JPH06237914A - Mri device - Google Patents

Abstract

PURPOSE:To provide an MRI device capable of providing images with satisfactory image quality in a short time by utilizing a GRASS method and a CE- FAST method. CONSTITUTION:This MRI device reconstitutes one piece of an image by filling one space (k) with the data of respective collected echos while executing a pulse sequence C composed of view scan VCA for collecting an FID echo Ef and multiechos Ef2, Ef3 and Ef4 and view scan VCB for collecting a CE-FAST echo Ec and multiechos Ec2, Ec3 and Ec4. Thus, while the number of echos to be collected within the repetition time of respective two kinds of view scan is defined as (n), the data of echos just for one piece of an image can be collected within the 1/n scan time of the GRASS method and CE-FAST method. Since one piece of the image is constituted by combining the data of the FID echo and the data of the CE-FAST echo and the data are collected in a short time, the influence of chemical shift and the influence of body movement can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an MRI apparatus,
More specifically, the GRASS method or the CE-FAST method is used to perform the FID echo or CE within the repetition time.
-An MRI apparatus that collects FAST echoes and reconstructs an image based on the data of the FID echoes or the data of the CE-FAST echoes.

[0002]

2. Description of the Related Art steady state free prec
As a method of observing an ession signal, the GRASS method,
The CE-FAST method and the like are known. In the GRASS method, as shown in a pulse sequence D in FIG. 16, a FID echo E is formed by continuously applying an α ° pulse with a short repetition time TR and focusing by switching the read gradient RD.
f is collected one by one at each repetition time TR. The view scan VD is repeated by the number of phase encodes that fills the k space, and an image is reconstructed from the collected FID echo Ef data. In the figure, PD is a phase encode gradient and RWD is a rewinder.

In the CE-FAST method, as shown in a pulse sequence G of FIG. 17, an α ° pulse is continuously applied with a short repetition time TR, and α ° .α ° (α ° in the previous view scan VG and The CE-FAST echo Ec focused by the α ° series in the current view scan VG is collected one by one at each repetition time TR. k
View scan VG by the number of phase encodes filling the space
Is repeated to reconstruct an image from the collected CE-FAST echo Ec data. In the figure, PG is a phase encode gradient and RWG is a rewinder.

[0004]

The GRASS method, C
A conventional M for performing imaging by applying the E-FAST method
The RI apparatus can acquire one image in a short time because the repetition time TR is short (that is, the scan time is short). On the other hand, as shown in the pulse sequence H of FIG. 18, after applying one α ° pulse, the read gradient RH is switched rapidly and by the number of phase encodes that fills the k space, and one image portion is scanned. EPI method for collecting data of echoes (E1, E2, E3, ...) Is known. Focusing only on the speed of the scan time, the conventional MRI apparatus is far inferior to the MRI apparatus that performs imaging by applying the EPI method.

Therefore, a first object of the present invention is GRA.
An object of the present invention is to provide an MRI apparatus capable of obtaining an image in a shorter time by using the SS method. A second object of the present invention is to provide an MRI apparatus capable of obtaining an image in a shorter time by using the CE-FAST method. A third object of the present invention is GR
An object of the present invention is to provide an MRI apparatus capable of obtaining an image of good quality in a shorter time by using the ASS method and the CE-FAST method.

[0006]

SUMMARY OF THE INVENTION In a first aspect, the present invention utilizes a GRASS method to achieve FI within a repetition time.
An MRI apparatus for collecting D echoes and reconstructing an image, comprising: FID multi-echo focusing means for focusing multi-echoes of the FID echo by switching the lead gradient after collecting the FID echo; and focusing by the switching of the lead gradient. FID multi-echo collecting means for collecting multi-echo of FID echo and its FID
A multi-echo data of the FID echo collected by the multi-echo collecting means and the data of the FID echo apply a phase encode gradient corresponding to each echo such that one k space is filled before the collection of the corresponding echo. F
FI for applying an ID phase encode gradient applying means and a rewinder for rewinding the phase encode gradient corresponding to each echo after collecting the multi-echo of FID echo.
An MRI apparatus comprising: a D rewinder applying unit and an FID image reconstructing unit that reconstructs one image based on the data of each echo.

