DE102006024245A1 - Medical instrument such as a neural implant, biopsy needle or an artificial landmark for implanting into human body, comprises a sample for permitting localization of the medical instruments into the human body, and transponder - Google Patents

Abstract

The medical instrument (1) for implanting into human body by 19F-nuclear magnetic resonance (NMR) imaging technique, comprises a sample (2) for permitting localization of the medical instruments into the human body, and a transponder. The medical instrument is a neural implant, a micro pump for the controlled and localized release of pharmaceuticals in the body, biopsy needle, a minimally invasive instrument, an endoscope or an artificial landmark applicable by the endoscope. The sample shows different forms, which permit to differentiate the instruments on a 19F-NMR imaging from each other. An independent claim is included for a procedure for the localization of a medical instrument.

Description

The The invention relates to a medical instrument, which is targeted introduction in the human body is determined and in particular an implant, a surgical instrument or an artificial one Landmark, as well as its use and a localization procedure of the instrument in the human body.

Currently New types of implants are being developed that are complex physiological Take over functions can. For example, neural implants are being developed that are selective Stimulate nerves in the central nervous system and so paralyzed or Can help people that can not communicate due to amyotrophic lateral sclerosis. Such Electrodes implanted in the brain can register neuronal signals and to a limb prosthesis forward or control a computer cursor.

However, such electrodes must be implanted with high precision in the central nervous system, in order to ensure the interconnection with the relevant nerve cells. Positioning during implantation is preferably assisted by imaging. For this purpose, x-ray images, eg fluoroscopy images recorded with a C-arm device, are generally used, provided that the implants have a corresponding X-ray contrast. However, this is often not the case, since such implants are very small and have only a low X-ray contrast. Imaging by MRI (Magnetic Resonance Imaging) also requires a suitable contrast to the surrounding tissue and, moreover, a size of the implant of several mm ³ , since the resolution of the MRI is approximately in the millimeter range.

comparable Problems with the localization of implants can also be seen in implants in other body regions arise, for example in the area of the spinal cord, myocardium etc. too other implant types we use micropumps for controlled and localized Drug release, minimally invasive surgical devices, stents, etc., must can be represented in the anatomical context, which is currently only limited possible is.

A similar Problem arises when tracking instrument tips, for example, biopsy needle tips within the body. in the MRI creates such a needle a complex artifact, its location assignment a blur having.

The US 2005/0273002 A1 describes a device for implanting of artificial Landmarks or imaging marks to a specific position within to identify a tissue. The under the skin used Landmark includes a first element that is visible with a first imaging modality and a second element visible with a second imaging modality is. The imaging modalities can be used for Example ultrasound, x-ray, CT or MRI. Thus, the first element is off, for example PVA and the second metal.

In the article by R. Schwarz et al .: "Gastrointestinal Transit Times in Mice and Humans Measured with ²⁷ AL and ¹⁹ F Nuclear Magnetic Resonance" in Magnetic Resonance in Medicine, Vol. 48, pp. 255-261, 2002, is a A method for measuring the passage of food through the gastrointestinal tract in humans by means of a 19F sample. One subject swallowed a perfluorononane-filled capsule, at which time both 1H and 19F NMR images were taken with a 1.5T MR clinical system. Since the capsule was excellently identified by 19F NMR imaging, the transit of the capsule through the gut could be visualized. However, this document is not concerned with the representability and localization of implants or other medical instruments in the human body.

The The object of the invention is to provide a medical instrument, in particular an implant, a surgical instrument or a artificial To provide landmark, which better than the previous Procedures in the human body can be located.

