JP4106294B2 - Magnetic resonance imaging device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a problem apparatus and a magnetic resonance imaging apparatus, and more particularly, to an apparatus for supplying a problem to a subject in order to capture a functional image with the magnetic resonance imaging apparatus, and an apparatus for capturing a functional image using magnetic resonance. .
[0002]
[Prior art]
In the field of cognitive science, a functional image of the brain is imaged by fMRI (Functional Magnetic Resonance Imaging) using a magnetic resonance imaging apparatus. The functional image is taken while giving a predetermined problem to the subject. There are two ways of giving a problem, block design and event-relevant design, which are used depending on the purpose of the experiment (for example, see Non-Patent Document 1).
[0003]
[Non-Patent Document 1]
Yoioka et al., Functional MRI (2) Application to cognitive science, “Diagnostic Imaging”, Shujunsha, 2002, Vol. 22, No. 5, p. 475-482
[0004]
[Problems to be solved by the invention]
The block design is suitable for experiments that specify the activation site of the brain, but cannot be used for the purpose of examining temporal changes in the signal at the activation site. On the other hand, the event related design is suitable for an experiment for examining a temporal signal change in the activation site, but cannot be used for the purpose of specifying the activation site. For this reason, in order to investigate the temporal signal change in the activated region by the event-related design, it is necessary to specify the activated region by the block design in advance.
[0005]
Therefore, the problem of the present invention is to provide a problem device that makes it possible to determine an activation part and determine a temporal change in the part by event-related design, and a magnetic resonance imaging apparatus equipped with such a problem apparatus. Is to realize.
[0006]
[Means for Solving the Problems]
(1) An invention in one aspect for solving the above-described problem is an apparatus for supplying a subject to a subject in order to take a functional image with a magnetic resonance imaging apparatus, and supplying the subject to the subject. And a control means for causing the problem supply means to supply a predetermined number of times at a predetermined time interval after a predetermined suspension period. It is a problem device.
[0007]
(2) An invention according to another aspect for solving the above-described problem includes an imaging unit that captures a functional image of a subject using magnetic resonance, a problem supply unit that supplies the subject to the subject, and a control unit. In the magnetic resonance imaging apparatus, the control unit causes the task supply unit to supply a task by event-related design a predetermined number of times at a predetermined time interval after a predetermined pause period. This is a magnetic resonance imaging apparatus.
[0008]
In the inventions according to the above aspects, since the control means causes the problem supply means to supply the problem by the event relayed design for a predetermined number of times at a predetermined time interval after a predetermined pause period, the event relay Although it is a Ted design, an effect similar to that of the block design can be obtained, whereby it is possible to specify an activation site of the brain and to obtain a temporal change in a signal at the specified site.
[0009]
The control means preferably causes the problem supply means to repeat problem supply in the above-described manner for a predetermined number of times from the viewpoint of improving the accuracy of the experiment. The subject is preferably a visual input to the subject in terms of examining an activation site related to vision. The task is preferably an operation for allowing the subject to use muscles, from the viewpoint of examining an activation site related to the muscles.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiment. FIG. 1 shows a block diagram of the magnetic resonance imaging apparatus. This apparatus is an example of an embodiment of the present invention. An example of an embodiment related to the magnetic resonance imaging apparatus of the present invention is shown by the configuration of the apparatus.
[0011]
As shown in FIG. 1, the apparatus has a magnet system 11. The magnet system 11 includes a main magnetic field coil unit 101 and a gradient coil unit 105. Each of these coil portions has a substantially cylindrical shape and is arranged coaxially with each other. The direction of the bore of the magnet system 11 is a vertical direction. This is called a vertical bore magnet system.
[0012]
A subject 31 to be photographed is seated on a seat 43 and carried into a substantially cylindrical internal space of the magnet system 11. The direction of the central axis of the generally cylindrical inner space is the vertical direction. Note that the shape of the internal space is not limited to a cylindrical shape, and may be a columnar space having a cross section of an appropriate shape. By sitting on the seat 43, the subject 31 stands upright. The seat 43 on which the subject 31 is seated is driven by the seat drive unit 111 and advances and retreats in the vertical direction.
