Spin exciting method, magnetic resonance imaging method, and magnetic resonance imaging system

• US 20030011367A1
• Filed: 07/09/2002
• Published: 01/16/2003
• Est. Priority Date: 07/10/2001
• Status: Active Grant

• Current Assignee: GE Medical Systems Global Technology Company LLC (GE Healthcare Technologies, Inc.)
• Original Assignee: GE Medical Systems Global Technology Company LLC (GE Healthcare Technologies, Inc.)
• Inventors: Asano, Kenji, Kosugi, Susumu
• Granted Patent: US 6,771,069 B2
• Time in Patent Office: Days
• US Class Current: 324/309
• CPC Class Codes: G01R 33/5615 Echo train techniques involving acquiring plural, differently encoded, echo signals after one RF excitation, e.g. using gradient refocusing in echo planar imaging [EPI], RF refocusing in rapid acquisition with relaxation enhancement [RARE] or using both RF and gradient refocusing in gradient and spin echo imaging [GRASE]
• CPC Class Codes: G01R 33/5617 using RF refocusing, e.g. RARE

Abstract

The present invention aims at making it possible to successfully achieve fast recovery during magnetic resonance imaging in which the fast spin echo technique combined with the inversion recovery technique is implemented. A 180° x pulse is applied in order to excite spins. Thereafter, when an inversion time TI has elapsed, a 90° x pulse is applied in order to excite the spins. Thereafter, when a half of a time esp has elapsed, a 180° y pulse is applied in order to excite the spins. Thereafter, when the time esp has elapsed, the 180° y pulse is applied an odd number of times in order to sequentially excite the spins. Thereafter, when a half of the time esp has elapsed, the 90° x pulse is applied in order to excite the spins.

Claims

1. A spin exciting method for producing an image using a magnetic resonance signal induced by spins in a subject being imaged according to the fast spin echo technique combined with the inversion recovery technique, comprising the steps of:

exciting spins with application of a 180°

pulse;

exciting the spins with application of a first 90°

x pulse after the elapse of a first time;

exciting the spins with application of a 180°

y pulse after the elapse of a second time;

exciting the spins by applying the 180°

y pulse an odd number of times after the elapse of a third time that is double the second time; and

exciting the spins with application of a second 90°

x pulse after the elapse of the second time.

2. A spin exciting method according to claim 1, wherein the second 90°

x pulse is a +90°

x pulse.

3. A spin exciting method according to claim 2, wherein the first time is shorter than the polarity recovery time for spins that are used for imaging.

4. A spin exciting method according to claim 1, wherein the second 90°

x pulse is a −

90°

x pulse.

5. A spin exciting method according to claim 4, wherein the first time is longer than the polarity recovery time for spins that are used for imaging.

6. A spin exciting method according to claim 1, wherein excitation is always selective excitation.

7. A magnetic resonance imaging method for producing an image using a magnetic resonance signal induced by spins in a subject being imaged according to the fast spin echo technique combined with the inversion recovery technique, comprising the steps of:

exciting spins with application of a 180°

pulse;

exciting the spins with application of a first 90°

x pulse after the elapse of a first time;

exciting the spins with application of a 180°

y pulse after the elapse of a second time;

exciting the spins by applying the 180°

y pulse an odd number of times after the elapse of a third time that is double the second time;

exciting the spins with application of a second 90°

x pulse after the elapse of the second time;

reading a spin echo during the third time; and

producing an image according to the spin echo.

8. A magnetic resonance imaging method according to claim 7, wherein the second 90°

x pulse is a +90°

x pulse.

9. A magnetic resonance imaging method according to claim 8, wherein the first time is shorter than the polarity recovery time for spins that are used for imaging.

10. A magnetic resonance imaging method according to claim 7, wherein the second 90°

x pulse is a −

90°

x pulse.

11. A magnetic resonance imaging method according to claim 10, wherein the first time is longer than the polarity recovery time for spins that are used for imaging.

12. A magnetic resonance imaging method according to claim 7, wherein excitation is always selective excitation.

13. A magnetic resonance imaging method according to claim 12, wherein a series of excitations starting with excitation initiated with application of the 180°

pulse and ending with excitation initiated with application of the second 90°

x pulse is started a plurality of times at successive time instants within the first time with slices changed sequentially.

15. A magnetic resonance imaging system according to claim 14, wherein the second 90°

x pulse is a +90°

x pulse.

16. A magnetic resonance imaging system according to claim 15, wherein the first time is shorter than the polarity recovery time for spins that are used for imaging.

17. A magnetic resonance imaging system according to claim 14, wherein the second 90°

x pulse is a −

900 x pulse.

18. A magnetic resonance imaging system according to claim 17, wherein the first time is longer than the polarity recovery time for spins that are used for imaging.

19. A magnetic resonance imaging system according to claim 14, wherein excitation is always selective excitation.

20. A magnetic resonance imaging system according to claim 19, further comprising a control device for starting a series of excitations, which starts with excitation initiated with application of the 180°

pulse and ends with excitation initiated with application of the 90°

x pulse, a plurality of times at successive time instants within the first time with slices changed sequentially.

14. A magnetic resonance imaging system for producing an image using a magnetic resonance signal induced by spins in a subject being imaged according to the fast spin echo technique combined with the inversion recovery technique, comprising:

a spin exciting device for exciting spins with application of a 180°

pulse, exciting the spins with application of a first 90°

x pulse after the elapse of a first time, exciting the spins with application of a 180°

y pulse after the elapse of a second time, exciting the spins sequentially by applying the 180°

y pulse an odd number of times after the elapse of a third time that is double the second time, and exciting the spins with application of a second 90°

x pulse after the elapse of the second time;

an echo reading device for reading a spin echo during the third time; and

an image producing device for producing an image according to the spin echo.