JP2006346054A - Magnetic resonance imaging apparatus - Google Patents

Magnetic resonance imaging apparatus Download PDF

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JP2006346054A
JP2006346054A JP2005174488A JP2005174488A JP2006346054A JP 2006346054 A JP2006346054 A JP 2006346054A JP 2005174488 A JP2005174488 A JP 2005174488A JP 2005174488 A JP2005174488 A JP 2005174488A JP 2006346054 A JP2006346054 A JP 2006346054A
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magnetic resonance
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JP4961116B2 (en
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Tomotsugu Hirata
Hisaaki Ochi
智嗣 平田
久晃 越智
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Hitachi Medical Corp
株式会社日立メディコ
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic resonance imaging apparatus having a high speed and high sensitivity and capable of acquiring magnetic resonance spectra from a plurality of regions. <P>SOLUTION: The apparatus comprises a receiver probe, a sequence control means, and an operation means. The receiver probe is made by arranging a plurality of small-sized coils, whose ratio of the length in the short axis direction to that in the long axis direction is one to two or more, in the short axis direction. The sequence control means controls generation of a high frequency magnetic field, generation of gradient magnetic fields which give positional information of the small-sized coil in the long axis direction, and detection of a plurality of magnetic resonance signals by the plurality of small-sized coils. The operation means calculates, using the plurality of magnetic resonance signals, spectrum information containing spatial information of the small-sized coils in the short axis direction that corresponds to the sensitivity region of each small-sized coil and positional information of the small-sized coil in the long axis direction given by the gradient magnetic fields. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetic resonance imaging apparatus, and more particularly to an apparatus suitable for measuring a magnetic resonance signal including information on chemical shift.

  A magnetic resonance imaging apparatus excites nuclear magnetization of nuclei such as hydrogen contained in a subject by irradiating a subject placed in a static magnetic field with a high-frequency magnetic field of a specific frequency, and generates magnetism generated from the subject. Resonance signals can be detected to obtain physical and chemical information. Currently, in magnetic resonance imaging (hereinafter abbreviated as MRI) widely used in magnetic resonance imaging apparatuses, an image reflecting the density distribution of hydrogen nuclei contained mainly in water molecules in a subject is acquired. For this MRI, there is a method of separating magnetic resonance signals for each molecule by using a difference in resonance frequency (hereinafter referred to as chemical shift) due to a difference in chemical bonds of various molecules including hydrogen nuclei. This method is called magnetic resonance spectroscopy (hereinafter abbreviated as MRS) (see, for example, Non-Patent Document 1).

  FIG. 1 shows an example of an MRS pulse sequence executed by the magnetic resonance imaging apparatus. In the figure, RF indicates the application timing of the high-frequency magnetic field, Gz, Gx, and Gy indicate the application timings of the gradient magnetic fields in three directions, respectively, and A / D indicates the signal sampling time. The illustrated pulse sequence is a typical MRS pulse sequence. First, by applying the first high-frequency magnetic field RF1 and the first slice-selecting gradient magnetic field Gs1 at the same time, a predetermined slice plane in the subject is obtained. Only the nuclear magnetization of hydrogen nuclei contained in can be brought into an excited state. Here, RF1 is an excitation RF pulse called a 90-degree pulse that rotates a nuclear magnetization vector by 90 degrees, and Gs1 has a magnetic field strength gradient in the Z-axis direction for selecting a slice plane perpendicular to the Z-axis. It is a gradient magnetic field. Further, by applying a rephase gradient magnetic field Gs1 ′ subsequent to Gs1, the phases of the nuclear magnetization vectors phased during the application of Gs1 can be aligned. Next, after applying TE / 2 (TE is referred to as an echo time) from the application of RF1, the second high-frequency magnetic field RF2 and the second slice selection gradient magnetic field Gs2 are applied simultaneously, thereby causing the nuclear magnetic field in the excited state. The magnetic resonance echo signal SIG1 having a peak at a time after TE / 2 can be generated. Here, RF2 is an excitation RF pulse called a 180 degree pulse that rotates the nuclear magnetization vector by 180 degrees, and Gs1 is a gradient magnetic field in the Z axis direction for selecting a slice plane perpendicular to the Z axis. By applying inverse Fourier transform to the measured signal SIG1, it is possible to obtain a magnetic resonance spectrum of a region (measurement region) where the signal is emitted.