[0013]
A predetermined task is supplied to the subject 31 by the task supply unit 121. The photographing of the functional image is performed while giving a subject to the subject 31. For example, a visual input is given as the task. Note that the input is not limited to visual input, and may be input to appropriate sensory organs such as auditory sense, smell sense, taste sense, and touch sense. Thereby, the activation site | part relevant to each sense can be investigated. Moreover, it may be a problem that requires muscular exercise, for example, operation of a predetermined instrument with limbs. As a result, the activation site related to each muscle exercise can be examined.
[0014]
The head of the subject 31 is accommodated in an RF coil (radio frequency coil) portion 33 attached to the upper portion of the backrest portion of the seat 43. The RF coil unit 33 is configured using, for example, a TEM resonator (transverse electromagnetic mode resonator) type RF coil. The RF coil unit 33 also has a substantially cylindrical shape, and is disposed coaxially with the main magnetic field coil unit 101 and the gradient coil unit 105 in the internal space of the magnet system 11.
[0015]
The main magnetic field coil unit 101 forms a static magnetic field in the internal space of the magnet system 11. The main magnetic field coil unit 101 is configured using, for example, a superconducting coil. Of course, it is possible to use not only superconducting coils but also normal conducting coils.
[0016]
The gradient coil unit 105 generates a gradient magnetic field for giving a gradient to the static magnetic field strength. There are three types of gradient magnetic fields that are generated: a slice gradient magnetic field, a read out gradient magnetic field, and a phase encode gradient magnetic field. The gradient coil unit 105 corresponds to these three types of gradient magnetic fields. Has three gradient coils (not shown).
[0017]
The RF coil unit 33 forms a high-frequency magnetic field for exciting spins in the body of the subject 31 in the static magnetic field space. Hereinafter, the formation of a high-frequency magnetic field is also referred to as transmission of an RF excitation signal. The transmission of the RF excitation signal may be performed by a dedicated RF coil for transmission other than the RF coil unit 33. The RF coil unit 33 also receives an electromagnetic wave generated by excited spin, that is, a magnetic resonance signal.
[0018]
The gradient driving unit 131 gives a drive signal to the gradient coil unit 105 to generate a gradient magnetic field. The gradient driving unit 131 includes three systems of driving circuits (not shown) corresponding to the three systems of gradient coils in the gradient coil unit 105.
[0019]
The RF drive unit 141 gives a drive signal to the RF coil unit 33 and transmits an RF excitation signal to excite spins in the body of the subject 31. The data collection unit 151 takes in the reception signal received by the RF coil unit 33 and collects it as digital data.
[0020]
A control unit 161 is connected to the seat drive unit 111, the task supply unit 121, the gradient drive unit 131, the RF drive unit 141, and the data collection unit 151. The control unit 161 controls the seat driving unit 111 or the data collection unit 151 to perform shooting.
[0021]
The control unit 161 is configured using, for example, a computer. The controller 161 has a memory (not shown). The memory stores a program for the control unit 161 and various data. The function of the control unit 161 is realized by the computer executing a program stored in the memory. Note that the task supply unit 121 may be controlled by a control device of another system that cooperates with the control unit 161.
[0022]
The output side of the data collection unit 151 is connected to the data processing unit 171. Data collected by the data collection unit 151 is input to the data processing unit 171. The data processing unit 171 stores the data collected by the data collection unit 151 in a memory. A data space is formed in the memory. This data space corresponds to k-space. The data processing unit 171 reconstructs an image by performing two-dimensional inverse Fourier transform on k-space data.
[0023]
The data processing unit 171 is configured using, for example, a computer. A program for the data processing unit 171 and various data are stored in the memory of the data processing unit 171.
[0024]
The data processing unit 171 is connected to the control unit 161. The data processing unit 171 is above the control unit 161 and supervises it. The function of this apparatus is implement | achieved when the data processing part 171 runs the program memorize | stored in memory.
[0025]
A display unit 181 and an operation unit 191 are connected to the data processing unit 171. The display unit 181 is configured by a graphic display or the like. The operation unit 191 includes a keyboard having a pointing device.
