JP5484001B2 - Magnetic resonance imaging apparatus and image correction method - Google Patents

Description

  The present invention measures magnetic resonance (Nuclear Magnetic Resonance, hereinafter referred to as NMR) signals from hydrogen, phosphorus, etc. in a subject and images nuclear density distribution, relaxation time distribution, etc. The present invention relates to a Resonance Imaging (hereinafter referred to as “MRI”) apparatus, and more particularly to an image correction technique for correcting non-uniform sensitivity of an image caused by sensitivity distribution data of a radio frequency (hereinafter referred to as RF) coil used for reception.

  An MRI apparatus measures, as a received signal, an NMR signal generated by a nuclear spin that constitutes a subject, particularly a human tissue, and the shape and function of the head, abdomen, limbs, and the like are two-dimensionally or three-dimensionally measured. A device for imaging. In imaging, the NMR signal is given different phase encoding depending on the gradient magnetic field and is frequency-encoded and measured as time-series data. The measured NMR signal is reconstructed into an image by two-dimensional or three-dimensional Fourier transform.

  In recent MRI apparatuses, a target image can be obtained by using a multiple coil having a plurality of RF receiving coils to obtain a composite image by synthesizing a plurality of tomographic images obtained for each RF receiving coil. Has been done. Although this method has an advantage that a composite image having a high S / N ratio can be obtained, the nonuniformity of the sensitivity distribution data of each RF receiving coil is reflected in the composite image, and the sensitivity or luminance is not uniform (hereinafter referred to as “non-uniformity”). , Referred to as non-uniform sensitivity) may be acquired.

  As a technique for correcting the non-uniform sensitivity in the composite image, the sensitivity distribution data of the RF receiving coil is calculated, correction coefficient data is calculated based on the sensitivity distribution data, and the non-uniform sensitivity of the composite image is calculated using the correction coefficient data. There is a technology to correct this. As an example of a method for calculating the sensitivity distribution data of the RF receiving coil, the ratio of the image obtained using the RF receiving coil to the image obtained using the whole body RF coil having uniform sensitivity distribution data is used. , A method of calculating the sensitivity distribution data of the RF receiving coil (Patent Document 1), a method of approximating the low frequency component of the RF receiving coil as the sensitivity distribution data of the RF receiving coil (Patent Document 2), a uniform phantom in advance There are a method of taking an image and regarding the tomographic image as sensitivity distribution data (Patent Document 3), a method of calculating sensitivity distribution data of an RF receiving coil by a numerical calculation by a magnetic field analysis method (Non-Patent Document 1), and the like.

  In addition, when the sensitivity distribution data and the image data do not match, the sensitivity correction is not successful, so a method for compensating for the mismatch between these data has been proposed (Patent Document 4).

JP-A-8-56928 JP 2002-272705 A Japanese Unexamined Patent Publication No. 7-59750 Special Table 2007-503904

ISMRM 1405, 1999 DF Kacher, et al.

  However, in the technique described in Patent Document 4, when using a multiple coil composed of a plurality of RF receiving coil elements, each coil element moves independently as the subject itself or the subject moves. Compensation for such cases is not considered.

  An object of the present invention is to perform sensitivity distribution measurement and compensation when a subject moves between the main measurements when performing image luminance correction based on a mismatch between sensitivity distribution data and synthesized image data in an MRI apparatus. An apparatus and an image correction method thereof are provided.

  In order to achieve the above object, in the present invention, an image of a subject is acquired from a receiving unit having an RF coil and a reception signal acquired from the subject using the RF coil based on a predetermined sequence. A magnetic resonance imaging apparatus that corrects image sensitivity and sensitivity non-uniformity using the sensitivity distribution data of the RF coil, and the control unit performs the sensitivity distribution measurement and the main measurement. A magnetic resonance imaging apparatus configured to correct the sensitivity distribution of an image at the time of the main measurement and an image correction method thereof are provided.

