JPH1133011A - Image forming method by magnetic resonance imaging - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming method whereby cross sections involving the longitudinal direction of a biopsy instrument inserted in the part for diagnosis from outside the subject are photographed for display so that the biopsy instrument can be guided efficiently to the target affected part without losing sight of the position of the end of the biopsy instrument. SOLUTION: In an image forming method using an MRI, for an area 11 of interest involving a biopsy instrument 12 inserted toward the part for diagnosis from outside the subject, three echoes generated by the sequential application of inclined magnetic fields along the directions of the axes of the volume of the area 11 of interest are converted into projection signals by Fourier transform, and the positions and velocities of the passage coordinates of at least two of three points at the end of the biopsy instrument at the times when the three echoes are generated are calculated to determine the vector of the biopsy instrument in its advancing direction, to determine a cross section 23 passing through the end of the biopsy instrument and being parallel to the vector in the advancing direction, after which an MRI image is photographed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic resonance imaging apparatus (hereinafter, referred to as an MRI apparatus) for obtaining a diagnostic image by utilizing a nuclear magnetic resonance phenomenon generated in a living tissue of a subject. Calculate the position and traveling direction of the tip of the biopsy device inserted into the diagnostic site, determine the position and direction of the imaging cross section including the longitudinal direction of the biopsy device, image the cross section, reconstruct and display the image About the method.

[0002]

2. Description of the Related Art In recent years, an MRI apparatus has not only measured a tomographic image of a diagnostic site of a subject but performed image diagnosis, and also inserted a biopsy instrument such as a biopsy needle or a catheter directly into the diagnostic site. (Interventional)
Radiology). In such an IVR procedure, it is necessary to find a target diseased part using the captured MRI image, and to insert a biopsy device into the target diseased part and to perform a procedure immediately. It is necessary to detect the position of the tip and guide it to the affected part.
In this regard, using a biopsy device with a built-in nuclear magnetic resonance substance at the tip, this is used for EPI (echo planar imaging).
Attempts have been made to monitor at a high time resolution by a high-speed imaging method such as a method.

[0003]

However, in such a method, the MRI image can only take a cross-section in a certain direction at a certain time interval irrespective of the movement of the biopsy instrument. Therefore, there was a problem that the biopsy device initially seen in the field of view gradually shifted out of the field of view, making it impossible to reliably track the biopsy device.

Further, the present applicant has proposed a method of detecting the tip position of a moving biopsy instrument in real time and a method of stippling the tip position on a cross-sectional image measured in advance (Japanese Patent Laid-Open No. 9-1997). 122096).

However, in this method, although the biopsy device can be reliably tracked, the imaging section is independent of the direction of travel of the biopsy device, and the position of the tip of the biopsy device is indicated by a point. Therefore, the longitudinal direction of the biopsy device could not be displayed. Therefore, there has been a problem that the two-dimensional and three-dimensional positional relationship between the biopsy device and the target diseased part cannot be sufficiently grasped.

Accordingly, an object of the present invention is to provide an image forming method for taking an image of the longitudinal direction of a biopsy instrument without losing the position of the tip of the biopsy instrument without addressing such problems. . In addition, the present invention makes it easy to grasp the two-dimensional and three-dimensional positional relationship between the biopsy device and the target diseased part,
It is an object of the present invention to provide an image forming method that enables a biopsy device to be efficiently guided to a target diseased part.

[0007]

In order to achieve the above object, an image forming method according to the present invention comprises: a static magnetic field generating means for applying a static magnetic field to a subject; and a gradient magnetic field generating means for applying a gradient magnetic field to the subject. A probe for irradiating a diagnostic site of a subject with a high-frequency signal and receiving a high-frequency signal emitted by nuclear magnetic resonance of living tissue of the subject, and a high-frequency for driving the probe to irradiate and receive the high-frequency signal A transmitting and receiving unit, a computer that performs control of the high-frequency transmitting and receiving unit according to a pulse sequence at the time of imaging and performs an image reconstruction operation using a high-frequency signal received by a probe, and inputs an image signal generated by the computer as a tomographic image 1) Irradiation of a high-frequency signal to a region of interest including a biopsy device inserted into a diagnostic site from outside the subject And selective excitation of a region of interest by the application of one of the gradient magnetic field that follows, thereby sequentially performed for three axes orthogonal to the measurement of the echo signals generated,
2) The three generated echoes are converted into projection signals by Fourier transform, and by calculating the projection signals, at least two of the passing coordinates of the three points at the tip of the biopsy instrument at the time when the three echoes are generated, respectively. Calculate the position and speed, determine the direction of travel of the biopsy device, 3) determine the cross-section in the direction parallel to the direction of travel, passing through the tip of the biopsy device, take an MRI image of this cross-section, indicate.

