JP6121664B2 - Magnetic resonance apparatus and program - Google Patents

Description

  The present invention relates to a magnetic resonance apparatus for imaging a predetermined part, and a program applied to the magnetic resonance apparatus.

  As a method for diagnosing a subject using a magnetic resonance apparatus, a method is known in which a contrast agent is administered to a subject and image data of each time phase appearing after the contrast agent is administered is acquired.

JP 2011-167408 A

  Recently, contrast-enhanced dynamic imaging tests using sodium gadoxetate (Gd-EOB-DTPA: hereinafter referred to as EOB) have been frequently performed in liver MRI examinations, but gadolinium chelates ( Compared with Gd-DTPA), the dose is halved. Therefore, in the imaging using EOB, there is a problem that the time for which the concentration of the contrast agent becomes constant is short, and artifacts such as ringing and blurring are likely to appear. For this reason, it is desired to reduce artifacts such as ringing and blur.

In the first aspect of the present invention, a navigator signal is collected from a first region including a predetermined part of a subject, and an image of the predetermined part is reconstructed from a second region including the predetermined part. A magnetic resonance apparatus for collecting imaging data used sometimes,
Scanning means for executing a scan for collecting the navigator signal and the imaging data;
Correction means for correcting the signal intensity of the imaging data based on the navigator signal;
Reconstruction means for performing image reconstruction based on imaging data whose signal intensity is corrected;
Is a magnetic resonance apparatus.

In the second aspect of the present invention, navigator signals are collected from a first region including a predetermined part of the subject, and an image of the predetermined part is reconstructed from the second region including the predetermined part. A magnetic resonance apparatus for collecting imaging data used sometimes,
Scanning means for executing a scan for collecting the navigator signal and the imaging data;
Correction means for correcting a flip angle of an RF pulse of a sequence used when acquiring the imaging data based on the navigator signal;
This is a magnetic resonance apparatus.

In a third aspect of the present invention, navigator signals are collected from a first region including a predetermined part of the subject, and an image of the predetermined part is reconstructed from the second region including the predetermined part. A program of a magnetic resonance apparatus that performs a scan to collect imaging data that is sometimes used,
Correction processing for correcting the signal intensity of the imaging data based on the navigator signal;
Reconstruction processing to perform image reconstruction based on imaging data whose signal intensity is corrected;
Is a program for causing a computer to execute.

According to a fourth aspect of the present invention, navigator signals are collected from a first region including a predetermined part of the subject, and an image of the predetermined part is reconstructed from the second region including the predetermined part. A program of a magnetic resonance apparatus that performs a scan to collect imaging data that is sometimes used,
Correction processing for correcting a flip angle of an RF pulse of a sequence used when acquiring the imaging data based on the navigator signal;
Is a program for causing a computer to execute.

  Since the imaging data or the flip angle is corrected based on the signal intensity, artifacts such as ringing and blur can be reduced.

1 is a schematic view of a magnetic resonance apparatus according to a first embodiment of the present invention. It is a figure which shows the scan performed with a 1st form. It is a figure which shows an imaging | photography area | region schematically. It is a figure which shows the flow when imaging a subject in a 1st form. It is explanatory drawing of the breath holding scan BH. It is an explanatory view when detecting the position P ₀ of the SI direction of the edge of the liver during the breath-hold scan BH. It is a diagram showing a signal intensity _N 1 to N _z position _{P 0} + [Delta] d. It is a figure which shows the profile F roughly. It is an explanatory view of correcting the imaging data _S 1 to S _z using equation (1) '. Is a diagram showing an example of a case where a plurality of imaging sequence is performed between the navigator sequence NS _n and NS n _{+ 1.} It is the schematic of MR apparatus of the 2nd form. It is a figure which shows the scan performed with a 2nd form. It is a figure which shows an imaging region roughly. It is a figure which shows the flow of a 2nd form. It is explanatory drawing of the breath holding scan BH. FIG. 6 is an explanatory diagram when calculating the signal intensity of the imaging region R. It is an explanatory view of correcting the imaging data _S 1 to S _z using equation (2) '. It is explanatory drawing of the scan performed with a 3rd form. It is a figure which shows the flow when imaging a subject in a 3rd form. It is explanatory drawing of the prescan A. FIG. It is a figure which shows an edge position profile schematically. It is a figure which shows an example of the range AW at the end of spitting. 6 is an explanatory diagram of a main scan B. FIG. It is a figure which shows the detected signal strength. It is explanatory drawing when imaging data is correct | amended using Formula (3). It is explanatory drawing of the scan performed with a 4th form. It is a figure which shows the flow when imaging a subject in a 4th form. It is a figure which shows an example of trigger level TL. 6 is an explanatory diagram of a main scan B. FIG. It is a figure which shows the detected signal strength. It is explanatory drawing when correcting imaging data using Formula (4). It is the schematic of MR apparatus of the 5th form. It is a figure which shows the scan performed with a 5th form. A navigator signal A ₁ collected by the navigator sequence NS _1, is a diagram showing the imaging data S ₁ that has been collected by the imaging sequence IS _1. Is a diagram illustrating a navigator signal A ₂ collected by the navigator sequence NS _2. It is explanatory drawing of the correction method of flip angle (alpha). It is a diagram showing the imaging data _S 1 to S _z obtained by the breath-hold scan BH. It is the schematic which shows MR apparatus of the 6th form. It is a figure which shows the scan performed with a 6th form. It is a diagram illustrating a navigator signals A ₁ and imaging data S ₁ that has been collected by the sequence C _1. It is a diagram illustrating a navigator signal A ₂ and the imaging data S ₂ collected by the sequence C _2. It is an illustration of a correction method for flip angle α of RF pulses X ₃ of the sequence C _3. It is a figure which shows a mode that the signal strength _{N3_corr} after correction _{| amendment} was calculated. It is an explanatory view of correcting the flip angle of the sequence C _4.

  Hereinafter, although the form for inventing is demonstrated, this invention is not limited to the following forms.

(1) First Embodiment FIG. 1 is a schematic view of a magnetic resonance apparatus according to a first embodiment of the present invention.
A magnetic resonance apparatus (hereinafter referred to as “MR apparatus”, MR: Magnetic Resonance) 100 includes a magnet 2, a table 3, a receiving coil 4, and the like.

  The magnet 2 has a bore 21 in which the subject 12 is accommodated, a superconducting coil 22, a gradient coil 23, and an RF coil 24. The superconducting coil 22 applies a static magnetic field, the gradient coil 23 applies a gradient magnetic field, and the RF coil 24 transmits an RF pulse. In place of the superconducting coil 22, a permanent magnet may be used.

  The table 3 has a cradle 3a. The cradle 3a is configured to be able to move into the bore 21. The subject 12 is transported to the bore 21 by the cradle 3a.

  The reception coil 4 is attached to the abdomen of the subject 12. The receiving coil 4 receives a magnetic resonance signal from the subject 12.