These task completed the invention characterized in that the instrument with a fluorine-containing sample which is the location of the medical instrument in the human body allowed by 19F NMR imaging.

normal Clinical MRI images are based on the signal from the hydrogen nucleus (1H). 19F NMR imaging, on the other hand, is rarely used since the human body contains very little fluorine. In principle, the core 19F is due to its 100% natural Occurrence and its high gyromagnetic ratio but extremely suitable for NMR. About that lets out 19F NMR imaging can also be performed on most clinical MRI scanners since the resonance frequency of the 19F core with, for example, 59 MHz at 1.5 Tesla very close to the resonance frequency of 63 MHz of the 1H nucleus lies. The normally tuned to this frequency amplifier and Other electronic components of the MRI system can therefore also be used for 19F NMR imaging or spectroscopy can be used.

Of the Advantage of the invention is that the fluorine (ie 19F) containing Sample is selectively displayed with 19F NMR imaging. Thereby she is also in confusing easy to recognize anatomical structures. The 19F NMR images can then superimposed with the 1H NMR images, to represent the position of the instrument on the latter.

The Invention can not only be used for marking surgical instruments, Stents, implants and the like are used, but also for Marking and representation of artificial landmarks in the body. The use of artificial Landmarks is based on the task, during an investigation body regions to mark them for latter Follow-up examinations and / or therapies easily and safely found again can be. For example, a gastroenterologist recognizes during an endoscopy a tumor or a polyp. He can only use the endoscope surface look at it and treat it in a minimally invasive way. He is missing however, information on vascularization, internal constitution (liquid, firm etc.), extension perpendicular to the intestinal wall u. a .. there the intestine is highly flexible and no natural Landmarks, it is extremely advantageous endoscopically an artificial one To be able to set a landmark, which is labeled with a fluorine-containing sample or exclusively from a fluorine-containing sample, which in a following Radiological examination with 19F-NMR easily retrievable is. Other uses include biopsies, for example in the chest or prostate or in the colon: this can be done while taking the biopsy at the same time a biocompatible landmark can be set to particular at multiple biopsies later to be able to make an assignment to the relevant lesion.

One Endoscope (conventional or capsule) is here with a device equipped with the injection of a Teflon-coated landmark allowed in a designated location. A biopsy device becomes advantageous coupled with a landmark injection device.

The fluorine-containing sample is therefore preferably made of a biocompatible material, according to a particularly preferred embodiment, this material is Teflon (polytetrafluoroethylene). Teflon is biologically inert and contains extremely high levels of fluorine, giving it a strong 19F NMR signal. However, the T ₂ relaxation times of Teflon are very short because it is a solid. Meanwhile, many MRI systems can also work with ultrashort echo times (UTE), so that a representation of Teflon with 19F NMR imaging is possible.

Especially Preferably, the sample is a Teflon sheath of the medical Instrument.

alternative to Teflon can for the sample will be chosen any other fluorine-containing compound in particular a liquid Fluorine compound such as perfluorononane or perfluoropolyether, also dissolved fluorine salts are conceivable. In the case of a liquid Sample is preferably enclosed in a suitable capsule, their outer shape arbitrary is.

The Medical instrument marked with 19F is preferably made of electric made of insulating material to produce no artifacts in the MRI.

According to one particularly preferred embodiment is a set of several medical instruments used where the fluorine-containing samples of the instruments are different from each other Have shapes that allow the instruments on a 19F NMR image to distinguish from each other. This embodiment is particular for artificial Landmarks advantageous because then several distinguishable from each other Landmarks can be set. The shape of the samples (or in the case of liquid fluorine compounds the Shape of the capsule) may, for example, be elliptical, angular, tetrahedral or characteristic constrictions or the like identifiable on a 19F NMR image are.

claimed is also the use of such a medical instrument to locate it in the human body by 19F NMR imaging.

The The invention is also directed to a method of localizing such Instruments in the human body directed, in which with a magnetic resonance tomograph 1H NMR images the study volume, at the same meeting, without rearrangement of the patient, 19F NMR images of the examination volume The position of the instrument on the 19F NMR images and from this the corresponding position of the instrument the 1H NMR images is derived.

The Imaging of 1H and 19F images without rearrangement of the patient the advantage that the images are easily registered with each other can, that is called, that position on a 19F image of a position on a 1H image can be assigned.