Further, according to the image forming method of the present invention, a cross section passing through the tip of the biopsy instrument and parallel to the traveling direction vector and another plane having an arbitrary angle with respect to this plane (for example, an orthogonal plane) are formed. Shoot. By alternately repeating the process of determining the cross section from the progression vector of the biopsy device and these imaging processes, it is possible to display these two imaging cross-sections side by side on a display, and the positional relationship of the biopsy device in the affected area However, it becomes easier to grasp. Depending on how another plane having an arbitrary angle is determined, a stereo image or the like can be formed.

More specifically, the image forming method of the present invention provides a high-frequency signal for a region of interest including a biopsy instrument inserted into a diagnostic site from outside of a subject in the above steps 1) and 2). Simultaneously irradiates and applies a gradient magnetic field to selectively excite the region of interest, apply a gradient magnetic field whose magnetic field intensity changes in the X-axis direction, generate echoes, and convert the received echoes to projection signals by Fourier transform Then, from the phase distribution of the projection signal, the X-axis direction position and the X-axis direction velocity component at the time tl of the tip of the biopsy device are obtained, and (b) irradiation of a high-frequency signal and application of a gradient magnetic field are performed for the region of interest. Simultaneously, the region of interest is selectively excited, a gradient magnetic field whose magnetic field intensity changes in the Y-axis direction is applied to generate an echo, and the received echo is converted into a projection signal by Fourier transform, and the phase distribution of the projection signal Or , Obtains a Y-axis direction position and the Y-axis direction speed component at time t2 of the distal end portion of the biopsy instrument, (c)
For the region of interest, high-frequency signal irradiation and application of a gradient magnetic field are simultaneously performed to selectively excite the region of interest, apply a gradient magnetic field whose magnetic field intensity changes in the Z-axis direction, generate an echo, and Fourier transform the received echo. It is converted into a projection signal by the conversion, and the Z-axis direction position and the Z-axis direction velocity component at the time t3 of the tip of the biopsy instrument are obtained from the phase distribution of the projection signal. Here, the order of (a), (b), and (c) can be set arbitrarily. For example, the order of (c), (b), and (a) may be performed.

[0010] From the position and velocity components in each axial direction obtained in each process of (a), (b) and (c), at least two of the three passing coordinates at time tl, t2 and t3, The average speed of the tip of the biopsy device is calculated to determine the traveling direction vector of the biopsy device.

In the present invention, the biopsy device is preferably made of a non-magnetic substance, and at least the tip of the biopsy device preferably contains a substance that generates nuclear magnetic resonance by a high-frequency magnetic field in a magnetic field space.

[0012]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an MRI apparatus used for implementing the present invention. This MRI apparatus obtains a tomographic image of a diagnostic site by using a nuclear magnetic resonance phenomenon generated in a living tissue of a subject. As shown in FIG.
1, a gradient magnetic field generating means 2, a gradient magnetic field power supply 3, a probe 4, a high frequency transmitting / receiving unit 5, a computer 6, and a display 7.

The static magnetic field generating means 1 generates a uniform static magnetic field around the subject 9 placed on the table 8 in a direction perpendicular to the body axis direction. It is arranged in a spacious space around 8 and consists, for example, of permanent magnets or magnetic field generating coils.

The gradient magnetic field generating means 2 applies X, Y, Z
It gives the gradient magnetic field Gx, Gy, Gz in the axial direction, and the table
It is arranged in a space with a certain extent around 8.
The gradient magnetic field power supply 3 drives the gradient magnetic field generating means 2.