  That is, the image processing process in the apparatus of the present invention is configured as follows. Immediately before or during the acquisition of sensitivity distribution data and immediately before or during the acquisition of composite image data, position information that is data for measuring the three-dimensional object position coordinates is acquired for the entire RF coil or for each coil element. The deformation amount and the movement amount of the subject are calculated from the difference between the two pieces of position information, and the sensitivity distribution data or the synthesized image data is moved / deformed based on the calculated values.

  According to the present invention, even when the subject moves for some reason between the acquisition of the sensitivity distribution data and the acquisition of the composite image data, the sensitivity nonuniformity can be corrected more accurately.

It is a figure which shows an example of the whole fundamental structure of the MRI apparatus which concerns on each Example. It is a figure for demonstrating acquisition of the one-dimensional data of 3 axis directions of X, Y, Z of k space based on a 1st Example. It is a figure for demonstrating creation of the one-dimensional image data of a triaxial direction based on a 1st Example. It is a figure for demonstrating the movement and shape deformation | transformation of the test object of a 3 axis direction which concern on a 1st Example. It is a figure for demonstrating the variation | change_quantity preparation of the data immediately before the sensitivity distribution of X and Y direction and data just before this measurement based on a 1st Example. It is a figure for demonstrating the movement / deformation | transformation process based on 1st Example. It is a process flowchart of the apparatus which concerns on a 1st Example, and is a figure which shows the case where a body coil is used for a position measurement. It is a process flowchart of the apparatus which concerns on a 1st Example, and is a figure which shows the case where a multiple array coil is used for a position measurement. It is a process flowchart of the apparatus which concerns on a 2nd Example, and is a figure which shows the case where position measurement is performed just before this measurement. It is a process flowchart of the apparatus which concerns on a 2nd Example, and is a figure which shows the case where position measurement is performed at the time of this measurement. It is a figure explaining the one-dimensional data acquisition for every RF receiving coil in a multiple coil in connection with the process of the apparatus which concerns on a 3rd Example. It is a figure explaining a movement / deformation | transformation process and sensitivity distribution measurement synthetic image preparation in connection with the process of the apparatus which concerns on a 3rd Example. It is a figure which shows the process flowchart of the apparatus which concerns on a 3rd Example. It is a figure which shows the process flowchart of the apparatus which concerns on a 4th Example.

  Hereinafter, preferred embodiments of the MRI apparatus of the present invention will be described in detail with reference to the accompanying drawings. Note that, in the drawings for explaining the embodiments, parts having the same function are given the same reference numerals, and repeated explanation thereof is omitted. In this specification, a subject whose image is picked up by an MRI apparatus is called a subject or a subject. In addition, “processing” executed by the CPU of the control unit as a program may be referred to as “function”, “program”, “unit”, or “means”. For example, the “sensitivity correction process” is “sensitivity correction function”, “sensitivity correction program”, “sensitivity correction unit”, or “sensitivity correction unit”. Furthermore, the position and size or shape of the image of the subject obtained by subject position measurement will be collectively referred to as “position information”.

  First, an overall outline of an example of an MRI apparatus common to the embodiments will be described with reference to the drawings. FIG. 1 is a block diagram illustrating an example of the overall configuration of the MRI apparatus according to each embodiment. This MRI apparatus uses a NMR phenomenon to obtain a tomographic image of a subject. As shown in FIG. 1, a static magnetic field generation system 2, a gradient magnetic field generation system 3, a transmission system 5, and a reception system 6 are used. And a signal processing system 7, a sequencer 4, and a central processing unit (hereinafter referred to as CPU) 8 as a processing unit.

  The static magnetic field generation system 2 generates a uniform static magnetic field in the direction perpendicular to the body axis in the space around the subject 1 if the vertical magnetic field method is used, and in the direction of the body axis if the horizontal magnetic field method is used. Thus, a permanent magnet type, normal conducting type or superconducting type static magnetic field generating source is arranged around the subject 1.

