EP1343430A1 - Manipulator for a closed magnetic resonance tomograph - Google Patents

Abstract

The invention relates to a manipulator to be used in a closed magnetic resonance tomograph, comprising a traversing MRT channel for inserting a patient bed for female patients in prone position during MR mammography, a support arm and a receiving housing on the front thereof intended for the instruments used to treat the patients. Said manipulator is used to introduce the instruments into the channel parallel to its longitudinal axis, to continuously position the mamma in every direction and can be additionally actuated in situ on said position on the mamma. The invention aims at improving a manipulator for an MRT with the purpose of providing greater stiffness and smaller overall dimensions and optimizing the manipulation while increasing operating safety. To this end, the manipulator according to the invention is characterized in that the support arm of said manipulator is rotationally mounted and can be positioned in horizontal and vertical direction on the proximal side thereof.

Description

Manipulator for a closed magnetic resonance tomograph

The present invention relates to a manipulator for use in a closed magnetic resonance tomograph MRI with a continuous channel for inserting a patient support for female patients in a prone position in MR mammography, with a support arm and a receiving housing at its tip for the instruments for treating the patient, with which these can be moved into the channel parallel to its longitudinal axis, can be positioned steplessly in any direction with respect to the position of the breast and can also be operated on the breast in this position. In contrast to the open MRT, a closed MRT is characterized by the continuous channel without additional lateral openings.

In the case of the closed MRT known from practice, the MRI-assisted mammography with the resulting further treatment steps, for example a biopsy with a possibly subsequent therapy, is carried out in a large number of steps in which the patient repeatedly exits into the channel of the device. and must be run in. One reason for this is that the surgical treatment steps when using a closed MRI on the patient could previously only be carried out outside the device. This means a great deal of time, great physical and psychological strain on the patient and an additional risk due to possible changes in the position of the mother, especially in the case of longer time sequences of the work steps. Likewise, the long expenditure of time means correspondingly high costs of the therapy.

From DE-196 39 975 an MRI with a continuous channel for receiving the patient is known, but which has no further devices or instruments for treating the patient. In EP-A-0 534 607 there is an MRI with two described ring-shaped magnets, within which the patient lies and between which a mechanical device for heat treatment of tumors of the patient by means of laser energy (not detailed) is attached from the side. A previous biopsy is not intended for the MRI according to the EP and would have to be done outside the device in another way beforehand. EP-A-0 534 607 therefore gives no suggestion of improving the situation described above.

Furthermore, from DE 196 26 286 AI and DE 295 21 366 UI breast coils for use on open MRT are known, which are laterally provided with biopsy devices movable in different degrees of freedom, but are only accessible from outside the MRI. Therefore, an MRI-assisted biopsy can only be performed with these devices outside of a closed MRI, the patient having to be moved out of the measurement position in the channel of the MRI for the intervention. The biopsy could therefore not be performed on the MRI under visual control, that is, online on the computer.

In contrast, US Pat. No. 5,443,068 describes a system for an MRI-based but non-invasive treatment of tumors by local ultrasound heating. The system consists of a closed MRI (with a continuous channel) for one-sided insertion of a patient bed, into which a manipulator with an ultrasound transducer is integrated directly below the bed surface. The manipulator has a trough-shaped support arm for receiving the focusing ultrasound transducer which can laterally be displaced in all three spatial axes and always radiates upwards, as well as the coupling medium required for the transmission of the ultrasound waves. For the transmission of the ultrasound waves to the patient's body, there is a membrane on the coupling medium, on which the patient's body, preferably the breast, rests and clings to it. The lateral displaceability of the ultrasound transducer in the coupling medium takes place for each of the three spatial axes. via cardan shafts and gears separately for each spatial axis, whereby the electric drives are outside the MR magnetic field and do not influence it.