The probe 4 irradiates a high-frequency magnetic field to a diagnostic site of the subject 9, and also performs NMR analysis of the living tissue of the subject 9.
It receives a high-frequency signal emitted by the phenomenon, and has an irradiation coil and a reception coil inside (the irradiation coil and the reception coil may be physically separated). The high-frequency transmitting / receiving section 5 irradiates and receives a high-frequency signal from the probe 4 to the subject 9.

The computer 6 controls the gradient magnetic field power supply 3 and the high-frequency transmission / reception unit 5 in accordance with a pulse sequence at the time of imaging, and performs image reconstruction processing of a signal received by the probe 4. Further, the display 7 receives the image signal generated by the computer 6 and displays it as a tomographic image.

Next, an image forming method of the present invention which is performed using such an MRI apparatus will be described. In this method, first, the tip position and the traveling direction vector of the biopsy instrument inserted into the subject are detected, and then the imaging section direction is determined from the traveling direction vector of the biopsy instrument so that the longitudinal direction of the biopsy instrument is included in the field of view. , Thereby obtaining an image in which the biopsy device is always visible in the field of view following the moving biopsy device.

In FIG. 2, the region of interest including the biopsy device 12 inserted from the outside of the subject toward the diagnosis site is denoted by 11,
It is assumed that the tip of the biopsy instrument is moving at a constant speed v in the region of interest. The biopsy instrument 12 is made of a non-magnetic substance, and its tip portion contains a substance that causes an NMR phenomenon by irradiation of a high-frequency magnetic field in a magnetic field space, for example, a substance containing hydrogen, carbon, or the like.

In such a state, the gradient magnetic field whose magnetic field intensity changes in the Z-axis direction with the high-frequency magnetic field 31 at time to in FIG.
Gz32 is simultaneously applied to selectively excite the region of interest 11. At this time, the tip 12a of the biopsy device 12 is at the position 13 in FIG. Next, a gradient magnetic field 33 whose magnetic field intensity changes in the X-axis direction is applied for a time T, and the polarity of the amplitude of the gradient magnetic field 33 is inverted for 2T, and the polarity of the amplitude is inverted again for a time T. Apply. At this time, at time tl, which is 2T time after the application of the gradient magnetic field 33, the time integrated value of the amplitude of the gradient magnetic field becomes 0, so that the echo 34 is generated.

The echo 34 is detected by the probe 4 shown in FIG. 1 and stored in the computer 6 via the high frequency transceiver 6. Here, between the times to and tl, the distal end of the biopsy device 12 moves from the position 13 to the position 14 as shown in FIG.

Subsequently, at time t2, the high frequency magnetic field 35 and Z
A gradient magnetic field Gz36 whose magnetic field strength changes in the axial direction is simultaneously applied to selectively excite the same region of interest. At this time the biopsy device
The tip of 12 is further advanced than the position of 14 and is at the position of 15.
Next, a gradient magnetic field 37 in which the magnetic field strength changes in the Y-axis direction is set for a time T.
And then invert the polarity of the amplitude of the gradient magnetic field 37, apply for 2T, and then invert the polarity of the
Apply T only. At this time, 2T after applying the gradient magnetic field 37
At time t3 after the time, the time integrated value of the amplitude of the gradient magnetic field becomes 0, so that the echo 38 is generated. This echo 38
Are detected by the probe 4 shown in FIG. 1 and stored in the computer 6 via the high-frequency transceiver 5. Here, between the times t2 and t3, the tip of the biopsy device 12 moves from the position 15 to the position 16 as shown in FIG.

At time t4, a high-frequency magnetic field 39 and a gradient magnetic field Gz40 whose magnetic field intensity changes in the Z-axis direction are simultaneously applied to selectively excite the same region of interest. At this time, the distal end of the biopsy device 12 is further advanced from the position 16 and is at the position 17. Next, a gradient magnetic field 41 in which the magnetic field intensity changes in the Z-axis direction is applied for a time T, and the polarity of the amplitude of the gradient magnetic field 41 is inverted for a time 2T.
And then invert the polarity of the amplitude again and apply for the time T only. At this time, at time t5, which is 2T time after the application of the gradient magnetic field 41, the time integrated value of the amplitude of the gradient magnetic field becomes 0, so that the echo 42 is generated. This echo 42 is also stored in the computer 6 via the high frequency transceiver 5 by the probe 4 shown in FIG. Here, between the times t4 and t5, the tip of the biopsy device 12 moves from the position 17 to the position 18 as shown in FIG.