  Here, the measurement region is determined by the slice plane defined by the slice selection gradient magnetic fields Gs1 and Gs2 and the effective sensitivity region of the receiving coil. That is, as shown in FIG. 2, for example, when a high-frequency coil capable of exciting the entire subject is used as a transmission high-frequency coil and a cross section (slice surface) parallel to the small reception coil is excited, Spectroscopy information is obtained from the overlapping portion of the effective sensitivity area of the receiving coil.

  For the MRS that measures a single region, the method of acquiring spectra of many regions (pixels) simultaneously and imaging each molecule is called magnetic resonance spectroscopic imaging (hereinafter abbreviated as MRSI). By using this MRSI, it is possible to visually grasp the concentration distribution for each metabolite (see, for example, Non-Patent Document 2).

  Methods for measuring nuclear magnetic resonance spectrum information can be roughly divided into two types depending on the type of receiving coil used. One is to detect the signal using the small planar coil described above, and to select the position of the measurement area based on the sensitivity distribution of the coil. The other is to detect the signal using a large three-dimensional coil. In this method, the position of the measurement region is selected using a gradient magnetic field. In the former method, position selection by a gradient magnetic field may be used in combination as described above.

  As described above, in MRSI measurement, position information is usually given by applying a gradient magnetic field, and this makes it possible to obtain spectra of a large number of regions (pixels). In general, as a method of providing position information of the measurement region with a gradient magnetic field, an operation (operation called phase encoding) in which signal measurement is repeated by gradually changing the gradient magnetic field application amount in each spatial coordinate axis direction is used, A measurement method for acquiring two-dimensional spatial information by applying phase encoding in a double loop shape is called a 3D-CSI method. For example, when measuring a two-dimensional spectrum image having a matrix number of 16 × 16 using the 3D-CSI method, signal measurement of 16 × 16 = 256 times is repeated. Usually, since the repetition time interval (TR) requires about 2 seconds, a long measurement time of 512 seconds is required for 256 signal measurements.

  As a high-speed MRSI measurement method for shortening the measurement time, echo planar spectroscopic imaging (hereinafter referred to as EPSI, Patent Document 1) proposed by Matsui et al. Is known. In this method, at the time of signal detection, the gradient polarity of the readout gradient magnetic field is periodically reversed to detect continuously generated eco-signals (hereinafter referred to as eco-train signals). Since the eco-train signal obtained by one excitation / measurement includes spectrum information and one-dimensional spatial information, when measuring a two-dimensional image having a matrix number of 16 × 16, the one-dimensional phase is measured. The encoding may be performed, and the signal measurement is repeated 16 times. Therefore, when TR is 2 seconds, a measurement time of 32 seconds is required for 16 signal measurements.

Journal of Magnetic Resonance, Vol. 70, pp. 488-492, published in 1986

Magnetic Resonance in Imaging Volume 30 Pages 641-645 Published in 1993 Japanese Patent Publication No. 5-85172

  Although the above-described “method using a small planar coil” has a high SNR (signal-to-noise ratio) of the magnetic resonance spectrum obtained because of the high detection sensitivity of the coil itself, only one region of spectrum can be obtained in one measurement. It is not suitable for MRSI measurement. The above-mentioned “method using a large three-dimensional coil” can simultaneously acquire spectra from multiple regions and can be applied to both MRS and MRSI, but the SNR of the magnetic resonance spectrum obtained because the detection sensitivity of the coil itself is low. Has the disadvantage of being low.

  In addition, as described above, the 3D-CSI method, which is one MRSI measurement method, requires a long measurement time.

  In addition, the EPSI method, which is one of the MRSI measurement methods described above, has a disadvantage in that the SNR of the obtained image is lowered because it is necessary to widen the measurement signal band as the speed increases.

