receive a signal emitted by the MR-active substance (5); and the second coil (9) is connectable or is connected to actuating electronics set up to generate a magnetic field that is at least one of constant over time or of low frequency.

11. A production process for production of a magnetic field probe (1), the process comprising: disposing a first coil (7) in a curable material (19); introducing an MR-active substance (5) into the material (19); and then curing the curable material (19).

12. The production process for production of a magnetic field probe (1) according to claim 11 wherein the MR-active substance (5) is introduced into an internal volume (27) surrounded by an outer surface (25) of a curable material (19) and the material (19) is then cured, wherein the curing of the material (19) is preceded by arrangement of a first coil (7) within the internal volume (27), characterized in that the curing of the material (19) is preceded by arrangement of a second coil (9) in the material (19).

13. The production process as claimed in claim 11, wherein the material (19) is cured by at least one of electromagnetic radiation, a variation in temperature, or catalytically.

14. The production process as claimed in claim 11, wherein a quantum (29) of the curable material (19) is first laid out and cured on a working surface (31), and the cured quantum (29) is then turned over and serves as a basis (33) for the further production of the magnetic field probe (1).

15. A method of operating the magnetic field probe (1) according to claim 1, the method comprising: receiving a signal from the MR-active substance (5) with the first coil (7), and generating a magnetic field with the second coil (9) that is constant over time or a low-frequency magnetic field.

16. A method of operating the magnetic field probe (1) as claimed in claim 1 for shifting a resonance frequency of the MR-active substance (5) during an MR measurement on a measurement object (21), the method comprising: shifting the resonance frequency to such an extent that one said resonance frequency of the MR-active substance (5) falls out of at least one of (a) at least one of a receiving range or transmission range of an MR instrument used for the MR measurement, (b) out of a measurement range of a measurement signal generated by the measurement object in the MR measurement, or (c) out of a transmission range of an excitation impulse used for the MR measurement.

17. A method of operating the magnetic field probe (1) according to claim 1, the method comprising: dephasing a signal generated by the MR-active substance (5) using the second coli (9).

18. The magnetic field probe (1) as claimed in claim 4, wherein the MR-active substance (5) forms direct contact the material (19) of the capsule (3).

19. The magnetic field probe (1) as claimed in claim 5, wherein at least one of the windings (13, 15) of the first coil (7) and of the second coil (9) or the magnetic fields generated by the first coil (7) and the second coil (9) are oriented orthogonally to one another.

20. The production process as claimed in claim 11, wherein material properties of the MR-active substance (5) and of the curable material (19) are chosen such that the MR-active substance (5), after being introduced into the material (19), takes on an elliptical geometry.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0072] The invention is now described in detail with reference to a few working examples, but is not limited to these few working examples. Further variants of the invention and working examples result from combination of the features of individual or multiple claims with one another and/or with individual or multiple features of the working examples and/or of the above-described variants of inventive devices and processes.

[0073] The figures show:

[0074] FIG. 1 a working example of a magnetic field probe of the invention,

[0075] FIG. 2 a working example of a production process of the invention for production of a magnetic field probe according to FIG. 1, and

[0076] FIG. 3 an alternative working example of a production process of the invention for production of a magnetic field probe according to FIG. 1.

DETAILED DESCRIPTION

[0077] In the description of various working examples of the invention that follows, elements of corresponding function are given identical reference numerals even in the case of different configuration or shaping.

[0078] The magnetic field probe 1 shown in FIG. 1 has a capsule 3 made of ultraviolet light-cured material 19. The capsule 3 is spherical. The capsule 3 is in solid form and closed off from the outside. The surface 25 forms a continuous face; only at four points do terminals 35 and 37 for a first coil 7 and second coil 9 embedded in the capsule 3 project out of the capsule 3. Formed in the middle of the capsule 3 is a cavity 11 completely filled with an MR-active substance 5, which in the working example described here consists essentially of water doped with a substance having the effect that the susceptibility of the MR-active substance 5 is equal to the susceptibility of the material 19 of the capsule 3 and to the susceptibility of the first coil 7 and second coil 9 consisting of copper wire.

[0079] The first coil 7 has a winding 13. The winding 13 is configured such that the coil 7 forms a solenoid coil. The second coil 9 also has a winding 15. The coil 9 in the working example described here is likewise a solenoid coil. The first coil 7 has an internal diameter corresponding to the external diameter of the volume 17 occupied by the MR-active substance. The first coil 7 is arranged within a volume surrounded by the second coil 9. The first coil 7 and the second coil 9 are oriented orthogonally to one another.

[0080] The MR-active substance 5 is encapsulated in the capsule 3. The MR-active substance 5 is enclosed in the capsule 3.

[0081] The MR-active substance 5 is disposed within an internal volume 27, with the internal volume 27 in the working example described here occupying that volume surrounded by the outer surface 25 of the cured material 19.

[0082] The second coil 9 in solenoid form, in the volume 17 formed by the MR-active substance 5, generates a homogeneous magnetic field when a potential difference is applied to the terminals 37 of the second coil 9 and therefore a current flows through the second coil 9.

