JP4703161B2 - Nuclear magnetic resonance imaging system - Google Patents

Description

  The present invention relates to a nuclear magnetic resonance imaging apparatus (hereinafter referred to as an MRI apparatus), and in particular, a surgical navigation system that uses an MRI image as a guide for surgery or treatment, or an arbitrary cross-section designated by a specific pointing device during surgery. The present invention relates to an MRI apparatus having an interactive scan (ISC) function that enables imaging.

  In recent years, a technique (I-MRI: Interventional-MRI or Intraoperative-MRI) using an MRI image as a monitor for puncture monitoring or percutaneous treatment at the time of surgery has been developed and put into practical use. In I-MRI, there is a demand for arbitrarily setting a tomographic plane to be imaged during surgery or treatment, and imaging in real time, and various methods using a tomographic plane indicating device have been proposed.

  This method is called interactive scan (ISC), and a cross-section including a designated position is determined by designating a region to be imaged by a tomographic plane indicating device, and the cross-section is imaged and displayed in real time by an MRI apparatus. Is. As the tomographic plane indicating device, there are a method in which the positions of a plurality of light emitting diodes provided on the pointer are detected by an infrared camera, a method in which a reflecting sphere provided on the pointer is detected by two infrared cameras, and the like. 1 and Patent Document 2 propose.

  On the other hand, a system called a surgical navigation system using a position detection device and volume data such as MRI images and CT images captured in advance has been put into practical use. In this system, a desired position is designated with respect to a patient with a pointer or the like during the operation, and the operation is guided by displaying three orthogonal cross sections of the patient including the designated position on the monitor. It is applied to high-precision surgical operations such as surgery. Such surgical navigation techniques are described in, for example, Patent Document 3 and Patent Document 4.

Both of these ISC and surgical navigation are techniques involving detection of an actual position to be imaged or an actual position to display a cross section, and it is considered that the convenience of I-MRI is increased by combining them. For example, it is possible to check the progress of treatment by performing a difference or addition of both images.
Furthermore, endoscopes and microscopes are frequently used in the above-described high-precision surgical operations, and images from these image devices are also used as surgical guides.
US Pat. No. 5,365,927 US Patent No. 6026315 JP 2002-35007 A JP 2003-79637 A

  In conventional surgical navigation and ISC, if the start of operation is instructed via the input / output device, the operation continues until an end command is sent. Therefore, when combining these technologies, the start and end of the operation are instructed each time. The operation of such a device is a burden on the surgeon. When information from a modality other than the MRI apparatus, for example, an image or video of a video apparatus such as an endoscope or a microscope is used in combination, the data is taken into the recording apparatus at the start of surgical navigation or ISC and is continued until the end. Therefore, there is a problem that the capacity of the storage device is greatly increased.

  Therefore, an object of the present invention is to provide an MRI apparatus capable of executing both functions with good operability in an MRI apparatus having a surgical operation support function such as a surgical navigation system and an ISC function. Another object of the present invention is to provide an MRI apparatus that reduces the burden on the storage device and has excellent operability. Furthermore, the present invention solves the problem of positional displacement caused by body movement or the like that may occur between the acquisition of an image used for navigation and the execution of ISC, and allows the progress of surgery and treatment to be observed with high-quality MRI images. An object is to provide a possible MRI apparatus.

  An MRI apparatus of the present invention that solves the above problems includes an MR imaging unit that images a subject using nuclear magnetic resonance, and a position detection unit that detects a desired position of the subject placed on the MR imaging unit. An image recording unit that captures and stores an image captured by the MR imaging unit and an image or video from another imaging device, and position information of a predetermined position detected by the position detection unit, and an imaging cross section of the MR imaging unit A calculation unit that converts the information into the position information, a control unit that controls the MR imaging unit and the video recording unit based on information from the calculation unit, and a display unit that displays the image. Instructing means for instructing a desired position of the sample, and detecting means for detecting a position instructed by the instructing means, and the control unit is configured to record the video when the instructing means is within the detection range of the detecting means Of various videos in the club Performs interrupt, the instruction means and controlling said image recording unit so as not to perform various video capture when detecting an out of range of the detection means.