  The magnetic resonance imaging apparatus of the present invention comprises a static magnetic field generating means for generating a static magnetic field, a gradient magnetic field generating means for generating gradient magnetic fields in three directions orthogonal to each other, and a nuclear magnetic field on a subject placed in the static magnetic field. Operations of a high-frequency magnetic field generating means for generating a high-frequency magnetic field that causes resonance, a detecting means for detecting a nuclear magnetic resonance signal generated from the subject, the gradient magnetic field generating means, the high-frequency magnetic field generating means, and the detecting means And a calculation means for calculating a magnetic resonance spectrum using the nuclear magnetic resonance signal, and the detection means has a ratio of the length in the minor axis direction to the major axis direction of 1: 2 or more. A reception probe in which a plurality of small coils are arranged in the short axis direction is provided, and the sequence control means includes a control for generating the high-frequency magnetic field and a gradient magnetic field for providing position information in the long axis direction of the small coils. And a control for detecting a plurality of nuclear magnetic resonance signals with the plurality of small coils, and the computing means is configured to detect a small coil corresponding to a sensitivity region of each small coil from the plurality of nuclear magnetic resonance signals. Spectral information having spatial information in the short axis direction and position information in the long axis direction of the small coil applied by the gradient magnetic field is calculated.

  The magnetic resonance imaging apparatus of the present invention also includes a static magnetic field generating means for generating a static magnetic field, a gradient magnetic field generating means for generating gradient magnetic fields in three directions orthogonal to each other, and a nucleus placed on a subject placed in the static magnetic field. A high-frequency magnetic field generating means for generating a high-frequency magnetic field that causes magnetic resonance, a detecting means for detecting a nuclear magnetic resonance signal generated from the subject, the gradient magnetic field generating means, the high-frequency magnetic field generating means, and the detecting means A sequence control means for controlling the operation; and an arithmetic means for calculating a magnetic resonance spectrum using the nuclear magnetic resonance signal, wherein the detection means has a ratio of the length in the minor axis direction to the major axis direction of 1: 2 or more. A reception probe in which a plurality of small coils are arranged in the short axis direction, and the sequence control means controls the generation of the high-frequency magnetic field and a phase error that gives positional information of the small coils in the long axis direction. A control for generating a code gradient magnetic field and a control for detecting a plurality of nuclear magnetic resonance signals with the plurality of small coils are performed in order, and the computing means is configured to detect the plurality of the phase encode gradient magnetic fields that are repeatedly detected. Spectral information having spatial information in the short axis direction of the small coil corresponding to the sensitivity region of each small coil and position information in the long axis direction of the small coil provided by the phase encoding gradient magnetic field Is calculated.

  The magnetic resonance imaging apparatus of the present invention also includes a static magnetic field generating means for generating a static magnetic field, a gradient magnetic field generating means for generating gradient magnetic fields in three directions orthogonal to each other, and a nucleus placed on a subject placed in the static magnetic field. A high-frequency magnetic field generating means for generating a high-frequency magnetic field that causes magnetic resonance, a detecting means for detecting a nuclear magnetic resonance signal generated from the subject, the gradient magnetic field generating means, the high-frequency magnetic field generating means, and the detecting means A sequence control means for controlling the operation; and an arithmetic means for calculating a magnetic resonance spectrum using the nuclear magnetic resonance signal, wherein the detection means has a ratio of the length in the minor axis direction to the major axis direction of 1: 2 or more. A plurality of small coils arranged in the short axis direction, and the sequence control means provides the position information of the small coils in the long axis direction after performing the control to generate the high frequency magnetic field. And performing the control while reversing the polarity of the readout gradient magnetic field at a high speed and the control for detecting a plurality of nuclear magnetic resonance echo train signals with the plurality of small coils, and the computing means comprises the plurality of nuclear magnetic resonances. Spectral information having spatial information in the short axis direction of the small coil corresponding to the sensitivity region of each small coil and position information in the long axis direction of the small coil given by the readout gradient magnetic field is calculated from the echo train signal. It is characterized by doing.

  Here, the shape of the small coil is not particularly limited to a ratio of the short axis to the long axis of 1: 2 or more, and a rectangle of less than 1: 2 may be used.

