JP2002336213A - Mri apparatus adjusting method and mri apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress dispersion of image qualities of MR images of multiple slices. SOLUTION: This MRI apparatus adjusting method is not only scanning for adjusting a transmission gain and a receiving gain of a single slice to be a center but also scanning for adjusting transmission gains and receiving gains of respective two or more slices and the transmission gains and the receiving gains of the respective slices are optimized based on the obtained data. This method can provide a similar quality MR image for any slice.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an MRI (Magnetic
More particularly, the present invention relates to an MRI apparatus adjustment method and an MRI apparatus that can adjust any slice to an optimum transmission gain and an optimum reception gain.

[0002]

2. Description of the Related Art The flip angle changes depending on the driving power of a transmission coil of an MRI apparatus, and the NMR signal intensity changes. Therefore, by adjusting the transmission gain that determines the driving power of the transmission coil, the driving power of the transmission coil is optimized so that the NMR signal intensity is maximized.

Further, if the amplification degree of the NMR signal received by the receiving coil is not appropriate, a post-stage circuit (AD converter, etc.)
Input signal (amplified NMR)
Signal) is too large or too small. Therefore, by adjusting the reception gain that determines the amplification degree of the NMR signal, the amplification degree of the NMR signal is optimized to match the dynamic range of the subsequent circuit.

For example, when the imaging pulse sequence is the pulse sequence of the spin echo method shown in FIG. 14, not only the phase gradient (gradient of the phase encode axis) of the imaging pulse sequence is added, but also sufficiently longer than the longitudinal relaxation time T1 ( FIG. 15 shows a transmission gain adjustment pulse sequence with a repetition time of at least three times longer than TR.
The collection of projection data as shown in (1) is repeated while changing the transmission gain (this is called a transmission gain adjustment scan), and the transmission gain that maximizes the area of the obtained projection data is used to collect image creation data. Is determined as the transmission gain at the time of scanning (this is referred to as main scanning). Also, collecting projection data by the reception gain adjustment pulse sequence without adding only the phase gradient of the imaging pulse sequence (the same repetition time TR is the same) is repeated while changing the reception gain (this is called reception gain adjustment scan). The reception gain at which the area of the obtained projection data is about 90% of the saturation value is determined as the reception gain at the time of the main scan.

[0005]

Conventionally, as shown in FIG. 16, when a plurality of slices L1 to L7 are photographed, the transmission gain and the reception gain are adjusted for the central slice L4, and the optimized transmission is performed. The gain and the reception gain have been applied to all slices L1 to L7.

However, as shown in FIG. 17, the MR image of the center slice L4 is optimal, but the MR images of slices farther from it (eg, L1 and L7) are not optimal (for example, the luminance is low). Low). This is presumably because the RF intensity and the NMR signal intensity are not uniform in all slices due to the electrical and magnetic structure of the subject α, the distance from the coil to the slice, and the non-uniformity of the magnetic field of the MRI apparatus.

Therefore, an object of the present invention is to provide an MR which can adjust the transmission gain and the reception gain to the optimum values in any slice.
An object of the present invention is to provide an I apparatus adjustment method and an MRI apparatus.

[0008]

According to a first aspect, the present invention provides a repetition time TR which does not add only the phase gradient of the imaging pulse sequence and is sufficiently longer than the longitudinal relaxation time T1.
Collection of projection data for one slice by the transmission gain adjustment pulse sequence set as s is repeated at two or more slice positions while changing the transmission gain, and transmission at each slice position is performed based on the obtained projection data. There is provided an MRI apparatus adjustment method characterized by determining gains. The first
In the MRI apparatus adjustment method according to the aspect described above, the transmission gain adjustment scan is not performed only for one central slice, but is performed for each slice at two or more slice positions. Then, the transmission gain of each slice for performing the main scan is determined based on the projection data of the same slice or the nearest slice in the transmission gain adjustment scan. Therefore, the transmission gain can be optimized in all of the plurality of slices during the main scan.

