JP4807822B2 - Magnetic resonance imaging system - Google Patents

Description

  The present invention relates to a magnetic resonance imaging apparatus, and more particularly to an MRI apparatus and a space filler that display a water / fat separation image of a subject.

  An imaging object of a magnetic resonance imaging apparatus (MRI apparatus) that is currently widely used in the clinic is a main constituent substance of a subject, proton. By imaging the spatial distribution of proton density and the spatial distribution of the relaxation phenomenon in the excited state, the form or function of the head, abdomen, limbs, etc. can be photographed two-dimensionally or three-dimensionally.

  Next, an imaging method of the MRI apparatus will be described. In the MRI apparatus, different phase encodings are given depending on the gradient magnetic field, and echo signals obtained by the respective phase encodings are detected. As the number of phase encodings, values such as 128, 256, 512, etc. are usually selected per image. Each echo signal is usually obtained as a time-series signal composed of 128, 256, 512, and 1024 sampling data. These data are two-dimensionally Fourier transformed to create one MR image.

  Protons are present in water and fat in animal tissues, but the chemical shift differs depending on the binding form. Attempts have been made to separate and draw an image of protons in water and an image of protons in fat using this chemical shift difference.

  For example, as one method for obtaining an image in which fat is suppressed, there is a method of obtaining a plurality of images having different echo times (TE) and obtaining a water / fat separated image by calculation. As a typical method, there is a method described in Non-Patent Document 1. As other methods for obtaining a water / fat separated image by calculation, methods described in Patent Document 1 and Non-Patent Document 2 are known.

  In the method of obtaining a water / fat separated image by calculation between a plurality of images created from a plurality of signals having different TEs as described above, an unintended phase is generated in the signal due to non-uniform static magnetic field or local magnetic field disturbance. As a result, the captured image may be deteriorated in image quality.

  As a method for solving the phase shift of the water / fat separated image by calculation, methods described in Patent Documents 2, 3, 4, and Non-Patent Document 3 are known.

JP 2002-301041 A JP 2002-306441 A JP 2002-306445 A JP 2001-340314 A W. Thomas Dixon et al. Simple Proton spectroscopic Imaging. RADIOLOGY. Vol. 153. 189-194 Qing-San Xiang and Li An.Water-Fat Imaging with Three-Point Direct Phase Encoding Proc., SMR 3rd Meeting.658. (1995) Bernard D. Cooms et al., Two-Point Dixon Technique for Water-FAT Signal Decomposition with B0 In homogeneity Correction, Magnetic Resonance in Medicine, Vol. 38, 884-889 (1997)

  Although the above-described conventional technique can suppress deterioration in the image quality of the captured image due to the phase shift of the water / fat separated image, the image quality may be deteriorated depending on the region to be imaged of the subject. In other words, when performing water / fat separation imaging, if the imaging target part of the subject is separated into a plurality of parts such as legs, these parts are separated from each other. Even if a calculation method is used, the phase shift cannot be corrected and the quality of the captured image is deteriorated.

  This problem can be improved by degrading the image quality in the water / fat separated image by filling a substance that emits a magnetic resonance signal between the separated parts of the subject.

  However, in imaging using an MRI apparatus, there is a demand to obtain not only water / fat separated images but also images having various contrasts such as T1 enhancement and T2 enhancement. When photographing in a sequence, depending on the photographing sequence, a signal from the space filling material may be strong, which may cause a problem that the fine contrast of the image at the photographing target portion is deteriorated.

  Such a problem can be prevented by changing the space filling material for each imaging sequence or removing the space filling material if unnecessary, but in that case, the subject needs to be taken in and out of the imaging space. Therefore, the same slice cannot be photographed, and the photographing operation becomes complicated and the photographing time is extended.

  The object of the present invention is to suppress the signal from the space filler over a plurality of sequences in photographing with water / fat separated images, and display a fine signal without changing the space filler for each sequence. An object of the present invention is to provide an MRI apparatus and a space filler that can obtain a high-quality image.

