WO2009016207A1

WO2009016207A1 - Magnet coil system for exerting force on an endoscopy capsule

Info

Publication number: WO2009016207A1
Application number: PCT/EP2008/060006
Authority: WO
Inventors: Rainer Graumann; Rainer Kuth
Original assignee: Siemens Aktiengesellschaft
Priority date: 2007-08-02
Filing date: 2008-07-30
Publication date: 2009-02-05
Also published as: DE102007036242A1; DE102007036242B4

Abstract

A magnet coil system (2) comprises a three-dimensional working area (12) into which at least part of a patient (14) can be introduced, a plurality of single coils (8), which can be driven individually, for producing at least one basic magnetic field (20) for predeterminably exerting force without making physical contact, on an endoscopy capsule (16), which can be navigated magnetically and has a magnetic moment (18), in the working area (12), a stabilization system (22, 24, 36) for stabilization and homogenization of the basic magnetic field (20) for MR imaging of the patient (14) in the working area (12), an RF coil system (29) for producing an excitation field (33) and for receiving a resonance field (35) for the MR imaging, an installation control system (34) for the MR imaging.

Description

description

Magnetic coil system for exerting force on an endoscopy capsule

The invention relates to a magnetic coil system for applying force to an endoscopy capsule.

Such a magnet coil system is e.g. known from DE 101 42 253 Cl. It has a work space in the one

Patient is at least partially recoverable. With such a system, it is possible to rely on e.g. also known from DE 101 42 253 Cl, located in the working space endoscopy capsule or endocapsule without contact, in a predeterminable direction and strength of a force or torque, hereinafter always referred to for the sake of simplicity as force exerted. Thus, a so-called capsule endoscopy (Magnetically Guided Capsule Endoscopy - MGCE) can be performed on the patient, in which the capsule in the patient is selectively and arbitrarily moved. An endocapsule usually has a camera for imaging. However, this is only an examination of the internal surfaces of the patient, e.g. the inner intestinal wall in the gastrointestinal tract possible.

For the use of capsule endoscopy additional radiological imaging of the patient is helpful in many cases, using fluoroscopy to obtain image information from the inside of the patient with the MGCE invisible. This increases both diagnostic and therapeutic safety. For example, X-ray imaging can be performed on the patient.

On the other hand, one of the biggest limitations of radiology is the lack of immediate therapy options, since radiology can only be used to reproduce reproducible pathologies in rare cases, eg directly under the skin or through a body orifice. A direct access through tools, like Needles, for example, from outside the patient, ie minimally invasive, are only possible in rare cases.

It is known to combine an MGCE with an X-ray image. This will be the benefits of the full

Imaging of the patient and a significantly increased availability of pathologies by the endocapsule united.

It is known to connect an X-ray system externally to the magnetic coil system, e.g. in the form of a approach to the coil system C-arm.

It is also known to nest both systems, e.g. in the magnet coil system, an independent X-ray system, e.g. a CT device, integrate. X-ray sources and receivers are then e.g. arranged between or in the region of the magnet windings of the coil system.

With regard to the capsule endoscopy, such X-ray devices always represent external devices which can not be fully integrated, since they operate on the X-ray basis in contrast to capsule endoscopy based on magnetic field.

The object of the present invention is to specify an improved magnet coil system and an improved method for magnetic capsule navigation.

The invention is based on the recognition that an MR imaging is also suitable for imaging the patient's interior and that this, like the MGCE, works on a magnetic field basis. The idea of the invention is therefore that it would be advantageous to extend the system to MGCE so that it can be used for both capsule navigation and MR imaging, i. to combine an MR scanner and MGCE in a single system.

The invention is solved with respect to the magnetic coil system by such with a three-dimensional working raum, in which a patient is at least partially recoverable, with a plurality of individually controllable individual coils for generating at least one basic magnetic field for specifiable non-contact force on a magnetically navigable, a magnetic torque endoscopy capsule in the working space, such as from DE 103 40 925 known , In this case, a magnetic moment is to be understood as meaning, for example, a permanent magnet, a magnet coil or any other element which generates a magnetic field fixed at the endocapsule.

According to the invention, the magnet coil system contains a stabilization system for stabilizing and homogenizing the basic magnetic field for MR imaging of the patient in the work area, an RF coil system for generating an excitation field and for receiving a resonance field for MR imaging, and a system controller for the MR imaging MR imaging.