  The MR apparatus 100 further includes a contrast medium injection device 5, a transmitter 6, a gradient magnetic field power source 7, a receiver 8, a control unit 9, an operation unit 10, a display unit 11, and the like.

The contrast medium injection device 5 injects a contrast medium into the subject.
The transmitter 6 supplies current to the RF coil 24, and the gradient magnetic field power supply 7 supplies current to the gradient coil 23.
The receiver 8 performs signal processing such as detection on the signal received from the receiving coil 4.

  The control unit 9 transmits necessary information to the display unit 11 and reconstructs an image based on the data received from the receiver 8 so as to realize various operations of the MR apparatus 100. Control the operation of each part. The control unit 9 is configured by, for example, a computer. The control unit 9 includes a correction unit 91 and a reconstruction unit 92.

  The correcting unit 91 corrects the signal intensity of the imaging data. The correction unit 91 includes a signal intensity data creation unit 91a, a detection unit 91b, a calculation unit 91c, and the like.

Signal strength data generating means 91a, based on the navigator signal _{A n,} to create a signal strength data _{D n} representing the variation of the SI direction of the signal strength of the navigator region _{R nav} (e.g., see FIG. 5).
The detection means 91b detects the signal intensity at the position of the liver based on the signal intensity data.
The computing unit 91c obtains corrected imaging data using an expression described later.

  The reconstruction unit 92 reconstructs an image using the corrected imaging data.

  The control unit 9 is an example constituting the correcting unit 91 and the reconfiguring unit 92, and functions as these units by executing a predetermined program.

The operation unit 10 is operated by an operator and inputs various information to the control unit 9. The display unit 11 displays various information.
The MR apparatus 100 is configured as described above.

FIG. 2 is a diagram showing a scan executed in the first form, and FIG. 3 is a diagram schematically showing an imaging region.
In the first mode, a breath holding scan BH is executed.
The breath-hold scan BH is a scan that is executed in a state where a contrast medium is injected into the subject and the subject holds the breath. In the breath holding scan BH, the navigator sequence NS _n (n = 1 to z) and the imaging sequence IS _n (n = 1 to z) are alternately executed.

The navigator sequence NS _n is a sequence for acquiring signal strength data representing a change in signal strength in the SI direction in the navigator region R _nav including the boundary between the lung and the liver. The imaging sequence IS _n is a sequence for acquiring imaging data used when reconstructing an image of the imaging region R including the liver.
The flow when executing the breath holding scan BH will be described below.

FIG. 4 is a diagram showing a flow when the subject is imaged in the first embodiment.
In step ST1, a contrast medium is injected into the subject, and a breath-hold scan BH is executed. In the breath holding scan BH, as shown in FIG. 5, the navigator sequence NS _n and the imaging sequence IS _n are executed alternately. When navigator sequence NS _n is executed, navigator signals A _n (n = 1 to z) are acquired from navigator region R _nav, and when imaging sequence IS _n is executed to reconstruct an image of imaging region R Imaging data S _n (n = 1 to z) used in the above is collected. Signal strength data generating means 91a (see FIG. 1) is a one-dimensional Fourier transform of the navigator signals _{A n} (1D-FT) and the signal intensity data _D 1 ~ representing a change in the SI direction of the signal strength of the navigator region _{R nav Dz} is created. After obtaining the signal intensity data _D 1 to D _z, the process proceeds to step ST2.

At step ST2, the detection means 91b (see FIG. 1) detects the position _{P 0} of the SI direction of the edge of the liver during the breath-hold scan BH.

Figure 6 is an explanatory view when detecting the position P ₀ of the SI direction of the edge of the liver during the breath-hold scan BH.

In this embodiment, a navigator sequence is used in which the lung side has a low signal and the liver side has a high signal. Accordingly, a step in signal intensity appears at the boundary between the lung and the liver. By detecting this step, the position P ₀ of the edge of the liver can be detected. In this embodiment, since the subject holds his / her breath, it can be considered that the position of the edge of the liver does not move during the scan. Therefore, the position of the liver edge detected using any one of the signal intensity data D _{1 to} D _z can be set as the liver edge position P ₀ during the breath holding scan. . Here, the detected position of the liver edge with a signal intensity data D _1, and the position P ₀ of the liver edge between the breath-hold scan.

After detecting the position P ₀ of the liver edge, the process proceeds to step ST3.
In step ST3, the detection means 91b detects the signal intensity N ₁ to the signal intensity N ₁ to the position P ₀ + Δd separated from the liver edge position P ₀ by the distance Δd from the liver edge position P ₀ for each signal intensity data D _{1 to} D _{z. Nz} is detected. FIG. 7 shows signal intensities N _{1 to} N _z at the position P ₀ + Δd. By detecting the signal intensities N _{1 to} N _z , it is possible to obtain a profile F representing the time change of the signal intensity in the liver. FIG. 8 schematically shows the profile F thereof. As the concentration of the contrast agent flowing into the liver increases, the value of the signal intensity N _n increases. Therefore, it can be seen from the profile F that the concentration of the contrast agent flowing into the liver increases with time. If the value of Δd is too small, there is a high possibility that the signal strength of the step appearing at the boundary between the liver and the lung will be detected, so there is a possibility that the signal strength of the lung side region will be detected. On the other hand, if the value of Δd is too large, the signal intensity of the intestinal region may be detected. Therefore, Δd needs to be set so that the signal intensity inside the liver can be detected. As an example, by setting Δd = 5 cm, it is possible to avoid the danger of detecting the signal intensity of a part other than the liver.
After obtaining the profile F, the process proceeds to step ST4.

In step ST4, based on the signal intensity _N 1 to N _z, to correct the imaging data _S 1 to S _z obtained imaging region by the imaging sequence. This correction is performed using the following equation.
S _{n, corr} = S _n * N _i / N _n (1)

S _n : Imaging data obtained immediately after the n-th navigator signal S _{n, corr} : Imaging data after correcting S _n N _i : i-th signal selected from signal intensities N _{1 to} N _z strength n _n: n-th signal intensity

The computing unit 911c (see FIG. 1) calculates the corrected imaging data Sn _{, corr} using the equation (1). In equation (1), and the imaging data _{S n} and _N i / _{N n} times. Therefore, it is possible to correct the difference in signal intensity of the imaging data S _{1 to} S _z caused by the difference in the concentration of the contrast agent flowing into the liver. In Equation (1), N _i is the i-th signal strength selected from the signal strengths N _{1 to} N _z , and N _i can be, for example, i = 1, that is, N _1. . When i = 1, equation (1) is rewritten as follows.
S _{n, corr} = S _n * N ₁ / N _n (1) ′

Hereinafter, a method of correcting the imaging data S _{1 to} S _z using the expression (1) ′ will be described with reference to FIG.

FIG. 9 is an explanatory diagram when the imaging data S _{1 to} S _z are corrected using the equation (1) ′.