In order to achieve the above object, the present invention is configured as follows.
(1) When a water / fat separation image is taken by a magnetic resonance imaging apparatus, the substance is 70 to 150 mM nickel chloride in a space filling body that is placed between separation parts of a subject and filled with a substance that emits MR signals. It shall be.

(2) In said (1), a flexible material shall be used for the material of the filler accommodating part of a space filler.

(3) Static magnetic field generating means, magnetic field applying means for applying a gradient magnetic field and a high frequency magnetic field to the subject, receiving means for receiving a nuclear magnetic resonance signal from the subject, and nuclear magnetic resonance received by the receiving means Based on the signal, operation processing means for reconstructing a tomographic image of the subject, image display means for displaying the reconstructed tomographic image, and operations of the static magnetic field generating means, the magnetic field applying means, and the receiving means are controlled. In the magnetic resonance imaging apparatus comprising the control means, the arithmetic processing means removes a region of the space filler in the image using an image acquired by photographing the subject together with the space filler, and Obtain a water / fat separation image of the subject.

(4) In the above (3), the arithmetic processing means designates at least one point on the image display means, and thereby removes the region of the space filler displayed on the image display means including this point. It shall be.

(5) In the above (4), the arithmetic processing means is displayed on the image display means including this point by designating one point on one slice of the multi-slice displayed on the image display means. Further, it is assumed that the area of the space filling body is removed by all slices of the multi-slice.

(6) In the above (4), when the plurality of subject images photographed together with the space filler are acquired, the arithmetic processing means removes the space filler region from one image to another image. Is also applied to remove the space filler region.

(7) In the above (4), the arithmetic processing means uses a three-dimensional region expansion method to extract the region of the space filler.

(8) In (4), the arithmetic processing means automatically discriminates a region of a substance that emits an MR signal other than the subject based on the local signal intensity and standard deviation of the image displayed on the image display means. And

(9) Magnetic resonance imaging in which a gradient magnetic field and a high-frequency magnetic field are applied to a subject arranged in a static magnetic field, and a tomographic image of the subject is reconstructed and displayed based on a nuclear magnetic resonance signal generated from the subject. In the method, a space filler filled with 70 to 150 mM nickel chloride is placed between the separated parts of the subject and the separated parts are photographed at the time of photographing the water / fat separated images.

  According to the present invention, it is possible to suppress artifacts due to phase shift at the time of imaging a separation part of a subject during water / fat separation imaging, and even when performing a plurality of sequences other than water / fat separation imaging. Provided are an MRI apparatus and a space filler that can suppress a decrease in contrast due to a high signal from a space filler and obtain a high-accuracy image in a short photographing time without taking specimens out of the photographing space for each sequence. be able to.

  Embodiments of the present invention will be described below with reference to the drawings.

  A first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic configuration diagram of an MRI apparatus to which the present invention is applied.

  In FIG. 1, an MRI apparatus includes a magnet 102 that generates a static magnetic field in an imaging space in which a subject 101 is disposed, a gradient magnetic field coil 103 that generates a gradient magnetic field in the space where the static magnetic field is generated, and a space region. An RF coil 104 that generates a high-frequency magnetic field and an RF probe 105 that detects an MR signal generated by the subject 101 are provided.

  The magnet 102 generates a uniform static magnetic field in a direction orthogonal to or parallel to the body axis of the subject 101.

  The gradient magnetic field coil 103 is composed of gradient magnetic field coils in three directions of x, y, and z, and each generates a gradient magnetic field in response to a signal from the gradient magnetic field power supply 109.

  The RF coil 104 generates a high-frequency magnetic field in response to a signal from the RF transmitter 110 and excites atomic nuclei constituting the imaging cross section of the subject 101 to cause nuclear magnetic resonance.

  The RF probe 105 receives an NMR signal that is an echo signal by nuclear magnetic resonance of the biological tissue of the subject 101. The NMR signal received by the RF probe 105 is detected by the signal detection unit 106, processed by the signal processing unit 107, and converted into an image signal by calculation. Then, the captured image is processed by the image processing unit 113, and the image is reconstructed and displayed on the display unit 108.