DE 198 18 785 AI, on the other hand, describes a manipulator for a closed MRI with a continuous channel for inserting a patient support for female patients in a prone position in MR mammography, with a support arm and a receiving housing at its tip for the instruments for treating the patient which can be moved into the channel parallel to its longitudinal axis, can be steplessly positioned in any direction with respect to the position of the breast and can also be operated on the breast in this position. The support arm is inserted in a swivel arm, which is guided in a hanging manner from a horizontally guided slide on a frame that occupies the entire cross section of the MRT channel, perpendicular to the MRT channel. By swiveling the swivel arm, moving the slide and moving the manipulator parallel to the longitudinal axis of the channel, the tip can be moved in any direction to the position of the breast, but for swiveling the swivel arm horizontally up and down, the swivel arm is swiveled as well the sledge has to be moved.

Proceeding from this, the task of the present invention is to further develop a manipulator for an MRI as described at the beginning and to improve its handling. On the one hand, the structure should be simplified in favor of a smaller size and a higher rigidity, on the other hand, the movement sequences when moving the manipulator tip to the position of the breast should be redesigned for easier control and increased operational reliability. The position of the patient, the patient support and the MRI, which were positioned in relation to one another before the use of the MRT, should be able to be maintained over the entire surgical site. To achieve the object, the invention proposes the features that are stated in the characterizing part of claim 1. Further advantageous features which further develop the invention can be seen in the characterizing parts of the subclaims.

Details are explained in the following and with reference to Figures 1 to 7. Show it:

1 a and b each a top view of the manipulator in the neutral basic position or schematically in both horizontal pivot end positions,

2 shows a side section through the manipulator,

3 shows a section through the MRT with the manipulator approximately along the line AA of FIG. 1, but in the laterally extended position,

4 and 5 sections of the receiving housing at the tip of the manipulator from above and from the side,

7 a-h the individual process steps at the tip of the manipulator during the biopsy.

The manipulator shown in the figures is intended for use in a closed MRI with a continuous channel 1, which is indicated in FIG. 3 and in which from one side a table 2 serves as a support for the manipulator and a patient bed 3 for female patients for MR mammography and any further treatment. On the table 2, the manipulator and the patient couch 3 are guided in the longitudinal direction of the table as two separate units one behind the other, the table being designed as a running rail under the support points 4. It goes without saying that the The entire manipulator as well as the patient bed 3 and the table 2 are made of MRI-compatible materials.

In the following, the horizontal direction perpendicular to the longitudinal direction of the table 2 and the channel 1 (see FIGS. 1 a, 1 b and 3) is used as the x-axis and the vertical direction perpendicular to the x-axis (see FIG. 2) as the y-direction and 3) understood. The axis, which is perpendicular to the axes x and y and thus runs parallel to the longitudinal direction of the table 2 and the channel 1, is referred to below as the z axis (see FIGS. 1 a, 1 b and 2).

The patient (not shown) is shown on the patient couch (the position of the mother 5 is shown, for example, in FIG. 2) in the prone position, the mother 5 projecting downward through two openings 6. The positions of the breast (breasts) possible due to the anatomical differences lie in the area of the two windows 7 indicated in FIG. 3, which show the working area of the manipulator in the vertical plane perpendicular to the longitudinal direction of the table 2 or the channel 2 (x / y- Level). The breast 5 to be treated in each case is fixed there in the longitudinal direction by pressure plates 6 or / and a frame and is positioned on the table 2 in the isocenter of the MRT by moving the patient bed 3. The manipulator is then, as shown in FIGS. 1 a and b and 2, pushed on the table with its tip 8 in the Z direction to the breast 5 to be examined. The instruments required for the treatment are accommodated in or at this tip 8 (cf. FIGS. 2 and 4 to 6).

The manipulator essentially consists of two subassemblies, a gimbal-type swivel device for the support arm 9 and the manipulator arm, consisting of the support arm 9 and the tip 8 attached to it, with a housing for medical instruments. As shown in FIG. 2, the cardanically acting pivoting device for the support tube 9 is built on a base plate 10 which is mounted on the table 1 so as to be displaceable in the z direction.