  In the MRI apparatus of the present invention, it is preferable that the position detection unit includes a second detection unit that detects a position of a specific point or a specific feature fixed to the subject, and the control unit includes: When the second detection unit detects that the specific point or the specific feature has moved, the imaging section of the MR imaging unit is corrected based on the movement amount.

  In the MRI apparatus of the present invention, the control unit includes a position corresponding to the detected position from the 3D image of the subject stored in the video recording unit based on the position information of the position detected by the position detecting unit. Image creating means for creating a cross-sectional image is provided, and the cross-sectional image is displayed on the display unit.

  In this case, preferably, the image creating unit has a function of creating an addition image and / or a difference image between the created cross-sectional image and the cross-sectional image created by the MR imaging unit and displaying the resultant image on the display unit. More preferably, the position detection unit includes a second detection unit that detects a position of a specific point or a specific feature fixed to the subject, and the control unit includes a second detection unit that detects the specific point. When it is detected that a point or a specific feature has moved, the position of the cross section created by the image creating means or the imaging cross section of the MR imaging section is corrected based on the amount of movement.

  According to the MRI apparatus of the present invention, in the apparatus having the ISC function, the capturing of the image and the video to the video recording unit is controlled by using whether the instruction means is within the detection range or out of the range of the position detection unit. The operator does not need to manually operate the video recording unit during the operation, and the operability is good. Further, since unnecessary images and videos are not taken into the video recording unit, a recording operation can be performed without increasing the capacity.

  According to the MRI apparatus of the present invention, the second detection means for detecting a specific point or a specific feature fixed to the subject is provided, so that an image of the subject can be obtained in real time using the ISC function. In the case of acquisition, even if there is a movement such as body movement in the subject, a desired cross section can be imaged automatically following it.

  In addition, the MRI apparatus of the present invention can add a surgical navigation function. At that time, by creating a difference image or an addition image between a cross-sectional image captured in real time and a preoperative image created by surgical navigation, The progress of surgery and treatment can be observed in real time. At this time, the positional deviation between the preoperative image and the intraoperative image can be corrected by detecting the movement of a specific point or a specific feature fixed to the subject by the second detection means.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing an overall outline of an MRI apparatus incorporating a surgical navigation system. This MRI apparatus is a vertical magnetic field type open type apparatus in which magnets are arranged at the top and bottom, and is configured so that surgery and treatment can be performed with the subject lying in an open static magnetic field space. It mainly includes an MR imaging unit, a three-dimensional position detection unit, a control unit 23, a video recording unit 34, an input / output unit 36, and the like. In the MRI apparatus, an imaging apparatus 40 such as an endoscope or a microscope is set as necessary.

  The MR imaging unit includes a static magnetic field generation unit including an upper magnet 3 and a lower magnet 5 that generate a uniform static magnetic field in a space in which a subject is laid down, a column 7 that connects the upper magnet 3 and the lower magnet 5, and a target. A bed 21 on which the specimen 24 is placed, a monitor 13 for displaying an image taken by the MR imaging section, a gradient magnetic field coil (not shown) arranged close to the static magnetic field generating section, and a high-frequency magnetic field on the subject 24 And an RF receiving coil for receiving an NMR signal generated from the subject 24. The gradient magnetic field coil, the RF transmission coil, and the RF reception coil are connected to a gradient magnetic field generation unit, an RF transmission unit, and an RF reception unit (not shown), respectively. The monitor 13 is fixed to the upper magnet 3 via a support portion 15.

  The three-dimensional position detection unit includes a position detection device 9 equipped with two infrared cameras 25, a reference tool 17 serving as a reference position for coordinates in the imaging space, and a pointer 27 for indicating an arbitrary position of the subject 24. And a calculation unit 19 that receives the position data of the pointer 27 detected by the infrared camera 25 and converts it into data in the apparatus coordinate system or the image coordinate system. The position detection device 9 is supported by the gantry via the arm 11 so that the position of the pointer 27 can be set at any position where it can be easily detected.

