MAGNETIC RESONANCE IMAGING APPARATUS AND RF PULSE APPLYING METHOD

• US 20090270720A1
• Filed: 04/23/2009
• Published: 10/29/2009
• Est. Priority Date: 04/24/2008
• 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: Iwadate, Yuji, Kanda, Kenichi, Yamazaki, Aki
• Granted Patent: US 9,316,713 B2
• Time in Patent Office: Days
• US Class Current: 600/413
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: G01R 33/543 Control of the operation of the MR system, e.g. setting of acquisition parameters prior to or during MR data acquisition, dynamic shimming, use of one or more scout images for scan plane prescription G01R33/546 takes precedence
• CPC Class Codes: G01R 33/546 Interface between the MR system and the user, e.g. for controlling the operation of the MR system or for the design of pulse sequences
• CPC Class Codes: G01R 33/5676 Gating or triggering based on an MR signal, e.g. involving one or more navigator echoes for motion monitoring and correction

Abstract

A magnetic resonance imaging apparatus includes a scan section for executing a navigator sequence which transmits an RF pulse to a subject to obtain each magnetic resonance signal as navigator data. Upon execution of the navigator sequence, the scan section excites both a navigator area having two regions from which intensities of different navigator data signals are obtained, said two regions containing a body-moved region of the subject, and a region different from the two regions simultaneously, and transmits the RF pulse in such a manner that the phase of navigator data obtained from the different region differs from the phase of at least one region of navigator data obtained from the two regions.

Claims

1. A magnetic resonance imaging apparatus comprising:

a scan section configured to execute a navigator sequence which transmits an RF pulse to a subject to obtain each magnetic resonance signal as navigator data,

wherein upon execution of the navigator sequence, the scan section is configured to simultaneously excite both a navigator area having a first region and a second region from which intensities of different navigator data signals are obtained, and a third region from the first and second regions, and to transmit the RF pulse such that a phase of navigator data obtained from the third region differs from a phase of at least one region of navigator data obtained from the first and second regions, wherein the first and second regions include at least a body-moved region.

2. The magnetic resonance imaging apparatus according to claim 1, wherein the scan section is configured to transmit the RF pulse such that an intensity of a navigator data signal obtained from the third region falls between the intensities of the navigator data signals obtained from the first and second regions.

3. The magnetic resonance imaging apparatus according to claim 1, wherein the scan section is configured to transmit the RF pulse to a lung and a liver set as the first and second regions and a subcutaneous fat set as the third region, respectively.

4. The magnetic resonance imaging apparatus according to claim 3, wherein the scan section is configured to transmit the RF pulse to the subcutaneous fat set as the third region, which is located in a plane orthogonal to the navigator area.

5. The magnetic resonance imaging apparatus according to claim 3, wherein the scan section is configured to execute the navigator sequence such that the phase of navigator data obtained from the subcutaneous fat differs from the phase of navigator data obtained from the liver.

6. The magnetic resonance imaging apparatus according to claim 5, wherein the scan section is configured to execute the navigator sequence such that the intensity of a navigator data signal obtained from the subcutaneous fat is lower than the intensity of a navigator data signal obtained from the liver.

7. The magnetic resonance imaging apparatus according to claim 1, wherein the scan section is configured to execute the navigator sequence such that, upon excitation of the navigator sequence, a gradient magnetic field assumes a spiral trajectory on a k space.

8. The magnetic resonance imaging apparatus according to claim 1, wherein the scan section is configured to transmit RF pulses for exciting the first and second regions and the third region in cylindrical form respectively.

9. The magnetic resonance imaging apparatus according to claim 7, wherein a number of turns at the time that the gradient magnetic field assumes a spiral trajectory on a k space, is determined based on an interval between the navigator area and the third region.

10. The magnetic resonance imaging apparatus according to claim 7, wherein a gradient magnetic field is generated so as to assume a spiral trajectory outside as viewed from the center of the k space.

11. The magnetic resonance imaging apparatus according to claim 7, wherein the gradient magnetic field is generated so as to assume a spiral trajectory in the center of the k space as viewed from outside the k space.

12. An RE pulse applying method comprising:

executing a navigator sequence for transmitting an RF pulse to a subject and thereby obtaining each magnetic resonance signal as navigator data, wherein exciting the navigator sequence comprises;

simultaneously exciting both a navigator area having a first region and a second region which intensities of different navigator data signals are obtained, and a third region from the first and second regions, wherein one of the first and second regions is a body-moved region; and

transmitting the RF pulse such that a phase of navigator data obtained from the third region differs from a phase of at least one region of navigator data obtained from the first and second regions.

13. The RF pulse applying method according to claim 12, further comprising transmitting the RF pulse such that an intensity of a navigator data signal obtained from the third region falls between the intensities of the navigator data signals obtained from the first and second regions.

14. The RF pulse applying method according to claim 12, further comprising transmitting the RF pulse to a lung and a liver set as the first and second regions and a subcutaneous fat set as the third region, respectively.

15. The RF pulse applying method according to claim 14, further comprising transmitting the RF pulse to the subcutaneous fat set as the third region, which is located in a plane orthogonal to the navigator area.

16. The RF pulse applying method according to claim 14, further comprising executing the navigator sequence such that a phase of navigator data obtained from the subcutaneous fat differs from a phase of navigator data obtained from the liver.

17. The RF pulse applying method according to claim 16, further comprising executing the navigator sequence such that an intensity of a navigator data signal obtained from the subcutaneous fat is lower than an intensity of a navigator data signal obtained from the liver.

18. The RF pulse applying method according to claim 12, further comprising executing the navigator sequence such that, upon excitation of the navigator sequence, a gradient magnetic field assumes a spiral trajectory in a k space.

19. The RF pulse applying method according to claim 12, further comprising transmitting RF pulses for exciting the first and second regions and the third region in cylindrical form respectively.

20. The RF pulse applying method according to claim 18, further comprising determining a number of turns at a time that the gradient magnetic field assumes the spiral trajectory on the k space, based on an interval between the navigator area and the third region.