US20030055436A1 - Navigation of a medical instrument - Google Patents

Abstract

Invention of a device for the insertion of medical instruments into the human body.

Description

PROBLEM
• With the German patent specification DE 198 44 767 A1, a method attaching markers to a medical instrument that are detectable under MRI is already known. The orientation of the instrument within the MRI device can be determined with these points. However, the respective allocation of the measured markers to the instrument markers is impeded due to the similarity of the signal-emitting substance to the instrument material. The non-availability of an instrument fixation to the patient proves to be a further disadvantage. Such fixation could be achieved by use of trocars. FIGS. 2, 3,[0001]4 and5 show a device ensuring a minimally-invasive approach to the brain through a hole in the top of the skull. Such trocar is already known from patent specification DE 197 26 141 and prevents the risk of the so-called Brain Shift, which signifies the uncontrolled shifting of the brain inside the surrounding skull during an operation. This problem is not limited to the neuro field, but occurs whenever shifting tissue is punctured. The disadvantages of this kind of trocars are the following points:
• The adjustment of a navigation system adapting the devices to MRI imaging to such a neuro trocar is difficult.[0002]
• The neuro trocar is manufactured of titanium alloy, so that it is depicted as a homogenous formation with indistinct rim demarcation in the MR image. A three-dimensional orientation is difficult to assess. This, however, is highly essential, with the neuro trocar, unlike a stereotactic system, having no own reference point as it is fixed to the patient.[0003]
• The invention presented herein aims to solve these and other problems.[0004]
SOLUTION
• The invention is described in detail in the following figures:[0005]
• FIG. 1 Problem of navigation[0006]
• FIG. 2 Navigation points at a device[0007]
• FIG. 3 Navigation points at the instrument insertion channel of the device[0008]
• FIG. 4 Angle measurement between instrument insertion channel and device[0009]
• FIG. 5 Navigation with active and passive material contrast[0010]
• FIG. 6 Device with a stabilization channel[0011]
• FIG. 7 Attachment of MRI markers to the combination of device, instrument and angle measuring system[0012]
• FIG. 8 Linear propulsion at the instrument insertion channel[0013]
• FIG. 9[0014]aDevice ensuring tilting motions of the instrument insertion channel
• FIG. 9[0015]bSectional image of the device ensuring tilting motions
• FIG. 10 Device with double-walled and contrast medium-filled top on the instrument insertion channel[0016]
• FIG. 11 Device with motor-powered adjustable instrument insertion channel[0017]
• The problem of the conventional neuro trocar being not sufficiently identifiably with regard to its orientation within the MRI, as described in patent DE 197 26 141, can be solved by designing a device of a material that is totally invisible under MRI. If then a minimum of three MRI compatible points are marked on it, an exact orientation can be determined by these three points; its position in the MRI procedure can be precisely assessed, and a virtual image of the trocar can be shown in the MRI picture.[0018]
• Various systems for the technical realization of these points are described below.[0019]
• The problem is shown in FIG. 1. The[0020]medical instrument1 with its reactive coordination system x′y′z′ shall be determined in its position relative to the patient coordination system xyz.
• Both the adjustment of the[0021]instrument insertion channel10 and the adjustment of thedevice3, which essentially corresponds to thedevices1 and2, can by correlated to each other by an angle adjustment (see FIG. 4). An angle adjustment for theazimuth angle14 and an angle adjustment for thezenith angle15 are possible on thedevice3. When the position of thedevice3 is known, the position of theinstrument insertion channel10 will also be known automatically. By an automatic pick-off of angular movement not shown in FIG. 4, azimuth and zenith angle could be directly measured and included into the MR image. The MR image could then always adjust to the orientation of the instrument insertion channel, so that theoperation site16 will always be optimally in the sight vane in the imaging of the MRI device. In such case, markers according to theprinciples20′,20″ and20′″ stated herein could be adapted in thedevice3 or in a top forangle measurement21. Reversedly, it is also possible to measure the angle within the MR image and then to adjust at the device, i.e. the device follows the MR image.
• The fixation of the[0022]instrument insertion channel10 in a certain position can be achieved by tightening afixing screw22 as shown in FIG. 5.
• Through the[0023]instrument insertion channel10, a tube can be inserted deep into the operation site, which will then serve as a channel for inserting further instruments as shown in FIG. 6, the advantage being a stabilization of the instruments inserted under navigation. Thestabilization channel23 then holds the inserted instruments. FIGS. 8 and 9 show a possibility where the instrument or thestabilization channel23 can be cramped into amounting6, which is shifting in axial direction on theinstrument insertion channel10.Such mounting6 can be lowered manually or automatically by a motor, electrically, hydraulically, by pneumatic power or by wire pull.
• The orientation of the instrument insertion channel can be achieved by tilting. To allow this, two[0024]movable laminas7 and8, relative to thedevice2 and shifting to each other (as shown in FIG. 9), are attached to the device. Theinstrument insertion channel10 is guided through an oblong opening9 in each lamina. By mechanical manual or automatic shifting of the laminas to each other, the instrument insertion channel is tiltable in various directions. Electrical, hydraulic or pneumatic actuations are possible for automatic shifting.
• A further possibility of adjustment of the[0025]instrument insertion channel10, as shown in FIG. 11, to position the instrument insertion channel by means such as a rotating and tilting motion via aworm wheel11 mechanically or by motor, pneumatically, or by wire pull.
• The orientation of the instrument is directly readable by the scaling at the positioning unit. It could also be monitored via the above-mentioned markers in the MR image.[0026]