[0026]
The display unit 181 displays the reconstructed image and various information output from the data processing unit 171. The operation unit 191 is operated by a user and inputs various commands and information to the data processing unit 171. The user operates the apparatus interactively through the display unit 181 and the operation unit 191.
[0027]
The portion comprising the magnet system 11, the seat drive unit 111, the gradient drive unit 131, the RF drive unit 141, the data collection unit 151, the control unit 161, the data processing unit 171, the display unit 181 and the operation unit 191 is an imaging unit in the present invention. This is an example of the embodiment. The assignment supply unit 121 is an example of an embodiment of assignment supply means in the present invention. The part composed of the control unit 161 and the data processing unit 171 is an example of an embodiment of the control means in the present invention.
[0028]
A portion including the problem supply unit 121, the control unit 161, and the data processing unit 171 is an example of an embodiment of the present invention. An example of an embodiment related to the subject device of the present invention is shown by the configuration of the present device.
[0029]
FIG. 2 shows a flow diagram of the operation of this apparatus. As shown in the figure, in the stage 201, preparation of the problem apparatus and preparation for scanning by MRI are performed. These are performed by the user through the display unit 181 and the operation unit 191.
[0030]
As part of the preparation of the task apparatus, a task to be given to the subject 31 and how to give it are set. As the problem, for example, visual input using a specific video or the like is used. Event-relevant design is set as a way to give this task. How to give a subject by event-related design will be described later.
[0031]
Scan conditions are set as part of preparation for scanning by MRI. A pulse sequence and its parameters are set by setting the scan conditions. As the pulse sequence, a pulse sequence for high-speed scanning such as EPI (echo planar imaging) is selected.
[0032]
Next, in stage 203, a scan in which the problem apparatus and the MRI are synchronized is executed. That is, under the control of the control unit 161, a task is given from the task supply unit 121 to the subject 31, and the magnet system 11 is operated to perform scanning. Scanning is performed continuously for a predetermined time. Images are sequentially reconstructed based on data obtained by continuous scanning. By performing high-speed scanning by EPI or the like, a head tomogram with high temporal resolution can be obtained continuously.
[0033]
FIG. 3 shows a time chart of how to give a task. As shown in (1) of the figure, the rest period is a first period in which no task is given, the next task period is a task (task) period in which a task is given, and the rest and the task are repeated alternately. Each of the rest period and the task period has a predetermined length.
[0034]
As shown in (2), how to give a task in a task period is to repeatedly give a task at a predetermined time interval. That is, for example, a visual input by a specific video is instantaneously given at a predetermined time interval. The time interval for giving the task is longer than the expected brain hemodynamic response. As a result, the assignment method becomes event-related design. Hereinafter, the issue supply is also referred to as an event.
[0035]
Due to such a problem supply, an intensity change of the magnetic resonance signal corresponding to the problem supply occurs at the activation site in the brain, for example, as shown in (3). On the other hand, in the part which is not activated, as shown in (4) for example, there is no change in the signal intensity corresponding to the problem supply.
[0036]
Next, in step 205, image data extraction is performed. Image data extraction is performed by the data processing unit 171. In the image data extraction, pixel values are extracted for each pixel coordinate with respect to a continuous image obtained during the photographing period. Thereby, time-series data based on pixel values is obtained for each pixel coordinate.
[0037]
Next, block stage image statistical analysis is performed in stage 207. The block-type image statistical analysis is performed by the data processing unit 171. Block-type image statistical analysis is a technique for analyzing images taken with a block design problem, and is well known in this technical field.
[0038]
The method of giving a problem in this apparatus is an event related design, but it is possible to perform a block-type image statistical analysis on the result by repeating a plurality of times during a task period.
[0039]
By block-type image statistical analysis, it is checked whether the time series data is significantly larger than the data during the rest period, and if it is significantly larger, it is determined that there is activation of the brain cells. The
[0040]
The determination of the presence / absence of a significant difference is performed based on, for example, whether the average value of the data during the task period is greater than the variance of the data during the rest period with respect to the average value of the data during the rest period. In that case, the presence or absence of the significance of the data can be accurately determined by using the data of the rest period and the task period alternately repeated a predetermined number of times. Note that the rest period and the task period are not necessarily repeated a plurality of times, and the rest period may be provided once or before and after the task period.