According to a second aspect, the present invention provides an M
In the RI device adjustment method, a transmission gain adjustment pulse sequence for collecting projection data for another slice is inserted while the transmission gain adjustment pulse sequence is repeated for collecting projection data for one slice. An MRI apparatus adjustment method is provided. In the MRI apparatus adjustment method according to the second aspect, while the transmission gain adjustment pulse sequence for one slice is repeated while changing the transmission gain, the transmission gain adjustment pulse sequence for another slice is inserted. The time required for the adjustment scan can be reduced.

In a third aspect, the present invention provides a method for collecting projection data for one slice by a reception gain adjustment pulse sequence that does not add only the phase gradient of an imaging pulse sequence, while changing the reception gain. MRI characterized by repeatedly receiving at each slice position and determining a reception gain at each slice position based on the obtained projection data.
An apparatus adjustment method is provided. MRI according to the third aspect
In the apparatus adjustment method, the scan for adjusting the reception gain is not performed only for one central slice, but is performed for each slice at two or more slice positions. Then, the reception gain of each slice for performing the main scan is determined based on the projection data of the same slice or the nearest slice in the reception gain adjustment scan. Therefore, the reception gain can be optimized in all of the plurality of slices during the main scan.

According to a fourth aspect, the present invention provides an M
In the RI device adjustment method, while repeating the reception gain adjustment pulse sequence to collect projection data for one slice, inserting a reception gain adjustment pulse sequence for collecting projection data for another slice. An MRI apparatus adjustment method is provided. In the MRI apparatus adjustment method according to the fourth aspect, while repeating the reception gain adjustment pulse sequence for one slice while changing the reception gain, the reception gain adjustment pulse sequence for another slice is inserted. The time required for the adjustment scan can be reduced.

In a fifth aspect, the present invention provides a transmission coil for transmitting an RF pulse, transmission power adjusting means for adjusting the driving power of the transmission coil in accordance with a transmission gain, and a transmission power adjusting means for applying a gradient magnetic field. Gradient coils, receiving coils for receiving NMR signals, and driving the transmitting coils, gradient coils, and receiving coils to collect image creation data for one slice by an imaging pulse sequence. The main scanning means which repeats at each slice position, and the transmission coil, the gradient coil, and the reception coil are driven so that only the phase gradient of the imaging pulse sequence is added and the repetition time TRs is sufficiently longer than the longitudinal relaxation time T1. Collect projection data for one slice by gain adjustment pulse sequence Transmission gain adjusting scanning means for repeating the above at two or more slice positions while changing the transmission gain, and transmission gain at each slice position determined based on the obtained projection data and passed to the main scanning means. An MRI apparatus comprising an adjustment unit is provided. In the MRI apparatus according to the fifth aspect, the MRI apparatus adjustment method according to the first aspect can be suitably implemented.

According to a sixth aspect, the present invention provides an M
In the RI apparatus, the transmission gain adjustment scanning means may include a transmission gain for collecting projection data for another slice while repeating a transmission gain adjustment pulse sequence for collecting projection data for one slice. Provided is an MRI apparatus characterized by including an adjustment pulse sequence. In the MRI apparatus according to the sixth aspect, the MRI apparatus adjustment method according to the second aspect can be suitably implemented.

In a seventh aspect, the present invention provides a transmission coil for transmitting an RF pulse, a gradient coil for applying a gradient magnetic field, a reception coil for receiving an NMR signal, Receiving amplitude adjusting means for adjusting the amplification degree of the NMR signal, and collecting the image creation data for one slice by the imaging pulse sequence by driving the transmission coil, the gradient coil, and the reception coil. The projection for one slice is performed by the main scanning unit that repeats at each slice position described above, and the reception gain adjustment pulse sequence that drives the transmission coil, the gradient coil, and the reception coil and does not add only the phase gradient of the imaging pulse sequence. Acquiring data means changing the receiving gain to two or more slice positions An MRI apparatus comprising: a receiving gain adjusting scanning unit that repeats; and a receiving gain adjusting unit that determines a receiving gain at each slice position based on the obtained projection data and passes the determined receiving gain to the main scanning unit. provide. In the MRI apparatus according to the seventh aspect, the MRI apparatus adjustment method according to the third aspect can be suitably implemented.