• In order to adapt the device to the imaging of the MRI device, a navigation system is to be integrated into the device itself. FIG. 2 shows a[0027]device2 with aninstrument insertion channel10 and three laterally extendedreflectors12. The threemountings13 for thereflectors12 can be manufactured from one piece or can be three separate parts. Thereflectors12 could also be active optical light-emitting diodes. In such arrangement, the three reflectors orsending elements12 can be monitored by an external camera system, and, due to the relative position of these three elements to each other, the spatial orientation of the device can be calculated and then be integrated in the MR image. Better still is the application of markers which are directly identified by the “magnet” (MRI), since this will prevent inaccuracies upon matching the coordination systems.
• FIG. 3 shows that this navigation device can also be directly connected to the[0028]instrument insertion channel10. There could also be a navigation system for thedevice2 as well as for theinstrument insertion channel10, resulting in having two navigation systems working with either different wavelengths or different codification or with different geometrically designedreflectors12. The device can be manufactured of a material that is not depictable under MRI or with other radiological imaging methods. Single parts or areas of the device could be designed of a material that is actively or passively identifiable under MRI. For instance, the entire device for the operation under MRI could be manufactured of plastics such as PEEK, and only certain parts would be designed of titanium. The device could also be designed to have hollow spaces containing a liquid which will emit active signals, such as liquids with unpaired proton spin, for instance a gadolinium-based liquid. FIG. 10 shows a double-walled top filled with a signal-emitting liquid. FIG. 5 shows a device4 designed completely of plastics, preferably PEEK (polyetheretherketone). This device4 is screwed into the skull with a self-cuttingthread19. Owing to the hardness of the plastic material, the device can be manufactured with a self-cutting thread. Such plastic device4 is preferably designed as a disposable. Two navigation points, which could be placed inside the device either separated from one another or together, shall be exemplarily described at this device. As one possibility, the adjustingscrew17 in this PEEK instrument could be made of titanium. Titanium is imaged negatively, as a black spot, in the MRI device, so that the position of the device4 is recognizable. With two further titanium points, the orientation of the device4 can be identified in a similar way as with the navigation system of FIGS.3 or2. A gadolinium-containing liquid is filled into ahollow space18 in this device4. This liquid is an active liquid for the MRI device, to be imaged as a white spot in the MR image. With three such hollow spaces filled with a gadolinium-containing liquid, here also the position of the device4 can be determined. It is now possible to combine such active spots such as thehollow spaces18 with the respective active orpassive points17, or self-reflecting or luminous marker points12, which will be identified by the MRI device or a navigation system connected to the MRI device. In this way, the localization and navigation of the device within the MRI is ensured. By use of various positioning points depicted differently in the MR image, it is possible to achieve an exact allocation of the measured points to the points at the device.
• A so-called TrackPointer, as described in patent specification 298 21 944.1, can also be connected to the device by implanting it in the[0029]instrument insertion channel10.
• The orientation of the instrument with regard to the operation system, or, in other words, the adaptation of the image to the device presented herein via the MRI device, can also be realized with the markers, according to the[0030]principle20 stated herein, not only attached to thedevice3 itself, but also to theinstrument24, being inserted into the minimally-invasiven channel2 for a certain procedure, and to the angle measuring system25 (FIG. 7).
• FIG. 7 shows the process of pushing an[0031]instrument24 through thedevice3 into the operation area. Amarker20′ is placed at itsdistal end20′, asecond marker20″ in the insertion center of thedevice3 as shown in FIG. 5. Thethird marker20′″ is positioned on theangle measuring system25, which is freely adjustable around the device. The plane visible in the MR image will then be extended by the threepoints20′,20″, and20′″. Thus one will always see the instrument with its inserted length in the brain region, which is determined by the third point placed on the circularangle measuring system25. Such marking points could also be designed as small coils, as, for example, laid open with number 200 in patent application U.S. Pat. No. 5,353,795 by Sven P. Souza in FIG. 2. Such an element is an arrive coil sending with a certain frequency and being deflected according to the system presented in the above-mentioned patent.
• Such a device can be used to insert probes, for mechanical and mechanical-surgical instruments or endoscopes. The[0032]instrument insertion channel10 could also be designed in form of several lumens, resulting in several channels instead of only one. The device can also be used to insert larger instruments in open OP's. Such a device could be designed as either reusable or disposable instrument.
• A system as presented herein can be used not only for surgical interventions and procedures, but also for the insertion of electrodes to fight Parkinson's disease. It could also be applied as a shunt.[0033]
NAMES
• [0034]1 Device
• [0035]2 Device, general for adaptation to a navigation system
• [0036]3 Device
• [0037]4 Plastic device
• [0038]5 Double-walled top filled with contrast medium
• [0039]6 Mounting
• [0040]7 Movable lamina
• [0041]8 Movable lamina
• [0042]9 Opening
• [0043]10 Instrument insertion channel
• [0044]11 Worm wheel
• [0045]12 Reflector/optically emitting elements
• [0046]13 Reflector fitting
• [0047]14 Angle adjustment azimuth angle
• [0048]15 Angle adjustment zenith angle
• [0049]16 Operation site
• [0050]17 Titanium screw
• [0051]18 Hollow space filled with gadolinium-containing liquid
• [0052]19 Self-cutting thread
• [0053]20 MRI markers according to one principle presented herein
• [0054]21 Top with angle adjustment
• [0055]22 Fixing screw
• [0056]23 Stabilization channel
• [0057]24 Instrument
• [0058]25 Angle measuring system