A hole in the base plate serves as a bearing for a common horizontal swivel direction (approximately x ~ direction in the middle position) for a structurally rigidly connected assembly consisting of swivel housing 11, drive block 12 and drive housing 13, and thus also for the support arm 9 about the axis 14 This swiveling movement is driven by an MRI-compatible motor, preferably a piezomotor 15, which drives a pinion 17 via a belt drive 16, alternatively a gear transmission, which in turn engages in a curved toothed segment 18 firmly attached to the base plate 10 and thus a Relative movement of the drive block (12) to the base plate (10) around the axis 14 causes.

The support arm 9 of the manipulator, which is oriented in the neutral direction according to FIGS. 1 a and 2 in the z direction, penetrates the swivel housing 11 and the drive housing 13 through a breakthrough which is provided in each of these components (see FIG. 2). The receiving sleeve 19 for the support arm 9 in the area of the swivel housing 11 perpendicular to the sleeve axis on both sides horizontally projecting bolts 20 which are mounted in the swivel housing 11 and allow a vertical swivel movement of the support arm 9 (approximately y-direction in the middle position). As with the horizontal pivoting movement described above, the vertical pivoting movement is driven by an MRI-compatible motor, preferably a piezomotor 21, which, arranged in the drive housing 13, drives a worm thread 22, which in turn drives into a curved toothed segment firmly attached to a holding sleeve 23 for the support arm 8 24 engages and thus in this area a relative movement from the drive housing 13 to the support arm 9 around the Bolt 20 causes. This area is only shown in detail in FIG. 2, whereas FIGS. 1 a and b only schematically show the position of the manipulator arm 9 in the swivel housing 11 and the drive housing 13.

As described above, the manipulator is displaced in the z direction by manually moving the base plate 10 on the table 2 relative to the patient bed. In addition, a fine adjustment of the manipulator along the support arm axis (corresponds to the z direction in the middle position) is outside of the MRT via a set screw 25 which engages in a thread connected to the holding sleeve 23 and acts against a stop 26 placed on the support arm 9. Channel possible. As an alternative to the manual adjusting screw 25, in the case of computer-aided positioning in the MRI, it is advisable to drive the adjusting screw with a piezomotor suitable for MRI.

The second assembly of the manipulator comprises the manipulator arm, which is described in more detail below with reference to an overview according to FIG. 2 and the detail sections according to FIGS. 4 and 5.

The manipulator arm consists of the support arm 9 and the attached tip 8 with a receptacle for medical instruments. It is, as described above, inserted with the support arm 9 in the holding sleeve 23 and the receiving sleeve 19 so as to be displaceable and pivotable in its longitudinal axis. In the area between the holding sleeve 23 and the tip 8, the support arm is cut open at the top and bottom to form a continuous recess 27. This recess 27 serves in the manner described later for receiving the interchangeable surgical instruments. Furthermore, the support arm has a continuous instrument channel 29 between the proximal end 28 and the recess 27. This instrument channel 29 is used in particular to push through and operate the instruments required for treatment from the proximal end 28 to the tip 8 of the manipulator arm.

Another important component of the manipulator arm is the instrument holder 30, which is inserted into the recess 27 and has an interior 31. The instrument holder 30 can be swiveled vertically and - after rotation of the support tube 9 in the holding sleeve 23 and the holding sleeve 19 by 90 ° - also horizontally about the circular segment 32 as a plain bearing surface around the invariant point 33. The circular segment 32 is formed from the rear of the distal end piece 34 of the manipulator and has a vertical (in relation to the position shown in FIGS. 4 and 5) T-guide 35 in which the end face 36 of the instrument holder 30, which is designed as a counterpart, slides ,

In the interior 31 of the instrument receptacle 30 there is the receptacle housing 37 which can be displaced therein in the z direction (based on the horizontal central position) and in which the instruments used for the treatment can be inserted and replaced. The displacement on the housing is done manually using a push rod

38 from the proximal end 28 of the manipulator arm. The hub

39 of the push rod 38 is limited, as shown in FIG. 2, by an adjustable stop 40. The receiving housing 37 also has a recess 41 on the proximal side for the insertion of a surgical instrument, which opens on the distal side into a countersunk bore 42 in the receiving housing 37 and this then leads into a trocar 43 connected to the receiving housing. The trocar 43 in the end face 36 of the instrument holder 30 is additionally guided through a sliding sleeve 44 through a bore in the distal end piece 34 of the manipulator.