  The gradient magnetic field power supply 109, the RF transmitter 110, and the signal detector 106 are controlled by the controller 111, and the control time chart is generally called a pulse sequence. The bed 112 is for the subject to lie down.

  When taking a water / fat separation image by an MRI apparatus, if the imaging target parts of the subject are separated from each other, for example, in the case of both legs, an artifact depending on the phase shift occurs, and the image Disturbance may occur.

  In the first embodiment of the present invention, a space filler is installed between the separation sites of the subject in order to prevent this artifact. The space filler will be described below.

  FIG. 2 is a diagram illustrating a case where a space filler 401 is installed between both legs of the subject 101.

  In FIG. 2, the space filling body 401 is made by filling a flexible container having a capacity of 10 L (liter) with 3.8 L (liter) of 108 mM nickel chloride. This space filling body 401 is disposed in a space between both lower leg portions 402. At this time, since the material of the container filled with the space filling body 401 is a flexible material such as resin, the container is deformed, and both the lower leg portions of the subject and the space filling body 401 can be sufficiently adhered to each other. it can.

  Next, the effect when a plurality of sequences are performed with the space filler 401 installed will be described.

  FIG. 3 is a diagram showing a case where the lower limbs are photographed using the space filler 401 under the water / fat separation T1 water-weighted photographing condition (550 ms / 26 ms / 90 °). The parentheses indicate imaging parameters, and indicate TR (repetition time), TE (echo time), and FA (flip angle) in the order of description.

  In FIG. 3, since the area 1103 indicating the space filler 401 has the same signal intensity as the divided parts 1101 and 1102 of the subject, the area 1103 indicating the space filler 401 is not emphasized and the divided part of the subject. 1101 and 1102 are clearly displayed.

  Following the water-fat separation T1 water-weighted imaging conditions, a sequence of the following imaging conditions (not shown) is continuously performed.

  Water fat separation T1 fat weighted imaging condition (550 ms / 26 ms / 90 °), water fat separation T2 water weighted photographing condition (400 ms / 17.1 ms / 30 °), water fat separation T2 fat weighted photographing condition (400 ms / 17.1 ms) / 30 °), T1 image (380 ms / 19 ms / 60 °), proton density / T2 (4000 ms / 25 ms / 90 °), STIR image (4400 ms / 20 ms / 90 °), 3D-BASG image (17 ms / 8.5 ms) / 50 °).

  When the above-mentioned 108 mM nickel chloride is used as the space filling body 401 when photographing a series of this sequence, the space filling body covers a plurality of sequences as compared with the case where other substances are used. A region 401 is not emphasized, contrast deterioration is suppressed, and a clear image is displayed. For this reason, it is not necessary to replace or remove the space filler 401 for each sequence, and the imaging time can be shortened.

  In addition, in the first embodiment, 108 mM nickel chloride is used as the space filling body 401, but 70 mM to 150 mM nickel chloride may be used, and in this case, the same effect is obtained. be able to.

  Note that the brightness of the space filler slightly increases for the STIR image and the 3D-BASG image, so that the contrast removal can be improved by performing the signal removal processing of the space filler described below.

  It should be noted that the signal removal processing of the space filling material can also be performed for other sequences, and the contrast of the image can be further improved.

  FIG. 4 is an operation flowchart of signal removal of the space filler 401.

  With reference to FIG. 4, the signal removal procedure of the space filler 401 will be described.

  First, the space filler 401 is arranged in the separation site space of the subject as shown in FIG. 2 (step 1).

  Next, water / fat separation photography is performed with the space filler 401 arranged (step 2). When shooting with multi-slices, it is desirable that the gain for each slice be constant.

  FIG. 5 is a diagram showing an example of an image photographed by the water / fat separation photographing.

