JPH08280646A - Magnetic resonance imaging apparatus - Google Patents

Abstract

PURPOSE: To obtain correct results of inspection corresponding to the intensity of a signal of an intrinsic nuclear spin by correcting a space distribution characteristic of the sensitivity of a detection coil according to the detection coil used. CONSTITUTION: A high frequency coil 10 ideal for a part to be inspected of a subject 1 is mounted and the part to be inspected is arranged at the center of a magnet 2. An NMR signal is measured to match the operation of a photographing sequence. The NMR signal is inputted into an electronic computer 13 via a connection circuit 11 and an amplification circuit 12. An identification signal of the detection coil 10 is inputted into the electronic computer 13 from the connection circuit 11 and an arithmetic processing of the NMR signal is selected to correct the characteristic of the detection coil 10 by the signal. The correction processing is performed by computing and obtaining a sensitivity distribution using a low frequency component of the NMR signal measured. The results of the computation are shown on a display monitor 15. Thus, the space distribution characteristic of the sensitivity of a detection means can be corrected uniformly according to the detection means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic resonance imaging apparatus (hereinafter referred to as "MRI apparatus"), and in particular, an MRI apparatus equipped with a compensation process suitable for obtaining an inspection result with a uniform signal intensity in a predetermined inspection area. Regarding the device.

[0002]

2. Description of the Related Art An MRI apparatus is a nuclear magnetic resonance (hereinafter, referred to as NMR
It is a device that non-invasively inspects the subject by measuring the tomographic image and the local spectrum of the internal tissue of the human body, which is the subject. As shown in FIG. 6, a standard MRI apparatus includes a magnet 601 that generates a uniform magnetic field, three gradient magnetic field coils 602 that generate gradient magnetic fields in three orthogonal directions, and a gradient magnetic field power supply that drives these coils. 603 to 605, an irradiation high-frequency coil 606 that generates a high-frequency magnetic field that excites nuclear spins at the inspection site,
A high-frequency transmitter 607 that drives the coil, a high-frequency coil 608 for detection that detects an NMR signal from the excited nuclear spin as an electric signal, a signal amplification circuit 609 connected to the coil, and a subject from the NMR signal. Signal processing for generating an image of
02 and the driving of the high frequency coil 606 and a computer 610 for controlling the timing of signal detection according to a predetermined sequence, a monitor display 611 for displaying the generated image, and a patient table for moving the subject 1 to the measurement position. 612 and. In these devices, in order to prevent electromagnetic noise from being mixed into the detection high-frequency coil 608 and deterioration of inspection results, a magnet 601 and a patient table 612 are arranged in an electromagnetically shielded examination room, and a control system for operating from the outside is provided. The operator console 613 is placed outside the examination room.

In such an MRI apparatus, as a diagnostic apparatus, 1) the intensity of the detected NMR signal accurately reflects the actual position of the examination site and the state of nuclear spin, 2).
The test result has useful information for diagnosis, that is, N
A high S / N ratio of the MR signal is an important item. As for the item 1), the static magnetic field magnet, the gradient magnetic field coil, and the irradiation high-frequency coil exhibit optimal characteristics near the center thereof, and are sufficiently large so as to have optimal characteristics in the target inspection region. Is desired. However, the size of the device is limited to realize the device, and thus the generated magnetic field is distorted. In order to correct the distortion of the magnetic field and generate a uniform inspection result in the entire inspection region, various correction processes are added to the NMR signal. For example, in the technique disclosed in Japanese Patent Application Laid-Open No. 59-190643, the NMR image generated by the poor uniformity of the static magnetic field and the linear distortion of the gradient magnetic field is different from the actual body and position of the examination site. The problem that does not correspond is corrected by the calculation process. Further, in Japanese Patent Laid-Open No. 1-308537, an NMR image is obtained after removing the influence of spatial nonuniformity of a high frequency magnetic field.
RI equipment has been proposed.