  According to the present invention, the one-dimensional spatial information in the short axis direction of the small coil is associated with the position information of the small coil on a one-to-one basis, and the one-dimensional spatial information in the long axis direction of the small coil is applied to the gradient magnetic field. Therefore, a magnetic resonance spectroscopic image having a high SNR can be acquired in a short time.

Hereinafter, embodiments of the magnetic resonance imaging apparatus of the present invention will be described with reference to the drawings.
3A to 3C are external views of a magnetic resonance imaging apparatus to which the present invention is applied. FIG. 3A is a horizontal magnetic field type magnetic resonance imaging apparatus using a tunnel magnet that generates a static magnetic field with a solenoid coil, and FIG. 3B is a hamburger in which the magnets are separated up and down in order to increase the feeling of opening. This is a type (open type) vertical magnetic field type magnetic resonance imaging apparatus. FIG. 3C shows the same tunnel-type magnetic resonance imaging apparatus as that in FIG. 3A, but the feeling of opening is enhanced by shortening the depth of the magnet and tilting it obliquely. The present invention can be applied to a magnetic resonance imaging apparatus having a known structure including these magnetic resonance imaging apparatuses.

  FIG. 4 is a block diagram showing an example of a magnetic resonance imaging apparatus to which the present invention is applied. This magnetic resonance imaging apparatus has a static magnetic field coil 2 for generating a static magnetic field, a gradient magnetic field coil 3 for applying gradient magnetic fields in three directions orthogonal to each other, and a subject 1 in a space where the subject 1 is placed. A transmission high-frequency coil 5 for irradiating a high-frequency magnetic field and a reception high-frequency coil (hereinafter simply referred to as a reception coil) 6 for receiving a magnetic resonance signal generated from the subject 1 are provided. Moreover, the shim coil 4 which can adjust a static magnetic field uniformity may be provided. Various types of static magnetic field coils 2 are employed according to the structure of the apparatus shown in FIG. The gradient magnetic field coil 3 and the shim coil 4 are driven by a gradient magnetic field power supply unit 12 and a shim power supply unit 13, respectively. In FIG. 4, transmission and reception are separately shown as the high-frequency coil, but there is a configuration in which only one high-frequency coil that is used for both transmission and reception is used. That is, in the present invention, a multiple coil in which a plurality of small coils are arranged in a one-dimensional direction is used as a reception coil, but this can also serve for transmission. The high frequency magnetic field irradiated by the transmission high frequency coil is generated by the transmitter 7, and the magnetic resonance signal detected by the reception coil is sent to the computer 9 through the receiver 8. The calculator 9 performs various arithmetic processes on the magnetic resonance signal to generate spectrum information and image information. The computer 9 is connected to a display 10, a storage device 11, a sequence control device 14, an input device 15, and the like. The generated spectrum information and image information described above are displayed on the display 10 or recorded in the storage device 11. Or The input device 15 is used to input measurement conditions, conditions necessary for arithmetic processing, and the like, and these measurement conditions and the like are recorded in the storage device 11 as necessary. The sequence control device 14 controls the drive power supply unit 12 for the gradient magnetic field generating coil 3, the drive power supply unit 13 for the shim coil 4, the transmitter 7, and the receiver 9. The control time chart (pulse sequence) is set in advance by the imaging method and is stored in the storage device 14.

FIG. 5 shows an embodiment of a receiving coil of a magnetic resonance imaging apparatus to which the present invention is applied. This receiving coil is composed of eight rectangular surface coils (small coils) arranged in the direction of the short axis of each rectangle. Each small coil has a major axis that is eight times the length of the minor axis. Each has a resonance characteristic that matches the resonance frequency of the nucleus to be measured. Although not shown in the figure, this resonance circuit is constituted by a combination of a capacitor having an electric capacity C and a coil having an inductance L. Each small coil needs to be decoupled in order to reduce mutual interference between the coils. As this decoupling technique, known methods can be used, and these methods will be described below.
The mutual interference between the coils can be sufficiently reduced by separating the distance between the coils to about half of the short axis dimension of the coils. FIG. 6 shows an example of the arrangement of such small coils. In this case, signal measurement can be performed simultaneously with a plurality of small coils without providing a special decoupling circuit. However, with this configuration, the signal in the area between the coils cannot be measured.

