JP2002315731A - Magnetic resonance imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image with no luminous point artifact in a high speed photographing method (a parallel imaging method) in which in a region where high speed photographing on the heart, etc., is required, a signal obtained by using especially, a plurality of receiving coils and by thinning phase encodes in each receiving coil is developed by using sensitivity distribution of the receiving coil by means of matrix operation in relation to an MRI apparatus. SOLUTION: A mask for dividing a back ground (a low signal) region and a subject region of the image by using a sensitivity image on the whole test region is prepared and based on this mask, an operation for turning removal is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention measures a nuclear magnetic resonance (hereinafter, referred to as "NMR") signal from hydrogen, phosphorus, or the like in a subject, and visualizes a nuclear density distribution, a relaxation time distribution, and the like. Regarding a nuclear magnetic resonance imaging (MRI) device, in a region where high-speed imaging such as a heart is required, a signal obtained by thinning out phase encoding in each RF receiving coil, particularly using a plurality of RF receiving coils, is used for the RF receiving coil. The present invention relates to an MRI apparatus capable of obtaining an image free from artifacts in an imaging method (hereinafter, parallel imaging method) developed by matrix operation using a sensitivity distribution.

[0002]

2. Description of the Related Art In MRI, a sequence is repeatedly executed while changing an amount of phase encoding, and an echo signal necessary for reconstructing one image is acquired. Therefore, the number of repetitions greatly affects the image acquisition time. When performing high-speed imaging, generally, a multi-echo type sequence that generates a plurality of echo signals within one repetition or a sequence in which the repetition time interval is reduced to several to several tens of ms is used. . However, in a multi-echo type sequence, the contrast of an image may be reduced or image distortion may be caused. This causes a decrease in contrast because the echo time contributing to the contrast of the image is different for each echo signal in the multi-echo type sequence. In addition, since the echo times are different, if the phase change between the echo signals is different, image distortion appears in the image.

[0003] Further, when imaging a heart region (such as coronary artery imaging), it is necessary to acquire an image at a higher speed, and a high-speed imaging method called a parallel imaging method has been proposed. In the parallel imaging method, a sequence in which phase encoding is thinned out at equal intervals is executed using multiple RF receiving coils, and the number of repetitions is reduced to shorten the imaging time. Normally, when measurement is performed with the phase encoding thinned out at equal intervals, aliasing occurs in the image, but the image is developed by performing a matrix operation based on the sensitivity distribution of each RF receiving coil, and aliasing is removed. . In general, in the parallel imaging method, the imaging time can be reduced by several minutes of the RF receiving coil used for the imaging.

[0004]

In the parallel imaging method, the photographing time can be shortened without using a multi-echo type sequence, so that the effects of contrast reduction and image distortion can be reduced. However, the resulting image greatly changes depending on the arrangement of the multiple RF receiving coils and the shape of the sensitivity distribution. In particular, if a matrix operation is performed while including a low signal area such as a background, an error becomes large at the time of folding development due to the influence of noise, and an artifact of a luminescent spot may occur in an image. Also, each
To accurately calculate the sensitivity distribution of the RF receiver coil, it is desirable to calculate the sensitivity distribution using images measured with a body coil for the whole body with a relatively uniform sensitivity distribution. However, there is a problem that images cannot be obtained at the same time because there are no channels or the number of reception channels is small.

Accordingly, an object of the present invention is to suppress a calculation error at the time of matrix calculation, eliminate the occurrence of bright spot artifacts, and enable parallel imaging even in a device without a body coil for the whole body or a device with a small number of channels. It is in. Alternatively, even in an apparatus having a body coil for the whole body, the object is to simplify the apparatus configuration and the signal processing flow.

[0006]

In order to achieve the above object, the present invention comprises at least two RF receiving coils, and comprises the steps of: encoding a nuclear magnetic resonance signal received by the RF receiving coils; An image is obtained for each RF receiving coil by measuring so as to thin out, and the calculation of the aliasing removal of each image is performed using the reception sensitivity distribution of the RF receiving coil, and the images are combined to obtain one image. In the magnetic resonance imaging apparatus having a control unit, the control unit creates a mask in which a non-image area and an image area are separated in the reception sensitivity distribution, and performs an operation using the mask. In the receiving sensitivity distribution of the entire area including the RF receiving coil, a mask is created in which a non-image area and an image area are separated, and the receiving sensitivity distribution and the mask for each RF receiving coil The calculation may be performed using the above.
Further, the non-image area in the reception sensitivity distribution may be a low signal area, or the reception sensitivity distribution of the entire area including the RF reception coil may be obtained by calculation from signals of the plurality of RF reception coils. The apparatus may further include a second RF reception coil having a reception area including reception areas of the plurality of RF reception coils, and the control unit may obtain a reception sensitivity distribution of the entire area by the second RF reception coil.