Regarding the item 2), that is, the improvement of the S / N, the intensity of the NMR signal is improved by increasing the intensity of the static magnetic field. On the other hand, as an improvement on the detection coil side, in order to improve the induced voltage of the NMR signal to the detection coil, a method of bringing the nuclear magnetic moment and the detection coil close to each other is adopted. For example, in the case of a cylindrical detection coil, a detection coil is used for each part of the subject in order to make it as close as possible to the shape of the subject placed inside. That is, an MRI apparatus having separate detection coils for the head and the torso has been developed, and for the torso, a coil having an ellipsoidal cross-sectional shape has been developed to match the cross-sectional shape of the subject. ing. In addition, the surface coil developed to measure the spectrum from a specific site has made it possible to obtain local spectrum measurement and imaging data with higher sensitivity. As described above, in the MRI apparatus, it is common to prepare a detection coil for each examination site or for each examination purpose. In the MRI apparatus having a plurality of detection coils as described above, a technique for obtaining inspection data having a good S / N by each detection coil without complicated operations when inspecting each part (Japanese Patent Publication No. No. 25492), a technique for inputting an identification signal of a detection coil to a computer in order to prevent an accident due to excessive power supply to the coil, and accurately recognizing / recording the detection coil currently used from a plurality of detection coils (Japanese Patent Laid-Open No. Hei 10 (1999) -242242). 6-2
No. 01809 and Japanese Utility Model Publication No. 6-36802) have been proposed.

[0005]

By the way, the above-mentioned prior art was able to dramatically improve the diagnostic ability of the MRI apparatus by being able to improve the detection sensitivity of the NMR signal. There was a problem that the uniformity of the intensity of the signal data in the area had to be sacrificed to some extent. This is a problem caused by reducing the distance between the detection coil and the inspection site. Generally, the spatial distribution of the detection sensitivity of the detection coil is equivalent to the magnetic flux spatial distribution generated when a current is passed through the coil, and it is clear that the magnetic flux concentrates near the coil. The area of is measured with higher sensitivity than other areas. This tendency is particularly remarkable in the case of the surface type coil, and the vicinity of the detection coil is measured with high sensitivity, and the detection sensitivity sharply decreases as the distance from the detection coil increases.
Such a characteristic of the surface coil may cause inconvenience in diagnosis. For example, the NMR signal of subcutaneous fat existing in the vicinity of the coil has a particularly high intensity, which makes it difficult to determine the signal in the vicinity thereof. Alternatively, in image diagnosis, when a lesion site is specified by image density, deterioration of the spatial distribution characteristic of the sensitivity of these detection coils becomes a serious problem. However, in the conventional technique, emphasis is placed on improving the sensitivity of the detection coil, and the improvement of the spatial distribution of the sensitivity is second only.

In order to solve the deterioration of the image due to the non-uniformity of the sensitivity distribution of the detection coil, it is possible to obtain the sensitivity distribution of the detection coil in advance and correct the NMR signal by this, but the sensitivity distribution of the detection coil is Since it depends on the individual detection coil and the type of the detection coil, it is unreasonable to obtain the sensitivity distribution of the detection coil to be used each time. In particular, in the case of an MRI apparatus including a plurality of detection coils, it is necessary to obtain the sensitivity distribution for each detection coil and to perform the corresponding sensitivity distribution correction depending on the detection coil used. In addition, the sensitivity distribution may vary depending on the subject and the imaging conditions, and in such a case, there is a problem in that accurate correction cannot be performed even with the sensitivity distribution obtained in advance.

Therefore, an object of the present invention is to correct the characteristic of the sensitivity distribution of the detection coil to obtain an accurate inspection result corresponding to the original nuclear spin signal intensity, and particularly for a plurality of detection coils. An object of the present invention is to provide an MRI apparatus capable of automatically performing correction corresponding to each sensitivity distribution characteristic.