The known magnet system for capsule endoscopy consists of a series of coils which generate the magnetic fields and magnetic field gradients required to apply the force to the endocapsule. Among other things, according to the invention, those fields and gradients which are required for the MR imaging are also generated. The MR magnet is hereby e.g. built from the Helmholtz coils of the navigation magnet. The fields and gradients achievable with these coils are sufficient for low-end MR imaging. The further components still necessary for MR imaging - RF coil system and system control are complimented according to the invention. The plant control hereby includes e.g. a processing, reconstruction and visualization of a obtained MR-3D image data set with a.

Capsule endoscopy requires a magnet with large magnetic fluxes and very high flux density gradients. For the MR an extremely homogenous magnetic flux of very high temporal constancy or with very well known temporal changes is needed. Therefore, inventive according to the stabilization system, which makes the magnetic coil system suitable for MR imaging. For example, a system with improved power amplifiers for the coils of the magnetic coil system in comparison with pure capsule navigation is conceivable.

The modified magnetic coil system thus allows a combination of capsule endoscopy and MR imaging.

The RF coil system can be designed such that it uses the coils of the magnet coil system that are present for the MGCE or that they are suitably modified. However, the RF coil system can also contain a separate, ie additional excitation coil for generating the MR excitation field in the working space. Thus, the excitation field does not have to be generated by the coils of the magnet coil system used for the application of force, which allows an optimal design of both coil types.

The excitation coil may be a whole body coil. Such coils are already available, optimized for MR imaging and can be easily integrated into the coil system.

The RF coil system may include an MR receiver coil for the resonance field. This results in the same advantages as stated above for the additional excitation coil.

In this case, the MR receiver coil can be a surface coil that can be applied to the patient. This results in the same advantages as outlined above for the whole body coil.

A first alternative for stabilizing the basic magnetic field is that the stabilization system may contain additional coils, eg Helmholtz variants for generating the basic magnetic field. In addition, these coils are not present in a known system for pure MGCE and are specially supplemented for MR imaging. Another or additional measure for this is that the stabilization system may include iron hovering for the magnet coil system. The magnetic coils used for the MGCE are then qualitatively improved by the iron soiling, so that they can also produce fields of better quality, which are sufficiently homogeneous for MR imaging.

At least some of the coils involved in MR imaging, ie the MR magnets, can also be HTS coils. High-temperature superconductors (HTS) are available for this purpose in a known manner.

In an MR scanner with a static and non-switchable basic field, it is always problematic to pass through a magnetic endoscope due to the static B ₀ field gradient because this gradient is very steep and therefore the forces on the magnetic moment in the capsule are very high.

If the capsule is in the patient at the time of passing through the static field gradient, the direction of force and amplitude are virtually uncontrollable. If the patient is in the center of the magnet and the capsule is then to be supplied, the capsule must be transported through the static gradient, which is technically complicated. On the other hand, if the capsule is in the range of homogeneity, i. On the other hand, in the following it must always be ensured that the body region in which the capsule is located is in the homogeneity region of the magnet so that it does not reach the gradient region again.

Commercial MR magnets, ie MR coil systems, have a homogeneity volume of typically 20 cm to 50 cm diameter or edge length, which is generally smaller than the gastrointestinal tract of the patient. As long as only the B ₀ basic field is active, and the navigational gradient fields are turned off an ideal capsule magnet no force but only a torque, as long as its moment is not parallel to the Bo magnetic field. So you can use the MR gradient coils to apply forces in any direction, but the capsule direction always stays parallel to the B ₀ -FeId.

Therefore, the strong B ₀ -FeId necessary for MR imaging of the coil system for the MGCE can be switched off. If only the MGCE basic field or no longer exists, the introduction of the capsule magnet into the working space is facilitated. Namely, no or only a small BO gradient at the edge of the homogeneity range must be traversed by the magnetic moment.

The solenoid system may then include a flux pump for ramping at least a portion of the MR imaging coils. The field which is stronger than the MGCE and which is necessary for MR imaging is then built up after insertion or removal of the capsule into the working space, ie rambled, and degraded again before the capsule is removed or inserted. The flux pump can remain active during MR imaging, whereby the resonance frequency is tracked analogously.

The magnetic moment of the capsule may alternatively or additionally be removable, at least during the MR.

The magnet coil system may therefore comprise a working capsule with a, e.g. for MR imaging, deactivatable magnetic moment included.

The magnet coil system can contain an endocapsule, as is known, for example, from DE 10 2005 032 368 A1. This is also called Endoratte and is equipped with an out-patient extension or tail. The magnetic moment is then movable over the extension between working capsule located in the patient and the outside space outside the patient. For example, the appendage is a hollow or non-hollow cord that pulls the endocapsule behind it as it moves. Along or in this string, the magnetic moment of the capsule can be quickly and safely transported between the capsule and a patient's body opening through which the cord protrudes.

For this purpose, the endocapsule can have a tissue anchor known from DE 103 36 734 A1. Thus, the capsule is fixable in a place in the patient and remains there, even if the magnetic moment is removed.

The material of the magnetic moment in the endocapsule may be liquid, e.g. be made of a ferrofluid, be. Such a moment can at the o.g. Endoratte be filled or sucked through the tube-shaped extension into the capsule.

With regard to the method, the object of the invention is achieved by a method for magnetic capsule navigation in a patient who works with the aid of a magnetic coil system according to one of the claims 1 to 9 MR imaging based, in the MR imaging and force on the work capsule in temporal Change takes place.

The quality-reduced MR imaging described with reference to the magnetic coil system according to the invention can generally not be used simultaneously with the capsule endoscopy, especially if the capsule has a permanent magnet, since this would be changed in position by the MR imaging and which also interferes with MR imaging.

It can therefore be done by MR imaging, for example, a review of the diagnostic assumptions or a study of critical areas or identification and marking of pathological areas before inserting the capsule. The regions concerned may then, on the basis of the subsequent capsule navigation. An MR-based confirmation or result check can also take place after a successful diagnosis or therapy, ie capsule navigation.

The possibility of MR imaging integrated into the magnet coil system also results in better utilization and thereby cost savings with respect to the magnet coil system, if this, e.g. in clinical routine, is used alone for MR imaging, as long as it is not needed for capsule navigation.

The magnetic moment of the endocapsule, as mentioned, e.g. during MR imaging, are removed from the workspace.

If the endocapsule, as described above, is an endoratte, the magnetic moment can be removed over the extension, that is, removed from the working space filled with fields of critical field strength.

For the two modes MGCE and MR imaging of the coil system i.d.R. uses a common coordinate system. Coordinate flags, ie bookmarks, can then be generated in a 3D image data record of the MR imaging. These characterize locations or regions in the MR data set which require later optical observation and / or biopsy or therapy by means of endoscopy or MGCE. These bookmarks can then be approached directly by the endoscope or the endocapsule during the subsequent endoscopy or MGCE.

A virtual endoscopy can be generated from a 3D MR image data record, for example along a path which a working capsule has traveled or will cover. If the above-mentioned bookmarks are transmitted for this purpose, it is possible to navigate during the MGCE by means of a combination of virtual endoscopy and real endoscopy. Conversely, during endoscopy or MGCE, target points, areas or volumes can be defined as 3D bookmarks, which can then be detected selectively by means of MR imaging, for example, after removing the capsule or the magnetic moment from the body of the patient or working space.

For a further description of the invention reference is made to the embodiments of the drawing. It shows, in a schematic schematic diagram: FIG. 1 a magnetic coil system for MR imaging-based magnetic capsule navigation.

1 shows a magnet coil system 2, which consists of two subsystems, namely a navigation system 4 and an MR system 6 for magnetic resonance imaging. The navigation system 4 essentially corresponds to the magnetic coil system known from DE 103 40 925 B3 comprising fourteen controllable individual coils, of which the two coils 8a, b in the form of Helmholtz coils are shown by way of example in FIG. The navigation system 4 comprises with its housing 10 a working space 12, in which a patient 14 is introduced. In patient 14 there is one, e.g. from DE 101 42 253 Cl known endocapsule 16. The endocapsule 16 contains as a magnetic element or moment a magnet 18 in the form of a permanent magnet.

With its coils 8 a, b, the navigation system 4 generates a homogeneous basic magnetic field 20 in the working space 12. The basic magnetic field 20 together with a gradient field (not shown) serves to selectively apply force or torque to the magnet 18 and thus the endocapsule 16 in order to generate it to move arbitrarily specifiable direction in the patient 14 translationally and rotationally.

According to the invention, the known navigation system 4 is expanded by the MR system 6, which comprises two HTS field coils 22a, b and two HTS shield coils 24a, b. The field coils 22a, b and shield coils 24a, b are each of a thermal Shield 26 surrounded and serve to stabilize the basic magnetic field 20 in order to serve as a basic magnetic field for MR imaging can. Together they form a stabilization system 28 for the basic magnetic field 20.

The MR system 6 further comprises an RF coil system 29, comprising an excitation coil 30 for exciting a magnetic resonance in the patient 14 by an excitation field 33; and a receiver coil 32 for receiving the magnetic resonance field 35, in the example a surface coil which can be placed on the patient 14. Coil system 29, field coils 22a, b and shield coils 24a, b are connected to a system controller 34, which controls the MR imaging, as well as the signal processing, image display, etc. accomplished.

In an alternative embodiment, the navigation system 4 with respect to its coils 8a, b designed according to high quality, to produce the basic field 20 of high quality and thus suitable for MR imaging. The MR system 6 then contains no field coils 22a, b and

Shield coils 24a, b. The system control 34 is connected directly to the coils 8a, b. The increase in quality in the coils 8a, b is accomplished by an iron hoof 36 attached thereto, which thus represents the stabilization system for homogenizing the basic magnetic field 20.

In an alternative embodiment, the system controller 34 comprises a flux pump 38. This feeds the field coils 22a, b and shielding coils 24a, b such that they are merely jammed for MR imaging in order to stabilize the basic magnetic field 20 for this purpose. During the MGCE, the field coils 22a, b and shielding coils 24a, b are then not latched or energized.

In an alternative embodiment, the end capsule 16 contains an extension 40, ie is an endoratte known from DE 10 2005 032 368 A1. The extension 40 then extends through a body opening 42 of the patient 14 to the outside. outside space 43 and serves for transporting the magnet 18 which is removable from the endocapsule 16 in this embodiment.

For this purpose, in a first embodiment, the magnet 18 may be a hollow body which can be filled with a ferrofluid 44. The ferro fluid 44 is then pumped through the tubular extension 40 for navigation or force or movement of the endocapsule 16 in this. For magnetic resonance imaging, the ferrofluid 44 is removed again.

In a second embodiment, the magnet 18 is still a permanent magnet, but is transported along the extension 40, this time in the form of a cord, from the endocapsule to the exterior.

Claims

claims

1. Magnetic coil system (2) with a three-dimensional working space (12), in which a patient (14) is at least partially introduced, with a plurality of individually controllable individual coils (8) for generating at least one basic magnetic field (20) for the predetermined non-contact force on a magnetic navigable, a magnetic moment (18) having endoscopy capsule (16) in the working space (12), characterized by

a stabilization system (22, 24, 36) for stabilizing and homogenizing the basic magnetic field (20) for MR imaging of the patient (14) in the working space (12),

- An RF coil system (29) for generating an excitation field (33) and for receiving a resonance field (35) for the

MR imaging,

- An installation control (34) for MR imaging.

2. magnet coil system (2) according to claim 1, wherein the RF coil system (29) includes an excitation coil (30) for generating an MR excitation field (33) in the working space (12).

The magnet coil system (2) of claim 2, wherein the excitation coil (30) is a whole body coil.

4. magnet coil system (2) according to any one of the preceding claims, wherein the RF coil system (29) has an MR

Receiver coil (32) for receiving the resonant field (35).

5. Magnetic coil system (2) according to claim 4, wherein the MR receiver coil (32) is a patient on the (14) can be applied surface coil.

6. magnet coil system (2) according to any one of the preceding claims, wherein the stabilization system (22,24,36) additional coils (22,24) for generating the basic magnetic field (20).

7. Magnetic coil system (2) according to any one of the preceding claims, wherein the stabilization system (22,24,36) includes an iron hoof (36) for the magnetic coil system (2).

8. Magnetic coil system (2) according to one of the preceding claims, in which at least part of the coils (8, 22, 24) involved in MR imaging are HTS coils.

Magnetic coil system (2) according to one of the preceding claims, comprising a flow pump (38) for ramping at least part of the MR imaging coils (8, 22, 24).

10. Magnetic coil system (2) according to one of the preceding claims, with an endoscopy capsule (16) with a deactivatable magnetic moment (18).

11. The magnet coil system (2) according to claim 10, wherein the endoscopy capsule (16) is an endoratte with an outer cavity (43) reaching extension (40), wherein the magnetic moment (18) over the extension (40) between Endoscopy capsule (16) and outer space (43) is movable.

12. magnet coil system (2) according to claim 11, with a via the extension (40) transportable, the magnetic moment (18) generating ferrofluid (44).

13. A method for magnetic capsule navigation in a patient (14) with the aid of a magnet coil system (2) according to one of the claims 1 to 9, which is performed MR imaging-based, and in the MR imaging and force application to the endoscopy capsule ( 16) in temporal change.

14. The method of claim 13, wherein the magnetic moment (18) of the endoscopy capsule (16) during MR imaging from the working space (12) is removed.

15. The method of claim 14, wherein the endoscopy capsule (16) is an endo-mat with extension (40), wherein the magnetic moment (18) is removed via the extension (40).