When correcting imaging data _{S 1,} the n of the formula (1) 'may be substituted for n = 1.
_{S 1, corr = S 1 *} N 1 / N 1
= S ₁
Thus, imaging data _{S 1, corr} corrected is the same as the imaging data _{S 1} before correction.

However, when correcting the imaging data _{S 2,} the n of the formula (1) ', since n = 2 is substituted, the imaging data _{S 2, corr} corrected is expressed by the following equation.
S _{2, corr} = S ₂ * N ₁ / N ₂

Therefore, the corrected imaging data S _{2 and corr} are N ₁ / N ₂ times the uncorrected imaging data S ₂ .

Similarly, by changing the value of n in formula (1) ', the _{S n} by multiplying _N 1 / _{N n,} imaging data _{S n} after _correction, can be obtained _corr. After correcting the imaging data, the process proceeds to step ST5.

In step ST5, image reconstruction is performed using the corrected imaging data S1 _{, corr to} Sz _{, corr} , and the flow ends.

In the first embodiment, the imaging data S _{1 to} S _z acquired in the imaging sequence are corrected based on the signal intensities N _{1 to} N _z at the liver position obtained in the navigator sequence. Therefore, it is possible to correct the difference in signal intensity of the imaging data S ₁ to S _z caused by the difference in concentration of the contrast medium flowing into the liver, it is possible to reduce artifacts such as ringing and blur.

In the above example, the signal intensities N _{1 to} N _z are detected from the signal intensity data D _{1 to} D _z , respectively. However, some signal strengths among the signal strengths N _{1 to} N _z may be estimated from other signal strengths. In the first embodiment, since the signal strengths N _{1 to} N _z tend to increase with time (see FIG. 8), if the signal strengths N ₁ and N _z are known, the profile F in which the signal strength increases with time. Can be estimated. Therefore, an estimation means for estimating the profile F based on the signal strengths N ₁ and N _z may be provided, and the other signal strengths N _{2 to} N _z−1 may be estimated from the estimated profile F. In this case, since the signal intensities N _{1 to} N _z can be obtained simply by executing only the navigator sequences NS ₁ and NS _z , the time of the breath holding scan BH can be further shortened.

In the first embodiment, by using the n-th signal intensity N _n, it is corrected n-th imaging data S _n obtained immediately after the n-th navigator signal. However, by using the n-th signal intensity N _n, the n-th navigator imaging data S _n-1 n-1 th collected immediately before the signal may be corrected.

In the above description, the case where one imaging sequence IS _n is executed between the navigator sequences NS _n and NS _{n + 1} is described. However, a plurality of imaging sequences may be executed between the navigator sequences NS _n and NS _{n + 1} (see FIG. 10).

FIG. 10 is a diagram illustrating an example in which a plurality of imaging sequences are executed between the navigator sequences NS _n and NS _{n + 1} .

In FIG. 10, a plurality of imaging data are collected between navigator sequences NS _n and NS _{n + 1} . In such a case, each of the plurality of imaging data collected between the navigator sequences NS _n and NS _{n + 1} may be multiplied by N ₁ / N _n . For example, since the imaging data S _{21 to} S _2q are collected between the navigator sequences NS ₂ and NS ₃ , each of these imaging data S _{21 to} S _2q may be multiplied by N ₁ / N ₂ . Thus, imaging data _S 21 after the _{correction, corr to S 2q,} can be obtained _corr.

In FIG. 10, imaging data collected between the nth navigator signal and the (n + 1) th navigator signal is corrected using the _nth signal intensity Nn. However, imaging data collected between the (n-1) th navigator signal and the nth navigator signal may be corrected using the _nth signal intensity Nn.

  In the first embodiment, the imaging data is corrected after the breath holding scan BH is completed. However, the imaging data may be corrected while the breath holding scan BH is executed.

(2) Second form In the first form, the navigator signal and the imaging data are collected in separate sequences. In the second form, the navigator signal and the imaging data are collected in the same sequence. explain.

FIG. 11 is a schematic diagram of an MR apparatus according to the second embodiment.
The MR apparatus 200 of the second form has a signal intensity calculating means 91d instead of the signal intensity data creating means 91a and the detecting means 91b of the MR apparatus 100 of the first form. Other configurations are the same as those of the MR apparatus 100 of the first embodiment.

FIG. 12 is a diagram showing a scan executed in the second form, and FIG. 13 is a diagram schematically showing an imaging region.
In the second form, a breath holding scan BH is executed. In the breath holding scan BH of the second form, the sequence C _n (n = 1 to z) is executed. Sequence C _n is a sequence for acquiring the imaging data S _n to be used when reconstructing an image of the imaging region R. The sequence C _n is provided with a waiting time T _wait immediately before the gradient magnetic fields Gx and Gy are applied, and the navigator signal _An is acquired at the waiting time T _wait . Navigator signals A _n denotes the data of the center of k-space imaging region R. The waiting time T _wait is, for example, 20 μm.

Thus, each execution of the sequence C _n, in addition to the imaging data S _n, it is possible to obtain a navigator signal A _n. In the second embodiment, to correct the imaging data S _n by using the navigator signal A _n obtained by the sequence C _n. Hereinafter, a flow when imaging a subject in the second embodiment will be described.

FIG. 14 is a diagram showing a flow of the second embodiment.
In step ST1, a contrast medium is injected into the subject, and a breath-hold scan BH is executed. In the breath holding scan BH, the sequence C _n is executed as shown in FIG. By executing the sequence C _n , the navigator signal A _n (n = 1 to z) and the imaging data S _n (n = 1 to z) are collected. After executing the breath holding scan BH, the process proceeds to step ST2.

In step ST2, the signal intensity calculating unit 91d (see FIG. 11) calculates the signal intensity of the imaging region R for each of the navigator signals A _{1 to} A _z (see FIG. 16).

FIG. 16 is an explanatory diagram when the signal intensity of the imaging region R is calculated.
In the second mode, the signal intensity calculating unit 91d calculates the integrated values of the navigator signals A _{1 to} A _z obtained from the imaging region R. Thereby, the signal intensities N _{1 to} N _z of the imaging region R can be calculated. After calculating the signal strengths N _{1 to} N _z , the process proceeds to step ST3.

At step ST3, the on the basis of the signal intensity _N 1 to N _z, to correct the imaging data _S 1 to S _z of the resulting imaging region R by the sequence _C 1 -C _z. This correction is performed using the following equation.
S _{n, corr} = S _n * N _i / N _n (2)

S _n : n-th imaging data S _{n, corr} : imaging data after correcting S _n N _i : i-th signal intensity selected from signal intensities N _{1 to} N _z N _n : n-th signal Strength

The computing unit 91c (see FIG. 11) calculates the corrected imaging data _{Sn, corr} using the equation (2). In equation (2), and the imaging data _{S n} and _N i / _{N n} times. Therefore, it is possible to correct the difference in signal intensity of the imaging data S _{1 to} S _z caused by the difference in the concentration of the contrast agent flowing into the liver. N _{i in} Equation (2) is the i-th signal strength selected from the signal strengths N _{1 to} N _z , and N _i can be, for example, i = 1, that is, N _1. . When i = 1, equation (2) is rewritten as follows.
S _{n, corr} = S _n * N ₁ / N _n (2) ′

Hereinafter, a method of correcting the imaging data S _{1 to} S _z using the expression (2) ′ will be described with reference to FIG.

