JP2014166219A - Magnetic resonance apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic resonance apparatus in which generation of FID and STE are prevented.SOLUTION: An RF coil transmits an excitation pulse 90x and a refocusing pulse 180y. A gradient magnetic field coil applies four gradient magnetic field pulses G1-G4. The gradient magnetic field pulse G1 is applied between the excitation pulse 90x and the refocusing pulse 180y, and the gradient magnetic field pulse G2 is applied between the gradient magnetic field pulse G1 and the refocusing pulse 180y. The gradient magnetic field pulse G3 is applied after the refocusing pulse 180y, and the gradient magnetic field pulse G4 is applied after the gradient magnetic field pulse G3. Waiting time Tis provided between the gradient magnetic field pulses G3 and G4.

Description

  The present invention relates to a magnetic resonance apparatus that performs diffusion weighting.

  As a method for acquiring diffusion information, a method using MPG (Motion Probing Gradient) is known (see Patent Document 1).

JP 2012-157687 A

  As a sequence using MPG, a sequence using a refocus pulse for canceling the influence of B0 nonuniformity is known. However, when echoes are collected in this sequence, the echo signal may decrease due to the influence of body movement such as heartbeat. Thus, a method of correcting the flow velocity is known to suppress the signal drop of the echo. However, in the conventional flow velocity correction methods, an FID (free induction decay) signal or STE (stimulated echo) may occur. is there. Since FID and STE cause image degradation, it is desired to prevent FID and STE from being generated as much as possible.

A first aspect of the present invention is a magnet having an RF coil that transmits an excitation pulse and a refocus pulse, and a gradient coil that applies a plurality of gradient magnetic field pulses for performing diffusion weighting and flow velocity correction. A resonance device,
The plurality of gradient magnetic field pulses are:
A first gradient magnetic field pulse applied between the excitation pulse and the refocus pulse;
A second gradient magnetic field pulse applied between the first gradient magnetic field pulse and the refocus pulse and having a polarity opposite to that of the first gradient magnetic field pulse;
A third gradient magnetic field pulse applied after the refocusing pulse;
A fourth gradient magnetic field pulse applied after the third gradient magnetic field pulse and having a polarity opposite to that of the third gradient magnetic field pulse;
Contains
Magnetic resonance in which a waiting time is provided between the first gradient magnetic field pulse and the second gradient magnetic field pulse or between the third gradient magnetic field pulse and the fourth gradient magnetic field pulse Device.

A second aspect of the present invention includes an RF coil that transmits an excitation pulse, a first refocus pulse, and a second refocus pulse, and a plurality of gradient magnetic field pulses for performing diffusion weighting and flow velocity correction. A magnetic resonance apparatus having a gradient coil to be applied,
The plurality of gradient magnetic field pulses are:
A first gradient magnetic field pulse applied between the excitation pulse and the first refocus pulse;
A second gradient magnetic field pulse applied between the first refocus pulse and the second refocus pulse and having the same polarity as the first gradient magnetic field pulse;
A third gradient magnetic field pulse applied between the second gradient magnetic field pulse and the second refocusing pulse and having the same polarity as the first gradient magnetic field pulse;
When,
A fourth gradient magnetic field pulse applied after the second refocusing pulse and having the same polarity as the first gradient magnetic field pulse;
Contains
Between the first refocus pulse and the first gradient magnetic field pulse or the second gradient magnetic field pulse, or between the second refocus pulse and the third gradient magnetic field pulse or the fourth gradient magnetic field. This is a magnetic resonance apparatus in which a waiting time is provided between pulses.

A third aspect of the present invention includes an RF coil that transmits an excitation pulse, a first refocus pulse, and a second refocus pulse, and a plurality of gradient magnetic field pulses for performing diffusion weighting and flow velocity correction. A magnetic resonance apparatus having a gradient coil to be applied,
The plurality of gradient magnetic field pulses are:
A first gradient magnetic field pulse applied between the excitation pulse and the first refocus pulse;
A second gradient magnetic field pulse applied between the first refocus pulse and the second refocus pulse and having the same polarity as the first gradient magnetic field pulse;
A third gradient magnetic field pulse applied after the second refocus pulse and having the same polarity as the first gradient magnetic field pulse;
Contains
Between the first refocus pulse and the first gradient magnetic field pulse or the second gradient magnetic field pulse, or between the second refocus pulse and the second gradient magnetic field pulse or the third gradient magnetic field. This is a magnetic resonance apparatus in which a waiting time is provided between pulses.