The 1H and 19F NMR images can be slice images or three-dimensional images, preferably T1-weighted, T2-weighted or proton-weighted 1H NMR slice images of the relevant body region such as the brain made. Then, preferably, multiple layers are acquired with 19F-NMR with the same coordinates. Alternatively, 19F projection images can also be acquired in different projection directions, which have a higher signal-to-noise ratio than slice images.

Next The position of the fluorine-containing sample is preferred to the 19F images also taken the shape of the sample, which optionally a distinction possible from different instruments which have differently shaped 19F samples.

The Form of the sample determined from the 19F NMR images can then be described as Contour and / or colored filled at the corresponding position of the instrument on a 1H NMR image being represented.

According to one particularly preferred embodiment contains the medical instrument also has a transponder, which with a simple transponder reader can be identified. This is especially for artificial Landmarks advantageous because their position in the body then using RF rays can be verified.

Of the electrically insulating material can be, for example, ceramic, glass or plastic.

Especially preferred is a method in which a number of examination volumes contain medical instruments whose fluorine-containing Samples have different shapes from each other. The positions and forms of the samples are determined on the 19F-NMR images and assigned to the individual instruments. Based on the positions The 19F NMR images become the corresponding positions of the instruments derived on the 1H NMR images. The outer shape of the samples can be used for Example be designed so that the surface in an axis anisotropic or that it has a certain number of constrictions, e.g. 1 to 10 constrictions, the counted can be.

In Embodiments, in which the patient between the recording of the 1H NMR and the 19F NMR images has moved or where between these shots a certain amount of time has passed, the 19F NMR images have to The 1H NMR images are registered before the position of the instruments is determined on the 1H NMR images. Registration means in in this context, that the respective coordinate systems for example correlated by a transformation matrix become.

Around facilitating such registration is according to a another preferred embodiment provided that in addition to the medical instrument in the human body or more fluorine-containing landmarks in or outside of the body present, which are represented by 19F-NMR imaging, the additional ones Fluorine-containing landmarks can also be represented by 1H-NMR.

These additional Landmarks can therefore one filled with water Teflon capsule or a two-chamber capsule containing both with Water as well as with perfluoroethylene filled are. Also a liquid, which contains both fluorine and 1H atoms, for Example fluorinated hydrocarbons, can be used for this purpose. This extra Landmarks are then visible on both the 19F NMR and the 1H NMR images and can therefore be used to register both images to each other.

Instead of in the body used landmarks can also outside of the body appropriate landmarks are attached, which after imaging be removed again.

The The invention will now be described with reference to exemplary embodiments explained in more detail in the accompanying drawings. In the drawings show:

1 a schematic cross section through a medical instrument according to an embodiment of the invention;

2 a schematic representation of a 1H NMR image superimposed 19F NMR image with three landmarks.

1 shows very schematically an example of a medical instrument 1 which may be, for example, a stent, a catheter tip, a biopsy needle, an endoscope or an artificial landmark. At the actual main part 4 of the medical device is a fluorine-containing sample 2 attached. This may be, for example, an inserted Teflon part. In the example shown, the sample is 2 with two circumferential grooves or constrictions 3 which can be visualized by 19F NMR imaging, thereby allowing identification of the instrument.

2 schematically shows a sagittal 1H-NMR-sectional image 5 through the human head. On it is, for example, the cerebrum 6 and the cerebellum 7 to recognize. In the brain is a neural implant 1 used, which is provided according to the invention with a fluorine-containing sample. The This implant is difficult to identify on the 1H NMR image. The image is therefore superimposed with a 19F NMR image. In this picture are the three hatched markings 1 . 8a and 8b while the brain tissue gives no signal. The two marks 8a . 8b belong to out-of-the-head landmarks, which preferably contain both 19F and 1H nuclei and are therefore visible on both images. This allows co-registration of 19F to 1H NMR images. This in turn allows the position of the implant 1 within the brain due to the 19F NMR signal.

implant marks from fluorine-19 are physiologically inert and atoxic, do not need any Energy and are permanent. The visualization with 19F-NMR allows a Targeted navigation of the implants, with navigation through magnetic fields, endoscopically or by means of manicured (piezoelectric) motors he follows. In addition to ensuring implantation in the target structure Visualization also helps, damaging neurons or others Avoid structures. Ultimately, the longevity of the Fluorine-19-labeling sure that the implant will be used even after prolonged dwell time removal or maintenance with MRI.