FIG. 17 is an explanatory diagram when the imaging data S _{1 to} S _z are corrected using Expression (2) ′.
When correcting imaging data _{S 1,} the n of the formula (2) ', may be substituted for n = 1.
_{S 1, corr = S 1 *} N 1 / N 1
= S ₁

Thus, imaging data _{S 1, corr} corrected is the same as the imaging data _{S 1} before correction.

However, when correcting the imaging data _{S 2,} the n of the formula (2) ', since n = 2 is substituted, the imaging data _{S 2, corr} corrected is expressed by the following equation.
S _{2, corr} = S ₂ * N ₁ / N ₂

Therefore, the corrected imaging data S _{2 and corr} are N ₁ / N ₂ times the uncorrected imaging data S ₂ .

Similarly, by changing the value of n in formula (2) ', the _{S n} by multiplying _N 1 / _{N n,} imaging data _{S n} after _correction, can be obtained _corr. After correcting the imaging data, the process proceeds to step ST4.

In step ST4, image reconstruction is performed using the corrected imaging data S1 _{, corr to} Sz _{, corr} , and the flow ends.

In the second embodiment, the imaging data S _{1 to} S _z are corrected based on the signal intensities N _{1 to} N _z at the position of the liver obtained in the sequence C _n . Therefore, it is possible to correct the difference in signal intensity of the imaging data S ₁ to S _z caused by the difference in concentration of the contrast medium flowing into the liver, it is possible to reduce artifacts such as ringing and blur.

In the second embodiment, the navigator signal and the imaging data can be acquired from the imaging region R excited when the sequence C _n is executed. Therefore, since the region excited when acquiring the navigator signal is the same as the region excited when acquiring the imaging data, the accuracy of correction of the imaging data can be improved.

In the second embodiment, by using the n-th sequence C _n signal strength N _n collected by, and correcting the imaging data S _n collected by the n-th sequence C _n. However, by using the n-th sequence C _n signal strength N _n collected by the imaging data S _n-1 collected by the n-1 th sequence C _n-1 may be corrected.

(3) Third Embodiment In the first and second embodiments, the example in which the scan is executed in a state where the subject holds his / her breath was explained, but in the third embodiment, the subject was allowed to breathe freely. An example in which scanning is executed in a state will be described. The hardware configuration of the MR apparatus is the same as that in the first embodiment.

FIG. 18 is an explanatory diagram of a scan executed in the third mode.
In the third mode, pre-scan A and main scan B are executed.

Pre-scan A is a scan for detecting a respiratory signal. In the prescan A, navigator sequences NS _{1 to} NS _x are executed. The navigator sequences NS _{1 to} NS _x obtain signal strength data representing changes in signal strength in the SI direction within the navigator region R _nav , as with the navigator sequence NS _n (n = 1 to z) of the first embodiment. It is a sequence for.

The main scan B is a scan for acquiring imaging data used when reconstructing an image of the imaging region R including the liver. In the main scan B, the navigator sequence NS _n (n = 1 to z) and the imaging sequence IS _n (n = 1 to z) are alternately executed as in the breath holding scan BH of the first embodiment.

  Hereinafter, a flow when the subject is imaged by the pre-scan A and the main scan B will be described.

FIG. 19 is a diagram illustrating a flow when the subject is imaged in the third embodiment.
In step ST1, prescan A is executed (see FIG. 20).

FIG. 20 is an explanatory diagram of the pre-scan A.
In the prescan A, navigator sequences NS _{1 to} NS _x are executed. By executing the navigator sequences NS _{1 to} NS _x , navigator signals _An (n = 1 to x) are collected from the navigator region R _nav . Signal strength data generating means 91a (see FIG. 1) is a one-dimensional Fourier transform of the navigator signals _{A n} (1D-FT) and the signal intensity data _D 1 ~ representing a change in the SI direction of the signal strength of the navigator region _{R nav} to create a D _x. Since a step in signal strength appears at the boundary between the lung and the liver, the positions P _{1 to} P _x of the edges in the SI direction of the liver can be detected by detecting the step in the signal strength. By detecting the edge position of the liver for each of the signal intensity data D _{1 to} D _x , it is possible to know how the edge position of the liver changes with time. Therefore, it is possible to obtain an edge position profile representing a temporal change in the edge position of the liver. FIG. 21 schematically shows an edge position profile. After performing the pre-scan A, the process proceeds to step ST2.

  In step ST2, based on the edge position profile, a breathing end range AW of the subject 11 is obtained. FIG. 22 shows an example of the range AW at the end of spitting. The range AW at the end of exhalation of breathing can be obtained as a fixed range from the minimum value of the edge position of the liver, for example. After obtaining the range AW at the end of breathing, the process proceeds to step ST3.

In step ST3, the main scan B is executed.
FIG. 23 is an explanatory diagram of the main scan B.
In the main scan B, the navigator sequence NS _n (n = 1 to z) and the imaging sequence IS _n (n = 1 to z) are executed alternately.

In the main scan B, when the edge position of the liver detected in the navigator sequence is included in the range AW of the end of breathing exhalation, the imaging data acquired in the immediately subsequent imaging sequence is used as image reconstruction data. adopt. On the other hand, when the edge position of the liver detected in the navigator sequence is not included in the end-of-breathing end range AW, the imaging data acquired in the immediately following imaging sequence is not adopted as image reconstruction data. . For example, in FIG. 23, since the liver edge position P ₁ detected by the navigator sequence NS ₁ is out of the range AW at the end of breathing exhalation, the imaging data S ₁ acquired in the imaging sequence IS ₁ immediately after that Are not adopted as data for image reconstruction and are discarded.

On the other hand, the edge position P ₂ of the liver detected by the navigator sequence NS _2, so are included in the scope AW of end spitting respiratory, imaging data S ₂ acquired by the imaging sequence IS ₂ immediately thereafter, the image Adopted as reconstruction data. Similarly, since the liver edge position P ₃ detected by the navigator sequence NS _{3 is} also included in the end-of-breathing end range AW, the imaging data S ₃ acquired in the imaging sequence IS ₃ immediately after that is also Used as data for image reconstruction.
After executing the main scan B, the process proceeds to step ST4.