  By adding a waiting time, the degree of freedom of the position of the gradient magnetic field pulse on the time axis can be increased. Therefore, the area of the gradient magnetic field pulse that satisfies both the condition for correcting the flow velocity and the condition for eliminating or sufficiently reducing the FID or STE can be obtained.

It is the schematic of the magnetic resonance apparatus of one form of this invention. It is explanatory drawing of the sequence which performs flow velocity correction | amendment using MPG. It is a figure which shows an example of the sequence at the time of providing one refocusing pulse. It is explanatory drawing of the sequence of this form at the time of providing one refocus pulse. It is a figure which shows the example which provided waiting time _Twait between the gradient magnetic field pulses G1 and G2. It is a figure which shows an example which applied RF pulse -90x for returning transverse magnetization to longitudinal magnetization after the gradient magnetic field pulse G4. It is a figure which shows an example of the sequence at the time of providing two refocus pulses. It is explanatory drawing of the sequence of this form at the time of providing two refocus pulses. It is a figure which shows the example which provided waiting time _Twait in another position. It is a figure which shows the example of a sequence at the time of combining the gradient magnetic field pulses G2 and G3 into one gradient magnetic field pulse. It is a figure which shows the example which provided waiting time _Twait in another position.

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

FIG. 1 is a schematic view of a magnetic resonance apparatus according to one 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 11 is accommodated. The magnet 2 includes a superconducting coil 22, a gradient magnetic field coil 23, and an RF coil 24. Superconducting coil 22 applies a static magnetic field, gradient magnetic field coil 23 applies a gradient magnetic field pulse, and 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 3 a that supports the subject 11. The cradle 3a is configured to be able to move into the bore 21. The subject 11 is transported to the bore 21 by the cradle 3a.

  The reception coil 4 is attached to the subject 11. The receiving coil 4 receives a magnetic resonance signal from the subject 11.

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

The transmitter 5 supplies current to the RF coil 24, and the gradient magnetic field power source 6 supplies current to the gradient magnetic field coil 23.
The receiver 7 performs signal processing such as detection on the signal received from the receiving coil 4.

  The control unit 8 transmits necessary information to the display unit 10 and reconstructs an image based on data received from the receiver 7 so as to realize various operations of the MR device 100. Control the operation of each part.

The operation unit 9 is operated by an operator and inputs various information to the control unit 8. The display unit 10 displays various information.
The MR apparatus 100 is configured as described above.

  In this embodiment, a sequence for acquiring diffusion weighted image data using MPG (motion probing gradient) is executed. When a sequence using MPG is executed, the signal may decrease due to the influence of body movement such as heartbeat. Therefore, flow velocity correction using MPG is performed so that the signal does not decrease as much as possible. Hereinafter, an example of a sequence for performing flow velocity correction using MPG will be described.

FIG. 2 is an explanatory diagram of a sequence for performing flow velocity correction using MPG.
First, consider the case where the RF coil 24 transmits the excitation pulse 90x, and then the gradient magnetic field coil 23 applies four gradient magnetic field pulses G1 to G4. After the four gradient magnetic field pulses G1 to G4 are applied, data is collected in the data collecting unit A. For convenience of explanation, only one axis of the gradient magnetic field is shown. Further, the RF pulse and the gradient magnetic field pulse used in the data acquisition unit A are not shown.

  The four gradient magnetic field pulses G1 to G4 are mainly provided to realize two roles of diffusion enhancement and flow velocity correction.

The b value representing the diffusion weighting of the four gradient magnetic field pulses G1 to G4 is expressed by the following equation.

ここで、Ｇ（ｔ）：時点ｔにおける傾斜磁場の大きさ The four gradient magnetic field pulses G1 to G4 satisfy the following expression so that the flow velocity can be corrected.

Where G (t): magnitude of gradient magnetic field at time t

Further, the condition for generating the echo is expressed by the following equation.

  In the sequence using MPG, the gradient magnetic field pulses G1 to G4 are set so as to satisfy the above equations (1) to (3). In order to satisfy the above equations (1) to (3), the areas of the gradient magnetic field pulses G1 to G4 may be set as follows, for example.

| S1 | = | S2 | = | S3 | = | S4 | (4)
Here, S1: Area of the gradient magnetic field pulse G1
S2: Area of the gradient magnetic field pulse G2
S3: Area of the gradient magnetic field pulse G3
S4: Area of the gradient magnetic field pulse G4

Since the gradient magnetic field pulses G1 and G4 are positive gradient magnetic field pulses, the area S1 of the gradient magnetic field pulse G1 and the area S4 of the gradient magnetic field pulse G4 are positive values. On the other hand, since the gradient magnetic field pulses G2 and G3 are negative gradient magnetic field pulses, the area S2 of the gradient magnetic field pulse G2 and the area S3 of the gradient magnetic field pulse G3 are negative values.
By satisfying the above conditions, spin echoes can be generated while correcting the flow velocity.

  In FIG. 2, no RF pulse is shown between the excitation pulse 90x and the data acquisition unit A. However, in the actual sequence, a refocus pulse is provided to cancel the influence of B0 nonuniformity. Hereinafter, a case where one refocus pulse is provided and a case where two refocus pulses are provided will be described in order.

(1) Sequence when One Refocus Pulse is Provided FIG. 3 is a diagram illustrating an example of a sequence when one refocus pulse is provided.
In FIG. 3, the RF coil 24 transmits a refocus pulse 180y between the gradient magnetic field pulses G2 and G3. Since the spin is inverted by 180 ° by the refocus pulse 180y, the polarities of the gradient magnetic field pulses G3 and G4 are set to the opposite polarities to those in FIG. That is, the gradient magnetic field pulse G3 has a positive polarity, and the gradient magnetic field pulse G4 has a negative polarity. Therefore, in the case of the sequence shown in FIG. 3, Equation (2) is rewritten to the following Equation (5), and Equation (3) is rewritten to the following Equation (6).

  Therefore, when the refocus pulse 180y is provided, the gradient magnetic field pulses G1 to G4 may be set so as to satisfy the expressions (5) and (6) in addition to the expressions (1) and (4). By satisfying the expressions (1), (4), (5), and (6), it is possible to generate spin echoes while performing flow velocity correction.

However, the actual flip angle of the spin by the refocus pulse 180y may deviate from 180 °, thereby generating a free induction decay (FID) signal in addition to the spin echo. Since the FID signal causes image degradation, it is desirable that the FID signal is not generated as much as possible. However, if the areas of the gradient magnetic field pulses G1 to G4 are set so as to satisfy the equation (4), the absolute values of the areas of the gradient magnetic field pulses G1 to G4 are equal, so the FID signal cannot be erased. Therefore, as one method for preventing the generation of the FID signal, it is conceivable to set the area of the gradient magnetic field pulse so as to satisfy the following equation (7) instead of the equation (4).
S1 + S2 ≠ 0 (7)
Here, S1: Area of the gradient magnetic field pulse G1
S2: Area of the gradient magnetic field pulse G2

  When the areas of the gradient magnetic field pulses G1 and G2 are set so as to satisfy the expression (7), the areas of the gradient magnetic field pulses G1 to G4 become asymmetric, so that the FID signal can be reduced. Therefore, if the area of the gradient magnetic field pulses G1 to G4 can be set so as to satisfy Expression (7) in addition to Expression (1), Expression (5), and Expression (6), the FID signal can be reduced. A sequence that can be obtained is obtained. However, in the sequence of FIG. 3, the areas of the gradient magnetic field pulses G1 to G4 that satisfy both the conditions of the expressions (1), (5), and (6) and the expression (7) are obtained. I can't. Therefore, in the present embodiment, when one refocus pulse 180y is provided, the following sequence is used so that the areas of the gradient magnetic field pulses G1 to G4 that satisfy both the above conditions can be calculated (FIG. 4). reference).

FIG. 4 is an explanatory diagram of the sequence of this embodiment in the case where one refocus pulse is provided.
In FIG. 4, a waiting time T _wait is provided between the gradient magnetic field pulses G3 and G4. By providing the waiting time T _wait , the degree of freedom of the position of the gradient magnetic field pulses G1 to G4 on the time axis can be increased. Therefore, the conditions and expressions of Expression (1), Expression (5), and Expression (6) The areas of the gradient magnetic field pulses G1 to G4 that satisfy both of the conditions of (7) can be obtained.

In Equation (7), S1 + S2 ≠ 0, but the specific value of S1 + S2 depends on the image resolution res [mm]. Specifically, S1 + S2 may be set so that the phase rotates once by res [mm]. S1 + S2 is expressed by the following expression using the resolution res of the image.
S1 + S2 = 1 / γ / res (8)
Where γ: Proton gyromagnetic ratio res: Image resolution

The magnetorotational ratio γ of protons is γ = 42.58 [MHz / tesla] = 42.58 [1 / Tesla / μsec]. Therefore, for example, when res = 1 [mm] = 0.001 [meter], S1 + S2 has the following value.
S1 + S2 = 1 / 42.58 [1 / Tesla / μsec] /0.001 [meter]
= 23.49 [μsec * Tesla / meter]

  Therefore, the value of S1 + S2 can be calculated based on the image resolution res. The calculation of the value of S1 + S2 can be realized, for example, by providing the control unit 8 with a calculation means for calculating the value of S1 + S2 based on the image resolution res.

In FIG. 4, is provided with the waiting time _{T wait} between the gradient pulse G3 and G4, it may be provided latency _{T wait} between the gradient pulses G1 and G2. FIG. 5 shows an example in which a waiting time T _wait is provided between the gradient magnetic field pulses G1 and G2.

As shown in FIG. 5, even when the waiting time T _wait is provided, gradient magnetic field pulses G1 to G4 that satisfy both the conditions of the expressions (1), (5), and (6) and the expression (7). Can be obtained. Accordingly, the FID signal can be deleted (or the signal value of the FID signal can be made sufficiently small) while performing flow velocity correction.

  Note that an RF pulse for returning the transverse magnetization to the longitudinal magnetization may be applied after the gradient magnetic field pulse G4. FIG. 6 shows an example in which an RF pulse −90x for returning transverse magnetization to longitudinal magnetization is applied after the gradient magnetic field pulse G4. 6 shows an example in which the RF pulse −90x is applied to the sequence of FIG. 4, the RF pulse −90x may be applied to the sequence of FIG. 5.

  In FIGS. 4 to 6, the polarities of the gradient magnetic field pulses G1 to G4 are arranged in the order of (positive, negative, positive, negative). However, depending on conditions such as the excitation pulse and the refocusing pulse, the polarities are different. It is possible to make the order. For example, the order may be (negative, positive, negative, positive) or (positive, negative, negative, positive).

  Next, an example in which two refocus pulses are provided will be described.

(2) Sequence when two refocus pulses are provided
FIG. 7 is a diagram illustrating an example of a sequence when two refocus pulses are provided.
In FIG. 7, the RF coil 24 transmits a refocus pulse 180y1 between the gradient magnetic field pulses G1 and G2, and transmits a refocus pulse 180y2 between the gradient magnetic field pulses G3 and G4. Since each of the two refocus pulses 180y1 and 180y2 reverses the spin by 180 °, the polarities of the gradient magnetic field pulses G2 and G3 are set to the opposite polarities to those in FIG. That is, the gradient magnetic field pulses G2 and G3 have a positive polarity. Therefore, in the case of the sequence of FIG. 7, Equation (2) is rewritten to Equation (9) below, and Equation (3) is rewritten to Equation (10) below.

  Accordingly, when two refocus pulses 180y1 and 180y2 are provided, gradient magnetic field pulses G1 to G4 are set so as to satisfy Expressions (9) and (10) in addition to Expressions (1) and (4). Good. By satisfying the expressions (1), (4), (9), and (10), the spin echo can be generated while the flow velocity is corrected.

However, the actual flip angle of the spin caused by the refocus pulses 180y1 and 180y2 may deviate from 180 °, which causes STE (stimulated echo) in addition to the spin echo. Since STE causes image degradation, it is desirable to prevent STE from being generated as much as possible. However, if the areas of the gradient magnetic field pulses G1 to G4 are set so as to satisfy the expression (4), the absolute values of the areas of the gradient magnetic field pulses G1 to G4 are equal, and therefore the STE cannot be erased. Therefore, as one method for preventing the generation of STE, it is conceivable to set the area of the gradient magnetic field pulse so as to satisfy the following equation (11) instead of the equation (4).
S1-S4 ≠ 0 (11)
Here, S1: Area of the gradient magnetic field pulse G1
S4: Area of the gradient magnetic field pulse G4

  When the areas of the gradient magnetic field pulses G1 and G4 are set so as to satisfy the expression (11), the areas of the gradient magnetic field pulses G1 to G4 become asymmetric, so that STE can be reduced. Therefore, if the areas of the gradient magnetic field pulses G1 to G4 can be set so as to satisfy Expression (11) in addition to Expression (1), Expression (9), and Expression (10), STE can be reduced. A possible sequence is obtained. However, in the sequence of FIG. 7, the areas of the gradient magnetic field pulses G1 to G4 that satisfy both the conditions of the expressions (1), (9), and (10) and the expression (11) are obtained. I can't. Therefore, in the present embodiment, when two refocus pulses 180y1 and 180y2 are provided, the following sequence is used so that the areas of the gradient magnetic field pulses G1 to G4 satisfying both the above conditions can be calculated ( (See FIG. 8).

FIG. 8 is an explanatory diagram of the sequence of this embodiment in the case where two refocus pulses are provided.
In FIG. 8, a waiting time T _wait is provided between the refocus pulse 180y2 and the gradient magnetic field pulse G4. By providing the waiting time T _wait , the degree of freedom of the position of the gradient magnetic field pulses G1 to G4 on the time axis can be increased. Therefore, the conditions and expressions of the expressions (1), (9), and (10) The areas of the gradient magnetic field pulses G1 to G4 that satisfy both of the conditions of (11) can be obtained.

In Equation (11), S1−S4 ≠ 0, but the specific value of S1−S4 depends on the resolution of the image res [mm]. Specifically, S1-S4 may be set so that the phase rotates once by res [mm]. S1-S4 is expressed by the following equation using the resolution res of the image.
S1-S4 = 1 / γ / res (12)
Where γ: Proton gyromagnetic ratio res: Image resolution

The magnetorotational ratio γ of protons is γ = 42.58 [MHz / tesla] = 42.58 [1 / Tesla / μsec]. Therefore, for example, when res = 1 [mm] = 0.001 [meter], S1-S4 has the following values.
S1-S4 = 1 / 42.58 [1 / Tesla / μsec] /0.001 [meter]
= 23.49 [μsec * Tesla / meter]

  Therefore, the values of S1-S4 can be determined based on the image resolution res. The calculation of the value of S1-S4 can be realized, for example, by providing the control unit 8 with calculation means for calculating the value of S1-S4 based on the image resolution res.

In FIG. 8, is provided with the waiting time _{T wait} between refocusing pulses 180y2 and the gradient magnetic field pulse G4, may be provided latency _{T wait} to another location. FIG. 9 shows an example in which a waiting time T _wait is provided at another position.

FIG. 9A shows an example in which a waiting time T _wait is provided between the gradient magnetic field pulse G1 and the refocusing pulse 180y1. FIG. 9B shows an example in which a waiting time T _wait is provided between the refocus pulse 180y1 and the gradient magnetic field pulse G2. FIG. 9C shows an example of the gradient magnetic field pulse G3 and the refocus pulse 180y2. This is an example in which a waiting time T _wait is provided between them.

As shown in FIG. 9, even if the waiting time T _wait is provided, gradient magnetic field pulses G1 to G4 that satisfy both the conditions of the expressions (1), (9), and (10) and the expression (11). Can be obtained. Therefore, the STE can be erased (or the signal value of the STE can be made sufficiently small) while performing the flow velocity correction. In the sequence shown in FIGS. 8 and 9, an RF pulse for returning the transverse magnetization to the longitudinal magnetization may be applied after the gradient magnetic field pulse G4.

  8 and 9, the gradient magnetic field pulses G1 to G4 are all positive in polarity, but may be all negative in accordance with conditions such as an excitation pulse and a refocus pulse.

  In the examples of FIGS. 8 and 9, four gradient magnetic field pulses G1 to G4 are provided. However, the gradient magnetic field pulses G2 and G3 may be combined into one gradient magnetic field pulse (see FIG. 10).

FIG. 10 is a diagram showing an example of a sequence when the gradient magnetic field pulses G2 and G3 are combined into one gradient magnetic field pulse.
In FIG. 10, the gradient magnetic field pulses G2 and G3 are combined into one gradient magnetic field pulse Gc. Therefore, only three gradient magnetic field pulses G1, Gc, and G4 are applied before the data acquisition unit A. In the case of the sequence shown in FIG. 10, equation (2) is rewritten to the following equation (13), and equation (3) is rewritten to the following equation (14).

Further, the area of the gradient magnetic field pulse is set so as to satisfy the following condition so as not to generate STE.
S1-S4 ≠ 0 (15)
Here, S1: Area of the gradient magnetic field pulse G1
S4: Area of the gradient magnetic field pulse G4

In FIG. 10, a waiting time T _wait is provided between the gradient magnetic field pulse G1 and the refocus pulse 180y1. By providing the waiting time T _wait , the degree of freedom of the position of the gradient magnetic field pulses G1, Gc, and G4 on the time axis can be increased, so that the equations (1), (13), and (14) The areas of the gradient magnetic field pulses G1, Gc, and G4 that satisfy both the condition and the condition of Expression (15) can be obtained. Therefore, the STE can be erased (or the signal value of the STE can be made sufficiently small) while performing the flow velocity correction.

  In Expression (15), S1−S4 ≠ 0, but a specific value of S1−S4 can be obtained by Expression (12) using the resolution of the image res. The calculation of the value of S1-S4 can be realized, for example, by providing the control unit 8 with calculation means for calculating the value of S1-S4 based on the image resolution res.

In FIG 10, is provided with the waiting time _{T wait} between gradient magnetic field pulse G1 and refocusing pulse 180Y1, it may be provided latency _{T wait} to another location. FIG. 11 shows an example in which a waiting time T _wait is provided at another position.

FIG. 11A shows an example in which a waiting time T _wait is provided between the refocus pulse 180y1 and the gradient magnetic field pulse Gc. FIG. 11B shows an example in which a waiting time T _wait is provided between the gradient magnetic field pulse Gc and the refocus pulse 180y2, and FIG. 11C shows the refocus pulse 180y2 and the gradient magnetic field pulse G4. This is an example in which a waiting time T _wait is provided between them.

As shown in FIG. 11, even when the waiting time T _wait is provided, gradient magnetic field pulses G1 and Gc that satisfy both the conditions of the equations (1), (13), and (14) and the equation (15) are satisfied. , And the area of G4. Therefore, the STE can be erased (or the signal value of the STE can be made sufficiently small) while performing the flow velocity correction. In the sequence shown in FIGS. 10 and 11, an RF pulse for returning the transverse magnetization to the longitudinal magnetization may be applied after the gradient magnetic field pulse G4.

  In FIGS. 10 and 11, the gradient magnetic field pulses G1, Gc, and G4 are all positive in polarity, but may be all negative in accordance with conditions such as an excitation pulse and a refocus pulse. is there.

  In this embodiment, an example is shown in which the flip angle of the excitation pulse is 90 ° and the flip angle of the refocus pulse is 180 °. However, the flip angles of these pulses are limited to 90 ° and 180 °. It will never be done.

2 Magnet 3 Table 3a Cradle 4 Receiving coil 5 Transmitter 6 Gradient magnetic field power supply 7 Receiver 8 Control unit 9 Operation unit 10 Display unit 11 Subject 21 Bore 22 Superconducting coil 23 Gradient magnetic field coil 24 RF coil 100 MR apparatus

Claims (9)

An RF coil for transmitting an excitation pulse and a refocusing pulse;
A gradient coil for applying a plurality of gradient pulses for performing diffusion weighting and flow velocity correction;
A magnetic resonance apparatus comprising:
The plurality of gradient magnetic field pulses are:
A first gradient magnetic field pulse applied between the excitation pulse and the refocus pulse;
A second gradient magnetic field pulse applied between the first gradient magnetic field pulse and the refocus pulse and having a polarity opposite to that of the first gradient magnetic field pulse;
A third gradient magnetic field pulse applied after the refocusing pulse;
A fourth gradient magnetic field pulse applied after the third gradient magnetic field pulse and having a polarity opposite to that of the third gradient magnetic field pulse;
Contains
Magnetic resonance in which a waiting time is provided between the first gradient magnetic field pulse and the second gradient magnetic field pulse or between the third gradient magnetic field pulse and the fourth gradient magnetic field pulse apparatus. The first gradient magnetic field pulse, the second gradient magnetic field pulse, the third gradient magnetic field pulse, and the fourth gradient magnetic field pulse are set to satisfy the following conditions: The magnetic resonance apparatus described.

  3. The magnetic resonance apparatus according to claim 1, further comprising a calculating unit that calculates a sum of an area of the first gradient magnetic field pulse and an area of the second gradient magnetic field pulse based on an image resolution. An RF coil that transmits the excitation pulse, the first refocus pulse, and the second refocus pulse;
A gradient coil for applying a plurality of gradient pulses for performing diffusion weighting and flow velocity correction;
A magnetic resonance apparatus comprising:
The plurality of gradient magnetic field pulses are:
A first gradient magnetic field pulse applied between the excitation pulse and the first refocus pulse;
A second gradient magnetic field pulse applied between the first refocus pulse and the second refocus pulse and having the same polarity as the first gradient magnetic field pulse;
A third gradient magnetic field pulse applied between the second gradient magnetic field pulse and the second refocusing pulse and having the same polarity as the first gradient magnetic field pulse;
When,
A fourth gradient magnetic field pulse applied after the second refocusing pulse and having the same polarity as the first gradient magnetic field pulse;
Contains
Between the first refocus pulse and the first gradient magnetic field pulse or the second gradient magnetic field pulse, or between the second refocus pulse and the third gradient magnetic field pulse or the fourth gradient magnetic field. A magnetic resonance apparatus in which a waiting time is provided between pulses. The first gradient magnetic field pulse, the second gradient magnetic field pulse, the third gradient magnetic field pulse, and the fourth gradient magnetic field pulse are set to satisfy the following conditions: The magnetic resonance apparatus described.

  6. The magnetic resonance apparatus according to claim 4, further comprising calculation means for calculating a difference between an area of the first gradient magnetic field pulse and an area of the fourth gradient magnetic field pulse based on a resolution of the image. An RF coil that transmits the excitation pulse, the first refocus pulse, and the second refocus pulse;
A gradient coil for applying a plurality of gradient pulses for performing diffusion weighting and flow velocity correction;
A magnetic resonance apparatus comprising:
The plurality of gradient magnetic field pulses are:
A first gradient magnetic field pulse applied between the excitation pulse and the first refocus pulse;
A second gradient magnetic field pulse applied between the first refocus pulse and the second refocus pulse and having the same polarity as the first gradient magnetic field pulse;
A third gradient magnetic field pulse applied after the second refocus pulse and having the same polarity as the first gradient magnetic field pulse;
Contains
Between the first refocus pulse and the first gradient magnetic field pulse or the second gradient magnetic field pulse, or between the second refocus pulse and the second gradient magnetic field pulse or the third gradient magnetic field. A magnetic resonance apparatus in which a waiting time is provided between pulses. The magnetic resonance apparatus according to claim 7, wherein the first gradient magnetic field pulse, the second gradient magnetic field pulse, and the third gradient magnetic field pulse are set to satisfy the following condition.

9. The magnetic resonance apparatus according to claim 7, further comprising a calculation unit that calculates a difference between an area of the first gradient magnetic field pulse and an area of the fourth gradient magnetic field pulse based on an image resolution.

Images