[0083] If the second coil 9 is operated at constant current, there is thus a uniform change in the magnetic field strength in the volume 27 of the MR-active substance 5, such that the resonance frequency of the nuclear spins of the hydrogen nuclei present in the MR-active substance 5 is shifted by a current-dependent value. Some technical effects and practical applications in this regard have already been described above.

[0084] In alternative working examples that are not shown here, the first coil 7 and/or the second coil 9 are configured differently, such that, for example, the second coil 9 does not generate a homogeneous magnetic field, but rather a spatially varying magnetic field, for instance a linearly varying magnetic field. Some variants in this regard have already been described further up.

[0085] FIG. 2 shows, from the top downward, multiple steps of a process by which a magnetic field probe 1 according to FIG. 1 can be produced. In a first process step 100, the first coil 7 and the second coil 9 are positioned alongside one another. In a second process step 102, a droplet of curable material 19 that forms the capsule 3 of the magnetic field probe 1 after curing is then applied, such that the first coil 7 and the second coil 9 are arranged in the middle of the material 19. The terminals 35 and 37 of the first coil 7 and of the second coil 9 project out of the material 19.

[0086] In a third process step 104, a pipette 41 is then used to inject a small droplet of the MR-active substance 5 into the curable material 19. This is injected into a volume surrounded by the first coil 7. The introduction of the MR-active substance 5 into the material 19 displaces the material 19 at this point. The MR-active substance 5 forms a spherical geometry, the spherical surface of which is fully encapsulated within and by the material 19. In the working example shown here, the diameter of the volume 17 occupied by the MR-active substance 5 corresponds to the internal diameter of the first coil 7. The internal diameter of the first coil 7 may, for example, be 1 mm, and the external diameter thereof may, for example, be 1.4 mm. In an alternative working example, the internal diameter of the first coil 7 is greater than the diameter of the volume occupied by the MR-active substance 5.

[0087] In a next process step 106, the first coil 7 together with the MR-active substance 5 is pushed into the second coil 9, such that the winding 13 of the coil 7 is surrounded by the winding 15 of the second coil 9. The second coil 7 may have, for example, an internal diameter of 1.8 mm and an external diameter of 2.2 mm. The two coils 7, 9 in the working example described here are wound from enameled copper wire. After this process step, the winding 13 of the first coil 7 and the winding 15 of the second coil 9 both surround the volume 17 filled by the MR-active substance 5. The first coil 7, the second coil 9 and the MR-active substance 5 are shifted here such that they are disposed exactly in the middle of the material 19. At this juncture, the material 19 has not yet cured. Prior to curing of the material 19, in FIG. 2 and also in FIG. 3, the material 19 is additionally given the reference numeral 21 and is shaded dark grey.

[0088] In a final production step 108, the uncured material 19, 21 is then irradiated with UV light, such that the material 19 cures. After curing, the material 19, in FIG. 2 and also in FIG. 3, is additionally given the reference numeral 23 and is shaded light grey.

[0089] FIG. 3 illustrates an alternative production process of the invention for the magnetic field probe 1 from FIG. 1.

[0090] In a first process step 200, a droplet of an as yet uncured material 19, 21 is applied to a flat working surface 31. The material 19, 21 is then irradiated with UV light 39, such that the material 19 cures and forms a cured material 19, 23. This is effected in step 202. This gives rise to part of a capsule 3.

[0091] In the next process step 204, the cured material 19, 23 on the working surface 31 is turned over, such that the surface of the material 19, 23 that was in contact at first with the flat working surface 31 forms a flat base 33. The further process steps 206 to 214 by which the magnetic field probe 1 is produced are then executed on this base 33. Process steps 206 to 214 correspond to process steps 100 to 108 already described above in FIG. 2, with the positioning of the first coil 7 and of the second coil 9 in the middle of the material 19 having been facilitated since part of the capsule 3 has already cured and the first coil 7 the second coil 9 can therefore be positioned directly on the base 33. Further as yet uncured material 19, 21 is applied to the base 33 and then in multiple layers that are not shown explicitly in FIG. 3, which are cured layer by layer after each application, so as to give the overall result of a spherical capsule 3. The base 33 forms part of the capsule 3.

[0092] What is described in summary is a magnetic field probe 1 with a capsule 3 encapsulating an MR-active substance 5. What is more particularly proposed is that two coils 7, 9 are disposed in the capsule 3. Also described are advantageous production processes for magnetic field probes 1, and beneficial uses of the magnetic field probe 1 of the invention, as are methods in which such magnetic field probes 1 and arrangements of magnetic field probes 1 are used.

LIST OF REFERENCE NUMERALS

[0093] 1 magnetic field probe

[0094] 3 capsule

[0095] 5 MR-active substance

[0096] 7 first coil

[0097] 9 second coil

[0098] 11 cavity

[0099] 13 winding of 7

[0100] 15 winding of 9

[0101] 17 volume

[0102] 19 material

[0103] 21 material 19 before curing

[0104] 23 material 19 after curing

[0105] 25 surface

[0106] 27 internal volume

[0107] 29 quantum of 19

[0108] 31 working surface

[0109] 33 base

[0110] 35 terminal

[0111] 37 terminal

[0112] 39 UV light

[0113] 41 pipette