Claims (12)

1. A device for inserting medical instruments into the human body, comprising a connected navigation system which monitors and guides the device, wherein the connected navigation system comprises at least three positioning points, wherein the positioning points can be distinguished from one another by different imaging methods, and wherein the device is monitored and guided under magnetic resonance radiological imaging.

2. The device according toclaim 1, further comprising a scaling for an instrument insertion channel, so that the solid angle can be measured and adjusted preferably starting from a hole center.

3. The device according toclaim 1, wherein the positioning of an inserted instrument is performed by a tilting, or a tilting and rotating motion, of one of the device parts.

4. The device according toclaim 1, wherein the tilting, or tilting and rotating motion, of a device part is effected by an actuation.

5. The device according toclaim 1, wherein the orientation of the inserted instrument is optically indicated or scannable by sensors directly at the device.

6. The device according toclaim 1, wherein the device is identifiable by navigations systems under radiological imaging in total or in parts.

7. The device according toclaim 1, comprising a plurality of attached, optically active or optically reflecting positioning points, which are monitored by a respective camera system, and wherein from the position of the attached, optically active or optically reflecting positioning points to each other, the position and orientation of the device can be calculated.

8. The device according toclaim 1, further comprising a resonator system having passive electro-technical parts.

9. The device according toclaim 1, wherein the device works as an actively sending system.

10. The device according toclaim 1, further comprising a number of volumes which are filled with a magnetic liquid wherein the magnetic liquid is positively or negatively identifiable.

11. The device according toclaim 1, wherein the device is manufactured of a material non-identifiable under radiological imaging, and wherein the device further comprises certain materials which are positively (actively) or negatively (passively) identifiable under radiological imaging attached at several points.

12. The device according toclaim 6, wherein the device is identifiable by navigation systems under magnetic resonance tomagraphy (MRI), in total or in part.

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