[0007] Further, at least two RF receiving coils are provided, and the measurement of the nuclear magnetic resonance signal received by the RF receiving coils is performed so as to thin out the encoding step in the measurement space. A magnetic resonance imaging apparatus having a control unit for acquiring an image, performing an operation of removing aliasing of each morphological image from a sensitivity distribution based on a sensitivity image of the RF receiving coil, and combining the morphological images to obtain one morphological image; In the apparatus, the control means includes:
Create an overall sensitivity image by combining the sensitivity images obtained by the RF receiving coil, calculate the sensitivity distribution of each RF receiving coil using the overall sensitivity image, and use the overall sensitivity image as a non-image area and image of the image. A mask for dividing a region is created, and an operation is performed based on the mask.

Further, a first RF for receiving the entire measurement area
Receiving coil, comprising a plurality of second RF receiving coil to receive an area divided into at least two or more of the measurement area,
The measurement of the nuclear magnetic resonance signal received by each of the second RF receiving coils is measured so as to thin out the encoding step of the measurement space to obtain a sensitivity image and a morphological image for each of the second RF receiving coils, and the first A fold-removal operation of the morphological image is calculated from the sensitivity distribution obtained from the sensitivity image obtained by the RF receiving coil and the sensitivity image obtained by the second RF receiving coil, and the morphological images are combined to obtain one morphological image. In the magnetic resonance imaging apparatus having a control unit, the control unit creates a mask in which a non-image area and an image area are divided in the reception sensitivity distribution, and performs an operation using the mask.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a nuclear magnetic resonance imaging apparatus according to the present invention will be described in detail with reference to the drawings. FIG. 4 shows the configuration of a typical nuclear magnetic resonance imaging apparatus. A magnet 402 that generates a static magnetic field around the subject 401, a gradient coil 403 that generates a gradient magnetic field in the space, an RF coil 404 that generates a high-frequency magnetic field in this region, and an MR signal generated by the subject 401. There is an RF probe 405 to detect. The gradient magnetic field coil 403 is composed of gradient magnetic field coils in three directions of X, Y, and Z, and generates a gradient magnetic field in accordance with a signal from the gradient magnetic field power supply 409. The RF coil 404 generates a high-frequency magnetic field according to a signal from the RF transmission unit 410. The signal of the RF probe 405 is
The signal is detected by the signal detection unit 406, processed by the signal processing unit 407, and converted into an image signal by calculation. The image is displayed on the display unit 408. Gradient magnetic field power supply 409, RF transmitter 410,
The signal detection unit 406 is controlled by the control unit 411, and the control time chart is generally called a pulse sequence. The bed 412 is for the subject to lie down.

At present, the subject of MRI imaging is proton, which is a main constituent of the subject, which is widely used clinically. By imaging the spatial distribution of the proton density and the spatial distribution of the relaxation phenomenon of the excited state, the form or function of the human head, abdomen, limbs, etc. is two-dimensionally or three-dimensionally photographed.

As an example of the RF coil 405, a technique called "multiple RF coil" or "phased array coil" using a plurality of receiving coils is used. Multiple RF coils are a series of small RF receiver coils with relatively high sensitivity, and the signals acquired by each coil are combined to expand the field of view while maintaining the high sensitivity of the RF receiver coil. This is a receiving-only RF coil that is being developed. Array Head as multiple RF coil for horizontal magnetic field head
Coil for Improved Functional MRI (Christoph Leussl
er), 1996 ISMRM abstruct p.249. In addition, Helmet and C
ylindrical Shaped CP Array Coils for Brain Imaging:
A Comparison of Signal-to-Noise Characteristics
(HAStark, EMHaacke), 1996 ISMRM abstract p.141
There are two. Four Channel Wrap-Around Coil with Inductive D
ecoupler for 1.5T Body Imaging (T.Takahashi et.al),
There is a 1995 ISMRM abstruct p.1418.