[0008]

The MRI apparatus of the present invention which achieves these objects generates a uniform static magnetic field and a gradient magnetic field and a high frequency magnetic field having different strengths depending on the position in a measurement space in which a subject is placed. Magnetic field generation means, detection means for detecting the nuclear magnetic resonance signal generated from the examination site of the subject, a computer for signal processing the detected nuclear magnetic resonance signal, and a display means for displaying the calculation result of the computer, In an MRI apparatus provided with a magnetic field generation means and a control means for driving and controlling the detection means, the computer has a function of recognizing the type of the detection means, and changes the processing content of the signal processing according to the type of the detection means. It is configured as follows. In another aspect of the MRI apparatus of the present invention, the detecting means includes at least two or more detecting means arranged for each examination site of the subject, and the computer recognizes the detecting means being driven among these two or more detecting means. It has a function to do so, and changes the processing content of the signal processing according to the characteristics of the detecting means during driving.

The signal processing performed by the computer includes processing for correcting the signal corresponding to the characteristics of the detecting means so that the sensitivity distribution of the detecting means becomes uniform, and in particular, based on the nuclear magnetic resonance signal detected by the detecting means. It includes an algorithm for obtaining the sensitivity distribution characteristic of the detecting means and an algorithm for correcting the nuclear magnetic resonance signal detected by the detecting means based on the obtained sensitivity distribution characteristic.

[0010]

A high-frequency coil, which is a detection means suitable for the shape of the site and the purpose of the inspection, is previously attached to the inspection site of the subject, and the inspection site has a magnet as the magnetic field generating means, a gradient magnetic field coil, and a high-frequency wave for irradiation. It is arranged so as to be located at the center of the coil. The magnetic field generating means is operated by the control means in accordance with the target imaging sequence, and the
The signal is detected as an electric signal by a high frequency coil for detection mounted in the vicinity. The detected NMR signal is sent to a computer and subjected to calculation processing for generating an image. At this time, the computer recognizes the type of the high-frequency coil for detection used, and accordingly selects, for example, a process for correcting the characteristic of the sensitivity distribution of the high-frequency coil for detection or no correction process. Also, when partially driving a plurality of high-frequency coils or when driving one of the multiple high-frequency coils, the high-frequency coil that is being driven is recognized and the sensitivity distribution characteristics of the high-frequency coil that is being driven are identified. A combined correction process is performed. As a result, it is possible to automatically correct the sensitivity distribution of the high frequency coil used and obtain an accurate inspection result.

By obtaining the sensitivity distribution of the used high frequency coil from the actually measured data (NMR signal), it is possible to correspond to the characteristics of the used high frequency coil without obtaining the sensitivity distribution of the high frequency coil in advance. As a result, accurate sensitivity distribution correction is possible.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an embodiment of an MRI apparatus to which the present invention is applied. This MRI apparatus is arranged in a superconducting magnet 2 that generates a uniform static magnetic field in the space where the subject 1 is placed, and in a measurement space inside this magnet 2.
A three-axis gradient magnetic field coil 3 for generating a gradient magnetic field superimposed on the static magnetic field, a high-frequency coil 4 for generating a high-frequency magnetic field, and a driving power supply x5, a driving power supply y6 for driving the three-axis gradient magnetic field coil 3, respectively. A driving power supply z7, a driving power supply (transmission circuit) 8 for the high frequency coil 4, a patient table 9 into which the examination site of the subject 1 is inserted in the measurement space, and a high frequency coil for detecting an NMR signal of the examination site (hereinafter, (Detection coil) 10, amplification circuit 12, and amplified NMR
An electronic computer 13 for processing signals and its console 14
And a display monitor 15 for displaying the calculation result of the electronic computer 13, the superconducting magnet 2, the gradient magnetic field coil 3, the high frequency coil 4, the detection coil 10 and the patient table 9 are electromagnetically shielded in the examination room (in the figure). Is not shown). Further, this MRI apparatus has a detection coil 10
A connection circuit 11 is provided between the amplifier 12 and the amplifier 12, and the connection circuit 11 generates a signal for specifying the detection coil 10 for detection as described later, and at the same time, NMR.
The signal is connected to the amplifier circuit 12.