  The reference tool 17 links the coordinate system of the infrared camera 25 and the coordinate system of the MR imaging unit, includes three reflecting spheres 35, and is provided on the side surface of the upper magnet 3. The pointer 27 is provided with three reflecting spheres as with the reference tool 17 and is fixed to a surgical instrument such as a puncture needle. The relationship between the position of each reflecting sphere and the distal end of the surgical instrument is registered in advance in the calculation unit 19 (registered surgical instrument). When registering a surgical instrument, when one of the reflecting spheres of the pointer 27 is set as the origin, information such as the position of the other reflecting sphere, the position of the distal end of the surgical instrument, and the direction vector is stored in the storage unit in the calculation unit 19 It is an operation, and it can be done by setting a surgical tool with the pointer 27 fixed on a dedicated registration tool and reading the position of each reflection sphere with a position detector. Once registration is performed, special conditions are changed. If there is no such thing, there is no need to re-register. In this embodiment, the calculation unit 19 is constructed on a personal computer (PC), and continuously receives data from the infrared camera 25 via the RS232 cable 33 and the like and performs a predetermined coordinate conversion calculation. The position information of the pointer 27 necessary for surgical navigation and ISC is sent to the control unit 23.

  The control unit 23 controls the operation of the MR imaging unit and the video recording unit 34, and reconstructs an image captured by the MR imaging unit and uses an image stored in the video recording unit 34 to generate an image necessary for surgical navigation. Create (function of image creation unit 38). Specifically, based on the position information from the calculation unit 19, the MR imaging unit is driven to capture a cross-section including the position in real time according to a predetermined pulse sequence, and a real-time image is displayed on the monitor 13 (ISC function) . Further, based on the position information from the calculation unit 19, a predetermined cross-sectional image is created from the 3D image of the subject stored in advance in the video recording unit 34, and an addition image of the real-time image and the predetermined cross-sectional image as necessary. A difference image is created and displayed on the monitor 13 (surgical navigation function). The input / output unit 36 is for inputting various commands to the control unit 23.

  The video recording device 34 is compatible with both image and video formats, stores images taken by the MR imaging unit, pre-captured 3D images, and the like, as well as various imaging devices such as endoscopes and microscopes. When used together with the apparatus, the video from these imaging apparatuses is captured and stored. These images and videos are displayed on the monitor and monitor 13 of the input / output unit 36.

  Next, the operation of the MRI apparatus having the above configuration will be described with reference to FIGS. FIG. 2 is a flowchart showing the operation procedure, FIG. 3 is a diagram showing the timing of the operation, and FIG. 4 is a diagram showing an example of the GUI of the input / output unit 36.

  Various operation support software such as operation navigation software, ISC software, and video data recording are displayed as a GUI start menu. These are selected and activated (step 101). That is, the ISC / navigation start button 410 and the video data recording button 411 shown in FIG. 4 are selected. However, at this time point, each operation of the selected software does not start, but starts when the infrared camera 25 catches the pointer 27 as a trigger.

  Prior to the start of the operation, the 3D imaging button 408 or 409 is selected as necessary to execute 3D imaging of the subject (steps 102 and 103). The imaging buttons 408 and 409 can select whether to use a T1 image or a T2 image according to the imaging target tissue. The image data obtained by 3D imaging is used for associating (registering) the coordinates of the infrared camera with the image space coordinates, and can also be used as a preoperative MR image of the subject. In registration, a specific point on the subject is pointed with a surgical tool with a pointer 27 fixed and detected by the infrared camera 25, and both the position of the specific point in the camera coordinates and the position of the specific point in the image space coordinates are detected. A coordinate transformation matrix of coordinates is created and registered in the calculation unit 19 (step 103). The specific point on the subject is a point that can be discriminated in the captured MRI image and can be instructed by a surgical instrument. Specifically, the external point such as the tip of the ear or nose is used. When a characteristic part or a marker detectable by the MRI apparatus is attached, the marker position is set as a specific point.

  After the registration of the association between the camera coordinates and the image space coordinates is completed, when the infrared camera 25 catches the pointer 27 (step 104), recording from the imaging device 40 to the video recording unit 34 is started. (Step 105), navigation and ISC operations are started (Steps 106 and 107). In the MRI apparatus of this embodiment, by selecting the button 412, it is displayed whether or not the infrared camera is capturing a pointer.