An instrument 53 is inserted into the receiving housing 37 in an instrument adapter 54 shown in FIG. 2, and is axially displaceable with this in the recess 41. In the specific application of MRI mammography, the instruments used are, on the one hand, a biopsy device for taking a tissue sample and, on the other hand, the applicator of a cryo- or laser device for any subsequent cryotherapy or laser surgery. In this case, instrument adapters 54 specially designed for the instrument 53 used are used, which thus enable the respective instrument to be adapted to the cutout 41 of the receiving housing 37.

The instrument adapter 54 can be locked in various positions with the instrument 53 by means of a coupling device in the form of a rotatable link plate 58 which engages selectively in the receiving housing 37 and the instrument adapter 54 and can be removed from it in the proximal direction after loosening the coupling device. On the link plate 58 there is an articulated rod 59 which leads to the proximal end 28 and with which the instrument adapter 54 with the instrument 53 can be pulled out and removed from there and reinserted. The function of the link plate is described in more detail elsewhere in connection with Figures 6 a to h.

If sterile protection of the instruments used in the receptacle housing against external contamination by the trocar 43 is required, a sterile sleeve 55 must be used as a protective component on the end face 36 of the instrument receptacle 30, which is pierced by the trocar during the advancing movement of the receptacle housing 37.

The pivoting movement of the receptacle housing 37 takes place together with the instrument receptacle 30 in this and around the invariant point 33 (see FIG. 2) which lies outside the tip 8 and which is located at the tissue puncture point during an intervention and in which the respective instrument 53 and the trocar 43 is pivotable without changing its position to the puncture point. For this purpose, as shown in FIGS. 4 and 5, a pivot lever 46 with two legs 47 and 48 which are perpendicular to one another is mounted on the side of the instrument holder 30 on an axis 45 seated in the support tube 14 and has one leg 47 movable on the instrument holder 30 attacks and on the other leg 48 a push rod 49 is articulated. The stroke 50 generated by an axial movement pivots the pivot lever 46 about the axis 45, so that the leg 47 is rotated upwards and downwards and the instrument receptacle 30, which is articulated thereon and the receptacle housing 37 accommodated therein, also pivots with the trocar 43 instrument. The rotation by the angle 51 pivots the instrument holder 30, the push rod 49 having a graduation with a raster 52 at its proximal end. In a fan biopsy, for example, the instrument holder is pivoted 30 degrees by degrees using the push rod 49 up or down. In order to be able to pivot the instrument holder 30 to the left and right, the support tube 9 in the receiving sleeve 19 and in the holding sleeve 23 must be rotated through 90 °.

The actual process of the MRI-supported biopsy and the processes taking place in the manipulator arm, in particular in the instrument holder 30, are explained in detail below with reference to FIGS. 6 a to h.

First, the breast 5 of the patient lying on the patient support 3 in the MRT channel 1 in the prone position is positioned in the isocenter of the MRT in the area of the windows 7 (see FIG. 3) in the openings 6 and in a manner not shown, preferably with fixing plates, -frame or an anatomically shaped shell with puncture options, fixed. The slice images are then created in a conventional manner, with the target coordinates of any findings being recorded. If the result is positive, ie, in the case of a biopsy to be performed, the target tissue 56 is defined and its coordinates are converted into control commands for manipulator setting by means of piezoelectric motors (approximately x, y and z directions) by a control computer (not described further). In particular, the calculation of the control commands takes into account corrections due to the possible swivel angle of the manipulator arm deviating from the z-direction and the distance between tip 8 and target tissue in the breast 5 which is variable due to the swivel process in such a way that the feed path of the trocar 43 and the instrument 53 in the Mamma 5 can be set approximately independently of the possible swivel position.