  The gradient magnetic field generating system 3 includes a gradient magnetic field coil 9 wound in the three-axis directions of X, Y, and Z, which is a coordinate system (stationary coordinate system) of the MRI apparatus, and a gradient magnetic field power source 10 for driving each gradient magnetic field coil. The gradient magnetic fields Gx, Gy, Gz are applied in the three axial directions of X, Y, Z by driving the gradient magnetic field power supply 10 of each coil in accordance with a command from the sequencer 4 described later. At the time of imaging, a slice direction gradient magnetic field pulse (Gs) is applied in a direction orthogonal to the slice plane (imaging cross section) to set a slice plane for the subject 1, and the remaining two orthogonal to the slice plane and orthogonal to each other A phase encoding direction gradient magnetic field pulse (Gp) and a frequency encoding direction gradient magnetic field pulse (Gf) are applied in one direction, and information on the position in each direction is encoded in the echo signal.

  The sequencer 4 is a means for controlling to repeatedly apply a high-frequency magnetic field pulse (hereinafter referred to as “RF pulse”) and a gradient magnetic field pulse in a predetermined pulse sequence. The sequencer 4 operates under the control of the CPU 8 and is a tomographic image of the subject 1. Various commands necessary for data collection are sent to the transmission system 5, the gradient magnetic field generation system 3, and the reception system 6. The sequencer 4 and the CPU 8 can be collectively referred to as a control unit.

  The transmission system 5 irradiates the subject 1 with RF pulses in order to cause nuclear magnetic resonance to occur in the nuclear spins of the atoms constituting the living tissue of the subject 1, and includes a high-frequency oscillator 11, a modulator 12, and a high-frequency amplifier. 13 and a high frequency coil (transmission coil) 14a on the transmission side. The high-frequency pulse output from the high-frequency oscillator 11 is amplitude-modulated by the modulator 12 at a timing according to a command from the sequencer 4, and the amplitude-modulated high-frequency pulse is amplified by the high-frequency amplifier 13 and then placed close to the subject 1. By supplying to the high frequency coil 14a, the subject 1 is irradiated with the RF pulse.

The reception system 6 detects an echo signal (NMR signal) emitted by nuclear magnetic resonance of nuclear spins constituting the biological tissue of the subject 1 as a reception signal. The reception system 6 receives a high-frequency coil (reception coil) 14b on the reception side and It comprises a signal amplifier 15, a quadrature detector 16, and an A / D converter 17. After the NMR signal of the response of the subject 1 induced by the electromagnetic wave irradiated from the high frequency coil 14a on the transmission side is detected by the high frequency coil 14b arranged close to the subject 1 and amplified by the signal amplifier 15, The quadrature phase detector 16 divides the signal into two orthogonal signals at a timing according to a command from the sequencer 4, and each signal is converted into a digital quantity by the A / D converter 17 and sent to the signal processing system 7.
The signal processing system 7 performs various data processing and display and storage of processing results. The signal processing system 7 includes an external storage device such as an optical disk 19 and a magnetic disk 18 and a display 20 including a CRT. Is input to the CPU 8, the CPU 8 constituting the control unit executes processing such as signal processing and image reconstruction, and displays the tomographic image of the subject 1 as a result on the display 20 as well as external storage. Recording is performed on the magnetic disk 18 of the apparatus.

  The operation unit 25 is used to input various control information of the MRI apparatus and control information of processing performed by the signal processing system 7 and includes a trackball or mouse 23 and a keyboard 24. The operation unit 25 is arranged close to the display 20 and is used by an operator to interactively control various processes of the MRI apparatus through the operation unit 25 while looking at the display 20.

  In the MRI apparatus of FIG. 1, the high-frequency coil 14a and the gradient magnetic field coil 9 on the transmission side are within the static magnetic field space of the static magnetic field generation system 2 into which the subject 1 is inserted. If it is a horizontal magnetic field system, it is installed so as to surround the subject 1. The high-frequency coil 14b on the receiving side is installed so as to face or surround the subject 1.

  Currently, the radionuclide to be imaged by the MRI apparatus is a hydrogen nucleus (proton) that is a main constituent material of the subject as being widely used clinically. By imaging information on the spatial distribution of proton density and the spatial distribution of relaxation time in the excited state, the shape or function of the human head, abdomen, limbs, etc. can be imaged two-dimensionally or three-dimensionally. .