FIG. 3 shows a part of the signal detecting section of the multiple RF coil. In FIG. 3, four RF receiving coils 405 are respectively connected to a preamplifier 302 to form one multiple coil 301. The signal detection unit 406 includes four A / D conversion / quadrature detection circuits 303 connected in parallel, and the outputs of the respective preamplifiers are connected. The signal processing unit 407 obtains MRI images detected by the respective RF receiving coils 405 by Fourier transform, back projection method, wavelet transform, etc., for each signal, and performs an operation 304 for combining these image signals.
Consists of

Next, a photographing method will be described. FIG. 6 shows a general gradient echo sequence. 601 is a high frequency pulse, 602 is a slice selection gradient magnetic field pulse, 603 is a phase encoding gradient magnetic field pulse, 604 is a read gradient magnetic field pulse, 605 is a sampling window, 606 is an echo signal, and 607 is a repetition time (irradiation interval of the high frequency pulse 601).
It is. In MRI, the amount of the phase encoding gradient magnetic field pulse 603 is changed for each repetition time 607, different phase encodings are applied, and an echo signal 606 obtained by each phase encoding is detected. This operation is repeated by the number of phase encodings, and an echo signal necessary for reconstructing one image is acquired at an image acquisition time 608. The number of phase encodes is usually 1
Values such as 64, 128, 256, 512 are selected per image.
Each echo signal is usually obtained as a time-series signal composed of 128, 256, 512, and 1024 pieces of sampling data. These data are subjected to two-dimensional Fourier transform to create one MR image.

In the case of the parallel imaging method, which is high-speed imaging using a multiple RF receiving coil, the number of repetitions of imaging is reduced by thinning out the phase encoding step interval at a fixed rate. This thinning rate is generally called a double speed number. For example, when thinning out the phase encoding step by a factor of two, the double speed number is two. Hereinafter, the principle of the parallel imaging method will be described with reference to FIG. In the case of normal shooting, as shown in FIG. 2 (a), the signals 202n acquired with the respective phase encoding amounts are arranged to form data 201 for one image, and this is subjected to Fourier transform to obtain the data shown in FIG. 2 (c). To get such an image. Next, in the parallel imaging method, for example, when the phase encoding step interval is doubled and the data is thinned, FIG.
As shown in (b), data 204m is measured every other line,
Data corresponding to the 205m position is not measured. At this time,
Since the amount of measured data 204m is halved compared to normal shooting, the image is created by halving the matrix, but Fig. 2 (d)
Thus, an image in which aliasing has occurred is obtained. In FIG. 2, the y direction is defined as the phase encoding direction, and this aliasing occurs when an image in the phase encoding direction is aliased. That is, the subject image 2061 in the upper region 2071 and the lower region 2 of the subject 206 in the image 207 as shown in FIG.
The subject images 2062 in the 072 overlap and become an image 208 having a fold as shown in FIG. The signal aliasing generated in this way is removed by a signal processing method called SENSE (SENSE: Sensitivity Encoding for FastMRI (Klaas
P. Pruessmann et.al), Magnetic Resonance in Medici
ne 42: 952-962 (1999)).

Hereinafter, aliasing removal will be described. x,
Assuming that the image matrix in the y direction is X and Y, respectively, the pixel value at coordinates (x, y) (x: 1 ≦ x ≦ X, y: 1 ≦ y ≦ Y) in the image is s _i (x, y (Where i is the coil number and 2 ≦ i
≤ N). In the case of FIG. 2D, since the phase encoding step is thinned out twice, the matrix in the phase encoding direction of the thinned image is Y′≡Y / 2. Fig. 2 (d)
When the coordinates of the image are (x, y ') (1 ≦ y ′ ≦ Y ′), the pixel value s ′ (x, y ′) 208 is obtained by overlapping the two regions 2071 and 2072 of the original image 207. ,

[0016]

(Equation 1) Becomes Here, a represents a constant. Next, the sensitivity distribution and the image of the RF receiving coil will be described. Assuming that the two-dimensional sensitivity distribution of the i-th RF receiving coil is c _i (x, y), the received signal s _i (x, y) is the receiving coil sensitivity distribution c _i (x, y). Product of the proton density distribution p (x, y) of the subject,

[0017]

(Equation 2) It is represented by Using equation (2), equation (1) becomes

[0018]

(Equation 3) I can write Here, for simplicity,

[0019]

(Equation 4) In other words, equation (3) is

[0020]

(Equation 5) Becomes This can be represented as an N-by-2 matrix,

[0021]

(Equation 6) Becomes From this, if the sensitivity distribution C _{ij of the} coil is known,
By calculating the inverse matrix, the proton density distribution P _j of the subject is obtained.
I understand.

