JPH01146543A - Mri brain stereotaxic apparatus - Google Patents

Abstract

PURPOSE:To accurately apply puncture to an objective point to be operated by allowing the coordinates in the actual space to coincide with those in the image, by supporting a frame on which the head is mounted by the inner wall of an inclined magnetic field coil unit and supporting the position of the frame in correspondence with the center of an inclined magnnetic field. CONSTITUTION:Since a frame 39 is fixed to an inclined magnetic field coil 34 through an attachment 35 and a frame mount jig 30, the positional relation between the frame 39 and the inclined magnetic field coil 34 is uniquely determined. Since an operation objective point is generally present at the central part of the frame 39 and the center of the frame 39 can be set to the center of the magnetic field of the inclined magnetic field coil 34, the coordinates system (x, y, z) of the frame 39 can be allowed to coincide with the coordinates system of an image = the coordinates system (X, Y, Z) of the inclined magnetic field coil 34. That is, the operation objective point capable of being known on a strain free image can be immediately fixed on the actual head PH and puncture is performed to the operation objective point capable of being accurately fixed using an operation utensil.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to magnetic resonance (MR)
Magnetic resonance diagnostic equipment (hereinafter referred to as rMRIJ) uses the phenomenon of
It is called. ), and particularly relates to an MRI stereotactic neurosurgery device that makes it possible to match coordinates in real space with coordinates on an image.

(Prior art) Stereotactic neurosurgery (5terotaxy) is a procedure used in clinical neurosurgery to remove, destroy, and eject diseased areas such as brain IIfls. The operation is performed by identifying a surgical target point using the surgical method and puncturing the identified surgical target point.

Stereotactic brain surgery in which a surgical target point is identified using a magnetic resonance diagnostic device will be described below with reference to FIG.

That is, the frame 21 is attached to the patient's head Pl-1, and then the surgical tool 22 is attached to the frame 21. In this state, the diagnostic space DS of the magnetic resonance diagnosis Haff
and scan it. FIG. 4 shows a tomographic image generated and displayed by the above-described scan.

Here, an overview of the magnetic resonance diagnostic apparatus will be explained.

In other words, the magnetic resonance phenomenon is a phenomenon in which atomic nuclei with non-zero spin and magnetic moment placed in a D magnetic field resonantly absorb and emit only electromagnetic waves of a specific frequency.
γ is the gyromagnetic ratio specific to the type of atomic nucleus, and Ho'a
- Assuming the static magnetic field strength, this atomic nucleus resonates at the angular frequency ω0 shown in the following equation.

ωO舅γ110 The method of performing biological diagnosis using the above principle involves signal processing of electromagnetic waves of the same frequency as above, which are induced after the above-mentioned resonance absorption, to obtain, for example, a tomographic image of the subject. .

In this case, the collection of diagnostic information by magnetic resonance is
Although it is possible to excite and collect signals from all parts of a subject placed in the m field, due to limitations in the device configuration and clinical requirements for imaging images, in reality it is not possible to excite and collect signals from a specific slice plane. We are trying to collect those signals.

FIG. 5 is a diagram showing a general configuration of a magnetic resonance diagnostic apparatus using the above-described principle.

As shown in FIG. 5, the magnet assembly MA that accommodates the subject P therein includes, for example, a superconducting or normal conducting static magnetic field coil that generates a high-intensity static magnetic field that acts on the subject P. 1 and tilt along the X, Y, and Z axes to provide positional information regarding the excitation/signal collection site! i
It includes three gradient magnetic field coils 2 that generate fields, and a transmitting/receiving coil 3 that serves both as transmitting and receiving functions, for example, for excitation and signal collection.

It also has a static magnetic field control system 4 that performs excitation control of the static magnetic field coil 1 and coolant supply control. X, Y.

The Z-axis gradient magnetic field coil 2 has an X, Y, and Z-axis gradient magnetic field power supply 5.
Excitation is controlled by 6.7. The transmitter/receiver coil 3 is driven by a transmitter 8 during transmission (excitation) and by a receiver 9 during reception (signal collection).

In addition, there is a sequencer 10 that executes the generation sequence of gradient magnetic fields and transmission/reception signals by the X, Y, and Z axis gradient magnetic field electric +1!5, 6.7, transmitter 8, and receiver 9, and accessories such as this sequencer 10 and a bed. It is equipped with a computer system 11 that performs overall control and signal processing of the entire system including equipment, and a display system 12 that displays production operations.

Now, as shown in the tnS diagram, stereotactic brain surgery can be performed on the head PH by attaching the surgical tool 22 to the frame 21, but it is necessary to identify the surgical target point.

That is, it is assumed that the surgical target point T has been determined by looking at the image shown in FIG. It is necessary to know where this point T is located on FIG. 3. By matching the point T on the image with the actual point t, puncturing can be performed using the surgical tool 22.