  Next, the operation of the MRI apparatus according to the first embodiment will be described based on FIGS. 2A to 2E and FIGS. 3A and 3B.

  First, as shown in FIG. 2A, first data 202, 203, and 204 on the X, Y, and Z coordinate axes in each k space is extracted from the data acquired from the subject 201 by sensitivity distribution measurement. Next, using the pulse sequence used for sensitivity distribution measurement, the second data on each k-space coordinate axis is extracted for subject position measurement using only frequency encoding in the X, Y, and Z axis directions. .

  Next, as shown in FIG. 2B, the first data 202, 203, and 204 are subjected to a one-dimensional Fourier transform to obtain one-dimensional projection images 205, 206, and 207 on the X, Y, and Z axes. A one-dimensional projection image of data 2 is obtained, and position information indicating the position and size or shape of each of the first data and the second data is measured.

  As shown in FIG. 2C, the position movement 208 and the shape deformation 209 occur between the sensitivity distribution measurement and the main measurement for image acquisition due to the body movement and respiratory movement of the subject. For each of the axis, the Y axis, and the Z axis, as shown in FIG. 2D, deformation amounts and movement amounts 210, 211, and 212 are calculated from the positions and sizes of the images of the first data and the second data, respectively. Using the calculated data 210, 211, and 212, as shown in FIG. 2E, the sensitivity distribution data is moved and deformed 213 and 214 in each of the X, Y, and Z axes, and the composite image, size, and position are determined. Match. The movement / deformation process in the Z-axis direction is not shown. Thereafter, a sensitivity distribution image is created, and sensitivity correction processing is performed based on the created sensitivity distribution data.

  The operation of the MRI apparatus of the present embodiment described above will be described with reference to the processing flowchart of FIG. 3A. Unless otherwise specified, it is needless to say that each step of the following flowchart is executed as a process based on a program or the like in the sequencer 4 and the CPU 8 which are control units of the apparatus shown in FIG.

  First, as described with reference to FIGS. 2A and 2B, in step 301, sensitivity distribution measurement is performed, a sensitivity distribution measurement image is acquired, and data on the frequency space axis, which is a part of the measured data, is k. Data on the spatial axis is extracted and one-dimensional Fourier transform is performed on each axis. Threshold processing is performed on each data, and position information that is the position and size or shape of each axis of the subject is measured (S301). The detection of the position of the subject in this case corresponds to being performed during the sensitivity distribution measurement. At this time, the coil to be used may be a whole body coil or a multiple coil. The operation in the case of supporting multiple coils composed of a plurality of RF receiving coils will be described later with reference to FIG. 3B.

  In step 302, using the same pulse sequence as in step 301, using only frequency encoding in the X, Y, and Z axis directions, obtaining one-dimensional data for each axis, and similarly performing Fourier transform and processing, Position information that is the position and shape of the subject on each axis is measured (S302). In this case, the position measurement of the subject corresponds to being performed immediately before the main measurement.

  Subsequently, during the main measurement in step 305, the position / shape calculation process in step 303 and the sensitivity distribution measurement data movement / deformation process in step 304 are performed.

  In step 303, as shown in FIG. 2D, the movement amount and deformation amount of each axis are calculated by the difference processing of the position information indicating the subject position and shape obtained from step 301 and step 302 (S303). In step 304, as shown in FIG. 2E, the sensitivity distribution measurement image is moved / enlarged based on the calculated movement amount and deformation amount of each axis (S304).

  In step 305, the main measurement of the subject is performed in the same manner as in normal imaging, and an image of the subject is acquired (S305).

  In step 306, using the sensitivity distribution image moved and deformed in step 304, the sensitivity correction processing of the subject image acquired in the main measurement is performed (S306). Note that the movement / enlargement process is a relative process between the sensitivity distribution measurement image and the main measurement image of the subject, so if the main measurement can be performed at high speed, the movement / deformation of the main measurement subject image is performed. It is also possible to perform processing and then perform sensitivity correction processing.

  Finally, in step 307, the subject image that has undergone sensitivity correction processing is displayed on the display 20 of the signal processing system 7 in FIG. 1 (S307).