According to an eighth aspect, the present invention provides an M
In the RI apparatus, the reception gain adjustment scanning means may include a reception gain for collecting projection data for another slice while repeating the reception gain adjustment pulse sequence for collecting projection data for one slice. Provided is an MRI apparatus characterized by including an adjustment pulse sequence. In the MRI apparatus according to the eighth aspect, the MRI apparatus adjustment method according to the fourth aspect can be suitably implemented.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the drawings. Note that the present invention is not limited by this.

FIG. 1 shows an MR according to an embodiment of the present invention.
It is a block diagram which shows I apparatus. This MRI apparatus 100
, The magnet assembly 1 has a space portion (bore) for inserting the subject therein, and a static magnetic field coil 1p for applying a constant static magnetic field to the subject so as to surround the space portion; A gradient magnetic field coil 1g for generating a gradient magnetic field of the X, Y, and Z axes (a slice gradient axis, a read gradient axis, and a phase encode gradient axis are formed by a combination of the X, Y, and Z axes); A transmission coil 1t for applying an RF pulse for exciting spins of nuclei in the subject and a receiving coil 1r for detecting an NMR signal from the subject are arranged. The static magnetic field coil 1p, the gradient magnetic field coil 1g, the transmitting coil 1t, and the receiving coil 1r are connected to a static magnetic field power supply 2, a gradient magnetic field driving circuit 3, an RF power amplifier 4, and a preamplifier 5, respectively.

The sequence storage circuit 6 operates the gradient magnetic field drive circuit 3 based on the stored pulse sequence in accordance with a command from the computer 7 to generate a gradient magnetic field from the gradient magnetic field coil 1g of the magnet assembly 1 and The gate modulation circuit 8 is operated to modulate the carrier wave output signal of the RF oscillation circuit 9 into a pulse signal having a predetermined timing and a predetermined envelope shape, which is added to the RF power amplifier 4 as an RF pulse. After power amplification,
This is applied to the transmission coil 1t of the magnet assembly 1 to selectively excite a desired imaging surface. As described below, R
The transmission gain of the F power amplifier 4 is adjusted by the computer 7.

The preamplifier 5 includes a magnet assembly 1
, And amplifies the NMR signal from the subject received by the receiving coil 1r and inputs the amplified signal to the phase detector 10. Phase detector 10
Uses the carrier output signal of the RF oscillation circuit 9 as a reference signal,
The NMR signal from the preamplifier 5 is phase-detected and supplied to the AD converter 11. The AD converter 11 converts the analog signal after the phase detection into digital data and inputs the digital data to the computer 7. As described later, the reception gain of the preamplifier 5 is adjusted by the computer 7.

The computer 7 is in charge of overall control such as receiving information input from the operation console 12.
The computer 7 reads the digital data from the AD converter 11 and performs an image reconstruction operation to generate an MR image. The display device 13 displays the MR image.

FIG. 2 is a flowchart showing a transmission gain adjustment process by the MRI apparatus 100. In steps P2, P4, and P9, an appropriate waiting time is provided, and the execution timing of the transmission gain adjustment scan is adjusted.

In step P1, the transmission gain number i is initialized to "1". Here, it is assumed that ten transmission gains tx1 to tx10 are prepared in advance, and these transmission gains tx1 to tx10 are associated with transmission gain numbers i = 1 to 10.

In step P2, the transmission gain tx = tx
(At first, tx = tx1). In Step P3, the slice number n is initialized to “1”. Here, FIG.
It is assumed that the slice positions of the seven slices L1 to L7 are set in advance, and the slices L1 to L7 are associated with slice numbers n = 1 to 7.