[0041]
As described above, although the problem is supplied by the event-related design, the same image statistical analysis as that in the case where the problem is supplied by the block design can be performed, thereby checking the presence or absence of the activation site.
[0042]
Next, on the stage 209, the coordinates of the activation site are specified. The coordinate specification is performed by the data processing unit 171. The data processing unit 171 is performed based on the analysis at the stage 207. For example, as shown in FIG. 4, the identified coordinates are displayed on the tomographic image by appropriate marks such as a cross mark. Alternatively, it may be displayed in a light color such as red or orange. Thereby, the experimenter can confirm the activation site corresponding to the task.
[0043]
Next, on stage 211, TIC (time intensity curve) at the specified coordinates is displayed. The display of the TIC is performed by the data processing unit 171 through the display unit 181. The data processing unit 171 displays the change over time during the task period as a graph for the pixel value of the specified coordinate.
[0044]
Thus, for example, a TIC as shown in FIG. 5 is displayed together with the event occurrence time. Displaying together with the event occurrence time makes it easy to grasp the response (hemodynamic response) of the activation site. When there are a plurality of activation sites, a TIC is displayed for each site. The display is displayed on the same screen as the tomogram or on another screen.
[0045]
As the TIC to be displayed, for example, the TIC corresponding to the first event after the start of the task is displayed. As a result, it is possible to observe a TIC that is not affected by habituation due to repeated events.
[0046]
When it is predicted that there is no signal change due to habituation, the TIC to be displayed may be the sum of the TICs of a plurality of events added in time, or the average. As a result, it is possible to observe a TIC that is less affected by noise. When observing signal changes due to habituation, TICs corresponding to repeated events are continuously displayed.
[0047]
【The invention's effect】
As described above in detail, according to the present invention, there is provided a problem device that makes it possible to determine an activation part and determine a temporal change in the part by event-relevant design, and such a problem device. A magnetic resonance imaging apparatus can be realized.
[Brief description of the drawings]
FIG. 1 is a block diagram of an exemplary apparatus according to an embodiment of the present invention.
FIG. 2 is a flowchart of the operation of the apparatus according to the embodiment of the present invention.
FIG. 3 is a diagram illustrating an example of how to give a task;
FIG. 4 is a diagram illustrating an example of image display.
FIG. 5 is a diagram illustrating an example of a TIC display.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Magnet system 111 Seat drive part 121 Problem supply part 131 Gradient drive part 141 RF drive part 171 Data collection part 161 Control part 171 Data processing part 181 Display part 191 Operation part 31 Shooting object

Claims (5)

An imaging means for taking a functional image of a subject using magnetic resonance , a problem supply means for supplying a subject to the subject, and a magnetic resonance imaging apparatus having a control means ,
The control means causes the problem supply means to supply a problem by the event-related design a predetermined number of times at a predetermined time interval after a predetermined suspension period, and to synchronize with the supply of the problem. Causing the photographing means to photograph a functional image of the subject,
A magnetic resonance imaging apparatus comprising: a data processing unit that performs block-type image statistical analysis on the functional image data obtained by the imaging . The magnetic resonance imaging apparatus according to claim 1.
The magnetic resonance imaging apparatus characterized in that the data processing means determines whether or not it is an activation site based on data obtained during the pause period and data obtained during the period during which the task is supplied . The magnetic resonance imaging apparatus according to claim 1 or 2,
A specifying means for specifying an activation site in the functional image obtained by imaging,
A magnetic resonance imaging apparatus comprising: display means for displaying a time-dependent value at the position of the activation site specified by the specifying means by a TIC (Time Intensity Curve) . The magnetic resonance imaging apparatus according to any one of claims 1 to 3,
The magnetic resonance imaging apparatus according to claim 1, wherein the subject is a visual input to a subject. The magnetic resonance imaging apparatus according to any one of claims 1 to 3,
The magnetic resonance imaging apparatus according to claim 1, wherein the task is an operation for allowing a subject to use muscles .

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