In order to identify the above-mentioned surgical target point on the image and in practice, it is necessary to know the correspondence between the coordinates on the diagnostic space O8 in FIG. 3 and the coordinates on the image in FIG. 4. For this reason, gauge plates 23A and 23B are provided on both sides of the frame 21.
is installed.

In this case, the coordinate system of the frame 21 - the gauge plates 23A, 2
3B coordinate system (X, V, Z) and the image coordinate system - gradient magnetic field coil coordinate system (X, Y, Z) are different, so in FIG. statue 23
/M, 23B- and by knowing its position in the (X, Y, Z) system, (X, Y, Z') system → (x, y
, z) to find the transformation of the system. As a result, the correspondence between the head image PI-1= and the actual head PH and the surgical target point T (Xt, Yt, Zt') on the image and the actual surgical target point t (xt, yt, zt) can be determined. can be matched,
Puncture can be performed using the surgical tool 22 at the surgical target point t.

- The above explanation is based on the assumption that the actual object appears correctly in the image in both shape and positional relationship, but in reality, due to distortion of the static magnetic field and gradient magnetic field, the actual object appears in the image correctly in both shape and positional relationship. It doesn't appear correctly. That is, as shown in FIG. 6, the static magnetic field strength Ha should be spatially uniform, but it is distorted. Further, as shown in FIG. 7, although the gradient magnetic field strength G should be spatially linear, it is distorted. Due to these, the image has a positional shift.

That is, as shown in FIG. 8, the magnetic field strength corresponding to static magnetic field strength Ha + gradient magnetic field strength - Larmor frequency is distorted depending on the position where it should exhibit linear characteristics.

Therefore, although point A in the diagram should have a magnetic field strength of Ao,
− is. Also, since AO- should be the magnetic field strength at a point of 1 mA, the true image as shown in Figure 9(a) and the actual image as shown in Figure 9(b) are A and A'.
They appear in different positions, such as. Moreover, the distortion of the static magnetic field strength 1-1a and the distortion of the gradient magnetic field strength G become particularly problematic because they rapidly increase as the distance from the center of the magnetic field increases.

t C That is, since the gauge plates 23A and 23B are attached to both sides of the frame 21, for example, if the center of the frame 21 is the center of the magnetic field, the images 2 of the gauge plates 23A and 23B
3/M, 23B- has large distortion. Therefore, the gauge plate 23A appears on the image.

No matter how closely the positions of the images 23A' and 23B- of 23B are measured on the image, the error will be large.

On the other hand, since the surgical target area is a small area within 100φ at most, the surgical target point can be brought close to the center of the magnetic field. Therefore, by bringing the surgical target point close to the center of the magnetic field, the distortion of the surgical target point can be reduced.

According to the above, the image is not distorted around the surgical target point, but as a result of the distortion of the gauge image, the accuracy (X, Y
, Z) system coordinates and (X, y, Z) system coordinates, and furthermore, there is a problem that puncture cannot be performed correctly at the surgical target point.

(Problems to be Solved by the Invention) As described above, in the conventional technology, a gauge is placed in real space, and a surgical target point is identified by referring to the gauge image appearing in an image obtained by scanning. However, the problem is that the image itself is distorted due to distortion of the static magnetic field and gradient magnetic field, resulting in inaccurate identification.

SUMMARY OF THE INVENTION An object of the present invention is to provide an MRI stereotactic neurosurgical device that can match coordinates in real space with coordinates on an image and puncture correctly at a surgical target point. .

[Objective of the Invention (Means for Solving Problems) The present invention has a configuration in which the following means are taken to solve the above problems and achieve the object. That is, the present invention includes a frame that is detachably attached to the head of a subject, and this frame is supported on the inner wall of a gradient magnetic field coil unit of a magnet assembly of a magnetic resonance diagnostic apparatus, and the position of the frame is adjusted to the gradient magnetic field. The present invention is characterized by comprising a support member supported in correspondence with the center, and a stereotactic neurosurgery tool provided on the navigation frame.

(Function) According to this configuration, the frame on which the head is attached is supported on the inner wall of the gradient magnetic field coil unit, and the frame is supported with the position corresponding to the center of the gradient magnetic field, so the head is mechanically supported. By matching the coordinates in the real space of the part with the coordinates on the image, it becomes possible to improve the accuracy of the corresponding position of both coordinates at a position where the image is not distorted.

(Embodiment) An embodiment of the MRI stereotactic brain surgery apparatus according to the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a front view, and FIG. 2 is a perspective view. In both figures, the magnetic resonance diagnostic apparatus can adopt an intra-membrane configuration, and the main part of this embodiment is provided at the axial center of the gradient magnetic field coil, so here the gradient magnetic field coil is A portion of the unit in the axial direction is shown.