In a second aspect, the present invention provides a CE-FA
An MRI apparatus that collects CE-FAST echoes within a repeating time by using ST and reconstructs an image, and is a multi-echo of CE-FAST echoes by switching a lead gradient for focusing CE-FAST echoes. CE-FAST multi-echo focusing means for focusing and C for focusing by switching the lead gradient
CE-F collecting multi-echo of E-FAST echo
The AST multi-echo collecting means and each echo such that one k space is filled with the multi-echo data of the CE-FAST echo and the CE-FAST echo data collected by the CE-FAST multi-echo collecting means. CE-FAST phase encode gradient applying means for applying a corresponding phase encode gradient before collecting the corresponding echo, and CE-applying a rewinder for rewinding the phase encode gradient corresponding to each echo after collecting the CE-FAST echo. There is provided an MRI apparatus comprising a FAST rewinder applying means and a CE-FAST image reconstructing means for reconstructing one image based on the data of each echo.

In a third aspect, the invention is a GRASS.
Method or CE-FAST method is used to collect FID echo and CE-FAST echo within repetition time,
An MRI apparatus for reconstructing an image based on the FID echo data and the CE-FAST echo data, wherein FID multi-echo focusing means for focusing the multi-echo of the FID echo by switching the read gradient after collecting the FID echo. And FID multi-echo collecting means for collecting multi-echo of FID echoes that are focused by switching the lead gradient, and multi-echo data of the FID echo and the FID echo data collected by the FID multi-echo collecting means. FID partial phase encode gradient applying means for applying a phase encode gradient corresponding to each echo such that a predetermined portion of one k-space is filled, before collecting the corresponding echo, and after collecting multiple echoes of the FID echo The phase error corresponding to each echo And FID portion Riwinda applying means for applying a rewinder for rewinding the cord gradient, C
CE-FAST multi-echo focusing means for focusing multi-echo of CE-FAST echo by switching lead gradients for focusing E-FAST echo;
CE-F focused by switching the lead gradient
CE-FAST collecting multi-echo of AST echo
A portion other than the predetermined portion of one k-space by the multi-echo collecting means and the multi-echo data of the CE-FAST echo collected by the CE-FAST multi-echo collecting means and the CE-FAST echo data. CE-FAST in which a phase encode gradient corresponding to each echo is applied before the collection of the corresponding echo
CE-FA for applying a partial phase encode gradient applying means and a rewinder for rewinding the phase encode gradient corresponding to each echo after collecting the CE-FAST echo
ST partial rewinder applying means, multi-echo data of the FID echo, FID echo data, CE-F
Multi-echo data of AST echo and CE-FA
An MRI apparatus comprising: an image reconstructing means for reconstructing one image based on ST echo data.

[0009]

In the MRI apparatus of the present invention according to the first aspect,
It is not only necessary to collect only one FID echo within the repetition time, but also 1 after the FID echo is collected due to the switching of the lead gradient by the FID multi-echo focusing means.
One or more FID echoes are focused and collected by the FID multi-echo collection means. Here, the plurality of focused FID echoes are referred to as multi-echo. Then, the number of phase encodes forming the k-space is shared by each echo of the FID echo and the multi-echo, and one k-space is filled with the data of each collected echo to reconstruct one image. Therefore, if the number of echoes including the multi-echo that is collected within the repetition time is set to n and all the number of phase encodes forming the k space are equally shared by the n echoes, the conventional GRASS method is used. Echo data for one image can be collected with a scan time of 1 / n, and one image can be acquired in a short time.

In the MRI apparatus of the present invention according to the second aspect, not only is it necessary to collect only one CE-FAST echo within the repetition time, but the original gradient is switched by the CE-FAST multi-echo focusing means. One or more CE-F before focusing CE-FAST echo
Focus the AST echoes and collect them with CE-FAST multi-echo collection means. Here, the plurality of focused CE-FAST echoes are referred to as multi-echo. Then, the number of phase encodes forming the k space is set to CE-FA.
The ST echo and each echo of the multi-echo are shared,
One piece of image is reconstructed by filling one k-space with the collected data of each echo. Therefore, if the number of echoes including the above-mentioned multi-echo collected in a repetitive time is n and all the number of phase encodes constituting the k space are equally shared by the n echoes, the conventional CE-
Echo data for one image can be collected with a scan time of 1 / n of the FAST method, and one image can be acquired in a short time.