  The configuration example of the decoupling shown in FIG. 7 is a stack of small coils adjacent to each other. By adjusting the overlapping area of the small coils to an area ratio of about 10%, the electromagnetic interference of the small coils can be removed.

In the configuration example of the decoupling shown in FIG. 8, each small coil is connected to an amplifier (preamplifier) having an impedance of 3Ω or less via a coaxial cable, and the parallel resonance frequency of the capacitor C1 and the inductor L1 in the connection portion is The size of the inductor L1 is set so as to substantially match the resonance frequency of the coil. With such a configuration, even when the distance between the coils is reduced to about 5% of the dimensions of the coils, mutual electromagnetic interference can be sufficiently reduced, and simultaneous reception by a plurality of small coils is possible.
In the magnetic resonance imaging apparatus to which the present invention is applied, it is necessary to sample the output signals of all the small coils at the same time using the same number of amplifiers and A / D converters as the number of small coils used. Such an embodiment is shown in FIG.

  Hereinafter, a method for measuring spectroscopic imaging using the receiving coil composed of the eight small coils shown in FIG. 5 will be described. First, as shown in FIG. 5, the small coils are arranged such that the long axis direction of each small coil faces the X axis direction (the short axis direction faces the Y axis direction). When the MRS sequence shown in FIG. 1 is executed using the receiving coil shown in FIG. 5, eight magnetic resonances from each small coil can be obtained by applying a high frequency magnetic field once and measuring a magnetic resonance signal once. A signal can be obtained. Further, by performing inverse Fourier transform on the eight magnetic resonance signals measured, it is possible to obtain spectral information for eight regions generated from the effective sensitivity region of each small coil. That is, spectrum information (one-dimensional spectrum) for eight points in the Y-axis direction in which coils are arranged is obtained. The one-dimensional spectrum obtained with these small coils has a higher SNR than the spectrum obtained with a three-dimensional receiving coil having sensitivity over the entire measurement region.

Here, as shown in FIG. 10, the effective sensitivity area of one small coil in FIG. 5 is a rectangular parallelepiped having a ratio of the short axis to the long axis of about 1: 8, and therefore, the intersecting area with the selected slice cross section is The ratio of the short axis to the long axis is close to a rectangular parallelepiped with a ratio of about 1: 8.
Therefore, instead of the pulsy sequence shown in FIG. 1, the measurement is repeated eight times while changing the applied intensity of the phase encode gradient magnetic field Gp in the X-axis direction in eight steps according to the pulse sequence shown in FIG. Each spectrum information for 8 points in the Y-axis direction can be further divided into 8 points in the X-axis direction. Therefore, it becomes possible to obtain “spectrum information for 8 × 8 points (two-dimensional spectrum)” in eight measurements, and a phase encoding loop compared to the conventional 3D-CSI method described in “Background Art” above. Therefore, the measurement time can be shortened to 1/8.

Further, instead of the pulsy sequence of FIG. 1 described above, the signal is continuously generated by periodically inverting the gradient polarity of the readout gradient magnetic field Gr in the X-axis direction at the time of signal detection according to the pulse sequence shown in FIG. An eco-signal (eco-train signal) can be detected. Since the detected eco-train signal includes spectrum information and one-dimensional spatial information in the X-axis direction, the above-described signal rearrangement as shown in FIG. Each spectrum information for eight points in the Y-axis direction can be further divided into eight points in the X-axis direction (note that 2 obtained from odd-numbered echoes and even-numbered echoes separated by signal rearrangement in FIG. 13). A set of one-dimensional spectra is a set of spectra having a high SNR by adding together after phase correction). Accordingly, it is possible to obtain “8 × 8 spectral information (two-dimensional spectrum)” in one measurement, and there is no phase encoding loop as compared with the conventional EPSI method described in “Background Art” above. Therefore, the measurement time can be further reduced to 1/8.
In the above-described embodiment, the case where the number of small coils is eight has been described. However, the number of small coils may be plural, and is not limited to eight.