As shown in the figure, a frame mounting jig 30 is provided at the center in the axial direction corresponding to the axial magnetic field center of the gradient magnetic field coil 34 where distortion in the strength of the static magnetic field and the gradient magnetic field is smallest. For this frame attachment, the jig 30 has an annular base 31 at the center, and supports 32 are provided every 12o0 in the circumferential direction of the base 31. The radial ends of these struts 32 are supported by, for example, rivets 33 on the inner wall of a gradient coil unit 34 of a magnet assembly of a magnetic resonance diagnostic apparatus. A frame attachment 35 is disposed inside the annular base 31, and this frame attachment 35 is supported by positioning screws 36 provided at three different locations in the radial direction of the annular base 31.
> is positioned in the direction.

A protrusion 37 and a screw hole 38 are formed at three different locations in the radial direction of the frame attachment 35.
The hole 4° of the frame 39 corresponds to the screw hole 38.
The screw 42 is inserted through the through hole 41 of the frame 39.
is compatible.

The frame 39 is detachably attached to the patient's head PH and corresponds to the frame 21 in FIG. 3. The surgical tool 2 of FIG. 3 (not shown) is mounted on the frame 39.
2 is installed. Note that when attaching the frame 39 to the frame attachment 35, the frame 39 has already been attached.
is attached to the head PH. In addition, it is preferable that all the members mentioned above are non-magnetic materials.

Next, the operation of this embodiment configured as described above will be explained. That is, the frame 39 is attached to the gradient magnetic field coil 34 via the attachment 35 and the frame mounting jig 30.
Since the frame 39 and the gradient magnetic field coil 3
The positional relationship with 4 is uniquely determined. Also,
Generally, the surgical target point is located at the center of the frame 39, and the center of the frame 39 can be set at the center of the magnetic field of the gradient magnetic field coil 34 using the screw 36. Therefore, the coordinate system (X, V, Z) of the frame 39 and the coordinate system of the image - the coordinate system of the gradient magnetic field coil 34 (X, Y.

2) can be matched. In other words, the surgical target point known on the undistorted image can be immediately identified on the actual head PH, and the surgical target point that has been accurately identified can be punctured using a surgical tool. Become so.

In the above method, there is a method in which the gradient magnetic field coil 34 is fixed to a magnet assembly of a magnetic resonance diagnostic apparatus, a patient wearing a frame 39 is placed inside the gradient magnetic field coil 34, and the frame 39 is connected to the frame attachment 35.

In addition, the gradient magnetic field coil 34 is not fixed to the magnet assembly of the 8-position magnetic resonance diagnosis, and the frame 39 is first attached to the gradient magnetic field coil 34 outside the magnet assembly, and then the patient's head is attached to the frame 39. , gradient magnetic field coil 34. Frame 39. One method is to place the patient set within the magnet assembly.

Furthermore, the following example can be applied to the combination of a transmitting/receiving coil (one configured for both transmission and reception, or one configured for transmission and reception separately) and a gradient magnetic field coil. That is, the coil may be assembled in advance into the gradient magnetic field coil, and then the frame may be assembled.

Alternatively, the coils may be assembled into the frame and then assembled into a gradient magnetic field coil.

Furthermore, a coil may be arranged completely separately from the frame and the gradient magnetic field coil.

In addition, in the configuration shown in FIGS. 1 and 2, the frame attachment 35 and the frame mounting jig 30 are used so that the frame attachment 35 can be removed after identifying the surgical target point in order to secure a large surgical work space. Like the frame attachment 35 and the frame 39, protrusions and holes may be formed to improve positioning accuracy and facilitate attachment and detachment.

In addition, various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] As described above, the present invention includes a frame that is detachably attached to the head of a subject, and a frame that is supported on the inner wall of a gradient coil unit of a magnet assembly of a magnetic resonance diagnostic apparatus. Tilt the frame position to 111!
and a stereotactic neurosurgical tool provided on the frame,
It is now possible to mechanically match the coordinates of the head in real space and the coordinates on the image, and to improve the accuracy of the corresponding position of both coordinates at a position where there is no image distortion. It is possible to provide an MRI stereotactic neurosurgery device that can puncture a surgical target point.

[Brief explanation of the drawing]

and Fig. 4 are diagrams showing a conventional example, Fig. 5 is a diagram showing the configuration of a general magnetic resonance diagnostic apparatus, and Figs. 6 to 9 show the relationship between distortion of static magnetic fields and gradient magnetic fields and image distortion. FIG. 30... Frame installation jig, 31 base, 32...
- Post, 33... Rivet, 34... Gradient magnetic field unit, 35... Frame attachment, 36...
Screw, 37...Protrusion, 38...Screw hole, 4o...
Hole, 41...through hole, 42...screw. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure S Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] A frame that is detachably attached to the head of a subject, and this frame is supported on the inner wall of a gradient magnetic field coil unit of a magnet assembly of a magnetic resonance diagnostic apparatus, and the frame is supported so that the position of the frame corresponds to the center of the gradient magnetic field. An MRI stereotactic neurosurgery apparatus, comprising: a support member that supports the frame; and a stereotactic neurosurgery tool provided on the frame.