FIG. 2 is a detailed circuit diagram of the connection circuit 11. The detection coil 10 includes a connector 201 for making it possible to determine its type, and the connection circuit 11 has a connector 202 connected to the connector 201 of the detection coil 10 and inverter circuits 204a to 204d to which each terminal of the connector 202 is connected. And resistors 205, 20 inserted between the connector 202 and the inverter circuit 204.
6 and a coaxial cable 203 for inputting the NMR signal from the detection coil to the amplifier circuit 12. The outputs of the inverter circuits 204a to 204d are input to the computer 13.

The connectors 201 and 202 of the detection coil 10 have terminals T for representing, for example, 4 bits.
1 to T4 and a terminal TG connected to the ground potential G, and a 4-bit identification signal representing the type of the detection coil 10 is determined by the connection state of the terminal TG in the connector 201 and other terminals.

For example, in the case of the cervical spine coil shown in the drawing, the first
Since the bit and the second bit are connected to the ground potential G, the level becomes "L". The third bit and the fourth bit are at the “H” level because they remain the potentials obtained by dividing the voltage Vcc by the resistors 205 and 206. That is, a binary "1100" signal is input to the inverter circuits 204a to 204d. Each signal is the inverter circuit 204a-
It is inverted at d and becomes "0011", which is read by the computer 13. Thus, in the MRI apparatus shown in the embodiment,
For each high-frequency coil, the first high-frequency coil for the head (“0001” in binary) and the second high-frequency coil for the abdomen are 2
Number (binary number "0010"), cervical spine high frequency coil number 3 (binary number "0011"), spine high frequency coil number 4 (binary number "0100"), knee joint high frequency coil The identification signal is assigned as No. 5 (“0101” in binary). The electronic computer 13 can read which detection coil is used by these identification signals.

Next, the operation of the MRI apparatus configured as described above will be described. In FIG. 1, it is assumed that the inspection site is arranged at the center of the superconducting magnet 2 in a state in which the detection coil 10 dedicated to the cervical region is attached to inspect the cervical spine of the subject 1. An operator (not shown in the drawing) operates on the console 14 to control the electronic computer 13,
The shooting sequence that suits the purpose of inspection is activated. As an example, in the imaging sequence called the spin echo method shown in FIG. 3, in the period A, a 90 ° high-frequency magnetic field pulse is applied while the gradient magnetic field x is applied at an intensity of 3 mT / m. Here, the high frequency magnetic field pulse has a band component of 1 kHz.
Amplitude modulation is performed with a Gaussian waveform so as to be z. Due to the combination of the gradient magnetic field and the high-frequency magnetic field, the cervical vertebrae of the subject 1 extends along the body axis (matches the z axis)
Resonant excitation of nuclear spins on a cm-thick slice plane. In the period B, the gradient magnetic fields y and z are applied. By applying this gradient magnetic field, the precession motion of the nuclear spin resonantly excited in the period A is y.
Along the axis and the z axis, a phase difference proportional to the strength of the gradient magnetic field and the application time occurs. In the period C, the high frequency magnetic field of 180 ° is applied while the gradient magnetic field x is applied with the intensity of 3 mT / m again. Due to the combination of this gradient magnetic field and the high frequency magnetic field, the nuclear spins in the same slice plane invert the phase of their precession motion, and the same time is applied between the 90 ° high frequency magnetic field application and the 180 ° high frequency magnetic field application. At a time point (point) F after the passage, an NMR signal is presented as a spin echo. This has an effect of matching the phase of the precession motion of the nuclear spin diffused by the magnetic field distortion other than the applied gradient magnetic field after the resonant excitation of the nuclear spin in the period A. In the period D including the point F, the NMR is applied while applying the gradient magnetic field z.
Measure the signal. The measurement is performed at 256 (as an example) points at a sampling rate corresponding to the strength of the gradient magnetic field z and the size of the imaging region. The gradient magnetic field z is set so that the applied amount in the period B is equal to the applied amount up to the point F in the period D. As a result, the phase error of the precession motion of the nuclear spin due to the gradient magnetic field z is also canceled at the point F, so that the maximum intensity NMR signal can be detected and the position information corresponding to the z-axis coordinate center can be obtained. Will be encoded. After a predetermined waiting time (period E), period B
By changing the applied amount of the gradient magnetic field y applied in, the process from the period A to the period E is repeated and the NMR signal is measured.
By repeating this process 256 times, for example, the yz plane 2
A 56 × 256 matrix NMR signal is obtained.