In step ST4, from the signal strength data D ₁ to D _z, the position of the liver edge is to identify the signal strength data contained in the range AW of spitting breath end. Signal intensity data _D 1 position _P 1 to P _z hepatic edges in to D _z is known, since the range AW breathing spitting end is also known, the position _P 1 to P _z liver edge breathing It can be determined whether or not it is included in the range AW at the end of spitting. Therefore, it is possible to specify signal intensity data in which the position of the edge of the liver is included in the range AW at the end of breathing out of the signal intensity data D _{1 to} D _z . In FIG. 23, for example, the signal intensity data D ₁ has a liver edge position P ₁ that is out of the end-of-breathing end range AW, but the signal intensity data D ₂ , D ₃ , D _z, etc. The position of the edge is included in the end-of-breath exhalation range AW. After specifying the signal strength data, the process proceeds to step ST5.

In step ST5, the detection means 91b (see FIG. 1) obtains the signal intensity at a position separated by a distance Δd from the position of the liver edge to the liver side (I side) with respect to the signal intensity data specified in step ST4. To detect. FIG. 24 shows the detected signal strength. FIG. 24 representatively shows signal intensities N ₂ , N ₃ , and N _z detected for the signal intensity data D ₂ , D ₃ , and D _z . The signal intensities N ₂ , N ₃ , and N _z represent the signal intensities at positions that are separated from the liver edge positions P ₂ , P ₃ , and P _z by a distance Δd from the liver side (I side), respectively. After detecting the signal strength, the process proceeds to step ST6.

In step ST6, the imaging data adopted as data for image reconstruction is corrected. This correction is performed using the following equation.
S _{n, corr} = S _n * N ₂ / N _n (3)

S _n : n-th imaging data adopted as data for image reconstruction S _{n, corr} : Imaging data after correcting S _n N ₂ : signal intensity at position P ₂ + Δd of data D ₂ N _n : data Signal strength at position P _n + Δd of D _n

The computing unit 91c (see FIG. 11) calculates the corrected imaging data _{Sn, corr} using the equation (3). Hereinafter, a method for correcting the imaging data using Expression (3) will be described.

FIG. 25 is an explanatory diagram when the imaging data is corrected using Expression (3).
When correcting imaging data _{S 2,} the n of the formula (3) may be substituted for n = 2.
_{S 2, corr = S 2 *} N 2 / N 2
= S ₂

Thus, imaging data _{S 2, corr} corrected is the same as the imaging data _{S 2} before correction.

However, when correcting the imaging data _{S 3,} the n of the formula (3), since n = 3 is substituted, the imaging data _{S 3, corr} corrected is expressed by the following equation.
S _{3, corr} = S ₃ * N ₂ / N ₃
Thus, imaging data _{S 3, corr} corrected will _N 2 / _{N 3} times the uncorrected imaging data _{S 3.}

Similarly, by changing the value of n in formula (3), the imaging data _{S n,} which was adopted as data for image reconstruction by multiplying _N 2 / _{N n,} imaging data _{S n corrected, corr} Can be obtained. After correcting the imaging data, the process proceeds to step ST7.

  In step ST7, image reconstruction is performed using the corrected imaging data, and the flow ends.

In a third embodiment, and the imaging data S _n, which was adopted as data for image reconstruction N _{2 /} N _n multiplied. Therefore, it is possible to correct the difference in signal intensity of the imaging data S _n caused by the difference in concentration of the contrast medium flowing into the liver, it is possible to reduce artifacts such as ringing and blur.

  In the third embodiment, image reconstruction is performed using only the imaging data acquired when the position of the edge of the liver is included in the end-of-breathing end range AW. Even when a specimen is photographed, body movement artifacts such as ghosts can be reduced.

Instead of the signal intensity N ₂ of formula (3), it may be corrected imaging data using another signal strength N _i.

(4) Fourth Embodiment In the fourth embodiment, another example will be described in which a scan is executed in a state where the subject freely breathes. The hardware configuration of the MR apparatus is the same as that in the first embodiment.

FIG. 26 is an explanatory diagram of a scan executed in the fourth mode.
In the fourth mode, pre-scan A and main scan B are executed.

In prescan A, navigator sequences NS _{1 to} NS _x are executed as in the third embodiment.

In the main scan B, imaging sequences IS _{1 to} IS _w for collecting imaging data used when reconstructing an image of an imaging region including the liver are executed. In addition to the imaging sequences IS _{1 to} IS _w , a navigator sequence NS is executed. The navigator sequence NS is executed once or more immediately before each imaging sequence IS _{1 to} IS _w .

  Hereinafter, a flow when the subject is imaged by the pre-scan A and the main scan B will be described.

FIG. 27 is a diagram showing a flow when the subject is imaged in the fourth embodiment.
In step ST1, prescan A is executed. By executing the pre-scan A, an edge position profile (see FIG. 21) representing a temporal change in the liver edge position can be obtained as in the third embodiment. After performing the pre-scan A, the process proceeds to step ST2.

In step ST2, the trigger level TL is set based on the edge position profile. FIG. 28 shows an example of the set trigger level TL. The trigger level TL is used when the main scan B is executed. Specifically, the trigger level TL is the level of the edge of the liver when the imaging sequences IS _{1 to} IS _w (see FIG. 26) are executed in the main scan B. It represents the reference position. How the trigger level TL is used when executing the main scan B will be described later. The trigger level TL can be set, for example, between the maximum value and the minimum value of the position of the liver edge. After setting the trigger level TL, the process proceeds to step ST3.

In step ST3, the main scan B is executed.
FIG. 29 is an explanatory diagram of the main scan B.
In the main scan B, first, navigator sequences NS _{11 to} NS _1P are executed. Navigator sequence _NS 11 _{~NS 1P} determined signal strength data _D 11 _{to D 1P} navigator region _{R nav} based on the collected navigator signal _A 11 _{to A 1P,} the liver edge for each signal intensity data _D 11 _{to D 1P} Positions P _{11 to} P _1P are detected. Then, when the position of the liver edge is moved from the lower side of the trigger level TL (I side) to the upper (S side), it executes the imaging sequence IS _1. By executing the imaging sequence IS ₁ , imaging data S ₁ of the imaging region R is collected.

After executing the imaging sequence IS _1, navigator sequence _NS 21 _{~NS 2q} is executed. Then, when the position of the liver edge is moved from the lower side of the trigger level TL (I side) to the upper (S side), to perform the following imaging sequence IS _2. By executing the imaging sequence IS _2, imaging data S ₂ of the imaging region R are collected.

Similarly, the navigator sequence and the imaging sequence are executed. Finally running navigator sequence _NS z1 _{~NS zr,} when the position of the liver edge is moved from the lower side of the trigger level TL (I side) to the upper (S side), it executes the imaging sequence IS _w. By executing the imaging sequence IS _w, is collected imaging data S _w of the imaging region R, the scan B is completed. After the main scan B is completed, the process proceeds to step ST4.

In step ST4, the detection means 91b (see FIG. 1) detects the signal intensity data D _{1p to} D _wr acquired immediately before the imaging sequences IS _{1 to} IS _w from the liver edge position to the liver side (I side). ) Is detected at a position separated by a distance Δd. FIG. 30 shows the detected signal strength. FIG. 30 representatively shows signal intensities N ₁ , N ₂ , and N _w detected for the signal intensity data D _1p , D _2q , and D _wr . The signal intensities N ₁ , N ₂ , and N _w represent the signal intensities at positions separated from the liver edge positions P _1p , P _2q , and P _wr by the distance Δd on the liver side (I side), respectively. After detecting the signal strength, the process proceeds to step ST5.

In step ST5, to correct the imaging data _S 1 to S _w. This correction is performed using the following equation.
S _{n, corr} = S _n * N ₁ / N _n (4)

S _n : n-th imaging data S _{n, corr} : imaging data after correcting S _n N ₁ : signal intensity detected from signal intensity data immediately before the _first imaging data S ₁ N _n : n-th signal intensity detected from the immediately preceding signal strength data of the imaging data S _n

Hereinafter, a method for correcting imaging data using Expression (4) will be described.
FIG. 31 is an explanatory diagram when the imaging data is corrected using Expression (4).
When correcting imaging data _{S 1,} the n of formula (4) may be substituted for n = 1.
_{S 1, corr = S 1 *} N 1 / N 1
= S ₁

Thus, imaging data _{S 1, corr} corrected is the same as the imaging data _{S 1} before correction.

However, when correcting the imaging data _{S 2,} the n of formula (4), since n = 2 is substituted, the imaging data _{S 2, corr} corrected is expressed by the following equation.
S _{2, corr} = S ₂ * N ₁ / N ₂

Therefore, the corrected imaging data S _{2 and corr} are N ₁ / N ₂ times the uncorrected imaging data S ₂ .

Similarly, by changing the value of n in formula (4), the imaging data _{S n} by multiplying _N 1 / _{N n,} imaging data _{S n} after _correction, can be obtained _corr. After correcting the imaging data, the process proceeds to step ST6.

  In step ST6, image reconstruction is performed using the corrected imaging data, and the flow ends.

In the fourth embodiment, since the imaging data S _n are N _{1 /} N _n times, it is possible to correct the difference in signal intensity of the imaging data S _n caused by the difference in concentration of the contrast medium flowing into the liver Artifacts such as ringing and blur can be reduced.

In the fourth embodiment, since the position of the liver edge is to acquire imaging data when it reaches the trigger level TL, the variation in the position of the liver edge when acquiring the imaging data S ₁ to S _W smaller can do. Therefore, body motion artifacts such as ghosts can be reduced.

Note that the imaging data may be corrected using another signal intensity N _i instead of the signal intensity N ₁ in Expression (4).

(5) Fifth Embodiment In the first to fourth embodiments, an example of reducing artifacts such as ringing and blur by correcting imaging data has been described. However, in the fifth embodiment, the flip angle of the RF pulse is set. An example of reducing artifacts such as ringing and blur by correcting will be described.

FIG. 32 is a schematic view of an MR apparatus according to the fifth embodiment.
The MR apparatus 300 of the fifth embodiment has a correcting means 911 for correcting the flip angle of the RF pulse, instead of the correcting means 91 (see FIG. 1) of the MR apparatus 100 of the first embodiment. Other configurations are the same as those of the MR apparatus 100 of the first embodiment. The control part 9 is an example which comprises the correction | amendment means 911 and the reconfiguration | reconstruction means 92, and functions as these means by running a predetermined program.

FIG. 33 is a diagram illustrating a scan executed in the fifth mode.
In the fifth mode, a breath holding scan BH is executed. In the breath holding scan BH, the navigator sequence NS _n (n = 1 to z) and the imaging sequence IS _n (n = 1 to z) are alternately executed. An example of the imaging sequence IS _n is shown on the lower side of FIG. Here, as an example of the imaging sequence _{IS n, SPGR (Spoiled Gradient Recalled} ) sequence is shown. The flip angle α of the RF pulse _Xn is 90 °, for example.
Hereinafter, a method for executing the breath holding scan BH will be described.

In the breath holding scan BH, first, a navigator sequence NS ₁ and an imaging sequence IS ₁ are executed. FIG. 34 shows the navigator signal A ₁ collected by the navigator sequence NS ₁ and the imaging data S ₁ collected by the imaging sequence IS ₁ . Signal strength data generating means 911a (see FIG. 32), the navigator signal A ₁ Fourier transform one dimension, thereby, the signal intensity data D ₁ representing a change in the SI direction of the signal strength of the navigator region R _nav is obtained .

Detection means 911b (see FIG. 32) detects the level difference of the signal intensity of the signal intensity data _{D 1,} to detect the position _{P 1} of the SI direction liver edge. Then, the signal intensity N ₁ at a position P ₁ + Δd that is a distance Δd away from the liver edge position P ₁ on the liver side (I side) is detected.

After executing the imaging sequence IS _1, navigator sequence NS ₂ is executed. FIG. 35 shows the navigator signal A ₂ collected by the navigator sequence NS ₂ . The navigator signal A ₂ is subjected to a one-dimensional Fourier transform to obtain signal intensity data D ₂ representing a change in signal intensity in the SI direction within the navigator region R _nav . Then, to detect the signal intensity _{N 2} at position _{P 1} + [Delta] d of the signal intensity data _{D 2.}

Next, the flip angle α of the RF pulse X ₂ of the imaging sequence IS ₂ is corrected. Hereinafter, a method of correcting the flip angle α will be described with reference to FIG. The flip angle α is corrected using the following equation.
α _{n_corr} = arcsin {(N ₁ / N _n ) * sin α} (5)

α: Flip angle before correction of imaging sequence IS _n α _{n_corr} : Flip angle after correction of imaging sequence IS _n N ₁ : Signal intensity at position P ₁ + Δd of signal intensity data D ₁ N _n : Signal intensity data D _n Signal strength at position P ₁ + Δd

The computing means 911c (see FIG. 32) calculates the corrected flip angle α _{n, corr} using equation (5). Here, since n = 2, that is, the flip angle α of the RF pulse X ₂ of the imaging sequence IS ₂ is corrected, n = 2 may be substituted for n in the equation (5).
α ₂ — _corr = arcsin {(N ₁ / N ₂ ) * sin α}

Therefore, the corrected flip angle α 2 — _corr can be obtained. When the corrected flip angle α 2 — _corr is obtained, the flip angle α of the RF pulse X ₂ of the imaging sequence IS ₂ is corrected to α 2 — _corr , and scanning of the imaging region R is executed. Therefore, the imaging data S ₂ when the flip angle α = α 2 — _corr can be obtained.

Similarly, every time the navigator sequence NS _n is executed, the corrected flip angle α _{n_corr} is calculated using the equation (5), and the imaging sequence IS _n is executed. Therefore, it is possible to obtain the imaging data _{S n} when the flip angle _α = α n_corr. FIG. 37 shows the imaging data S _{1 to} S _z obtained by the breath-hold scan BH. After collecting imaging data _S 1 to S _z, it performs image reconstruction using these imaging data _S 1 to S _z. Thereby, the image data of the imaging region R can be obtained.

In the SPGR sequence, by obtaining the arcsine of (N ₁ / N _n ) * sin α, it is possible to collect imaging data S _{1 to} S _z in which the difference in contrast agent concentration is corrected. Artifacts can be reduced.

(6) Sixth Embodiment In the fifth embodiment, an example is shown in which navigator signals and imaging data are collected in separate sequences, but in the sixth embodiment, navigator signals and imaging data are combined into one sequence. An example of collecting with C _n will be described.

FIG. 38 is a schematic diagram showing an MR apparatus according to the sixth embodiment.
The MR apparatus 400 of the sixth embodiment includes a signal intensity calculation unit 911d instead of the signal intensity data creation unit 911a and the detection unit 911b of the MR apparatus 300 (see FIG. 32) of the fifth embodiment. The configuration of is the same as that of the fifth embodiment.

FIG. 39 is a diagram illustrating a scan executed in the sixth mode.
In the sixth embodiment, a breath holding scan BH is executed. In the breath holding scan BH, the sequence C _n (n = 1 to z) is executed as in the second embodiment.

First, the sequence _{C 1} is executed. FIG. 40 shows the navigator signal A ₁ and the imaging data S ₁ collected by the sequence C ₁ . Navigator signals A ₁ and imaging data S ₁ is collected by performing a sequence C _1. Signal strength calculating unit 911d (see FIG. 38) calculates the integral value of the imaging region R navigator obtained (see FIG. 13) signal _{A 1.} Thus, it is possible to calculate the signal intensity N ₁ of the imaging region R.

After executing the sequence C _1, the following sequence C ₂ is performed. Figure 41 shows the navigator signal _{A 2} and the imaging data _{S 2} collected by the sequence _{C 2.} Signal strength calculating unit 911d calculates the integral value of the resulting navigator signal A ₂ from the imaging region R. This allows to calculate the signal strength N ₂ of the imaging region R.

After executing the sequence _{C 2,} a sequence _{C 3} is performed. However, before executing the sequence _{C 3,} flip angle α of RF pulses _{X 3} of the sequence _{C 3} is corrected. Hereinafter, a method for correcting the flip angle α of the RF pulse X ₃ of the sequence C ₃ will be described.

Figure 42 is an explanatory view of a method of correcting a flip angle α of RF pulses _{X 3} of the sequence _{C 3.}
The flip angle α of the RF pulse X ₃ of the sequence C ₃ is corrected using the following equation.
α ₃ — _corr = arcsin {(N ₁ / N ₂ ) * sin α} (6)

alpha: uncorrected flip angle alpha _{3_Corr} of RF pulses _{X 3} of the sequence _{C 3:} Sequence _{C 3} of the RF pulses _{X 3} correction flip angle after N _1: signal intensity of the imaging region R obtained by the navigator signal _{A 1} N ₂ : Signal intensity of the imaging region R obtained by the navigator signal A ₂

The computing means 911c (see FIG. 38) calculates the corrected flip angle α 3 — _corr using equation (6). The signal intensities N ₁ and N _{2 in} equation (6) have already been calculated, and the flip angle α is a predetermined value. Therefore, the corrected flip angle α 3 — _corr can be obtained by substituting N ₁ , N ₂ , and α ₃ into Equation (6). After determining the flip angle alpha _{3_Corr} corrected, the flip angle alpha of RF pulses _{X 3} of the sequence _{C 3} is corrected to alpha _{3_Corr,} it executes the sequence _{C 3.} Therefore, the navigator signal A ₃ and the imaging data S ₃ can be obtained. Signal strength calculating unit 911d calculates the integral value of the navigator signal A ₃ obtained from the imaging region R, to calculate the signal strength N ₃ of the imaging region R.

After executing the sequence _{C 3,} sequence _{C 4} is performed. However, before executing the sequence _{C 4,} flip angle α of RF pulses _{X 4} of the sequence _{C 4} is corrected. The following describes a correction method of the flip angle α of RF pulses _{X 4} of the sequence _{C 4.}

Flip angle sequence _{C 3,} since it is corrected to alpha _{3_Corr} from alpha, signal strength _{N 3} of the sequence _{C 3} is a value obtained by a flip angle _α 3_corr. On the other hand, the signal intensity N ₁ sequence C ₁ is a value obtained by flip angle alpha. Therefore, the signal strengths N ₁ and N ₃ are obtained with different flip angles. Therefore, the signal intensity N ₃ is corrected to a value obtained by the flip angle α, similarly to the signal intensity N ₁ . Signal strength N ₃ can be corrected using the following equation (7).
N _n — _corr = N _n (sin α / sin α _n — _corr ) (7)

alpha: Sequence _{C n} of RF pulses _{X n} pre-correction flip angle alpha _{N_corr:} sequence _{C n} RF pulses _{X n} correction flip angle after N _n of: signal intensity of the imaging region R obtained by the navigator signal _{A n} N _{n — corr} : Value after correction of N _n

Here, since n = 3, that is, the signal intensity N ₃ is corrected, n = 3 may be substituted for n in the equation (7).
N ₃ — _corr = N _n (sin α / sin α 3 — _corr )

Therefore, the signal intensity N ₃ obtained by the flip angle α _{3_corr} can be corrected to the signal intensity N _{3_corr} obtained by the flip angle α. FIG. 43 shows a state in which the corrected signal intensity N 3 — _corr is calculated. After _{obtaining the} corrected signal intensity N 3 — _corr , the flip angle of the next sequence C ₄ is corrected.

Figure 44 is an explanatory view of correcting the flip angle of the sequence C _4.
The flip angle α of the RF pulse X ₄ of the sequence C ₄ is corrected using the following equation.
α _{n + 1_corr} = arcsin {(N ₁ / N _{n_corr} ) * sin α} (8)

The calculating means 911c calculates the corrected flip angle α _{n_corr} using the equation (8). Here, since the flip angle α of the RF pulse X ₄ of the sequence C ₄ is corrected, n = 3 may be substituted for n in the equation (8).
α ₄ — _corr = arcsin {(N ₁ / N 3 _—corr ) * sin α}

Therefore, the corrected flip angle α 4 — _corr can be obtained. After determining the flip angle alpha _{4_Corr} corrected, the flip angle alpha of RF pulses _{X 4} of the sequence _{C 4} corrects the alpha _{4_Corr,} executing sequences _{C 4.} Therefore, it is possible to obtain a navigator signal A ₄ and imaging data S _4. Signal strength calculating unit 911d calculates the integral value of the navigator signal A ₄ obtained from the imaging region R, to calculate the signal strength N ₄ of the imaging region R.

Similarly, each time the sequence C _n is executed, the signal intensity N _n is corrected using the equation (7), and then the corrected flip angle α _{n + 1_corr} is obtained using the equation (8), and the sequence is executed. To do. When the last sequence C _z is completed, image reconstruction is performed. Thereby, the image data of the imaging region R can be obtained.