Claims (16)

Medical Instrument ( 1 ), which is intended for targeted introduction into the human body and in particular an implant ( 2 ), a surgical instrument or an artificial landmark, characterized in that the instrument ( 1 ) with a fluorine-containing sample ( 2 ), which allows localization of the medical instrument in the human body by 19F-NMR imaging. Medical instrument according to claim 1, characterized in that the fluorine-containing sample ( 2 ) contains a liquid fluorine compound, in particular perfluorononane or perfluoropolyether. Medical instrument according to claim 1, characterized in that the fluorine-containing sample ( 2 ) Telfon (polytetrafluoroethylene) contains. Medical instrument according to claim 3, characterized in that the sample ( 2 ) a Teflon sheath of the implant ( 4 ), the surgical instrument or the artificial landmark. Medical instrument after one of the previous ones Claims, characterized in that it is a neural implant, a micropump for Controlled and localized release of pharmaceuticals in the body, one Biopsy needle, a minimally invasive instrument, an endoscope or is an insertable by an endoscope artificial landmark. Medical instrument after one of the previous ones Claims, characterized in that it contains a transponder. Set of a plurality of medical instruments according to one of the preceding claims, characterized in that the fluorine-containing samples ( 2 ) of the instruments have mutually different forms, which allow to distinguish the instruments on a 19F-NMR image from each other. 0 Use of one or more medical instruments according to one of the preceding claims, for the localization of the medical instrument ( 1 ) in the human body by 19F-NMR imaging. Method for localizing a medical instrument according to one of the preceding claims in an examination volume in the human body, in which - 1H-NMR images (with a magnetic resonance tomograph) 5 ) of the examination volume, - with a magnetic resonance tomograph, in particular in the same session as the 1H-NMR images without rearrangement of the patient, 19F-NMR images of the examination volume are taken, wherein - the position of the fluorine-containing sample ( 2 ) is determined on the 19F-NMR images, and from this the corresponding position of the instrument ( 1 ) is derived on the 1H-NMR images. A method according to claim 9, characterized in that in addition to the position and the shape of the sample ( 2 ) is determined from the 19F NMR layer images. Method according to claim 9 or 10, characterized that at least a 19F-NMR image superimposed on a 1H-NMR image is pictured. A method according to claim 11, characterized in that the form of the sample (19F-NMR images) determined ( 2 ) as a contour and / or colored filled at the corresponding position of the instrument on a 1H-NMR image ( 7 ) is pictured. Method according to one of claims 9 to 12, characterized in that in the examination volume several medical instruments ( 1 . 8a . 8b ) whose fluorine-containing samples have different shapes from each other, and that the positions and shapes of the samples ( 2 ) on the 19F NMR images and the individual instruments ( 1 . 8a . 8b ), and the corresponding positions of the instruments are derived on the 1H NMR images. Method according to one of claims 9 to 13, characterized that the 19F NMR images are registered with the 1H NMR images, before the position of the instrument or instruments on the 1H NMR images is / are determined. Method according to one of claims 9 to 14, wherein in addition to the medical instrument ( 1 ) in the human body one or more fluorine-containing landmarks ( 8a . 8b ) in or outside the body by 19F-NMR imaging, the additional fluorine-containing landmarks are also represented by 1H-NMR. Method according to claim 15 and 15, characterized in that the fluorine-containing landmarks ( 8a . 8b ) are used outside the body to register the 19F NMR layer images with the 1H NMR layer images.