This NMR signal is input to the amplifier circuit 12 via the coaxial cable 203 of the connection circuit 11, where amplification, detection, and digital conversion are performed, and the NMR signal is input to the electronic computer 13. The electronic computer 13 performs signal processing of the NMR signal to generate an image, and processing for correcting the characteristic of the spatial distribution of sensitivity of the detection coil in this calculation processing by the identification signal of the detection coil 10 from the connection circuit 11. It is determined whether or not to include. For example, the correction process is not performed for a coil having a uniform sensitivity distribution such as a cylindrical coil, and the correction process is performed for a coil having a large change in the sensitivity distribution in the case of a surface coil such as a cervical spine detection coil. Further, even in the case of a cylindrical coil, the correction process is performed for a deformed cylindrical coil whose cross section is elliptical.

In the embodiment of FIG. 1, since the identification signal indicating the detection coil 10 dedicated to the cervical spine is input to the electronic computer 13 in advance, correction of the spatial distribution of the sensitivity of the detection coil 10 is incorporated in the calculation algorithm. Sensitivity correction can also be performed based on the sensitivity distribution previously obtained by using a phantom or the like for the cervical spine detection coil, but preferably the sensitivity distribution is obtained and corrected using the measured NMR signal. As a result, the sensitivity of the actual detection coil itself can be corrected under the shooting conditions.

FIG. 4 shows an example of a suitable correction algorithm of the present invention. This is one in which a spatial distribution correction algorithm for the sensitivity of the detection coil is incorporated into an algorithm for reconstructing a tomographic image of the examination site of the subject 1 from the two-dimensional NMR signal data. In the image reconstruction algorithm, the two-dimensional Fourier transform processing 402 is performed on the NMR signal 401 of the 256 × 256 matrix by a conventional method, and the Fourier transform data 403 before the correction processing of the tomographic image corresponding to the inspection portion is performed.
Get. After that, the absolute value processing and the normalization processing 405 that makes the maximum amplitude constant are performed. On the other hand, the correction algorithm obtains the sensitivity distribution of the detection coil by using the low frequency component data of the NMR signal. That is, first, 256 × 25
16 × 1 near the center of 6 matrix NMR signal 401
Only the matrix data of No. 6 is extracted (406).
Next, new 256 x 256 matrix data (low frequency component data) in which the remaining part is replaced with data with zero value
Create 407. This low-frequency component extraction can be realized by using a low-pass filter such as a Butterworth type filter or a Gaussian filter, and a sensitivity distribution that well reflects the sensitivity distribution of the detection coil is obtained by appropriately determining the filter parameters. be able to. The matrix data 407 is similarly subjected to the two-dimensional Fourier transform processing (408), and the Fourier transform data 4 of the low frequency component is obtained.
09, and performs absolute value processing and normalization processing (41
0). The data (sensitivity distribution image) 411 obtained by this arithmetic processing does not show the details of the internal structure of the tissue of the examination site, but becomes an image showing a simple detection sensitivity distribution of the examination region. This is because in the two-dimensional Fourier transform method, the detailed information of the examination site of the subject exists not in the center of the 256 × 256 matrix data 401 but in the peripheral part, and the central part shows a rough distribution of shading.

The correction data 413 obtained by reciprocal processing 412 of the sensitivity distribution image 411 of the image data thus obtained is multiplied by the value of each matrix data of the absolute value image data 404 (414), and the normalization processing is performed again. By performing 415, the characteristic of the sensitivity distribution of the detection coil is corrected, and the corrected image data 416 of the accurate inspection result corresponding to the original nuclear spin signal intensity of the inspection region is obtained.