  In FIG. 5, the water / fat separation image 504 includes a region 503 showing the separated target portions 501 and 502 and the space filling body 401 that fills the space between them. Note that the water / fat separated image 504 is imaged at the lower leg of the subject, the imaging section is a COR section, and the following parameters are set as imaging conditions (TR = 550 ms, TE1 = 26 ms, FA = 90 °).

  Next, in order to create a mask for signal removal from the region 503 showing the space filling body 401, as shown in FIG. 6, it has the same number of pixels as the image shown in FIG. Process status map 505 is prepared (step 3).

  In the initial state, the pixel value 1 is input to all the pixels of the map 505. When performing multi-slice imaging, a processing status map is prepared for each slice.

  Next, the operator designates a part of the region 503 where the space filler 401 exists from the photographed image 504 (step 4).

  FIG. 7 is a diagram illustrating an example of designating an area 503 where the space filler 401 exists on the image 504.

  In FIG. 7, the operator observes a photographed image 504 and designates a region 503 where the space filler 401 exists by a circle 701.

When performing multi-slice imaging, the operator observes an image of each slice and designates an area where the space filler 401 exists in any slice. A circle 701 is designated, and the starting point, average signal strength f ₀ , and standard deviation σ are determined.

  Next, a region 503 where a space filler (phantom) 401 exists is extracted from the photographed image 504 (step 5).

  In the first embodiment of the present invention, the region expansion method is used as one method for extracting the region 503 where the space filler 401 exists.

  This region expansion method uses parameters a and b as expansion conditions, and the expansion conditions can be changed by changing the values of parameters a and b.

  FIG. 8A is an explanatory diagram of region expansion restriction due to local signal strength changes. For convenience of explanation, the region expansion direction is limited to one dimension.

In FIG. 8A, the signal intensity changes greatly between the _ninth point on the horizontal axis (hereinafter referred to as “P ₉ ”) and P ₁₀ . This change in such large signal intensity filler - it is considered to be occurring at the boundary of the object, to stop the area extension at P _9, and the extraction region from P ₀ to P _9.

  The area is expanded according to this condition when the following equation is established.

| F _i −f _i−1 | <α
Here, f _i is the signal strength of the extension point, f _i-1 is the signal strength of the reference point which is the point immediately before the extension point, and α is the local threshold.

  FIG. 8B is an explanatory diagram of region expansion restriction due to a global signal intensity change.

Signal intensity difference between the starting point is greater than the value β set in advance in P ₈ in FIG. 8 (b). It is considered to be within a certain range the signal strength of the space filler, the region growing stops at P ₇ immediately before exceeding the range, and the extraction region from P ₀ to P _7. The area is expanded according to this condition when the following expression is satisfied.

| F _i −f ₀ | <β
Here, f ₀ is the signal strength at the start point, and β is the global threshold.

  FIG. 8C is an explanatory diagram in the case of using a combination of local and global signal intensity changes in the region expansion condition.

In P ₄ in FIG. 8 (c), the difference in signal strength between the starting point has exceeded a certain range set. However, since the signal intensity has not changed much locally, the region expansion is continued. On the other hand, the signal intensity greatly varies locally between P ₇ and P ₈ in the figure, but since the difference in signal intensity from the start point is sufficiently small, the area expansion is continued again here. Since local in P _10, a large change in the global both signal strength occurs, region growing stops at this point.

  As described above, by combining both the local area and the global area, even if one side slightly exceeds the range of the expansion condition, the area expansion is performed if the other side sufficiently satisfies the expansion condition. Accordingly, the area can be expanded more flexibly. In this case, the condition for performing the area expansion is expressed by the following equation (1).

a × | f _i −f _i−1 | + b × | f _i −f ₀ | <γ −−− (1)
Here, parameters a and b represent weights for the expansion conditions of local and global signal intensity changes. γ indicates the overall strength of the constraint on the overall expansion condition. By using this region expansion condition, the target region can be extracted without being affected by the static magnetic field inhomogeneity seen in the photographed image 504 or the distortion of the signal intensity depending on the RF irradiation inhomogeneity.