Next, the three echoes 3 stored in this way are
The position coordinates and speed of the tip of the biopsy device 12 are obtained by the calculations of 4, 38, and 42.

First, when the tip of the biopsy device 12 moves from the position 13 to the position 14 between the times to and tl, the phase of the magnetic spin of the substance stored at the tip changes in the X-axis direction. By receiving the gradient magnetic field, the motor rotates with a magnitude proportional to the speed in the X-axis direction. The velocity v in the X-axis direction is represented by Expression (1), where γ is the gyromagnetic ratio, G is the amplitude of the gradient magnetic field, and θ is the magnitude of the phase.

[0026]

(Equation 1) According to this equation, the movement of the tip of the biopsy instrument 12 can be replaced with a phase change of the magnetic spin, and the position of the tip is determined by examining the phases of the echoes 34, 38, and 42 stored in the computer. Further, the moving speed of the tip can be detected.

For this purpose, the echo 34 stored in the computer is Fourier-transformed along the X-axis direction, and the phase distribution is obtained using the real part value and the imaginary part value. Here, the magnitude θ of the phase is represented by Expression (2).

[0028]

(Equation 2) The result of the Fourier transform along the X-axis direction represents the projection in the X-axis direction, and the place where the phase is largely changed corresponds to the tip moving at the speed v as shown in FIG. The horizontal axis represents the position rx in the X-axis direction. From the magnitude of the phase at that position and Expression (1), the velocity v in the X-axis direction at the tip is
x is required.

Similarly, when the tip of the biopsy device moves from the position 15 to the position 16 between times t2 and t3, the phase of the magnetic spin of the substance stored at the tip is inclined in the Y-axis direction. By receiving the magnetic field, the motor rotates with a magnitude proportional to the velocity in the Y-axis direction. The echo 38 stored in the computer is Fourier-transformed along the Y-axis direction, and the phase distribution is obtained by the equation (2) using the real part value and the imaginary part value. Also, from the result of the Fourier transform along the Y-axis direction (projection in the Y-axis direction), FIG.
As shown in FIG. 20, the position ry of the tip in the Y-axis direction is obtained,
From the magnitude of the phase at that position and Expression (1), the velocity vy in the Y-axis direction at the tip is obtained.

Similarly, when the tip of the biopsy device moves from the position 17 to the position 18 between times t4 and t5, the phase of the magnetic spin of the substance stored at the tip is inclined in the Z-axis direction. By receiving a magnetic field, the motor rotates with a magnitude proportional to the velocity in the Z-axis direction. The echo 42 stored in the computer is Fourier-transformed along the Z-axis direction, and a phase distribution is obtained using the real part value and the imaginary part value. From the projection in the Z-axis direction, which is the result of the Fourier transform along the Z-axis direction, the Z-axis position rz of the tip is obtained as shown in FIG. From the magnitude of the phase at that position and equation (1), the Z-axis direction velocity vz of the tip is obtained.

As described above, the three echoes obtained by executing the sequence shown in FIG. 3 are each subjected to Fourier transform, so that the position and speed of the tip of the biopsy instrument moving at a constant speed at time tl are obtained. It is possible to obtain each X-axis direction component (rx, vx), each Y-axis direction component (ry, vy) of the position and speed at time t3, and each Z-axis direction component (rz, vz) of the position and speed at time t5. it can. Here, assuming that the biopsy device is moving at a constant speed, from the relationship between the time, the position, and the speed described above, complete information of the position at the times tl, t3, and t5, that is, all of the X, Y, and Z axis directions Can be obtained. In an actual application, the interval between t1 and t3 and the interval between t3 and t5 are several ms to
Since it is a very short time of several tens of milliseconds, it can be approximated that the tip of the biopsy instrument moves by linear motion at a constant speed during this time.