In the MRI apparatus of the present invention according to the third aspect, the FID echo and the multi-echo of the FID echo, or the CE-FAST echo and the CE-F within the repetition time.
Collect multiple echoes of the AST echo. Then, a predetermined portion of the number of phase encodes forming the k space is set to F
The respective echoes of the ID echo and the multi-echo of the FID echo are shared, and the portions other than the predetermined portion are shared by the respective echoes of the CE-FAST echo and the multi-echo of the CE-FAST echo, and one data is collected for each echo. Reconstruct one image by filling k-space. Therefore, FID echo and multi-echo of FID echo and CE-FAST echo and CE-FAST collected within the repetition time
Let n be the number of echoes including the multi-echoes of the echoes, and, for example, let n be the number of all phase encodes forming the k space.
If the echoes are shared equally, the conventional GRASS
Method, it is possible to collect echo data for one image with a scan time of 1 / n of the CE-FAST method.
It is possible to acquire a single image in a short time.

Further, by combining FID echo and FID echo multi-echo and CE-FAST echo and CE-FAST echo multi-echo to form one image and collecting data in a short time, chemical shift can be achieved. It becomes possible to suppress the influence of and the influence of body movement.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail based on the embodiments shown in the drawings. The present invention is not limited to this. FIG. 1 is a block diagram of an MRI apparatus 1 according to the first embodiment of the present invention. The computer 2 controls the overall operation based on the instruction from the console 13. The sequence controller 3 operates the gradient magnetic field driving circuit 4 based on the stored sequence, and causes the gradient magnetic field coil of the magnet assembly 5 to generate a gradient magnetic field. Further, it controls the gate modulation circuit 7 to control the RF oscillation circuit 6
The RF pulse generated in 1 is modulated into a predetermined waveform and applied from the RF power amplifier 8 to the transmission coil of the magnet assembly 5. The NMR signal obtained by the receiving coil of the magnet assembly 5 is transmitted via the preamplifier 9 to the phase detector 10
To the computer 2 via the AD converter 11. The computer 2 is the NM obtained from the AD converter 11.
The image is reconstructed based on the data of the R signal and displayed on the display device 12.

FIG. 2 is an exemplary diagram of a pulse sequence executed by the MRI apparatus 1. In the view scan VA of this pulse sequence A, not only collecting one FID echo Ef within the repetition time TR as in the conventional GRASS method (see FIG. 16) but also switching the read gradient RA causes the second FID echo Ef2
Third FID echo Ef3, fourth FID echo Ef4
And collect these. Focusing on only one view scan VA, it is similar to the EPI method.

The phase encode gradient P1 is 1 shown in FIG.
The phase encoding gradient corresponds to the low frequency part KALL ± of one k space KA, and the number of phase encodings is k.
It is ¼ of the number of phase encodes that form the space KA.
The phase encode gradient P2 is the phase encode gradient P.
The gradient is such that when added to 1, it becomes a phase encoding gradient corresponding to the low-frequency part KAL ± in one k-space KA shown in FIG. The phase encode gradient P3 is the phase encode gradient P1 and the phase encode gradient P.
The gradient is such that when it is added with 2, it becomes a phase encoding gradient corresponding to the high frequency part KAH ± in one k space KA shown in FIG. The phase encode gradient P4 corresponds to the phase encode gradient corresponding to the high frequency part KAHH ± in one k space KA shown in FIG. 3 when added with the phase encode gradient P1, the phase encode gradient P2 and the phase encode gradient P3. The gradient is such that Further, the rewinder P5 has the phase encode gradient P1,
This is a gradient for rewinding the phase encode gradient P2, the phase encode gradient P3, and the phase encode gradient P4.