In step P4, a transmission gain adjustment pulse sequence is executed for slice Ln (first slice L1) to collect projection data, and obtain projection area Ta [n] (first Ta [1]).
The transmission gain adjusting pulse sequence has a repetition time T that is not only the phase gradient of the imaging pulse sequence set in advance but sufficiently longer than the longitudinal relaxation time T1 (more than three times longer than the imaging pulse sequence TR).
Rs is a pulse sequence. In step P5, the current transmission gain tx and the projection area Ta
[n] is stored.

In step P6, the slice number n is increased by "2". This is because an adjacent pulse is skipped as a next scan slice because an RF pulse for a certain slice affects an adjacent slice. In step P7, if the slice Ln corresponding to the slice number n exists, the process returns to step P4, and if not, the process proceeds to step P8. By the first steps P3 to P7, as shown in FIG. 3, the projection areas Ta [1], Ta [3], and Ta for the slices L1, L3, L5, and L7 with the transmission gain tx1.
[5] and Ta [7] are stored.

In step P8, the slice number n is initialized to "2".

In step P9, a transmission gain adjustment pulse sequence is executed for the slice Ln (first slice L2) to collect projection data, and obtain a projection area Ta [n] (first Ta [2]).
In Step P10, the current transmission gain tx and the projection area Ta [n] are stored.

At step P11, the slice number n is increased by "2". In step P12, if the slice Ln corresponding to the slice number n exists, the process returns to step P9, and if not, the process proceeds to step P13.
By the first steps P8 to P12, as shown in FIG. 3, the projection areas Ta [2], Ta [4], and T [4] for the slices L2, L4, and L6 with the transmission gain tx1.
a [6] is stored.

In step P13, the transmission gain number i is increased by "1". In Step P14, if the transmission gain txi corresponding to the transmission gain number i exists, the process returns to Step P2, and if not, the process proceeds to Step P15. By the above steps P1 to P14, as shown in FIG. 3, the projection areas Ta [1] to Ta [1] to slices L1 to L7 with transmission gains tx1 to tx10, respectively.
Ta [7] is stored. Then, the above steps P2 to P
The time required to execute 14 once is the repetition time TRs.

In step P15, as shown in FIG.
The transmission gain tx (tx5 in FIG. 4) that gives the maximum of the projection area Ta [1] of slice L1 is set to slice L1.
It is assumed that the optimum transmission gain Tx [1] is 1. Further, as shown in FIG. 5, the projection area Ta of the slice L2 is obtained.
Transmission gain tx that gives the maximum of [2] (tx6 in FIG. 5)
Is the optimal transmission gain Tx [2] of the slice L2.
Similarly, the optimum transmission gain Tx for slices L3 to L7
[3] to Tx [7] are determined. Then, the process ends.

As described above, it is possible to optimize the transmission gain in each of the slices L1 to L7. Further, since the transmission gain adjustment pulse sequence for the other slices L2 to L7 is inserted between the transmission gain adjustment pulse sequence repetition times TRs for the slice L1, the time required for the transmission gain adjustment scan is reduced. it can. That is, the conventional slice L4
It is not necessary to extend the time required for the scan for adjusting the transmission gain for only the transmission gain.

If it is not possible to insert the transmission gain adjustment scans of all the other slices between the transmission gain adjustment scans of one slice during the given repetition time TRs, all slices are divided into two or more groups. And the process of FIG. 2 may be executed for each group. In this case, the time required for the transmission gain adjustment scan is longer than the time required for the conventional transmission gain adjustment scan only for slice L4.