That is, at time tl, x1 = rx yl = ry-vy (t3-tl) zl = rz-vz (t5-tl), and at time t3, x3 = rx + vx (t3-tl) y3 = ry z3 = Rz−vz (t5−t3), and at time t5, x5 = rx + vx (t5−tl) y5 = ry + vy (t5−t3) z5 = rz By the above calculations, the position coordinates (xl, yl, zl) of the tip of the biopsy device at time tl, the position coordinates (x3, y3, z3) of the tip of the biopsy device at time t3, and time t
Position coordinates (x5, y5, z) of the tip of the biopsy device at 5
5) is required.

A vector 22 is determined from the position coordinates of any two of these three points. This vector 22 indicates the traveling direction of the biopsy device 12, and it is predicted from the position of the biopsy device at time t5 and this traveling direction that the biopsy device includes the tip of the biopsy device 12 and advances after time t5. The imaging cross section (FIG. 4A) including the region to be performed can be determined. Such an imaging section may be a section in the direction of 360 degrees with the vector 22 as an axis,
The biopsy device is appropriately selected so that the biopsy device is most easily grasped in relation to the target diseased part. The region where the biopsy device is predicted to advance is in the range of several milliseconds to several hundred milliseconds in terms of time.

When the position and direction of the section to be photographed are determined, the section is photographed by a known imaging method. As the imaging method,
Conventional imaging methods such as SE method and GFE method, or EPI method, FSE
Although a high-speed imaging method such as a scanning method can be employed, it is preferable to employ a high-speed imaging method when tracking the movement of the biopsy instrument in real time. The signal measured by the execution of the imaging sequence is stored in the computer 6, the image is reconstructed, and the obtained image is displayed on the display 7. Since the displayed image is an image along the longitudinal direction of the biopsy device, it is easy to grasp it two-dimensionally, and since the traveling direction is displayed, it is easy to grasp the relationship with the affected part.

In this case, the sequence (FIG. 3) for determining the position and speed of the tip of the biopsy instrument can be executed in a very short time of about 100 msec, and the subsequent calculation time by the computer is combined. The cross section can be determined within several hundred milliseconds. Therefore, Equation 1 is used as an imaging method.
The movement of the biopsy instrument can be monitored in real time by adopting a high-speed imaging method capable of imaging in 00 ms and alternately performing the cross-section determination and the imaging and display. FIG.
(A) calculating the position and the direction of travel of the tip of the biopsy instrument in this way, and determining the position and direction of the imaging section 51;
This shows a case where the process 52 of taking a cross section, reconstructing an image, and displaying the image is alternately repeated, thereby guiding the biopsy device tip to a target position while confirming the position of the biopsy device tip. It becomes possible.

It should be noted that the data obtained by executing the sequence shown in FIG. 3 is different from the data obtained by executing the same sequence without inserting a biopsy device, and the background noise is removed. Good. Thereby, the phase change caused by the movement of the tip of the biopsy instrument during the application of the gradient magnetic field can be emphasized. The method of taking the difference in this way includes an element that causes the phase of a magnetic spin such as a blood flow to rotate in the imaging cross section, and is suitable when it is difficult to identify the tip of the biopsy instrument.

Next, a second embodiment of the present invention will be described. In this embodiment, in addition to the direction vector indicating the traveling direction of the biopsy device obtained in the first embodiment, a direction vector orthogonal to the direction vector is obtained, and a cross section determined thereby is photographed and an image is reconstructed.

That is, in this embodiment as well, the pulse sequence shown in FIG. 3 is executed, and the direction vector representing the traveling direction of the biopsy device is obtained in the same manner. After the direction vector 22 (and the imaging section 23 including the direction vector) representing the direction of travel of the biopsy device is determined in this way, as shown in FIG. A vector 24 in a direction orthogonal to the direction is determined. Vector 24 is vector 22
From the orthogonal relationship with From this direction vector 24, an imaging section 25 orthogonal to the section 23 is determined.