  In this embodiment, when multiple coils are used when acquiring the sensitivity distribution measurement data in step 301 and the position information data of the subject position measurement (2) in step 302, as shown in FIG. The composite image processing (1) (S308) of 308 and the composite image processing (2) (S309) of step 309 are inserted. In the composite image processing (1) and (2), composite processing represented by the SOS (Sum Of Square) method is performed to create one-dimensional data. Then, movement / deformation processing is performed using the combined data obtained by the combined image processing (1) and (2) (S304).

  According to the present embodiment, at the time of sensitivity distribution data acquisition and main measurement image acquisition, position information is acquired during sensitivity distribution data acquisition and immediately before main measurement image data acquisition, and by the difference processing of both position information Since the sensitivity distribution data or the main measurement image data is corrected after calculating the movement amount and deformation amount of each axis, the sensitivity non-uniformity is more accurate even if the subject moves for some reason. Can be corrected.

  Next, a second embodiment will be described with reference to FIGS. 4A and 4B. The difference from the first embodiment is that the subject position measurement (1) is performed in the X, Y, and Z axis directions using a pulse sequence that uses only frequency encoding immediately before the sensitivity distribution measurement (S301) (S310). )It is in. That is, position measurement at the time of sensitivity distribution measurement is performed immediately before sensitivity distribution measurement. Also, using a pulse sequence that uses only frequency encoding, subject position measurement (2) (S302) is performed in the X, Y, and Z axis directions in the same manner immediately before the main measurement, or the main measurement (S305). Data on the k-space axis is extracted from the data on the frequency space axis that is a part of the data. The former performs position measurement to obtain the position information of the subject at the time of the main measurement immediately before the main measurement, and the latter performs position measurement of the subject at the time of the main measurement during the main measurement. Corresponds to that.

  The operation of the second embodiment will be described with reference to FIG. 4A. In addition, the latter method which uses a part of this measurement data for the detection of position information is demonstrated to FIG. 4B. Hereinafter, only different parts from the first embodiment will be described, and description of the same parts will be omitted.

  First, in step 310, the subject is measured one-dimensionally in the X, Y, and Z-axis directions, threshold processing is performed on the measured data, and the position information that is the position and shape for each axis of the subject is measured. The specimen position measurement (1) is performed immediately before the sensitivity distribution measurement (S310). At this time, the coil to be used may be a whole body coil or a multiple coil including a plurality of RF receiving coils.

  In step 302, for the detection of the position information of the object immediately before the main measurement, the same measurement and processing as in step 310 are performed, and the position information that is the position and shape or size of the object position of each axis is measured. Position measurement (2) is performed (S302). Others are the same as in the first embodiment.

  Next, in the second embodiment, the subject position measurement (2) is omitted, and the method of using the actual measurement data for detecting the position of the subject, that is, the case where the subject position measurement is performed during the actual measurement is shown in FIG. 4B. Will be described. Hereinafter, only different parts will be described, and description of the same parts will be omitted.

  After performing the main measurement (S305) in step 305, the processing in step 303 and step 304 is performed.

  That is, the main measurement is performed in step 305, and the main measurement image is acquired (S305). Then, data on the k-space axis is extracted from the measured data on the frequency space axis, and one-dimensional Fourier transform is performed on each axis. Threshold processing is performed on each data, position information that is the position and size of each axis of the subject is measured, and by difference processing with the position information data obtained in the subject position measurement (1), The movement amount and deformation amount of each axis are calculated (S303). The other steps 304, 306, 307 and the like are the same as those in the previous embodiments, and a description thereof will be omitted.

  According to the present embodiment, since the subject position is measured immediately before and during or before the sensitivity distribution measurement (S301), accurate measurement data movement / deformation processing can be performed. Accurate sensitivity correction and image display can be performed.

  Next, a third embodiment will be described with reference to FIGS. 5A, 5B, and 6. FIG. The difference from the previous embodiment is that the sensitivity cloth measurement data is processed for each of the data 505, 506, 507, 508 received from the plurality of RF receiving coils 501, 502, 503, 504 constituting the multiple coil. Is to do. Hereinafter, only portions different from the above-described embodiment will be described, and description of the same portions will be omitted.