  When navigation is started, when an arbitrary part of the subject 24 is pointed with a surgical tool to which the pointer 27 is fixed, the infrared camera 25 reads the position of the pointer 27 and sends the position information to the calculation unit 19. The calculation unit 19 stores the position (point) designated by the pointer 27 in the video recording device 34 using the coordinate information of the pointer 27 registered in advance and the coordinate conversion information between the camera coordinates and the image space coordinates. The position is converted into the position of 3D image coordinates, and one cross section including the point and two orthogonal cross sections orthogonal to the cross section are determined. The three orthogonal cross sections include, for example, three cross sections along the image space coordinates X, Y, and Z axes including the point A designated by the pointer, or a cross section B including the point A and orthogonal to the pointing direction of the pointer, Let A and two cross sections C and D be perpendicular to the cross section B including the axis of the surgical instrument. The information on the three orthogonal cross sections is transferred to the control unit 23, which creates an image of the three orthogonal cross sections from the 3D image stored in the video recording device 34 and displays the image on the monitor 13. If necessary, another image created from the 3D image, such as a volume rendering image, is simultaneously displayed.

  FIG. 4 is a diagram showing an example of an image displayed on the monitor 13, and the display screen 402 displays three cross-sectional images and volume rendering images created from 3D images captured before surgery.

  When the ISC is started, the calculation unit 19 converts the position and direction designated by the pointer 27 read by the infrared camera 25 into position data used by the MR imaging unit, and passes it to the control unit 23. The control unit 23 determines the gradient magnetic field so that the cross section perpendicular to the direction indicated by the pointer 27 includes the position (point) designated by the pointer 27, and executes a predetermined pulse sequence, and MR imaging The imaging by the unit is started. The reconstructed MR image is displayed on the monitor 13 in real time. A real-time image captured by ISC is displayed on the display screen 405 in FIG.

  Next, when the infrared camera 25 detects that the position of the tip of the pointer 27 has changed, the surgical navigation function creates three orthogonal sections including the new position, and the ISC function generates a section including the tip of the pointer 27. Take an image. By repeating the above operation every time the position of the pointer 27 is changed in this way, a cross-sectional image including the needle-piercing tip is always updated and displayed in real time.

  If the infrared camera 25 cannot grasp the position of the pointer 27 (step 111), the navigation software and the ISC software are stopped and the video recording from various video recording devices is stopped (steps 112 and 113). . Thereafter, until the end instruction (step 114) is received, when the infrared camera 25 captures the pointer 27 (step 104), the video capture, navigation, and ISC are resumed (steps 105 to 111). If there is a movement of the position detection device 9 or the position of the subject while the various software is stopped, 3D imaging is performed again, and registration for associating the camera coordinates with the image space coordinates is performed. After that (steps 102-103), the software is restarted.

  As described above, according to the present embodiment, since the pointer 27 triggers whether the infrared camera 25 is within the detection range or out of the range, the video is captured from various imaging devices, and the operation support software starts and ends. Unnecessary video capture can be stopped while the surgery support software is not operating, and an increase in the capacity of the video recording unit can be prevented. This situation is shown in FIG. 3 in comparison with the case of conventional surgery support software. In the figure, (a) shows the detection of the pointer by the infrared camera 25, and (b) and (c) show the timing of video / image recording according to the present embodiment and the timing of conventional video / image recording, respectively. As shown in the figure, conventionally, for example, even when the treatment is temporarily suspended and the pointer is not detected, once the surgery support software is started, video / image recording is continued until the end of the operation support software. According to the present embodiment, since video / image recording is started / interrupted with the detection of the pointer as a trigger, only necessary video / image recording can be performed.

  Next, as a second embodiment of the MRI apparatus of the present invention, the operation of the MRI apparatus provided with the addition image and difference image creation functions of both as an additional function of the ISC function and the surgical navigation function will be described.