Similarly, when photographing is performed at M times speed using N coils, Y'≡Y / M, 1 ≦ y ′ ≦ Y ′,

[0023]

(Equation 7) Becomes Here, b represents a constant. Since the aliasing is removed by the inverse matrix operation, the relationship between the number of coils and the double speed in the parallel imaging method is mathematically N ≧ M.

Usually, in the parallel imaging method, each RF
The sensitivity distribution C _ij of the receiving coil is obtained by, for example, pre-measurement or the like measured in advance. However, it is difficult to directly calculate the sensitivity distribution C _ij , and in general, an image obtained by each RF receiving coil is divided by using an image of a body coil for a whole body having a relatively uniform sensitivity distribution, and an approximate Matrix operation is performed by finding the sensitivity distribution of the coil.

FIG. 7 shows a process of a general parallel imaging method. The figure shows a configuration of one body coil for the whole body and three multiple RF receiving coils. First, sensitivity distribution calculation processing 7041 to 7043 is performed using the sensitivity image 701 acquired by the body coil for the whole body and the sensitivity images 7021 to 7023 acquired by each RF reception coil, and the sensitivity distribution 7051 of each RF reception coil is performed.
Get ~ 7053. As the sensitivity distribution calculation processing 704, the image of the body coil for the whole body as s _c (x, y), for example,

[0026]

(Equation 8) There is. Sensitivity distributions 7051 to 7053 calculated in this way
Then, a matrix is created by the matrix creation processing 706 using the main measurement images 7031 to 7033 having the aliases acquired by the respective RF receiving coils, and an image 708 from which aliasing has been removed by the inverse matrix calculation processing 707 is obtained. Next, a first embodiment of the present invention will be described.
This will be described with reference to FIG. In the conventional general parallel imaging method, a low signal area such as a background is not considered at all, but the present embodiment has a configuration in which a low signal area is considered. In other words, using the image of the body coil for the whole body, a mask 102 is created in Step 101 of mask creation, and Step 1 of performing mask processing is performed.
03 Create a post-processing mask 104 with improved accuracy,
It is configured to perform a matrix creation process 105 using a mask.
Here, the mask processing will be described. FIG. 5 shows the case of 3 × speed, and the image 501 has three regions 5041 of the normal image (FIG. 5 (b)),
This is the result of 5042 and 5043 overlapping (where Y'≡Y / 3, 1
≦ y ′ ≦ Y ′). In FIG. 5 (a), two points of interest A (x _A ,
y ′ _A ) 502 and B (x _B , y ′ _B ) 503 are provided. At this time, since the pixel values of points A and B are overlapped with the regions 5021 to 5023 and 5031 to 5033 in the figure,

[0027]

(Equation 9) Becomes Here, d represents a constant. However, 5021 is a signal of the background portion without the subject, and when performing a matrix operation using this, the matrix diverges at the time of the inverse matrix operation, and there was a case where an artifact of a bright spot occurred in the resulting image. . Therefore,
In order to eliminate such an influence of the background, a mask m (x, y) 102 as shown in FIG. 5C is used. Mask creation processing 10 in FIG. 1
As 1, for example, a threshold is provided for the sensitivity image 701 of the body coil for the whole body, and a pixel whose pixel value is equal to or less than the threshold as shown in FIG. This is referred to as a subject area 505. As a threshold setting method, for example, a threshold is set to about 1/10 of the maximum pixel value in the image, or a pixel value histogram 507 in the image as shown in FIG. The threshold 508 can be set accordingly. Next, a mask 102 in which, for example, the value of the subject region 505 is set to 1 and the value of the background region 506 is set to 0 by mask creation 101 is obtained. Then, for the obtained mask 102,
Mask processing 10 to further improve mask accuracy
Do 3 Then, a matrix creation process 105 is performed using the mask 104 after the process obtained by the mask process 103. As a result, the matrix operation can be performed excluding the background area, and thus the occurrence of bright spot artifacts can be eliminated.