  In the present embodiment, as shown in FIG. 5A, in one-dimensional measurement for measuring position information that is position and size, data from a plurality of RF receiving coils 501, 502, 503, and 504 constituting a multiple coil are used. Rather than combining them when performing one-dimensional measurement, position information that is the position and size in the three-axis directions is calculated for each of the RF receiving coils 501, 502, 503, and 504. That is, as shown in FIG. 5B, the displacement indicating the movement / deformation for each of the plurality of RF receiving coils based on the two position measurement data acquired for each RF receiving coil before the sensitivity distribution measurement and before the main measurement. The amount is calculated, and based on this displacement amount, the measured data of each RF receiving coil is used for displacement, and then a composite image 509 is created. After that, it is the same as the normal sensitivity correction process.

  The operation of the third embodiment will be described with reference to the flowchart of FIG. Hereinafter, only different points from the above-described embodiment will be described, and description of the same points will be omitted.

  In step 301, a plurality of sensitivity distribution measurements are performed for each of the plurality of RF receiving coils 501, 502, 503, and 504 forming a multiple coil. One-dimensional measurement data is extracted for each RF receiving coil from the sensitivity distribution measurement data. Threshold processing is performed on the measured data, and position information that is the position and size of each axis of the subject is measured (S301). At this time, the coil used is a multiple coil. Then, the position information indicating the position, size, or shape is measured for each RF receiving coil as described above without combining the data from each of the multiple coils.

  In step 302, the same measurement and processing as in step 301 are performed, and the position information that is the position and size of the object on each axis is measured as the position detection of the object during the main measurement (S302). Here, the position information indicating the position and the size or shape of each coil element is measured without combining the data of the plurality of RF receiving coils constituting the multiple coil.

  While performing the main measurement in step 305, the processing in step 303, step 304, and step 311 is performed.

  In this embodiment, in step 303, the displacement amount or the movement amount of each axis is determined from the difference between the position information indicating the subject position and the size or shape obtained from step 301 and step 302 for each coil element. It is calculated every time (S303). In step 304, displacement processing and movement processing of the sensitivity distribution measurement image are performed for each coil element based on the calculated displacement amount or movement amount (S304).

  In step 311, sensitivity distribution measurement image data of each of the plurality of coil elements constituting the multiple coil is synthesized (S311). Others are the same as in the previous embodiments.

  According to the present embodiment, it is possible to accurately compensate the correction even in the case where each element of the multiple coil moves independently, and more accurate measurement for local movement and movement. Data movement / deformation processing can be performed, and more accurate sensitivity correction and image display can be performed.

  Next, a fourth embodiment will be described with reference to FIG. The difference from the previous embodiment is not a sensitivity distribution measurement image, but a point that a sensitivity map is created for each RF receiving coil, moved and deformed, and then sensitivity map synthesis processing is performed.

  The operation of the fourth embodiment will be described with reference to FIG. Hereinafter, only different parts will be described, and description of the same parts will be omitted.

  After the sensitivity distribution measurement for each coil element in step 301, a sensitivity map creation process for creating a sensitivity map for each coil element is performed in step 312 (S312).

  Then, while performing the main measurement in step 305, the processes in step 303, step 304, and step 313 are performed. In step 304, the movement process of the sensitivity map image calculated for each coil element is executed based on the movement amount and deformation amount of each axis acquired in step 303.

  Subsequently, in step 313, a sensitivity map image that has been moved and deformed for each coil element is synthesized, and a synthesis sensitivity map is created (S313).

  The subsequent processes in steps 305, 306, and 307 are the same as in the previous embodiment, and finally the image after the correction process is displayed on the display.

  The present invention described in detail above is an MRI apparatus that measures NMR signals and images nuclear density distribution, relaxation time distribution, and the like, and in particular, image sensitivity nonuniformity caused by sensitivity distribution data of an RF receiving coil used for reception. This is useful as an image correction technique for correcting the above.

DESCRIPTION OF SYMBOLS 1 ... Subject, 2 ... Static magnetic field generation system, 3 ... Gradient magnetic field generation system, 4 ... Sequencer, 5 ... Transmission system, 6 ... Reception system, 7 ... Signal processing system, 8 ... Central processing unit (CPU), 9 ... Gradient magnetic field coil, 10 Gradient magnetic field power source, 11 High frequency transmitter, 12 Modulator, 13 High frequency amplifier, 14 a High frequency coil (transmitting coil), 14 b High frequency coil (receiving coil), 15 Signal amplifier, 16 ... quadrature detector, 17 ... A / D converter, 18 ... magnetic disk, 19 ... optical disk, 20 ... display, 21 ... ROM, 22 ... RAM, 23 ... trackball or mouse, 24 ... keyboard.

Claims (10)

A reception unit having an RF coil; and a control unit that acquires an image of the subject using a reception signal acquired from the subject using the RF coil based on a predetermined sequence, the control unit including the RF coil A magnetic resonance imaging apparatus that corrects the sensitivity non-uniformity of the image using the sensitivity distribution data of
The control unit measures position information of the subject at the time of sensitivity distribution measurement and main measurement, and corrects the sensitivity nonuniformity of the image at the time of main measurement based on the difference between the two measured position information. A magnetic resonance imaging apparatus. The magnetic resonance imaging apparatus according to claim 1,
The magnetic resonance imaging apparatus, wherein the control unit acquires the position information immediately before the sensitivity distribution measurement and the main measurement. The magnetic resonance imaging apparatus according to claim 1,
The said control part calculates the said positional information at the time of the said sensitivity distribution measurement using a part of measurement data at the time of the said sensitivity distribution measurement, The magnetic resonance imaging apparatus characterized by the above-mentioned. The magnetic resonance imaging apparatus according to claim 1,
The said control part calculates the said positional information at the time of the said main measurement using a part of measurement data at the time of the said main measurement, The magnetic resonance imaging apparatus characterized by the above-mentioned. The magnetic resonance imaging apparatus according to claim 1,
The RF coil is composed of a plurality of coil elements,
The control unit corrects nonuniform sensitivity of the image based on the difference in the position information, with respect to the image at the time of main measurement obtained by synthesizing reception signals received by the plurality of coil elements.
A magnetic resonance imaging apparatus. The magnetic resonance imaging apparatus according to claim 1,
The RF coil is composed of a plurality of coil elements,
The control unit combines the reception signals received by the plurality of coil elements to obtain the sensitivity distribution data, and moves and transforms the combined sensitivity distribution data according to the difference in the position information. Magnetic resonance imaging device. The magnetic resonance imaging apparatus according to claim 1,
The RF coil is composed of a plurality of coil elements,
The control unit calculates a movement / deformation amount for each of the plurality of coil elements, performs the composition after correcting the sensitivity distribution data according to the calculated movement / deformation amount,
A magnetic resonance imaging apparatus. The magnetic resonance imaging apparatus according to claim 1,
The RF coil is composed of a plurality of coil elements,
The controller performs correction based on the deformation / movement amount for the sensitivity distribution data acquired by each of the plurality of coil elements, before combining the reception signals of the plurality of coil elements.
A magnetic resonance imaging apparatus. According to a predetermined sequence, an image of the subject is acquired from a reception signal acquired from the subject using an RF receiving coil, and sensitivity nonuniformity of the acquired image is corrected using sensitivity distribution data of the RF receiving coil. An image correction method for a magnetic resonance imaging apparatus including a control unit, comprising:
The position information of the subject at the time of sensitivity distribution measurement and the actual measurement is measured, and the sensitivity nonuniformity correction of the image at the actual measurement is performed in consideration of the difference between the measured position information. An image correction method for a magnetic resonance imaging apparatus. An image correction method for a magnetic resonance imaging apparatus according to claim 9,
An image correction of a magnetic resonance imaging apparatus, wherein the sensitivity distribution data is displaced according to the difference of the position information, and the sensitivity nonuniformity of the image at the time of actual measurement is corrected based on the sensitivity distribution data after the displacement. Method.

Images