  FIG. 5 is a flowchart showing an operation procedure, and the same procedure as that in FIG. 2 is denoted by the same reference numeral. In this MRI apparatus, navigation and ISC imaging and video capturing are started and interrupted in the same manner as in the embodiment of FIG. 2 depending on whether or not the infrared camera 25 captures a pointer fixed to the surgical instrument. However, in the present embodiment, the cross-sectional image created by navigation and the ISC image are added and subtracted, and the result image is displayed on the monitor.

  That is, when each operation is started and an image of three orthogonal sections by surgical navigation and an image of an imaging section by ISC are created for one point A designated by the pointer 27, the control unit 23 One of the images (cross section B) and the real-time image by ISC are added / differed to create an added image 407 and a differential image 406 as shown in FIG. 4 and display them on the monitor 13 (steps 108 to 110). The three orthogonal cross-sections are images created from 3D images acquired before the start of surgery, while ISC images are images captured in real time during surgery. Therefore, it is possible to observe the progress of surgery and treatment by adding or subtracting these. For example, it is possible to observe how the treatment site gradually spreads in the case of heat treatment or the like. However, since both images are acquired at different times, if there is a body movement between the two images, a positional shift occurs. That is, an orthogonal cross section created from a 3D image acquired in advance may be an orthogonal cross section including a point deviated from the point indicated by the pointer 27. Therefore, prior to creating the addition image and the difference image, the positional deviation between the two images is corrected (step 108).

  As a method for correcting misalignment, a known method such as the method described in Japanese Patent Laid-Open No. 2003-339666 can be applied. Here, a case where a pointer that can be detected by the infrared camera 25 is attached to the subject will be described. FIGS. 6A and 6B are diagrams illustrating a state where the pointer 603 is mounted on the head 601 of the subject, where FIG. 6A is a side view and FIG. 6B is a diagram viewed from the top of the head. As shown in the figure, a belt-like wearing tool 602 having pointers 603 attached to at least three places is fixed to the head. By using the position information of the three pointers, it is possible to detect a three-dimensional position change due to body movement or the like. Then, when a 3D image is captured before the operation (step 103) and at the start of ISC (step 107), the relative position of the pointer 603 with respect to the reference tool 702 is detected by the infrared camera 701, for example, as shown in FIG. In this case, the infrared camera 701 may also be used as the infrared camera 25 of the position detection device 9, or another position detection device may be used.

  Then, when the position of the pointer 603 at the start of ISC has changed from the pre-operative position, for example, the imaging section of the ISC is corrected from 703 to 705 based on the detected position information. Alternatively, the imaging cross section by ISC is left as it is, and the center coordinates (point A) of the three orthogonal cross sections by the surgical navigation are corrected, and then recreated. Thus, in a state where the positional deviation is corrected, addition or difference between the surgical navigation image and the ISC image can be performed, and a high-quality image effective for diagnosis can be displayed.

  In this case, if the imaging cross section of the subject to be imaged in real time is fixed, a wearing tool with a pointer attached to the part corresponding to the imaging cross section is fixed, and the imaging cross section is corrected according to the movement of the pointer. By performing ISC imaging, the positional relationship between the 3D image used for surgical navigation and the ISC image can always be kept constant, and it is possible to cope with movements such as rotation that cannot be corrected by subsequent processing. In this case, the wearing tool to which the pointer is attached functions as a section indicating means in the ISC.

  Even in surgical navigation, the position of the surgical instrument to which the pointer 27 is attached is detected by the infrared camera 25. Therefore, in the position correction using the pointer described above, the position of the pointer 27 for surgical navigation and the pointer 603 for position correction are used. It is necessary to perform position detection separately. In some cases, it is difficult to attach a pointer depending on the surgical site or the patient's circumstances. In such a case, position detection means other than the pointer may be used for detecting the position shift. As such an example, FIG. 8 shows position detection by surface scanning using a laser.

  Even when performing position detection by the surface scan method, the affected part shape 802 obtained by surface scanning using the laser 801 is registered in the calculation unit 19 before the operation, and the affected part shape 803 is acquired and registered at any time during the operation. A positional deviation from the affected part shape 802 is calculated, and the imaging plane 804 in real-time imaging is corrected based on the calculated positional deviation and imaged. As a result, the positional relationship between the 3D image and the ISC image can always be kept constant as in the case where the pointer is attached.