6 a shows the tip 8 of the manipulator arm with instrument holder 30, which has not yet been pushed towards the breast for the biopsy to be performed. The receiving housing 37 with the instrument 53 in the instrument adapter 54 is located in the recess 41 in the retracted position, i. H. the trocar 43 is not extended. In this starting position, the instrument adapter 54 is locked by means of the link plate 58 at the rear end of the receiving housing 37. In this case, the instrument 53 is a biopsy device, the biopsy needle 57 of which is inserted into the trocar 43. The target tissue 56 for the biopsy in the breast 5 is also shown in FIGS. 6 a to h.

As shown in FIG. 6 b, the manipulator tip is first pushed manually against the breast 5 using the adjusting screw 25 (cf. FIG. 2) for the biopsy.

Once the target tissue 56 has been fixed, the needle 8 is pierced approximately in the x and y directions after the tip 8 has been readjusted until just before the target tissue (FIG. 6 c). The trocar 43 is advanced together with the receiving housing 37 in the interior 31 of the instrument holder 30 via the push rod 38 (see FIG. 5), which engages on the receiving housing 37. In this process, the penetration depth of the trocar is set by an adjustable stop 61 (cf. FIG. 5) and, if necessary, limited by the z-axis setting using the adjusting screw 25 with the piezomotor.

In this position, a tissue sample is taken from the target tissue 56 by actuating the biopsy device (instrument 53) via the biopsy needle 57 (FIG. 6 d). The biopsy device is triggered, for example, by rotating the link plate 58 via the rod 59 or a Bowden or cable pull (not shown) in a rod 59 designed in this case as a tube (cf. FIG. 2).

After sampling, the instrument adapter 54 with the biopsy device in the recess 41 of the receiving housing 37 is pulled back by tightening the rod 59, whereby the biopsy needle 57 with the tissue sample is drawn back into the trocar 43 (FIG. 6 e). , For this purpose, the locking of the instrument adapter 54 in the receiving housing 37 is to be released beforehand by a defined rotation of the link plate 58 via the rod 59. This retraction movement is limited by a proximal stop 62 for the link plate 58 in a corresponding rotational position on the receiving housing 37.

As shown in FIG. 6 f, the trocar 43 is partially pulled out by pulling back the receptacle housing 37 in the interior 31 of the instrument receptacle 30 with the push rod 38 to such an extent that the trocar tip for the insertion of instruments for any further treatment steps that may be required remains in the mom.

After a further defined rotation of the link plate 58, it is pushed by the proximal stop 62, so that the biopsy device with the instrument adapter 54 are decoupled from the receiving housing 37 and on the proximal one Side can be pulled out (Fig. 6g). Since the gate 43 is still inserted into the breast 43, another instrument 53 can be inserted into it for further treatment.

For example, for any further treatment, the biopsy device is exchanged for a cryo- or laser applicator. This is brought into the receiving housing 37 in the same way as the biopsy device, which is still positioned according to the target coordinates of the manipulator. In this fixed position, e.g. administered cryogenic or laser energy according to the size of a detected tumor.

6 h shows the principle of a fan biopsy. For this purpose, the instrument holder 30 with the holder housing 37 is pivoted by means of the push rod 49 and the pivot lever 46, as shown in FIG. 4.

Another possible embodiment of the manipulator is characterized in that the positioning drives are not motorized via the aforementioned mechanical transmission elements, but fluidically via hydraulic or pneumatic adjusting elements, preferably via adjusting pistons integrated in a closed control circuit.