In the sixth embodiment, a single sequence C _n, are collecting both the navigator signal A _n and imaging data S _n. In this case, by correcting the flip angle after correcting the signal intensity using the equation (7), the difference in the signal intensity of the imaging data obtained by the breath-hold scan BH can be reduced. And artifacts such as blur can be reduced.

  In the fifth and sixth embodiments, the case of breath-hold scanning has been described. However, as in the third and fourth embodiments, the scan is executed with the subject freely breathing to correct the flip angle. May be.

  In the first to sixth embodiments, the case where scanning is performed using a contrast medium has been described. However, the present invention uses a contrast medium if the signal intensity of imaging data changes with time. It can also be applied when not scanning.

  Furthermore, in the first to sixth embodiments, the case of performing image reconstruction of a part that moves is explained. However, the present invention can also be applied to the case of performing image reconstruction of a part that does not move. it can.

2 Magnet 3 Table 3a Cradle 4 Reception coil 5 Contrast medium injection device 6 Transmitter 7 Gradient magnetic field power supply 8 Receiver 9 Control unit 10 Operation unit 11 Display unit 12 Subject 21 Bore 22 Superconducting coil 23 Gradient coil 24 RF coil 91a, 911a Signal intensity data creation means 91b, 911b Detection means 91c, 911c Calculation means 92 Reconstruction means 100, 200, 300, 400 MR apparatus

Claims (21)

The navigator signal is collected from the first area including the predetermined part of the subject, and the imaging data used when reconstructing the image of the predetermined part from the second area including the predetermined part is collected. A magnetic resonance apparatus,
Scanning means for executing a scan for collecting the navigator signal and the imaging data;
Based on the navigator signal, signal strength data representing a change in signal strength in a predetermined direction of the first region is created, and based on the signal strength of the first position in the predetermined direction of the signal strength data. Correction means for correcting the signal intensity of the imaging data;
Reconstruction means for performing image reconstruction based on imaging data whose signal intensity is corrected;
A magnetic resonance apparatus. The correction means includes
And the signal intensity data creating means for creating the signal strength data,
Detecting means for detecting the signal intensity at the first position of the signal intensity data;
The magnetic resonance apparatus according to claim 1, wherein the signal intensity of the imaging data is corrected based on the signal intensity. The detection means includes
The position of the edge of the predetermined part is detected based on the signal intensity data, and the signal intensity at a position away from the edge position of the predetermined part by a predetermined distance is detected as the signal intensity of the first position. The magnetic resonance apparatus according to claim 2. The scanning means includes
Alternately collecting the navigator signal and the imaging data;
The correction means includes
Based on the signal strength at the first position of the signal strength data obtained by the i-th navigator signal and the signal strength at the first position of the signal strength data obtained by the n-th navigator signal, The magnetic resonance apparatus according to claim 2, wherein the imaging data collected immediately before or after the nth navigator signal is corrected. The scanning means includes
Alternately collecting the navigator signal and a plurality of imaging data;
The correction means includes
Based on the first position of the signal strength data obtained from the i-th navigator signal and the signal strength at the first position of the signal strength data obtained from the n-th navigator signal, the n th The imaging data collected between the navigator signal and the (n + 1) th navigator signal or the imaging data collected between the nth navigator signal and the (n-1) th navigator signal is corrected. 3. The magnetic resonance apparatus according to 3.   The magnetic resonance apparatus according to claim 4, wherein the i-th navigator signal is a first navigator signal.   The magnetic resonance apparatus according to claim 1, further comprising an estimation unit configured to estimate a profile representing a temporal change in signal intensity of the predetermined part. The correction means includes
Signal intensity calculating means for calculating the signal intensity of the first region based on the navigator signal;
The magnetic resonance apparatus according to claim 1, wherein the signal intensity of the imaging data is corrected based on the signal intensity. The scanning means includes
Alternately collecting the navigator signal and the imaging data;
The correction means includes
Based on the signal strength at the first position of the signal strength data obtained by the i-th navigator signal and the signal strength at the first position of the signal strength data obtained by the n-th navigator signal, The magnetic resonance apparatus according to claim 8, wherein the imaging data collected immediately before or after the n-th navigator signal is corrected. The scanning means includes
Alternately executing the navigator signal and a plurality of imaging data;
The correction means includes
Based on the signal strength at the first position of the signal strength data obtained by the i-th navigator signal and the signal strength at the first position of the signal strength data obtained by the n-th navigator signal, correcting the imaging data collected between the nth navigator signal and the n + 1th navigator signal, or the imaging data collected between the nth navigator signal and the (n-1) th navigator signal. Item 9. The magnetic resonance apparatus according to Item 8.   The magnetic resonance apparatus according to claim 9 or 10, wherein the i-th navigator signal is a first navigator signal.   The magnetic resonance apparatus according to claim 8, wherein the first region is the same as the second region. The predetermined part is a part that moves,
The scanning unit performs scanning for collecting the navigator signal and the imaging data while the subject is holding a breath. Magnetic resonance device. The predetermined part is a part that moves,
The scanning means performs a pre-scan for acquiring a respiratory signal and a main scan for collecting the navigator signal and the imaging data,
The magnetic resonance according to any one of claims 1 to 3, wherein the navigator signal is used to obtain a position of an edge of the body moving part and a signal intensity of the body moving part. apparatus. Based on the respiration signal, set a respiration range used when determining whether to employ the imaging data as data for image reconstruction,
In the main scan, when the navigator signal and the imaging data are alternately collected, and the position of the edge of the body moving part determined by the navigator signal is included in the respiration range, the navigator signal The magnetic resonance apparatus according to claim 14, wherein imaging data collected immediately before or immediately after is adopted as data for image reconstruction. Set the reference position of the edge of the body moving part based on the respiratory signal,
The magnetic resonance apparatus according to claim 14, wherein in the main scan, the imaging data is collected when a position of an edge of the body moving part reaches the reference position.   The magnetic resonance apparatus according to claim 1, wherein the navigator signal and the imaging data are collected in separate sequences.   The magnetic resonance apparatus according to claim 1, wherein the navigator signal and the imaging data are collected in the same sequence. The injected contrast agent into the subject, collecting said navigator signals and the imaging data, magnetic resonance device according to any one of claims 1 to 18.   The magnetic resonance apparatus according to claim 1, wherein the predetermined direction is an SI direction. The navigator signal is collected from the first area including the predetermined part of the subject, and the imaging data used when reconstructing the image of the predetermined part from the second area including the predetermined part is collected. A magnetic resonance apparatus program for executing a scan for performing
Based on the navigator signal, signal strength data representing a change in signal strength in a predetermined direction of the first region is created, and based on the signal strength of the first position in the predetermined direction of the signal strength data. Correction processing for correcting the signal intensity of the imaging data;
Reconstruction processing to perform image reconstruction based on imaging data whose signal intensity is corrected;
A program to make a computer execute.

Images