In steps P1 to P14 in which steps P8 to P12 are omitted, projection areas Ta [1], Ta [3] and Ta [5 for slices L1, L3, L5 and L7 at transmission gains tx1 to Tx10. ], Ta [7]
Is stored, and in step p15, as described above, the optimum transmission gain Tx for slices L1, L3, L5, and L7
[1], Tx [3], Tx [5], Tx [7] are determined, and the optimal transmission gain Tx [2] of the slices L2, L4, L6 = (Tx [1] + Tx [3]) / 2, Tx
[4] = (Tx [3] + Tx [5]) / 2, Tx [6]
= (Tx [5] + Tx [7]) / 2. By omitting the transmission gain adjustment scan for some slices as described above, the load of the transmission gain adjustment scan can be reduced. In particular, the determined repetition time TRs
This is effective when transmission gain adjustment scans of all other slices cannot be inserted between transmission gain adjustment scans of one slice.

FIGS. 6 and 7 show the MRI apparatus 100 described above.
6 is a flowchart showing a reception gain adjustment process according to the first embodiment. It is assumed that an appropriate waiting time is provided in steps P21 and P25, and the execution timing of the reception gain adjustment scan is adjusted.

In step P20, the group number k is initialized to "1". Note that all slices are divided into groups for each of the number of other slices that can be inserted during the scan for adjusting the reception gain of one slice (this is called the nesting number), and the number assigned to each group is the group number. k. The number of groups is K. Generally, when the number of slices is N, the number of nests is M, and up ｛｝ is a function that rounds up a decimal part and converts it to an integer, K = up ｛N /
(M + 1)}. For example, assuming N = 7 and M = 2, K = 3.

In step P21, the reception gain number i is initialized to "1". Here, it is assumed that ten levels of reception gains rx1 to rx10 are prepared in advance, and these reception gains rx1 to rx10 are associated with reception gain numbers i = 1 to 10.

In step P22, the reception gain rx = r
x (initially rx = rx1). In Step P23, the slice number n is initialized to “1”. here,
It is assumed that the slice positions of the seven slices L1 to L7 shown in FIG. 16 are set in advance, and these slices L1 to L7 are associated with slice numbers n = 1 to 7. In Step P24, the nesting number m is initialized to “0”.

In step P25, a reception gain adjustment pulse sequence is executed for the slice Ln (first slice L1) to collect projection data, and obtain a projection area Ra [n] (first Ra [1]). The reception gain adjustment pulse sequence is a pulse sequence to which only a preset phase gradient of the imaging pulse sequence is added (the repetition time is the same as the imaging pulse sequence TR). In Step P26, the current reception gain rx and the projection area Ra [n] are stored.

In Step P27, the nesting number m is increased by "1". In Step P28, if the nesting number m is not larger than the nesting number M, the process proceeds to Step P29, and if it is larger, the process proceeds to Step P31.

In step P29, the slice number n is increased by "3". This is because an adjacent pulse is skipped as a next scan slice because an RF pulse for a certain slice affects an adjacent slice. In Step P30, the slice number n
If there is a slice Ln corresponding to
The process returns to Step P5, and if not, the process proceeds to Step P31. By the first steps P22 to P30, as shown in FIG. 8, the projection areas Ra [1], Ra [4], and Ra for the slices L1, L4, and L7 at the reception gain rx1.
[7] is stored.

In step P31, the reception gain number i is increased by "1". In Step P32, if the reception gain rxi corresponding to the reception gain number i exists, the process returns to Step P22. If not, the process returns to Step P33.
Proceed to. As shown in FIG. 8, the projection areas Ra [1], Ra [4], and Ra [7] for the slices L1, L4, and L7 are stored at the reception gains rx1 to rx10 by the above steps P21 to P32. And
The time required to execute steps P22 to P32 once is the repetition time TR.

In step P33, the group number k is increased by "1". In step P34, if the group number k does not exceed the group K,
Returning to step 21, if it exceeds, the program proceeds to step P80 in FIG. In the second (k = 2) steps P21 to P34, as shown in FIG. 9, the reception gains rx1 to rx10
Store the projection areas Ra [2] and Ra [5] for the slices L2 and L5, respectively. In the third (k = 3) steps P21 to P34, the projection areas Ra [3] and Ra [6] for the slices L3 and L6 are stored with the reception gains rx1 to rx10, respectively, as shown in FIG. Is done. Step P
The repetition time T by adjusting the waiting time at 21, P25
R is maintained.