Correction function F in the reciprocal process 412
(S) 413 is usually F (s) = 1 / s (s is a function of the position indicating the sensitivity), but the very low sensitivity part is a region that contains almost no effective diagnostic information. By performing the reciprocal processing, noise may be conspicuous, which is not preferable for image diagnosis. In order to avoid such an inconvenience, 1 / s is used as F (s) in the high sensitivity region, and a correction function that uses a predetermined position of low sensitivity as a maximum value and an increase function of sensitivity in the lower sensitivity region is used. Preferably. As a concrete example of the correction function of such a characteristic,

[0022]

[Equation 1]

[0023]

[Equation 2]

[0024]

(Equation 3) And the like. In the formula, a and b are predetermined constants.

As a result, an image in which the sensitivity distribution of the detection coil 10 dedicated to the cervical spine is corrected is reconstructed, and the display monitor 1
5 is displayed.

Next, a case where the head of another subject is inspected by the MRI apparatus will be described. A cylindrical head-only detection coil is attached to the head of the subject, and the patient table is operated so as to be positioned at the center of the magnet. The operator activates a shooting sequence suitable for the inspection purpose by operating the console. As in the case of the examination of the cervical vertebrae described above, NMR signals of a 256 × 256 matrix are measured. After the measurement is completed, the electronic computer 13 processes the NMR signal to form a tomographic image. In this case, unlike the previous cervical spine processing, "0001" is input to the electronic computer as the identification signal of the detection coil. Therefore, the spatial distribution correction process of the algorithm shown in FIG. 4 is not performed, and the two-dimensional Fourier transform process 40 is performed on the 256 × 256 matrix NMR signal 401.
2, the Fourier transform data 403 before the correction processing of the tomographic image corresponding to the inspection portion of the head is obtained. This is because the cylindrical detection coil for the head exhibits a substantially uniform detection sensitivity distribution inside the cylinder.

As described above, according to this embodiment, by selecting the most suitable detection coil for the inspection site and connecting it to the apparatus,
The electronic computer 13 determines the type of the detection coil based on the identification signal, and selects a necessary processing algorithm according to the connected coil. As a result, when sensitivity correction is not necessary like a cylindrical coil, high-speed image processing can be performed by performing only necessary processing. Further, since it is not necessary to measure the characteristic data of the detection coil in advance and the correction data is created from the original measurement data, accurate correction is possible. Moreover, the correction can be performed regardless of the type of the detection coil. In the above embodiments, the case where the computer determines the identification signal of the detection coil and changes the processing content has been described, but the identification of the detection coil may be performed by input from the operator's console. Such an embodiment will be described with reference to the operation flow chart of FIG.

The operator selects the detection coil in consideration of the examination content and examination site of the subject and sets it on the examination site of the subject (501). This setting operation is performed on the patient table, and the patient table is moved to position the examination site of the subject and the detection coil at the center of the superconducting magnet. Next, the operator operates the keys on the operation console to input the information of the attached detection coil at the same time as inputting the name and registration number of the subject (502). This input is performed by inputting necessary items in accordance with the operation screen of the console or by selecting a predetermined coil from the options displayed as the menu screen.
Furthermore, select the shooting sequence that matches the inspection details,
The NMR signal is measured in the same manner as in the first embodiment (50
3). Next, the computer calculates the NM according to the processing program.
Prior to starting the calculation processing of the R signal data, the normal image reconstruction signal processing 505 is performed according to the identification information of the detection coil input from the operator console, or the image reconstruction including the processing for correcting the characteristic of the detection coil is performed. It is determined whether the configuration signal processing 506 is selected (504). These image reconstruction signal processing 50
5 and image reconstruction signal processing 506 including correction processing can be performed by the algorithm shown in FIG. 4, and the data processed in this way is managed by a data management program 507 that collects information such as imaging conditions and targets. . The presence / absence of correction processing is also input to this information. This completes the inspection.

According to this embodiment, the characteristic of the detection coil can be corrected by changing the calculation processing program of the NMR signal without changing the hardware configuration of the conventional MRI apparatus. Furthermore, there is a feature that the flexibility of the system can be secured even when a new high frequency coil is added.