  Next, the detailed procedure of the extended region method in step 5 will be described.

  FIG. 9 shows a flowchart of the region expansion method.

  FIG. 10 is an enlarged view of the rectangular area 702 on the image 504 shown in FIG. 7, and the area drawn with a broken line indicates an area corresponding to the pixel of the processing status map 505. FIG. 11 is a processing status map corresponding to FIG. The center of the circle 701 designated in step 5 above corresponds to the areas 801 and 901 in FIGS.

  The area 801 in FIG. 10 is set as the area expansion start position, and 0 is input to the start area 901 on the corresponding processing status map as shown in FIG. 11 (step 5-1). Further, as shown in step 4 above, the average signal intensity in the circle 701 is set to fo, and the standard deviation is set to σ.

  Further, the standard deviation σ in the circle 701 is set as the threshold value γ of the region expansion condition shown by the above equation (1). The start point and threshold value determined here are applied to all slices when shooting with multi-slices. The initial values of the expansion condition parameters a and b are specified in advance for each photographing sequence.

  Next, as shown in FIG. 11, the start point 901 is numbered 1 and the adjacent four points 902 to 905 on the top, bottom, left and right are set as extension points, and numbers 2 to 5 are assigned to the extension points (step 5- 2).

  In FIG. 11, the extension points are four points that are closest to each other, but a large region including more points may be used as the extension points.

  Next, the point with the smallest number is selected from the extension points assigned with the numbers (step 5-3).

Reference numerals 802 to 805 in FIG. 10 indicate pixels of the captured image at positions corresponding to the extension points 902 to 905 on the processing status map. The signal strengths of the extension point pixels _{802 to 805} are f _{802 to} f ₈₀₅ , the average signal strength of the circle 701 is f ₀ , and the signal strength of the pixel 801 corresponding to the reference point 901 is f as shown in Step 4 above. ₈₀₁ . F _i-1 of the signal intensity of the reference _point, when the signal strength of the expansion point is denoted as f _i, region growing condition is expressed by the following equation. (In this step, the reference point is equal to the starting point.)
Expansion condition: a × | f _i −f _i−1 | + b × | f _i −f ₀ | <| σ |
Expansion condition: a × | f _i −f _i−1 | + b × | f _i −f ₀ |> | σ |

  The region is expanded with a threshold value from the start point specified in step 4 above, and the processing status value is input to the processing status map. Here, since the portion where the processing status value = 2 is recognized as the boundary between the phantom and the subject surface, it is not used as the reference point for area expansion shown in the next step.

  When the processing of steps 5-3a to 5-3e is executed and the situation processing values are given to all the numbers 2 to 5 given in the above step 5-2, the pixel with the next smallest number after the start point is set as the reference point. (Step 5-4). Here, the pixel 902 given the number 2 is the reference point.

  FIG. 12 is a processing status map diagram showing the reference points and extension points of this step.

  In FIG. 12, when processing is performed on an adjacent point of the reference point, it is first determined whether or not the adjacent point becomes an extension point (step 5-5). This determination is made based on whether or not the following conditions are satisfied.

  That is, the above determination is made based on whether or not the situation processing value of the adjacent point is not 0 or 2 as the first condition and whether it has not been evaluated in the past as the second condition.

  The adjacent points satisfying the above conditions are given numbers (in this case, 6 to 8) in steps 5-5a as indicated by 1002 to 1004 in FIG. Return to Step 5-3.

  As shown in FIG. 12, if there are adjacent point candidates to be determined, but there is no adjacent point that satisfies the above condition, it is determined in step 5-5b whether there is an unprocessed pixel. . If it exists, the pixel with the next smaller number designated in step 5-4 is used as a reference point (step 5-5c), and the process returns to step 5-5. This adjacent point evaluation is performed until all the processed extension points are not satisfied, and the region extension procedure is terminated. If there is no unprocessed pixel in step 5-5b, the process proceeds to step 6.