Here, as the mask processing 103, for example, when a structure exists inside the object, the mask area is filled by interpolation to use the signal of that area as it is,
For example, a process for removing an isolated point erroneously taken in an area that cannot be originally calculated is performed. Also, in the matrix creation processing 105 using a mask, so that the background element is not included in the elements of the matrix,
A discriminating process for setting each element to 0 is performed. For example,

[0029]

(Equation 10) It is represented by When the background area is set to 0 and the image becomes unnatural, the processing may be performed with the elements of the matrix set to predetermined constants. For example

[0030]

[Equation 11] It is represented by Here, Const. Indicates an arbitrary constant. Further, each element as shown in the equation (10) is set to 0 in the matrix creation processing 105.
Is used, the product of the sensitivity distribution and the mask,

[0031]

(Equation 12) Thus, the determination process can be eliminated and the process can be simplified. Making some of the matrix elements "0" as in equation (10) is equivalent to reducing the matrix size of the matrix. That is, "check the state of aliasing for each pixel, determine the necessary and sufficient matrix size, and perform the necessary and sufficient calculation"
Will be. As a result, unnecessary noise is prevented from being mixed as compared with the related art, and the image quality is improved. There is also an advantage that the calculation time is shortened.

Although the matrix creation processing 105 is performed using the mask 104 after the processing, the calculation can be performed using the mask 102. Thereby, the processing flow can be simplified. Further, the mask 102 has been described as being divided into a background region and a subject region. However, the background region is not only a background outside the subject region but also a low signal region existing in the subject region (for example,
Voids).

Next, a second embodiment of the present invention will be described with reference to FIG. In this case, there is no image of the body coil for the whole body. In this case, the image of the body coil for the whole body necessary for calculating the sensitivity distribution of each RF receiving coil is created by the signal combining process 801. As a specific process of 801, for example, an image s acquired by each RF receiving coil
_i (x, y) and s _i (x, y) with low-pass filtered image
_{When i} (x, y), the pseudo body coil image after synthesis
s' _c (x, y) is

[0034]

(Equation 13) (Where * is the complex conjugate and || is the absolute value). However, since the sensitive region of the multiple RF receiving coil is narrower than that of a normal coil, the effect of shading may be large on an image of a pseudo body coil synthesized in this manner. Therefore, the sensitivity correction processing 802 is performed on the synthesized pseudo body coil image to generate a pseudo image 803 without shading, and the processing of the parallel imaging method is performed. In addition, as the sensitivity correction processing 802,
For example, a method of calculating and correcting shading from an image (JP-A-7-222724) is used.

As described above, by synthesizing the signals of the body coil for the whole body, the parallel imaging method can be performed even in an apparatus having no or no body coil for the whole body or an apparatus having a small number of usable coil channels. Becomes possible. Further, even in a device having a body coil for the whole body, since only the signal of the multiple RF receiving coil is processed, the device configuration, software configuration, and data flow can be simplified. For example, in a hamburger-type open MRI, reception by the irradiation coil may not be performed because the sensitivity of the irradiation coil is relatively low. Further, even if it can be physically received, if a receiving component is added only for the parallel imaging method, the cost of the MRI apparatus will increase.
However, by applying this embodiment, such disadvantages can be overcome. The calculation of the sensitivity distribution can be applied to multi-slice imaging and three-dimensional imaging. In multi-slice, equation (13) is calculated for each slice. Even in three-dimensional imaging, equation (13) is calculated for each slice.

The present invention is not limited to the contents disclosed in the above embodiments, but can take various forms in consideration of the gist of the present invention. In this embodiment, an example of the parallel imaging method using three multiple RF receiving coils has been described.
The number N of the receiving coils can be an arbitrary number of 2 or more. Also, the example of the multiple speed number M = 2,3 has been described, but the multiple speed number can be selected within the range of M ≦ N. Further, in the present invention, the gradient echo sequence has been described, but the parallel imaging method does not depend on the shape of the sequence. For example, SE sequence, FSE sequence, EPI sequence,
Applicable to spiral sequences, SSFP sequences, etc. Further, when the present invention is applied to three-dimensional measurement, data can be thinned out not only in the phase encoding direction but also in the slice encoding direction to increase the speed. Alternatively, data can be thinned out by combining the phase encoding direction and the slice direction to increase the speed. Further, when cardiac imaging is performed by applying the present algorithm, an image without bright spot artifacts can be acquired with high temporal resolution.