At step P80 in FIG. 7, as shown in FIG. 11, the projection area Ra [1] of the slice L1
The reception gain rx (rx5 in FIG. 11) that gives 90% of the saturation value of the signal is the optimum reception gain Rx [1] of the slice L1.
And As shown in FIG. 12, the reception gain rx (rx4 in FIG. 12) that gives 90% of the saturation value of the projection area Ra [2] of the slice L2 is set as the optimum reception gain Rx [2] of the slice L2. Similarly, optimal reception gains Rx [3] to Rx [7] of slices L3 to L7.
To determine. Then, the process ends.

As described above, it is possible to optimize the reception gain in each of the slices L1 to L7. Further, since the reception gain adjustment pulse sequence for another slice is inserted during the repetition time TR of the reception gain adjustment pulse sequence for a certain slice, the required time for the reception gain adjustment scan is longer than when no slice is inserted. Can be shortened.

Further, as described in the transmission gain adjustment processing, the load of the reception gain adjustment scan can be reduced by omitting the reception gain adjustment scan for some slices.

According to the MRI apparatus 100, as shown in FIG. 13, MR images having the same image quality can be obtained in all the slices L1 to L7 (for example, there is no variation in luminance).

[0047]

The MRI apparatus adjusting method and MR of the present invention
According to the I device, when capturing MR images for a plurality of slices, the optimum transmission gain and reception gain can be adjusted for each slice, so that MR images of the same image quality can be obtained for any slice.

[Brief description of the drawings]

FIG. 1 is a block diagram of an MRI apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart of a transmission gain adjustment process according to an embodiment of the present invention.

FIG. 3 is a time chart showing timings of a plurality of slices and a scan for adjusting a transmission gain.

FIG. 4 is a characteristic diagram of a transmission gain and a projection area in a first slice.

FIG. 5 is a characteristic diagram of a transmission gain and a projection area in a second slice.

FIG. 6 is a flowchart of a reception gain adjustment process according to an embodiment of the present invention.

FIG. 7 is a flowchart that follows the reception gain adjustment process of FIG. 6;

FIG. 8 is a time chart showing a plurality of slices in a first group and timings of scanning for adjusting a reception gain.

FIG. 9 is a time chart showing timings of a plurality of slices of a second group and a scan for adjusting a reception gain.

FIG. 10 is a time chart showing a plurality of slices of a third group and the timing of a scan for adjusting the reception gain.

FIG. 11 is a characteristic diagram of a reception gain and a projection area in a first slice.

FIG. 12 is a characteristic diagram of a reception gain and a projection area in a second slice.

FIG. 13 is a conceptual diagram illustrating that there is no variation in image quality for each slice.

FIG. 14 is an illustration of an imaging pulse sequence.

FIG. 15 is a view showing an example of projection data.

FIG. 16 is a conceptual diagram showing a plurality of slices.

FIG. 17 is a conceptual diagram illustrating that there is variation in image quality for each slice.

[Explanation of symbols]

 Reference Signs List 100 MRI apparatus 1 Magnet assembly 1t Transmission coil 1r Receiving coil 4 RF power amplifier 5 Preamplifier 7 Computer 8 Sequence storage circuit

Continued on the front page (72) Inventor Tetsuji Tsukamoto 127 Gee Yokogawa Medical System Co., Ltd., 4-7 Asahigaoka, Hino-shi, Tokyo (72) Inventor Toshimitsu Takahashi 1-1-1 Umezono, Tsukuba, Ibaraki, Tsukuba Central Office No. 2 AIST (72) Inventor Xiao Rui Tei 1-1-1 Umezono Tsukuba City, Ibaraki Pref. Central Tsukuba Office No. 2 AIST (72) Inventor Toshio Iijima Tsukuba Ibaraki 1-1-1, Umezono-shi, Tsukuba Central 2nd AIST F-term in AIST (reference) 4C096 AA20 AB04 AB09 AB39 AD02 AD07 AD10 AD25 BB32 CC15 CC38 CD03