Further, in the above-described embodiment, the “ratio of the major axis and minor axis of the small coil” and the “number of divisions in the major axis direction by the gradient magnetic field” are the same so that the aspect ratio of one point (one pixel) is 1. However, the aspect ratio of one point (one pixel) may not be 1, and the “ratio of the major axis and minor axis of the small coil” and “the number of divisions in the major axis direction by the gradient magnetic field” can be arbitrarily set. I can decide. (★ In the claims, is there a reason why the ratio of the short axis to the long axis of the coil is 1: 2 or more? In the superordinate concept, the coil shape is “rectangular”, and if for some reason 1: 2 or more is highly effective, I would like to make that claim a subordinate claim. Longer is better, and is it best to increase the number of coils accordingly?)
In the above-described embodiment, an example in which the long axis direction of each small coil faces the X axis direction (the short axis direction faces the Y axis direction) has been described, but the direction of each small coil is The position information can be given using a gradient magnetic field in the major axis direction of the coil, regardless of the direction.

The receiving coil set made up of a plurality of small coils does not need to be fixed and may be movable so that the operator can freely move it. In this way, when the measurement is performed with the operator moving the receiving coil set freely, it is necessary to detect the long axis direction of each small coil before measurement. It is necessary to know the position in the system. As a method for detecting the position of the receiving coil set, for example, a surgical navigation system and an interactive scanning technique that are put into practical use in an interventional technique for performing surgery while imaging with a magnetic resonance imaging apparatus can be applied.
That is, in the surgical navigation system, a magnetic resonance imaging apparatus is provided with a three-dimensional position detector equipped with a pair of infrared cameras, and a pointer called a pointer to which a marker that can be detected by the three-dimensional position detector is fixed is used during an operation. Point to the desired site on the patient. The three-dimensional position detector detects the position pointed to by the pointer, associates it with the apparatus coordinates of the magnetic resonance imaging apparatus or the three-dimensional image data coordinates acquired in advance, and the apparatus coordinates of the tip of the pointer (and its pointing direction) Is sent to the magnetic resonance imaging apparatus as position information. Based on this positional information, the magnetic resonance imaging apparatus creates and displays a cross-sectional image including the point pointed by the pointer from the three-dimensional image data.

  In the interactive scan technology, a surgical tool in which a marker that can be detected by a three-dimensional position detector is fixed is registered in advance, and the position of the marker is detected by the three-dimensional position detector. This is a technique for determining the cross section including the tool tip and sequentially taking pictures.

In the present invention, for example, a predetermined point (for example, three points including the center) of the receiving coil is pointed by a pointer, and the major axis direction of each small coil is determined based on the position information of the three points detected by the three-dimensional position detector. The absolute spatial position of the receiving coil set (position in the device coordinate system) can be grasped.
Alternatively, a technique similar to the technique described in Patent Document 1 below can be used. In this technique, an imaging cross-section specifying device in which three spherical objects including a substance (MR marker) having a resonance frequency different from the resonance frequency of a substance to be imaged by a magnetic resonance imaging apparatus is used, and these three spherical shapes are used. By detecting the position of an object with a magnetic resonance imaging apparatus, an imaging section determined by the three positions is imaged. In the present invention, for example, such an imaging cross-section specifying device is attached integrally with the receiving coil set, and the position of the spherical object is detected by the receiving coil provided in the device separately from the receiving coil set.

As described above, the embodiment of the MRS measurement method using the receiving coil including a plurality of small coils has been described. Next, the display of the multipoint magnetic resonance spectrum thus obtained will be described. As described above, in the magnetic resonance imaging apparatus of the present invention, the MRS pulse sequence is executed using a receiving coil having a plurality of small coils, and the sensitivity of each small coil is obtained from the obtained plurality of nuclear magnetic resonance signals. Spectral information having spatial information in the short axis direction of the small coil corresponding to the region and position information in the long axis direction of the small coil provided by the gradient magnetic field is calculated. Since the spectrum indicates the signal intensity for each frequency, for example, a graph having the frequency as the horizontal axis and the signal intensity as the vertical axis can be displayed for each pixel. In this case, it is possible to observe at a glance in which region the target substance, for example, a metabolite such as lactic acid is increasing.

  Alternatively, it is possible to calculate the peak area of the substance of interest and display it as a shading or topography for each region corresponding to the small coil. In this case, the values between the regions may be interpolated as necessary. Such gray-scale display or topographic display of the target substance can also be displayed superimposed on the tissue image when another tissue image (for example, MR image) is obtained for the measurement region.

  When the spectral information is displayed superimposed on the tissue image, it is necessary to know the position of the receiving coil (small coil) in the magnetic resonance imaging apparatus coordinates. As a method for detecting the coil position, the above-described surgical navigation system and interactive scan technology can be applied. In the present invention, for example, a predetermined point (for example, three points including the center) of the receiving coil is pointed by a pointer, and is acquired in advance by a magnetic resonance imaging apparatus based on the position information of these three points detected by a three-dimensional position detector. A cross-sectional image including three points is displayed from the three-dimensional MR image, and the grayscale image is displayed so that the three points on the image coincide with the grayscale image points corresponding to the predetermined points of the receiving coil. .

The figure which shows an example of a MRS pulse sequence. The figure which shows the relationship between a measurement area | region and a receiving coil. 1 is an external view of a magnetic resonance imaging apparatus to which the present invention is applied. 1 is a diagram illustrating a configuration example of a magnetic resonance imaging apparatus to which the present invention is applied. The figure which shows an example of the receiving coil used by this invention. The figure which shows an example of the decoupling used by this invention. The figure which shows an example of the decoupling used by this invention. The figure which shows an example of the decoupling used by this invention. The figure which shows the structural example of the receiver used by this invention. The figure which shows the relationship between the receiving coil and measurement area | region used by this invention. The figure which shows the pulse sequence used in the Example of this invention. The figure which shows the pulse sequence used in the Example of this invention. Explanatory drawing of the signal rearrangement method in EPSI.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Subject, 2 ... Static magnetic field coil, 3 ... Gradient magnetic field coil, 5 ... High frequency coil for transmission, 6 ... High frequency coil for reception (reception probe), 8 ... Reception 9 ... Calculator (calculation means), 10 ... Display (display means), 11 ... Storage means, 14 ... Sequence control device, 15 ... Input device.

Claims (5)