[0037]

The present invention has been configured as described above.
The bright spot artifact can be eliminated by the parallel imaging method. In addition, a parallel imaging method can be performed even in an apparatus having no body coil for the whole body. Further, even in a device having a body coil for the whole body, the parallel imaging method can be performed only by the signal of the multiple RF receiving coil, so that the number of channels used can be reduced, and the device configuration and the processing / data flow can be simplified.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating signal processing according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating the folding of an image by the parallel imaging method.

FIG. 3 is a diagram showing a receiving unit of an RF coil to which the present invention is applied.

FIG. 4 is a diagram showing an overall configuration of an MRI apparatus to which the present invention is applied.

FIG. 5 is a view for explaining image folding in the present invention.

FIG. 6 is a view for explaining a general gradient echo sequence.

FIG. 7 is a diagram illustrating processing of a conventional parallel imaging method.

FIG. 8 is a view for explaining signal processing according to the second embodiment of the present invention.

[Explanation of symbols]

601 high frequency pulse, 602 slice selection gradient magnetic field, 603
Phase encoding gradient magnetic field pulse, 604 read gradient magnetic field pulse, 605 data sample window, 606 echo signal, 607 repetition time interval, 608 image acquisition time,
401 subject, 402 magnet, 403 gradient coil, 404
RF coil, 405 RF probe, 406 signal detector, 407
Signal processing unit, 408 display unit, 409 gradient power supply, 410 R
F transmission unit, 411 control unit, 412 bed

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G01N 24/04 520C

Claims (7)

[Claims] Claims 1. At least two RF receiving coils,
The measurement of the nuclear magnetic resonance signal received by the RF reception coil is measured so as to thin out the encoding step of the measurement space, an image is obtained for each RF reception coil, and the reception sensitivity distribution of the RF reception coil is used to obtain an image. In a magnetic resonance imaging apparatus having control means for performing aliasing removal calculation and combining the images to obtain one image, the control means includes a mask which separates a non-image area and an image area in the reception sensitivity distribution. And performing a calculation using the mask. 2. The control unit creates a mask in which a non-image area and an image area are separated in a reception sensitivity distribution of an entire area including the RF reception coil, and generates the reception sensitivity distribution and the mask for each RF reception coil. 2. The magnetic resonance imaging apparatus according to claim 1, wherein the calculation is performed using the magnetic resonance imaging apparatus. 3. The magnetic resonance imaging apparatus according to claim 1, wherein the non-image area in the reception sensitivity distribution is a low signal area. 4. The control unit according to claim 2, wherein the receiving sensitivity distribution of the entire area including the RF receiving coil is calculated from the signals of the plurality of RF receiving coils.
The magnetic resonance imaging apparatus according to claim 1. A second RF reception coil having a reception area including a reception area of the plurality of RF reception coils, wherein the control unit obtains a reception sensitivity distribution of the entire area by the second RF reception coil. 3. The magnetic resonance imaging apparatus according to claim 2, wherein: 6. At least two RF receiving coils,
The measurement of the nuclear magnetic resonance signal received by the RF receiving coil is performed such that the encoding step in the measurement space is thinned out to obtain a sensitivity image and a morphological image for each RF receiving coil, and the sensitivity based on the sensitivity image of the RF receiving coil is obtained. In a magnetic resonance imaging apparatus having a control unit for performing an operation of removing aliasing of each morphological image from the distribution and combining the morphological images to obtain one morphological image, the control unit obtains a morphological image with each RF receiving coil. A sensitivity image is created by combining the sensitivity images, a sensitivity distribution of each RF receiving coil is calculated using the sensitivity image, and a mask for separating a non-image area and an image area of the image is created using the sensitivity image. And performing an operation based on the mask. 7. A first RF receiving coil for receiving an entire measurement area, and a plurality of second RF receiving coils for receiving at least two divided areas of the measurement area, wherein each of the second RF reception coils is provided. The measurement of the nuclear magnetic resonance signal received by the reception coil is measured so as to thin out the encoding step of the measurement space, a sensitivity image and a morphological image are obtained for each of the second RF reception coils, and the sensitivity by the first RF reception coil is obtained. A magnetic resonance apparatus comprising: a control unit for performing an operation for removing aliasing of the morphological image from an image and a sensitivity distribution obtained from the sensitivity image by the second RF receiving coil, and combining the morphological images to obtain one morphological image. In the imaging apparatus, the control unit creates a mask that divides a non-image area and an image area in the reception sensitivity distribution, and performs an operation using the mask. Magnetic resonance imaging apparatus.