By repeating such a view scan VA by the number of phase encodes of the phase encode gradient P1, the low frequency part KALL ± on the k space KA shown in FIG. 3 is filled with the data of the FID echo Ef, and the low frequency part is obtained. KAL
The ± is filled with the data of the second FID echo Ef2, the high frequency portion KAH ± is filled with the data of the third FID echo Ef3, and the high frequency portion KAHH ± the fourth FID echo Ef.
Filled with 4 data. The computer 2 uses the data of the FID echo Ef filling the thus obtained one k-space KA, the data of the second FID echo Ef2, and the third FID.
Data of echo Ef3 and fourth FID echo Ef4
One image is reconstructed based on the data of 1 and displayed on the display device 12.

In the above-mentioned MRI apparatus 1, the echo data of one image is converted into the pulse sequence A of the conventional GRASS method by the pulse sequence A (see FIG. 16).
Can be acquired in 1/4 time, and one image can be acquired in a short time. Further, by switching the lead gradient, the fifth FID echo and the sixth F echo
ID echoes, ... May be collected. If the number of echoes collected within the repetition time TR is n and all the number of phase encodes forming the k-space KA are equally shared by the n echoes, the scan time is 1 / n of the conventional GRASS method. The echo data for one image can be collected with. Further, since the α ° pulse is continuously applied at each repetition time TR, it is possible to obtain an image having a better S / N as compared with the EPI method.

In addition to the method shown in FIG. 3, for example, as shown in FIG. 4, the k-space KA is assigned to the echoes by filling the high frequency parts KAHH + and KAH + of the positive electrode with the data of the FID echo Ef. Low frequency part of positive electrode KAL
L + and KAL + are filled with the data of the second FID echo Ef2, the negative low-frequency portion KALL- and KAL- are filled with the data of the third FID echo Ef3, and the negative high-frequency portion KAHH- and KAH- are filled with the fourth data. FID echo E
It is also possible to equally share the number of phase encodes forming the k-space KA among the four echoes so as to be filled with the data of f4. You can change the contrast of the image by changing the sharing method. In addition, the pulse sequence A includes MCT (Magnetization T
It is also possible to arbitrarily add various preparation sequences such as ransfer contrast, T1 emphasis, and T2 emphasis. Further, by adding a phase encode P6 and a rewinder P7 to the slice axis of the pulse sequence A, 3
It is also possible to use the D pulse sequence Aa (see FIG. 5).

FIG. 6 is a block diagram of an MRI apparatus 101 according to the second embodiment of the present invention. The computer 102 controls the overall operation based on an instruction from the console 113.
The sequence controller 103 operates the gradient magnetic field driving circuit 104 based on the stored sequence,
A gradient magnetic field is generated by the gradient magnetic field coil of the magnet assembly 105. Further, the gate modulation circuit 107 is controlled to modulate the RF pulse generated by the RF oscillation circuit 106 into a predetermined waveform, and the RF pulse is applied from the RF power amplifier 108 to the transmission coil of the magnet assembly 105. The NMR signal obtained by the receiving coil of the magnet assembly 105 is
It is input to the phase detector 110 via the preamplifier 109, and further input to the computer 102 via the AD converter 111. The computer 102 reconstructs an image based on the data of the NMR signal obtained from the AD converter 111, and displays it on the display device 112.

FIG. 7 is an exemplary diagram of a pulse sequence executed by the MRI apparatus 101. In the view scan VB of this pulse sequence B, the repetition time T
In the R, not only is one CE-FAST echo Ec collected as in the conventional CE-FAST method (see FIG. 17), but the second CE is switched by switching the lead gradient RB.
-Fast echo Ec2, 3rd CE-FAST echo Ec3, 4th CE-FAST echo Ec4 are focused, and these are collected. Focusing on only one view scan VA, it is similar to the EPI method.

The phase encode gradient P8 is 1 shown in FIG.
The phase encoding gradient corresponds to the low frequency portion KBLL ± of one k space KB, and the number of phase encodings is k.
It is 1/4 of the number of phase encodes that form the space KB.
The phase encode gradient P9 is the phase encode gradient P.
The gradient is such that when it is added with 8, it becomes a phase encoding gradient corresponding to the low frequency portion KBL ± of one k space KB shown in FIG. The phase encode gradient P10 is
This is a gradient that, when added to the phase encode gradient P8 and the phase encode gradient P9, becomes a phase encode gradient corresponding to the high frequency part KBH ± in one k space KB shown in FIG. Phase encode gradient P11
Is a high frequency part KBH of one k space KB shown in FIG. 8 when added with the phase encode gradient P8, the phase encode gradient P9 and the phase encode gradient P10.
The gradient is a phase encode gradient corresponding to H ±. The rewinder P12 is a gradient that rewinds the phase encode gradient P8, the phase encode gradient P9, the phase encode gradient P10, and the phase encode gradient P11.

By repeating such a view scan VB as many times as the number of phase encodes of the phase encode gradient P8, the high frequency portion KBHH ± on the k space KB shown in FIG. 8 is filled with the data of the CE-FAST echo Ef, and the high frequency portion. KBH ± is filled with the data of the second CE-FAST echo Ec2, and the low-frequency part KBL ± is the third CE-FAS.
Filled with data of T echo Ec3, low frequency part KBLL
± is filled with the data of the fourth CE-FAST echo Ec4. The computer 102 fills the thus obtained one k-space KB with the data of the CE-FAST echo Ec, the data of the second CE-FAST echo Ec2, and the third CE.
-FAST echo Ec3 data and fourth CE-F
Based on the data of the AST echo Ec4, one image is reconstructed and displayed on the display device 112.

In the above-described MRI apparatus 101, the echo data of one image is processed by the pulse sequence B in the pulse sequence G of the conventional CE-FAST method (see FIG. 1).
It can be acquired in 1/4 of the time (see 7) and one image can be acquired in a short time. In addition, by switching the lead gradient, the fifth CE-FA
The ST echo, the sixth CE-FAST echo, ... May be collected. If the number of echoes collected within the repetition time TR is n and all the number of phase encodes constituting the k-space KB are equally shared by the n echoes, it is 1 / n of the conventional CE-FAST method. Echo data for one image can be collected during the scan time.
Further, since the α ° pulse is continuously applied at each repetition time TR, it is possible to obtain an image having a better S / N as compared with the EPI method.

In addition to the method shown in FIG. 8, the method of sharing the k-space KB with each echo is, for example, as shown in FIG. 9, the high frequency portions KBHH + and KBH + of the positive electrode are CE-F.
The positive low-frequency portion KBLL + and KBL + are filled with the data of the AST echo Ec, and the negative low-frequency portion KBLL + is filled with the data of the second CE-FAST echo Ec2.
-, KBL- is filled with the data of the third CE-FAST echo Ec3, and the negative high frequency portions KBHH-, KBH-
It is also possible to equally share the number of phase encodes forming the k-space KB with the four echoes so that − is filled with the data of the fourth CE-FAST echo Ec4. You can change the contrast of the image by changing the sharing method. In addition, the pulse sequence B includes MCT (Magnetization Transfer Contras
It is also possible to arbitrarily add various preparation sequences such as t), T1 emphasis, and T2 emphasis. Also,
It is also possible to add a phase encode P13 and a rewinder P14 to the slice axis of the pulse sequence B to form a 3D pulse sequence Ba (see FIG. 10).

FIG. 11 shows the MRI of the third embodiment of the present invention.
3 is a block diagram of main parts of the device 201. FIG. The computer 202
The overall operation is controlled based on the instruction from the console 213. The sequence controller 203 operates the gradient magnetic field driving circuit 204 based on the stored sequence, and causes the gradient magnetic field coil of the magnet assembly 205 to generate a gradient magnetic field. Further, the gate modulation circuit 207 is controlled to modulate the RF pulse generated by the RF oscillation circuit 206 into a predetermined waveform, and the RF pulse is applied from the RF power amplifier 208 to the transmission coil of the magnet assembly 205. The NMR signal obtained by the receiving coil of the magnet assembly 205 is input to the phase detector 210 via the preamplifier 209, and further to the computer 202 via the AD converter 211. The computer 202 reconstructs an image based on the NMR signal data obtained from the AD converter 211,
It is displayed on the display device 212.

FIGS. 12A and 12B are illustrations of two types of view scans VCA and VCB in the pulse sequence C executed by the MRI apparatus 201. In the view scan VCA of the pulse sequence C ((a) of FIG. 12), the phase encode gradient P15 and the phase encode gradient applied to the phase encode axis are compared with the view scan VA of the pulse sequence A of the first embodiment. P16, phase encode gradient P17, phase encode gradient P18 and rewinder P19 are different.

The phase encode gradient P15 is the positive low frequency portion KCLL + of one k space KC shown in FIG.
Is the phase encode gradient corresponding to, and the number of phase encodes is 1 / the number of phase encodes constituting the k-space KC.
8 The phase encode gradient P16 is a gradient that, when added to the phase encode gradient P15, becomes a phase encode gradient corresponding to the positive low-frequency part KCL + of one k space KC shown in FIG. The phase encode gradient P17 is the phase encode gradient P15.
And when added to the phase encode gradient P16,
The gradient is a phase encoding gradient corresponding to the high frequency part KCH + of the positive electrode in one k space KC shown in FIG. The phase encode gradient P18 is added to the phase encode gradient P15, the phase encode gradient P16, and the phase encode gradient P17, and the high frequency part KCHH + of the positive electrode in one k space KC shown in FIG.
Is a gradient corresponding to the phase encoding gradient corresponding to. The rewinder P19 is a gradient that rewinds the phase encode gradient P15, the phase encode gradient P16, the phase encode gradient P17, and the phase encode gradient P18. By repeating such a view scan VCA for the number of phase encodes of the phase encode gradient P15, the collected data of the FID echo Ef, the data of the second FID echo Ef2, and the third FID.
Data of echo Ef3 and fourth FID echo Ef4
Data, the positive electrode side on the k space KC shown in FIG. 13 is filled.

In the view scan VCB of the pulse sequence C ((b) of FIG. 12), the phase encode gradient applied to the phase encode axis is higher than that of the view scan VB of the pulse sequence B of the second embodiment. P2
0, phase encode gradient P21, phase encode gradient P
22, phase encode gradient P23 and rewinder P2
4 is different.

The phase encode gradient P20 is determined by the negative high frequency portion KCHH- of one k space KC shown in FIG.
Is the phase encode gradient corresponding to, and the number of phase encodes is 1 / the number of phase encodes constituting the k-space KC.
8 The phase encode gradient P21 is such a gradient that when added to the phase encode gradient P20, it becomes a phase encode gradient corresponding to the negative high-frequency part KCH- in one k space KC shown in FIG. The phase encode gradient P22 is the phase encode gradient P20.
And when added to the phase encode gradient P21,
The gradient is a phase encoding gradient corresponding to the negative low-frequency part KCL- of the one k-space KC shown in FIG. The phase encode gradient P23 is added to the phase encode gradient P20, the phase encode gradient P21, and the phase encode gradient P22, and the negative low-frequency part KCLL− of one k space KC shown in FIG.
Is a gradient corresponding to the phase encoding gradient corresponding to. The rewinder P24 is a gradient that rewinds the phase encode gradient P20, the phase encode gradient P21, the phase encode gradient P22, and the phase encode gradient P23.

By repeating such a view scan VCB as many times as the number of phase encodes of the phase encode gradient P20, the data of the CE-FAST echo Ec, the data of the second CE-FAST echo Ec2, and the third data which are collected.
CE-FAST echo Ec3 data and fourth C
Data of E-FAST echo Ec4, k shown in FIG.
The negative electrode side on the space KC is filled. The computer 202 reconstructs one image based on the data of each echo that fills one k-space KC thus obtained, and the display device 2
Display at 12.

In the above MRI apparatus 201, echo data for one image can be collected by the pulse sequence C in the same time as the pulse sequences A and B, and one image can be collected in a short time. You can get it. Further, by switching the lead gradient, a fifth FID echo, a sixth FID echo, ... Or a fifth FID echo.
CE-FAST echo, sixth CE-FAST echo, ... View scan VCA, VC
If the number of echoes collected in each repetition time TR of B is n and all the number of phase encodes forming the k-space KC is equally shared by the echoes of the view scans VCA and VCB, the conventional GRASS is used. Law, C
Echo data for one image can be collected with a scan time of 1 / n of the E-FAST method. Also,
Since the α ° pulse is continuously applied at each repetition time TR, it is possible to obtain an image having a good S / N as compared with the EPI method.

Further, the image is an FID echo (E
f, Ef2, Ef3, Ef4) data and CE-FAS
By reconstructing based on the data of the T echo (Ec, Ec2, Ec3, Ec4) and collecting the data in a short time, the characteristics of the CE-FAST echo, which is sensitive to body movement, are alleviated. Further, the higher the FID echo is, the more the influence of the chemical shift is accumulated.
Since it is reconstructed based on the data including the CE-FAST echo, it is less likely to be affected by the chemical shift.

In addition to the method shown in FIG. 13, the k-space KC is assigned to each echo as shown in FIG. 14, for example, as shown in FIG. View Scan VCA FID Echo E
f data, second FID echo Ef2 data, third
Of the FID echo Ef3 and the data of the fourth FID echo Ef4,
View scan VCB on KCH ± (left diagonal line in the figure)
CE-FAST Echo Ec data, second CE
-FAST echo Ec2 data, third CE-FAS
The k-space KC is filled with the data of the T echo Ec3 and the data of the fourth CE-FAST echo Ec4.
It is also possible to equally share the number of phase encodes constituting the two types of view scans VCA and VCB. Furthermore, it is possible to divide the number of phase encodes forming the k-space KC into one of the two types of view scans VCA and VCB and share them. You can change the contrast of the image by changing the sharing method.

In the pulse sequence C, MCT (M
It is also possible to arbitrarily add various preparation sequences such as agnetization transfer contrast, T1 emphasis, and T2 emphasis. This can change the contrast of the image. Further, a phase encode P25 and a rewinder P26 are added to the slice axis of the view scan VCA (see (a) of FIG. 15), and the phase encode P2 is added to the slice axis of the view scan VCB.
It is also possible to add 7 and the rewinder P28 (see (b) of FIG. 15) to form the 3D pulse sequence Ca.

[0035]

According to the MRI apparatus of the present invention according to the first aspect, assuming that the number of echoes of the FID echo and the multi-echo of the FID echo which are collected within the repetition time is n, it is 1 of the conventional GRASS method. It is possible to collect echo data for one image in a scan time of / n (n ≧ 2). Therefore, one image can be acquired in a short time.

According to the MRI apparatus of the present invention according to the second aspect, when the number of echoes of the CE-FAST echo and the multi-echo of the CE-FAST echo collected within the repetition time is n, the conventional CE- 1 / n of FAST method
Echo data for one image can be collected with a scan time of (n ≧ 2). Therefore, one image can be acquired in a short time.

According to the MRI apparatus of the present invention according to the third aspect, FID echoes and F
Assuming that the number of echoes including the ID echo multi-echo and the CE-FAST echo and the CE-FAST echo multi-echo is n, the conventional GRASS method, CE-FAST
It is possible to collect echo data for one image in a scan time of 1 / n (n ≧ 2) of the T method. Therefore, one image can be acquired in a short time. Further, the quality of the image can be improved.

[Brief description of drawings]

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

FIG. 2 is an exemplary diagram of a pulse sequence executed by the apparatus of FIG.

3 is an explanatory diagram of a k-space distribution based on echo data according to the apparatus of FIG.

FIG. 4 is an explanatory diagram of a k-space distribution based on echo data according to the apparatus of FIG.

5 is an exemplary diagram of a 3D pulse sequence based on the pulse sequence of FIG. 2. FIG.

FIG. 6 is a block diagram of an MRI apparatus according to a second embodiment of the present invention.

FIG. 7 is an exemplary diagram of a pulse sequence executed by the apparatus of FIG.

FIG. 8 is an explanatory diagram of a k-space distribution based on echo data according to the apparatus of FIG.

9 is an explanatory diagram of a k-space distribution based on echo data according to the apparatus of FIG.

10 is an exemplary diagram of a 3D pulse sequence based on the pulse sequence of FIG. 7. FIG.

FIG. 11 is a block diagram of an MRI apparatus according to a third embodiment of the present invention.

12 is an exemplary diagram of a pulse sequence executed by the apparatus of FIG.

FIG. 13 shows k according to echo data according to the apparatus of FIG.
It is explanatory drawing about distribution of space.

FIG. 14 is a k according to echo data according to the apparatus of FIG.
It is explanatory drawing about distribution of space.

15 is an exemplary diagram of a 3D pulse sequence based on the pulse sequence of FIG. 12;

FIG. 16 is a view showing an example of a conventional GRASS pulse sequence.

FIG. 17 is an exemplary diagram of a pulse sequence of a conventional CE-FAST method.

FIG. 18 is a view showing an example of a pulse sequence of the EPI method.

[Explanation of symbols]

 1, 101, 201 MRI apparatus 2, 102, 202 Computer 3, 103, 203 Sequence controller A, B, C Pulse sequence Ec CE-FAST echo Ef FID echo KA, KB, KC k space P1, P2, P3 Phase encoding gradient RA, RB, RC Lead gradient TR Repetition time VCA, VCB View scan

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Claims (3)

[Claims] 1. An MR for reconstructing an image by collecting FID echoes within a repetition time using the GRASS method.
I apparatus, FID multi-echo focusing means for focusing the multi-echo of the FID echo by switching the lead gradient after collecting the FID echo, and FID multi-collecting the multi-echo of FID echo focused by the switching of the lead gradient. Echo collecting means and FID collected by the FID multi-echo collecting means
FID phase-encoding gradient applying means for applying a phase-encoding gradient corresponding to each echo such that one k-space is filled with the multi-echo data of the echo and the FID echo data before collecting the corresponding echo; FID rewinder applying means for applying a rewinder for rewinding the phase encode gradient corresponding to each echo after collecting multiple echoes of echoes, and FID image reconstructing means for reconstructing one image based on the data of each echo An MRI apparatus comprising: 2. An MRI apparatus for reconstructing an image by collecting CE-FAST echoes within a repetitive time by using CE-FAST, and switching a read gradient for focusing the CE-FAST echoes. CE-
CE-FA for focusing multi-echo of FAST echo
ST multi-echo focusing means, CE-FAST multi-echo collecting means for collecting multi-echo of CE-FAST echo focused by switching the lead gradient, and CE-FAST echo collected by the CE-FAST multi-echo collecting means 1 k from the multi-echo data of the above and the CE-FAST echo data
CE-FAST for applying a phase encode gradient corresponding to each echo that fills the space before collecting the corresponding echo
CE-FAST for applying a phase encode gradient applying means and a rewinder for rewinding the phase encode gradient corresponding to each echo after collecting the CE-FAST echo.
An MRI apparatus comprising rewinder applying means and CE-FAST image reconstructing means for reconstructing one image based on the data of each echo. 3. The FID echo and CE-within the repetition time using the GRASS method or the CE-FAST method.
An MRI apparatus that collects FAST echoes and reconstructs an image based on the data of the FID echoes and the data of the CE-FAST echoes. The multi-echo of the FID echoes is focused by switching the read gradient after collecting the FID echoes. FID multi-echo focusing means and FI for focusing by switching the lead gradient
FID multi-echo collecting means for collecting multi-echo of D echo, multi-echo data of FID echo collected by the FID multi-echo collecting means and the F
FID partial phase encode gradient applying means for applying a phase encode gradient corresponding to each echo such that a predetermined part of one k space is filled with the data of the ID echo before collecting the corresponding echo, and FID echo After collecting multiple echoes, FID partial rewinder applying means for applying a rewinder for rewinding the phase encode gradient corresponding to each echo, and CE-FAST by switching the lead gradient for focusing CE-FAST echoes.
CE-FAST multi-echo focusing means for focusing multi-echo of T echo, CE-FAST multi-echo collecting means for collecting multi-echo of CE-FAST echo focused by switching of the lead gradient, and CE-FAST multi-echo thereof The multi-echo data of the CE-FAST echo collected by the collecting means and the C
CE-FAST partial phase encoding for applying a phase encoding gradient corresponding to each echo such that a portion other than the predetermined portion of one k space is filled with the data of the E-FAST echo before collecting the corresponding echo Gradient applying means, CE-FAST partial rewinder applying means for applying a rewinder for rewinding the phase encode gradient corresponding to each echo after collecting CE-FAST echoes, multi-echo data of the FID echo, FID
An MRI apparatus comprising: an image reconstructing means for reconstructing one image based on echo data, multi-echo data of CE-FAST echo, and data of CE-FAST echo.