DE102007036242B4 - Magnetic coil system for applying force to an endoscopy capsule together with the associated method - Google Patents

Abstract

Magnetic coil system (2) with a three-dimensional working space (12) into which a patient (14) is at least partially insertable, with a plurality of individually controllable individual coils (8) for generating at least one basic magnetic field (20) for predeterminable contactless application of force to a magnetically 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 MR imaging, - a system controller (34) for MR imaging, wherein the endoscopy capsule (16) has an outer area (43) reaching extension (40) and the magnetic moment (18) via the extension (40) between Endoskopiekapsel (16) and outer space (43) by means of a via the extension (40) transportable, the magnetic torque (18) generating ferrofluid (44) is movable.

Description

The invention relates to a magnetic coil system for applying force to an endoscopy capsule together with the associated method

Such a magnetic coil system is z. B. from the DE 101 42 253 C1 known. It has a working space into which a patient is at least partially insertable. With such a system can on a z. B. also from the DE 101 42 253 C1 known, 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 a 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 a consideration of the inner surfaces of the patient, z. B. the inner intestinal wall in the gastrointestinal tract possible.

Out DE 103 40 925 B3 is another magnet coil system for non-contact movement of a magnetic moment having element known. The magnetic coil system has a plurality of individually controllable individual coils for contactless application of force.

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 again the lack of immediate therapy option, since pathology that can be mapped by radiology is rarely seen, eg, in the case of radiology. B. can be reached directly under the skin or through a body opening. Direct access through tools such. As needles, from outside the patient, so minimal invasive, is possible only in rare cases.

It is known to combine an MGCE with X-ray imaging. This combines the benefits of full patient imaging and significantly increased endocapsular pathology.

It is known to connect an X-ray system externally to the magnetic coil system, for. B. in the form of approached to the coil system C-arm.

It is also known to nest both systems, z. B. in the magnetic coil system independent of this X-ray system, z. As a CT device to integrate. X-ray source and receiver are then z. B. between or in the region of the magnet windings of the coil system.

In terms of 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 the magnetic field-based capsule endoscopy.

Furthermore, it is off US 2007/0080686 A1 an RF coil system for generating an excitation field and for receiving a resonance field for MR imaging known. The system described there has, in particular, a system control for MR imaging.

WO 03/092496 A1 discloses a combined system that is designed for MR imaging and suitable for guiding a catheter. The tip of the catheter has a magnetic moment so that the orientation of the catheter tip can be aligned by an external magnetic field. For this purpose, homogeneous magnetic fields are sufficient. WO 03/092496 A1 does not describe a system of capsule endoscopy.

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. H. to combine an MR scanner and MGCE in a single system.

The invention is achieved with respect to the magnetic coil system by such a three-dimensional workspace, in which a patient is at least partially einbringbar with multiple, 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 Working space, such. B. from the DE 103 40 925 known. Under a magnetic moment here is one on the Endokapsel To understand fixed magnetic field generating element.

The magnetic moment is easily removable, at least during MR. The magnetic coil system includes a working capsule with a, z. B. for MR imaging, deactivatable magnetic moment.

The magnetic coil system contains an endocapsule, as z. B. from the DE 10 2005 032 368 A1 is known. 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.

The appendix is a hollow cord that pulls the endocapsule behind when moving. Along or in this string, the magnetic moment of the capsule can be quickly and safely transported between the capsule and a patient's orifice through which the cord protrudes.

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

According to the invention, the material of the magnetic moment in the endocapsule is liquid and made of a ferrofluid. Such a moment can at the o. G. Endoratte be filled or sucked through the tube-shaped extension into the capsule.

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 working space, an RF coil system for generating an excitation field and for receiving a resonance field for MR imaging, and a system control for the 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 z. B. constructed 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, for MR imaging still necessary component RF coil system and system control, are supplemented according to the invention. The plant control closes here z. B. 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, according to the invention, the stabilization system is present, which makes the magnet coil system suitable for MR imaging. It is conceivable z. B. a system with respect to the pure capsule navigation improved power amplifiers for the coils of the magnetic coil system.

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 resonant 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 additional coils, for. B. Helmholtz variants for generating the basic magnetic field may contain. 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 ones used for the MGCE Solenoids are then qualitatively enhanced by iron balance tuning so that they can also produce better quality fields that are sufficiently homogeneous for MR imaging.

At least part of the MR imaging coils, 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-disconnectable basic field, it is always problematic to pass through a magnetic endocapsule 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. In contrast, if the capsule is in the homogeneity region, i. H. 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 navigation gradient fields are turned off, an ideal capsule magnet will experience no force but only torque, as long as its momentum is not parallel to the B ₀ magnetic field. So you can use the MR gradient coils to exert forces in any direction, but the capsule direction always remains parallel to the B ₀ field.

Therefore, the necessary for MR imaging strong B ₀ field 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 B0 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 in relation to the MGCE and which is necessary for MR imaging is then built up after insertion or removal of the capsule into the working space, in other words rattling, 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.

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 10 based MR imaging, take place in the MR imaging and power on the working capsule in temporal change ,

Namely, the reduced-quality MR imaging described with reference to the magnet coil system can generally not be used simultaneously with the capsule endoscopy if the capsule has a permanent magnet, since this would be changed in position by the MR imaging, and the MR Imaging disturbs.

It can therefore by MR imaging z. As a review of the diagnostic assumptions or a study of critical areas or identification and marking of pathological areas before inserting the capsule done. The relevant regions can then be further explored with the help 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.

By integrated into the magnetic coil system option for MR imaging also better utilization and thereby cost savings with respect to the magnetic coil system, if this, z. As in clinical practice, is used alone for MR imaging, as long as it is not needed for capsule navigation.

According to the invention, the magnetic moment of the endocapsule, as mentioned, for. B. during MR imaging, are removed from the workspace.

The endocapsule is, as described above, a Endoratte, in which the magnetic moment on the extension away, so removed from the field filled with critical field strength working space can be.

For the two operating modes MGCE and MR imaging of the coil system, a common coordinate system is generally used. Coordinate flags, ie bookmarks, can then be generated in a 3D image data record of MR imaging become. 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.

From a 3D MR image data set, a virtual endoscopy can be generated, for. B. along a path that has covered a working capsule or will cover. If the o. G. Bookmarks can be navigated during the MGCE using a combination of virtual endoscopy and real endoscopy. Conversely, during endoscopy or MGCE, target points, areas, or volumes may be defined as 3D bookmarks, e.g. B. after removing the capsule or the magnetic moment from the body of the patient or work space can then be selectively detected by MR imaging.

For a further description of the invention reference is made to the embodiments of the drawing. It shows, in a schematic outline sketch:

1 a magnetic coil system for MR imaging-based magnetic capsule navigation.

1 shows a magnetic 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 corresponds essentially to that from the DE 103 40 925 B3 known magnet coil system of fourteen controllable individual coils, of which in 1 exemplarily the two coils 8a , b are shown in the form of Helmholtz coils. The navigation system 4 includes with its housing 10 a workroom 12 in which a patient 14 is introduced. In the patient 14 is one, z. B. from the DE 101 42 253 C1 known endocapsule 16 , The endocapsule 16 contains a magnet as a magnetic element or moment 18 in the form of a permanent magnet.

The navigation system 4 generated with its coils 8a , b a homogeneous basic magnetic field 20 in the workroom 12 , The basic magnetic field 20 used together with a gradient field, not shown, the targeted force or torque on the magnet 18 and with it the endocapsule 16 to this in any predetermined direction in the patient 14 to move translationally as well as rotationally.

The well-known navigation system 4 is according to the invention to the MR system 6 extended, which two HTS field coils 22a , b and two HTS screen coils 24a , b includes. The field coils 22a , b and shielding coils 24a , b are each of a thermal shielding 26 surrounded and serve to stabilize the basic magnetic field 20 to serve as a basic magnetic field for MR imaging. So together they form a stabilization system 28 for the basic magnetic field 20 ,

The MR system 6 further comprises an RF coil system 29 consisting of an excitation coil 30 to excite magnetic resonance in the patient 14 through an excitation field 33 ; and a receiver coil 32 for receiving the magnetic resonance field 35 , in the example one on the patient 14 coatable surface coil. coil system 29 , Field coils 22a , b and shielding coils 24a , b are with a plant control 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 the basic field 20 high quality and therefore suitable for MR imaging. The MR system 6 then contains no field coils 22a , b and shielding coils 24a , b. The plant control 34 is directly with the coils 8a , b connected. The quality increase in the coils 8a , b is due to an attached to this iron mood 36 accomplished, which thus the stabilization system for homogenization of the basic magnetic field 20 represents.

In an alternative embodiment, the plant control comprises 34 a river pump 38 , This energizes the field coils 22a , b and shielding coils 24a , b such that they are rammed only for MR imaging to this purpose, the basic magnetic field 20 to stabilize. During the MGCE are the field coils 22a , b and shielding coils 24a , b then not ratted or not energized.

According to the invention, the endocapsule contains 16 an extension 40 So, is one of the DE 10 2005 032 368 A1 known Endoratte. The extension 40 then passes through a body opening 42 of the patient 14 after in the outer space 43 and serves to transport the endocapsule in this embodiment 16 removable magnet 18 ,

For this purpose, the magnet 18 in a first embodiment, one with a ferrofluid 44 be fillable hollow body. The ferrofluid 44 is then over the tubular extension 40 for navigation or exercise of force or movement of the endocapsule 16 pumped into this. For magnetic resonance imaging, the ferrofluid 44 removed again.

Claims (11)

Magnetic coil system ( 2 ) with a three-dimensional work space ( 12 ) into which a patient ( 14 ) is at least partially introduced, with a plurality of individually controllable individual coils ( 8th ) for generating at least one basic magnetic field ( 20 ) for the specifiable non-contact application of force to a magnetically navigable, a magnetic moment ( 18 ) endoscopy capsule ( 16 ) in the workroom ( 12 ), characterized by - a stabilization system ( 22 . 24 . 36 ) for the stabilization and homogenization of the basic magnetic field ( 20 ) for MR imaging of the patient ( 14 ) in the workroom ( 12 ), - an RF coil system ( 29 ) for generating an excitation field ( 33 ) and for receiving a resonance field ( 35 ) for MR imaging, - a system control ( 34 ) for MR imaging, wherein the endoscopy capsule ( 16 ) one in the outer space ( 43 ) extending extension ( 40 ) and the magnetic moment ( 18 ) over the extension ( 40 ) between endoscopy capsule ( 16 ) and outdoor space ( 43 ) by means of an over the extension ( 40 ) transportable, the magnetic moment ( 18 ) generating ferrofluid ( 44 ) is movable. Magnetic coil system ( 2 ) according to claim 1, wherein the RF coil system ( 29 ) an excitation coil ( 30 ) for generating an MR excitation field ( 33 ) in the workroom ( 12 ) contains. Magnetic coil system ( 2 ) according to claim 2, wherein the excitation coil ( 30 ) is a whole body coil. Magnetic coil system ( 2 ) according to one of the preceding claims, in which the RF coil system ( 29 ) an MR receiver coil ( 32 ) for receiving the resonance field ( 35 ) contains. Magnetic coil system ( 2 ) according to claim 4, wherein the MR receiver coil ( 32 ) one on the patient ( 14 ) can be applied surface coil. Magnetic coil system ( 2 ) according to one of the preceding claims, in which the stabilization system ( 22 . 24 . 36 ) additional coils ( 22 . 24 ) for generating the basic magnetic field ( 20 ) contains. Magnetic coil system ( 2 ) according to one of the preceding claims, in which the stabilization system ( 22 . 24 . 36 ) an iron mood ( 36 ) for the magnet coil system ( 2 ) contains. Magnetic coil system ( 2 ) according to one of the preceding claims, in which at least a part of the MR-imaging coils ( 8th . 22 . 24 ) HTS coils are. Magnetic coil system ( 2 ) according to one of the preceding claims, with a flow pump ( 38 ) for ramping at least part of the MR imaging coils ( 8th . 22 . 24 ). Magnetic coil system ( 2 ) according to one of the preceding claims, with an endoscopy capsule ( 16 ) with a deactivatable magnetic moment ( 18 ). Method for magnetic capsule navigation in a patient ( 14 ) by means of a magnetic 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, the magnetic moment ( 18 ) of the endoscopy capsule ( 16 ) during MR imaging from the workspace ( 12 ) is removed by a ferrofluid ( 44 ) via an extension ( 40 ) of the endoscopy capsule ( 16 ) is transported.

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