Here, the coordinates of the tip of the biopsy instrument for determining the cross section 25 are the coordinates (x5, y) at time t5.
5, z5) can also be used, but in consideration of the difference between the imaging time of the imaging section 23 determined from the vector 22 and the imaging time of the imaging section 25 determined from the vector 24,
It is preferable to use the coordinates of the point where the tip of the biopsy instrument is predicted to advance during this time difference. Since the difference between the imaging times of the cross section 23 and the cross section 25 is known in advance by the imaging conditions, the position at which the cross section 25 is imaged is determined at the time when the cross section 25 is measured from the calculated position and speed of the biopsy instrument tip. The position where the section passes is predicted and determined. By photographing the cross section 25 using the position thus predicted and the information of the direction vector of 24, the image taken at the same time as the cross section 23 passes through the tip position of the biopsy instrument 12 found in the cross section 23. An equivalent image can be obtained.

As shown in FIG. 6, the images of the cross-sections 25 having different angles are displayed simultaneously on the display 7 so that the positional relationship between the biopsy instruments can be more three-dimensionally grasped. Become.

In the second embodiment, as in the first embodiment, as shown in FIG. 5B, the position and the traveling direction of the tip of the biopsy instrument are calculated, and the position and direction of the imaging section are calculated. A step 51 of determining (vector), a step 52 of photographing the determined section 23, reconstructing and displaying an image, and a step 53 of photographing a section 25 orthogonal to the section 23, reconstructing and displaying the image 53
Is alternately repeated. Thereby, the position of the tip of the biopsy device in the region of interest can be grasped from a more diversified visual field, so that the tip of the biopsy device can be efficiently guided to the target position.

In the above-described second embodiment, a case has been described where an image is taken of a section orthogonal to a section determined by a vector in the direction of travel of the biopsy instrument. Instead, the cross section may have an arbitrary angle. For example, a cross section having a predetermined angle from each other may be determined from a vector in the traveling direction of the biopsy instrument, and the two cross sections may be imaged and displayed. In this case, it is possible to form a stereo image by setting the angle of the two cross sections to an angle that allows stereo viewing (for example, about 5 to 7 degrees).

In addition to the above-described method, the method of obtaining the passing coordinates of the tip of the biopsy instrument is caused by a difference in magnetic susceptibility generated at the boundary between the biopsy instrument itself and the living tissue of the subject. Method using phase change (Ra
"Evaluation of the Susceptibility Effecton," published on pages 561 to 565 of diology (May, 1990).
The Phase Images of a Simple Gradient Echo ”). In this case, in the phase projection diagram of the echo generated by executing the sequence of FIG. 3, a position having a phase step indicates the position of the tip of the biopsy instrument.

[0044]

According to the image forming method using the MRI apparatus according to the present invention, the position of the phase change caused by the movement of the tip of the biopsy instrument during the application of the gradient magnetic field and the magnitude of the phase change allow the biopsy instrument to move. By obtaining the passing coordinates and speeds of at least two points of the tip, obtaining a traveling direction vector connecting the two points, and imaging at least one cross section determined from this vector, the position of the biopsy instrument tip can be determined. The longitudinal direction of the biopsy device can be displayed without loss. In particular, a plurality of cross sections are determined as the imaging cross section, and imaging,
By displaying the information, the two-dimensional and three-dimensional positional relationship between the biopsy device and the target diseased part can be sufficiently grasped, and the biopsy device can be efficiently guided to the target diseased part.

Further, by alternately repeating the process of determining the cross section including the tip of the biopsy device and the imaging process, the tip can be tracked in real time.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an MRI apparatus to which the present invention is applied.

FIG. 2 is a schematic diagram of a region of interest and a biopsy device for explaining an embodiment of the present invention.

FIG. 3 is a timing chart showing a pulse sequence used in the embodiment of the present invention.

FIGS. 4 (a) and (b) are schematic views of an imaging section and a biopsy device determined in an embodiment of the present invention, respectively.

FIGS. 5A and 5B are schematic diagrams each showing a process flow according to an embodiment of the present invention.

FIG. 6 is a schematic view showing an example of an image displayed by the image forming method of the present invention.