Reference list of characters:

1 MRI channel 32 circle segment

2 table 33 invariant point

3 patient bed 34 distal end piece

4 support points 35 T-guide

5 moms 36 front

6 openings 37 housing

7 windows 38 push rod

8 tip 39 stroke

9 support tube 40 stop

10 base plate 41 recess

11 swivel housing 42 bore

12 drive block 43 trocar

13 drive housing 44 sliding sleeve

14 axis 45 axis

15 Piezomotor 46 swivel lever

16 belt drive 47 legs

17 sprockets 48 legs

18 Curved toothed segment 49 Push rod

19 receiving sleeve 50 stroke

20 bolts 51 angles

21 Piezomotor 52 grid

22 screw thread 53 instrument

23 holding sleeve 54 instrument adapter

24 curved tooth segment 55 sterile sleeve

25 Set screw 56 Target tissue

26 stop 57 biopsy needle

27 Cut-out 58 Link plate

28 Proximal end 59 rod

29 Instrument channel 60 Piezomotor

30 Instrument holder 61 Stop

31 Interior 62 stop

Claims

Claims: 1. Manipulator for use in a closed magnetic resonance tomograph MRI with a continuous MRI channel (1) for inserting a patient couch (3) for female patients in prone position during MR mammography, with a support arm (9) and a receiving housing at its tip (8) for the instruments for treating the patient, with which the patient can be moved into the channel parallel to its longitudinal axis, the position of the breast (5) can be steplessly positioned in any direction and in this position can also be operated on the breast (5) , characterized in that the support arm is pivotally mounted and positioned on the proximal side in the horizontal and vertical directions. 2. Manipulator according to claim 1, characterized in that the patient bed (3) has two openings (6) for the mother (5) of the patient, under which a suitable fixing device, preferably a fixing frame and pressure plates for positioning and fixing the mother are attached , 3. Manipulator according to claim 1 or 2, characterized in that a) the support arm in a swivel housing (11) and a drive housing (13) is pivotally inserted via MRI-compatible piezo motors with transmission gear, b) the swivel housing (11) and that Drive housing (13) with a drive block (12) rigidly connected to form a structural unit, this unit is rotatably mounted on a base plate (10) about a vertical axis (14), an MRI-compatible piezomotor (15) in the drive block with a belt drive (16) or a gear transmission on a pinion (17) is arranged so that the pinion in a curved tooth segment (18), which is firmly connected to the base plate (10), engages to carry out a horizontal pivoting movement, c) the support arm (9) in the region of the pivoting housing (11) has bolts (20) projecting horizontally on both sides perpendicular to its longitudinal axis which it is pivoted vertically in the swivel housing (11) and in the drive housing (13) the drive (21) for the vertical swivel movement in the form of a piezo motor (21) used in the drive housing (13) with worm thread (22), which in a with Carrier arm connected curved tooth segment (24) engages, is arranged. 4. Manipulator according to one of claims 1 to 3, characterized in that the manipulator and the patient bed (3) are two separate units which are fastened one behind the other on a table (2) and on and with this on rails in the MRI channel ( 1) can be extended and retracted. 5. Manipulator according to one of claims 1 to 4, characterized in that the support arm (9) of the manipulator is cut open at its distal part in the region of the tip (8) and is open at the top and bottom. 6. Manipulator according to claim 5, characterized in that a) in the cut part in the area of the tip (8) sits an instrument holder (30) which is vertical and - after rotation of the support tube by 90 ° - also horizontally over a circle segment (32 ) can be pivoted about an invariant point (33) distal in front of the tip (8) of the manipulator outside the manipulator arm, the circle segment (32) sitting on the back of the distal tip (8) of the support arm (9), b) a receptacle housing (37) is arranged in the instrument receptacle (30), which is displaceable therein and in which the instrument adapter (54) sits, in which the instruments (53) used can be inserted and exchanged. Manipulator according to claim 6, characterized in that a swivel lever (46) with two legs (47, 48) standing perpendicular to one another is mounted on the side of the swivel housing on an axis (45) seated in the support arm (9). 47) movably engages on the housing and on the other leg (48) of which a pushrod (49) is articulated, which has a scale with a raster (52) at its proximal end. Manipulator according to one of the preceding claims, characterized in that the relative distance between the tip (8) of the manipulator and the patient bed (3) on the longitudinal axis of the MRI channel (1) can additionally be set with the aid of an adjusting screw (25) or a piezomotor.