  Returning to FIG. 4, the procedure for removing the signal of the space filler is continued. Next, it is evaluated whether or not the parameters are optimum (step 6).

  This evaluation is performed by displaying several consecutive slices at the same time after actually performing the extraction process, or actually creating a three-dimensional image from the extraction result. The operator looks at the extraction result, and if the result does not match the target area, the parameters a and b are changed and the extraction process is performed again.

Also, if the extraction area overflows greatly from the target area, the operator designates one point on the overflow area of the extraction result on the monitor screen, and performs reverse region growing with that point as the starting point. Remove region. Refer to the following literature for the reverse region growing method (extraction and three-dimensional display of the southern tissue by the region growing method. Sano, Oikawa, Isobe, Hitachi, Ltd., System Development Laboratory, Medical Imaging Technology, Vol. 12, No . 4, 379-383 (1994))
1 is input to a pixel whose processing status value of the processing status map obtained up to step 6 is not 0, and this is applied to the photographed image as a phantom removal mask (step 7). The signal of the space filler is removed by removing the signal from the extraction region.

  Next, in order to confirm the fine structure, the target image contrast is readjusted (step 8).

  As described above, the signal portion of the space filler 401 is removed, and the contrast of the image is improved. Since it is not necessary to replace the space filler 401, the position in each sequence does not change if the slice is the same slice. Therefore, the processing status map used in step 7 is also valid for other sequences as it is. For this reason, if the slice is the same, the same processing status map can be integrated for other sequences.

  Thus, by designating one point on the imaging result display screen of one sequence, the target area can be extracted from all sequences and all slices, and the work can be shortened.

  According to the first embodiment of the present invention configured as described above, 70 to 150 mM nickel chloride is filled as a space filler between the legs of the subject, so that water / fat separation imaging can be performed. In addition, it is possible to suppress artifacts due to phase shifts that occur due to the interval between the legs of the subject, and even when performing multiple sequences at the same time other than water / fat separation photography, Therefore, it is possible to obtain a highly accurate image by suppressing a decrease in contrast due to a high signal from the space filling material in a short photographing time without being taken in and out.

  Further, in this case, depending on the sequence, for the sequence in which the contrast is deteriorated, the space filler 401 removal program is executed to remove the signal of the space filler 401 and increase the contrast of the subject. Can do.

  Next, a second embodiment of the present invention will be described with reference to FIGS.

  The second embodiment of the present invention is applied to a method in which the region expansion performed in the two-dimensional direction in step 5 of the first embodiment is expanded in the three-dimensional direction.

  FIG. 13 is a diagram showing a flowchart when this three-dimensional region expansion method is performed, and FIG. 14 is a diagram showing the positions of reference points and expansion points when region expansion is performed in the three-dimensional direction.

  13 and 14, when performing region expansion in a three-dimensional direction, when the reference point for region expansion is 1301, the expansion points are six points 1302 to 1307 around the reference point.

  When the region expansion is performed three-dimensionally, it is not necessary to specify the region where the space filler exists in any slice as in step 4 of the first embodiment, and any region of the space filler may be used. Therefore, the work can be simplified.

  In FIG. 14, the extension points are the six closest points, but a large region composed of more points may be used as the extension points.

  Also in the second embodiment of the present invention configured as described above, the same effects as those of the first embodiment can be obtained.

  Next, a third embodiment of the present invention will be described with reference to FIG.

  In the third embodiment of the present invention, the start point is automatically extracted in step 4 of the first embodiment.

  Since the space filler 401 is a substance having a uniform concentration that emits MR signals, the signal value in the area of the space filler 401 has a smaller standard deviation than the signal value of the subject. Therefore, in step 4 of the first embodiment, as shown in FIG. 15, the captured image is divided into small sections, the section showing the highest signal intensity in the small sections, and the lowest standard deviation. This is the starting point for expansion.

  Thereby, even if an operator does not designate the area of the space filler 401, the area of the space filler 401 can be automatically removed.