[Explanation of symbols]

 1 ... Static magnetic field coil (static magnetic field generating means) 2 ... Gradient magnetic field coil (gradient magnetic field generating means) 4 ... Probe 5 ... High frequency transmitter / receiver 6 Computer 7 Display 9 Subject 11 Area of interest 12 Biopsy device

Claims (4)

[Claims] A static magnetic field generating means for applying a static magnetic field to a subject; a gradient magnetic field generating means for applying a gradient magnetic field in three orthogonal directions to the subject; A probe that irradiates a signal and receives a high-frequency signal emitted by nuclear magnetic resonance of the living tissue of the subject; a high-frequency transmitting and receiving unit that drives and drives the probe to irradiate and receive the high-frequency signal; A computer that performs the control according to a predetermined pulse sequence and performs an image reconstruction operation using the high-frequency signal received by the probe, and a display that inputs the image signal generated by the computer and displays it as a tomographic image A method for forming an image of a region of interest including a biopsy instrument inserted into a diagnostic site from outside the subject in a magnetic resonance imaging apparatus provided with 1) As the pulse sequence, selective excitation of the region of interest by irradiation of a high-frequency signal, application of one subsequent gradient magnetic field, and measurement of an echo signal generated thereby are sequentially performed on three axes orthogonal to each other. 2) convert the three generated echoes into projection signals by Fourier transform, and calculate the projection signals to calculate the passing coordinates of the three points at the tip of the biopsy instrument at the time when the three echoes are generated. Calculating the positions and velocities of at least two points of the biopsy device to determine the traveling direction vector of the biopsy device; 3) determining a cross section passing through the biopsy device tip and being parallel to the traveling direction vector; An image forming method using a magnetic resonance imaging apparatus, characterized in that a magnetic resonance imaging image is taken and displayed. 2. A cross-section in a direction passing through the tip of the biopsy instrument and having an arbitrary angle with respect to a cross-section in a direction parallel to the traveling-direction vector is determined from the advancing direction vector. The image forming method according to claim 1, wherein a resonance imaging image is taken and displayed. And (a) simultaneously irradiating a high-frequency signal and applying a gradient magnetic field to a region of interest including the biopsy instrument inserted into a diagnostic site from outside the subject to selectively excite the region of interest; A gradient magnetic field whose magnetic field intensity changes in the X-axis direction is applied to generate an echo, and the received echo is converted into a projection signal by Fourier transform. From the phase distribution of the projection signal, the tip of the biopsy device is obtained. (B) simultaneously irradiating a high-frequency signal and applying a gradient magnetic field to the region of interest to selectively excite the region of interest,
Applying a gradient magnetic field in which the magnetic field intensity changes in the axial direction to generate an echo, convert the received echo into a projection signal by Fourier transform, and determine the time of the tip of the biopsy instrument from the phase distribution of the projection signal Y-axis position at t2 and Y
(C) simultaneously irradiating a high-frequency signal and applying a gradient magnetic field to the region of interest to selectively excite the region of interest,
Applying a gradient magnetic field in which the magnetic field intensity changes in the axial direction to generate an echo, convert the received echo into a projection signal by Fourier transform, and determine the time of the tip of the biopsy instrument from the phase distribution of the projection signal Z-axis position and Z at t3
The process of determining the axial speed component, the three processes (a) to (c) are performed in an arbitrary order, and then, from the obtained axial position and speed components, time tl, t
2.Calculate the position coordinates of at least two of the three passing coordinates at t3 and the average speed of the biopsy device tip, obtain the traveling direction vector of the biopsy device, and pass through the biopsy device tip. The image forming method according to claim 1, wherein a cross section parallel to the traveling direction vector is determined, and a magnetic resonance imaging image is taken and displayed for the cross section. 4. A step of calculating a traveling direction vector by calculating passing coordinates of at least two points of the biopsy instrument tip and an average speed of the biopsy instrument tip at this time; 3. The magnetic resonance imaging apparatus according to claim 1, wherein a cross section in a direction parallel to the traveling direction vector is determined, and a process of capturing a magnetic resonance imaging image of the cross section is alternately repeated. 4. Image forming method.