In the above embodiments, a case has been described in which a plurality of different types of detection coils are selectively used for measurement, but the present invention partially uses multiple coils such as a phased array coil and a switched coil. It is also applicable when driving. That is, when a part of (a surface coil of) a coil formed by arranging a plurality of surface coils is sequentially driven, the correction algorithm is executed every time the driven coil is different, and the image data whose sensitivity is corrected for each coil is executed. To get Also in this case, when the multiple coils are connected, the electronic computer 13 determines that the multiple coils are connected by the identification signal or the input from the operator's console, and the sensitivity distribution correction is performed in the signal processing of the NMR signal. Signal processing including algorithms for. This signal processing is programmed to execute an algorithm for sensitivity distribution correction each time the driven coil is switched, and a uniform sensitivity correction is performed corresponding to the sensitivity distribution characteristics of the individual coils making up the multiple coils. It can be performed.

[0031]

According to the present invention, since the spatial distribution characteristic of the sensitivity of the detecting means is corrected according to the type of the detecting means used, the detecting coil having a shape suitable for the inspection site is used. Efficient and accurate inspection results can be obtained. Further, according to the present invention, by using the NMR signal detected by the detection means, by obtaining the sensitivity distribution of the detection means, it is not necessary to obtain the sensitivity distribution characteristic for each detection means in advance, and an accurate inspection result can be obtained. Obtainable.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an MRI apparatus using the present invention

FIG. 2 is a diagram showing details of a connection circuit of FIG.

FIG. 3 is a time chart diagram showing an example of a shooting sequence.

FIG. 4 is a diagram illustrating an image reconstruction algorithm according to the present invention.

FIG. 5 is a diagram illustrating an operation flow showing another embodiment of the present invention.

FIG. 6 is an overall configuration diagram of a conventional MRI apparatus.

[Explanation of reference numerals] 1 subject 2 superconducting magnet 3 gradient magnetic field coil 4 high frequency coil 5, 6, 7, 8 drive power supply 9 patient table 10 high frequency coil 11 connection circuit 12 amplification circuit 13 electronic calculator 14 operator console 15 display monitor

Claims (3)

[Claims] 1. A magnetic field generating means for respectively generating a uniform static magnetic field in a measurement space in which a subject is placed and a gradient magnetic field and a high frequency magnetic field having different intensities depending on positions, and nuclear magnetic resonance generated from an examination site of the subject. Detection means for detecting the signal,
In a magnetic resonance imaging apparatus comprising a computer that performs signal processing of the detected nuclear magnetic resonance signal, a display unit that displays the calculation result of the computer, and a control unit that drives and controls the magnetic field generation unit and the detection unit, The magnetic resonance imaging apparatus, wherein the computer has a function of recognizing the type of the detecting means, and is configured to change the processing content of the signal processing according to the type of the detecting means. 2. A magnetic field generating means for respectively generating a uniform static magnetic field and a gradient magnetic field and a high frequency magnetic field having different intensities depending on the position in a measurement space in which the subject is placed, and an examination site arranged for each examination site of the subject. At least two detecting means for detecting a nuclear magnetic resonance signal generated from the computer, a computer for processing the detected nuclear magnetic resonance signal, a display means for displaying a calculation result of the computer, the magnetic field generating means and the In a magnetic resonance imaging apparatus provided with a control unit that drives and controls a detection unit, the computer has a function of recognizing a detection unit that is being driven among the two or more detection units, and corresponds to a characteristic of the detection unit. A magnetic resonance imaging apparatus characterized in that the processing content of the signal processing is changed. 3. The signal processing comprises: an algorithm for obtaining a sensitivity distribution characteristic of the detection means based on the nuclear magnetic resonance signal detected by the detection means; and a nuclear magnetic resonance signal detected by the detection means. The magnetic resonance imaging apparatus according to claim 1 or 2, further comprising an algorithm for correcting based on a sensitivity distribution characteristic.