  1. A static magnetic field generating means for generating a static magnetic field, a gradient magnetic field generating means for generating gradient magnetic fields in three directions orthogonal to each other, and a high-frequency magnetic field for generating nuclear magnetic resonance in a subject placed in the static magnetic field are generated. A high-frequency magnetic field generating means, a detecting means for detecting a nuclear magnetic resonance signal generated from the subject, a sequence control means for controlling operations of the gradient magnetic field generating means, the high-frequency magnetic field generating means, and the detecting means; In a magnetic resonance imaging apparatus provided with a calculation means for calculating a magnetic resonance spectrum using a nuclear magnetic resonance signal,
    The detecting means includes a receiving probe in which a plurality of rectangular small coils are arranged in the short axis direction of the rectangle,
    The sequence control means is configured to control the generation of the high-frequency magnetic field, control to generate a gradient magnetic field that gives positional information in the long axis direction of the small coil, and detect a plurality of nuclear magnetic resonance signals by the plurality of small coils. Control and
    The arithmetic means, from the plurality of nuclear magnetic resonance signals, the spatial information in the short axis direction of the small coil corresponding to the sensitivity region of each small coil, and the positional information in the long axis direction of the small coil provided by the gradient magnetic field A magnetic resonance imaging apparatus characterized by calculating spectrum information including:
  2. A static magnetic field generating means for generating a static magnetic field, a gradient magnetic field generating means for generating gradient magnetic fields in three directions orthogonal to each other, and a high-frequency magnetic field for generating nuclear magnetic resonance in a subject placed in the static magnetic field are generated. A high-frequency magnetic field generating means, a detecting means for detecting a nuclear magnetic resonance signal generated from the subject, a sequence control means for controlling operations of the gradient magnetic field generating means, the high-frequency magnetic field generating means, and the detecting means; In a magnetic resonance imaging apparatus provided with a calculation means for calculating a magnetic resonance spectrum using a nuclear magnetic resonance signal,
    The detection means includes a receiving probe in which a plurality of small coils having a ratio of the length in the short axis direction to the long axis direction of 1: 2 or more are arranged in the short axis direction,
    The sequence control means includes a control for generating the high-frequency magnetic field, a control for generating a phase encoding gradient magnetic field for providing positional information of the small coil in the long axis direction, and a plurality of nuclear magnetic resonance signals by the plurality of small coils. Control in order to detect
    The arithmetic means includes, from the plurality of nuclear magnetic resonance signals repeatedly detected by changing the phase encoding gradient magnetic field, spatial information in the short axis direction of the small coil corresponding to the sensitivity region of each small coil, and the phase encoding gradient A magnetic resonance imaging apparatus that calculates spectral information having position information in a major axis direction of a small coil applied by a magnetic field.
  3.   3. The magnetic resonance imaging apparatus according to claim 2, wherein the control for generating the phase encoding gradient magnetic field changes an applied intensity according to a ratio between a short axis direction and a long axis direction of the small coil. Resonance imaging device.
  4. A static magnetic field generating means for generating a static magnetic field, a gradient magnetic field generating means for generating gradient magnetic fields in three directions orthogonal to each other, and a high-frequency magnetic field for generating nuclear magnetic resonance in a subject placed in the static magnetic field are generated. A high-frequency magnetic field generating means, a detecting means for detecting a nuclear magnetic resonance signal generated from the subject, a sequence control means for controlling operations of the gradient magnetic field generating means, the high-frequency magnetic field generating means, and the detecting means; In a magnetic resonance imaging apparatus provided with a calculation means for calculating a magnetic resonance spectrum using a nuclear magnetic resonance signal,
    The detection means includes a reception probe in which a plurality of small coils having a ratio of a length in the minor axis direction to the major axis direction of 1: 2 or more are arranged in the minor axis direction.
    The sequence control means performs the control to generate the high-frequency magnetic field, and then performs the control to generate while reversing the polarity of the readout gradient magnetic field that gives the positional information of the small coil in the long axis direction, and the plurality of small-sized magnetic fields. The coil simultaneously controls the detection of multiple nuclear magnetic resonance echo train signals,
    The calculation means includes, from the plurality of nuclear magnetic resonance echo train signals, spatial information in a short axis direction of a small coil corresponding to a sensitivity region of each small coil, and a long axis of the small coil provided by the readout gradient magnetic field. A magnetic resonance imaging apparatus characterized by calculating spectral information having directional position information.
  5. 5. The magnetic resonance imaging apparatus according to claim 4, wherein two sets of one-dimensional spectra obtained from an echo train signal comprising odd-numbered echoes and an echo train signal comprising even-numbered echoes are added together after phase correction. A magnetic resonance imaging apparatus.
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JPH01207044A (en) * 1988-02-15 1989-08-21 Yokogawa Medical Syst Ltd Receiving device of nuclear magnetic resonance image diagnostic apparatus
JPH07155304A (en) * 1993-12-07 1995-06-20 Hitachi Ltd Magnetic resonance photographing method
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JPS63137614A (en) * 1986-12-01 1988-06-09 Kubota Ltd Apparatus for harvesting fruits and vegetables
JPH01207044A (en) * 1988-02-15 1989-08-21 Yokogawa Medical Syst Ltd Receiving device of nuclear magnetic resonance image diagnostic apparatus
JPH07155304A (en) * 1993-12-07 1995-06-20 Hitachi Ltd Magnetic resonance photographing method
JPH1156808A (en) * 1997-08-25 1999-03-02 Hitachi Medical Corp Magnetic resonance device
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JP2004298212A (en) * 2003-03-28 2004-10-28 Ge Medical Systems Global Technology Co Llc Rf coil and magnetic resonance imaging apparatus

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