  Also in the third embodiment of the present invention configured as described above, the same effect as in the first embodiment can be obtained.

  Next, a fourth embodiment of the present invention will be described.

  In steps 1 and 2 of the first embodiment of the present invention, instead of using the space filler 401, an auxiliary device at the time of kinematic imaging is used.

  As a result, a clear image of the subject is obtained by removing the signal of the auxiliary device from the image taken at the time of kinematic imaging by the same method as the method for removing the space filler according to the first embodiment of the present invention. be able to.

  Also in the fourth embodiment of the present invention configured as described above, the same effects as those of the first embodiment can be obtained.

1 is a schematic configuration diagram of an MRI apparatus to which the present invention is applied. It is a figure which shows the space filler which put 108 mM nickel chloride. It is a figure which shows an example which image | photographed the leg under water fat separation T1 water emphasis imaging conditions using the space filler. It is a signal removal flowchart of the space filler which is the application object of the 1st Embodiment of this invention. It is a figure which shows the image used as a process target. FIG. 6 is a diagram illustrating a processing status map having the same number of pixels as in FIG. 5. It is explanatory drawing of designation | designated by the circle of a space filler material area | region. It is explanatory drawing of the restriction | limiting of the area expansion by a local and global signal strength change. It is an area expansion method flowchart. FIG. 8 is an enlarged view of a region 702 in FIG. 7. It is a figure which shows a process status map. It is a figure which shows a process status map. It is a flowchart in the case of performing area | region expansion in three dimensions. It is a figure which shows the adjacent point in three-dimensional space. It is a figure which shows the division | segmentation of the picked-up image for determination of the starting point of area expansion.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Subject 102 Static magnetic field magnet 103 Gradient magnetic field coil 104 RF coil 105 RF probe 106 Signal detection part 107 Signal processing part 108 Display part 109 Gradient magnetic field power supply 110 RF transmission part 111 Control part 112 Bed 113 Image processing part 401 Space filling body 501 , 502 Both legs of the subject 503 Space filling material 504 Captured image 505 Processing status map 701 Circle to be used as a reference for the area where the signal is to be removed 801 Start point corresponding to position 901 in the captured image 802 to 805 In the captured image Extension points corresponding to positions 902 to 905 901 Start point 902 to 905 Extension points 1001 Reference points 1002 to 1004 Extension points 1101 and 1102 Both legs 1103 Space filler 1301 Reference points in three dimensions 1302 to 1307 Three dimensions Expansion in

Claims (4)

A static magnetic field generating means;
Magnetic field applying means for applying a gradient magnetic field and a high-frequency magnetic field to the subject;
Receiving means for receiving a nuclear magnetic resonance signal from the subject;
An arithmetic processing means for reconstructing a tomographic image of the subject based on the nuclear magnetic resonance signal received by the receiving means;
Image display means for displaying the reconstructed tomographic image;
Control means for controlling the operation of the static magnetic field generating means, magnetic field applying means and receiving means ,
The arithmetic processing means obtains a water / fat separated image of the subject by removing an area of the space filler in the image using an image acquired by photographing the subject together with the space filler. the magnetic resonance imaging apparatus according to claim,
The arithmetic processing means designates one point on one slice of the multi-slice displayed on the image display means, so that the region of the space filler displayed on the image display means including this point A magnetic resonance imaging apparatus characterized by removing all slices. 2. The magnetic resonance imaging apparatus according to claim 1, wherein the arithmetic processing unit designates at least one point in one image when a plurality of subject images photographed together with the space filler are acquired. A magnetic resonance imaging apparatus for removing a region of a space filling body by applying removal of a region of a body to other images. The magnetic resonance imaging apparatus according to claim 1, wherein the arithmetic processing unit uses a three-dimensional region expansion method to extract the region of the space filler. 2. The magnetic resonance imaging apparatus according to claim 1, wherein the arithmetic processing means automatically discriminates the region of the space filler based on the local signal intensity and standard deviation of the image displayed on the image display means. Magnetic resonance imaging apparatus.

Images