  The above-described operation is repeatedly executed while the infrared camera 25 captures the pointer 27, and the cross-sectional image including the tip of the needle and the addition / difference image are constantly updated and displayed in real time.

  If the infrared camera 25 cannot grasp the position of the pointer 27 (step 111), the navigation software and the ISC software are stopped and the video recording from various video recording devices is stopped (steps 112 and 113). . Thereafter, until the end instruction (step 114) is received, when the infrared camera 25 captures the pointer 27 (step 104), the video capture, navigation, and ISC are resumed (steps 105 to 111).

  As described above, according to the present embodiment, as in the embodiment of FIG. 2, when the pointer 27 is captured by the infrared camera 25 as a trigger, the capturing of images from various image recording devices and the start of operation of the operation support software are started. By doing so, an increase in the capacity of the recording apparatus can be prevented. Further, according to the present embodiment, the preoperative image and the real-time image captured during the operation can always be displayed in the same positional relationship.

The figure which shows the whole outline | summary of the MRI apparatus provided with the surgery assistance function to which this invention is applied. The flowchart which shows operation | movement of one Embodiment of the MRI apparatus of this invention. The figure which shows the example of a display of a display part in the MRI apparatus of this invention Timing chart showing operation of the present invention and a conventional MRI apparatus The flowchart which shows operation | movement of other embodiment of the MRI apparatus of this invention. The figure which shows an example of the mounting tool for the position detection of an imaging cross section The figure explaining the photography cross-sectional position correction | amendment using the mounting tool of FIG. The figure explaining another method of imaging section position amendment

Explanation of symbols

DESCRIPTION OF SYMBOLS 9 ... Position detection device, 13 ... Monitor, 17 ... Reference tool, 23 ... Control part, 27 ... Pointer, 34 ... Video recording part, 36 ... Input / output part, 40 Other imaging devices

Claims (5)

An MR imaging unit that images a subject using nuclear magnetic resonance, a position detection unit that detects a desired position of the subject placed on the MR imaging unit, an image captured by the MR imaging unit, and other images A video recording unit that captures and stores an image or video from the imaging apparatus; a calculation unit that converts position information of a predetermined position detected by the position detection unit into position information of an imaging section in the MR imaging unit; and the calculation In a nuclear magnetic resonance diagnostic apparatus comprising: a control unit that controls the MR imaging unit and the video recording unit based on information from a unit; and a display unit that displays the image.
The position detection unit includes instruction means for indicating a desired position of the subject, and detection means for detecting a position indicated by the instruction means,
The control unit captures various videos in the video recording unit when the instruction unit is within the detection range of the detection unit, and captures various videos when the instruction unit is outside the detection range of the detection unit. A nuclear magnetic resonance diagnostic apparatus, characterized in that the video recording unit is controlled not to be performed. The nuclear magnetic resonance diagnostic apparatus according to claim 1,
The position detection unit includes a second detection unit that detects a position of a specific point or a specific feature fixed to the subject,
The control unit corrects the imaging section of the MR imaging unit based on the amount of movement when the second detection unit detects that the specific point or the specific feature has moved. Nuclear magnetic resonance diagnostic equipment. The nuclear magnetic resonance diagnostic apparatus according to claim 1 or 2,
The control unit creates an image creating unit that creates a cross-sectional image including a position corresponding to the detected position from a 3D image of the subject stored in the video recording unit based on position information of the position detected by the position detecting unit. And displaying the cross-sectional image on the display unit. The nuclear magnetic resonance diagnostic apparatus according to claim 3,
The image creation means creates an addition image and / or a difference image between the created cross-sectional image and the cross-sectional image created by the MR imaging unit, and displays the resultant image on the display unit. . The nuclear magnetic resonance diagnostic apparatus according to claim 4,
The position detection unit includes a second detection unit that detects a position of a specific point or a specific feature fixed to the subject,
When the second detection unit detects that the specific point or the specific feature has moved, the control unit determines the position of the cross section created by the image creation unit or the MR based on the amount of movement. A nuclear magnetic resonance diagnostic apparatus for correcting an imaging cross section of an imaging unit.