Claims (8)

[Claims] An acquisition of projection data for one slice by a transmission gain adjustment pulse sequence having a repetition time TRs sufficiently longer than the longitudinal relaxation time T1 without adding only the phase gradient of the imaging pulse sequence is referred to as transmission gain. A method for adjusting an MRI apparatus, wherein the method is repeated at each of two or more slice positions while changing, and a transmission gain at each slice position is determined based on the obtained projection data. 2. The method for adjusting an MRI apparatus according to claim 1, wherein, while repeating the transmission gain adjustment pulse sequence to collect projection data for one slice, projection data for another slice is collected. Apparatus adjustment method, which includes a transmission gain adjustment pulse sequence for use in the MRI apparatus. 3. Collection of projection data for one slice by a reception gain adjustment pulse sequence that does not add only the phase gradient of the imaging pulse sequence is repeated at two or more slice positions while changing the reception gain. An MRI apparatus adjustment method, wherein a reception gain at each slice position is determined based on the obtained projection data. 4. The MRI apparatus adjusting method according to claim 3, wherein, while repeating the reception gain adjusting pulse sequence to collect projection data for one slice, projection data for another slice is collected. Apparatus adjustment method, which comprises inserting a reception gain adjustment pulse sequence for use in the MRI apparatus. 5. A transmission coil for transmitting an RF pulse, transmission power adjusting means for adjusting driving power of the transmission coil according to a transmission gain, a gradient coil for applying a gradient magnetic field, and receiving an NMR signal. A receiving coil for
Main scanning means for driving the transmission coil, the gradient coil, and the reception coil to collect image creation data for one slice by an imaging pulse sequence at two or more slice positions, and the transmission coil; Driving the gradient coil and the receiving coil to collect projection data for one slice by a transmission gain adjustment pulse sequence having a repetition time TRs longer than the longitudinal relaxation time T1 without adding only the phase gradient of the imaging pulse sequence. Transmission gain adjusting scanning means for repeating the operation at each of two or more slice positions while changing the transmission gain, and transmission transmission at each slice position determined based on the obtained projection data and transmitted to the main scanning means. With gain adjustment means MRI apparatus characterized by a. 6. The MRI apparatus according to claim 5, wherein
The transmission gain adjustment scanning unit includes a transmission gain adjustment pulse sequence for collecting projection data for another slice while repeating the transmission gain adjustment pulse sequence for collecting projection data for one slice. An MRI apparatus comprising: 7. A transmission coil for transmitting an RF pulse, a gradient coil for applying a gradient magnetic field, a reception coil for receiving an NMR signal, and adjusting an amplification degree of the NMR signal according to a reception gain. Receiving amplification degree adjusting means to
Main scanning means for driving the transmission coil, the gradient coil, and the reception coil to collect image creation data for one slice by an imaging pulse sequence at two or more slice positions, and the transmission coil; Collecting projection data for one slice by a reception gain adjustment pulse sequence that does not add only the phase gradient of the imaging pulse sequence by driving a gradient coil and a reception coil means that two or more slices are obtained while changing the reception gain. An MRI, comprising: a reception gain adjustment scanning unit that repeats at a position; and a reception gain adjustment unit that determines a reception gain at each slice position based on the obtained projection data and passes it to the main scanning unit. apparatus. 8. The MRI apparatus according to claim 7, wherein
The reception gain adjustment scanning means may be a reception gain adjustment pulse sequence for collecting projection data for another slice while repeating the reception gain adjustment pulse sequence for collecting projection data for one slice. An MRI apparatus comprising: