Systems and methods for manipulating changes in phase encodes

• US 6,940,280 B2
• Filed: 04/16/2002
• Issued: 09/06/2005
• Est. Priority Date: 04/17/2001
• Status: Expired due to Fees

• 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
• Primary Examiner(s): Arana, Louis
• Assistant Examiner(s): Vargas, Dixomara
• Application Number:
  US10/123,329
• Publication Number:
  US 20020149366A1
• Time in Patent Office: 1,239 Days
• Field of Search: 324/306, 324/307, 324/309, 600/410, 600/411
• US Class Current: 324/307
• CPC Class Codes: G01R 33/561 by reduction of the scanning time, i.e. fast acquiring systems, e.g. using echo-planar pulse sequences

Abstract

To reduce artifacts caused by sudden change of a phase encode amount, data Hj, Mj, and Lj having a large phase encode amount are collected, and then, when collecting data C_3j-4, C_3j-3, and C_3j-2 having a small phase encode amount, a buffer pulse sequence having an intermediate phase encode amount (+9) or (+49) is inserted one or more times between both.

Claims

1. A data collection method comprising:

dividing a k space into (2I+1) regions, wherein the (2I+1) regions include a zeroth region positioned in a center of a phase encode axis, two first regions, and two Ith regions lying along the phase encode axis, wherein one of the first regions lies between the zeroth region and one of the Ith regions, a remaining region of the first regions lies between the zeroth region and a remaining region of the Ith regions;

repeating a magnetic resonance (MR) data collection from an nth region while changing n successively to fill the k space, wherein n ranges from 1 to I;

intermittently collecting MR data corresponding to the zeroth region after each successive change in n; and

inserting a pulse sequence for at least one time to collect data between the MR data collection from the nth region and said intermittently collecting the MR data corresponding to the zeroth region, wherein the pulse sequence corresponds to a phase encode amount that is included in one of the first regions, and the phase encode amount is represented by a polarity and a magnitude along the phase encode axis.

2. The data collection method of claim 1, wherein a difference between the phase encode amount included in one of the first regions and a phase encode amount included in the zeroth region is a minimum value among values of differences between phase encode amounts included in one of the first regions and phase encode amounts included in the zeroth region.

3. The data collection method of claim 1, further comprising generating images of a blood stream from data that fills the k space.

4. The data collection method of claim 1 wherein I is at least equal to 2.

5. A data collection method comprising:

dividing a k space into (2I+1) regions, wherein the (2I+1) regions include a zeroth region positioned in a center of a phase encode axis, two first regions, and two Ith regions lying along the phase encode axis, wherein one of the first regions lies between the zeroth region and one of the Ith regions, a remaining region of the first regions lies between the zeroth region and a remaining region of the Ith regions;

repeating a magnetic resonance (MR) data collection from an nth region while changing n successively to fill the k space, wherein n ranges from 1 to I;

intermittently collecting MR data corresponding to the zeroth region after each successive change in n; and

inserting;

when n equals one of 1 and 2, a first pulse sequence for (I−

1) times to collect data between the MR data collection from the nth region and said intermittently collecting the MR data corresponding to the zeroth region, wherein the first pulse sequence corresponds to a first phase encode amount that is included in one of the first regions, and the first phase encode amount is represented by a polarity and a magnitude along the phase encode axis; and

when n is at least equal to 3, a second pulse sequence for (I−

1) times to collect data between the MR data collection from the nth region and said intermittently collection the MR data corresponding to the zeroth region, wherein the second pulse sequence corresponds to a second phase encode amount that is included in an (n−

1)th region, and the second phase encode amount is represented by a polarity and a magnitude along the phase encode axis.

6. The data collection method of claim 5, wherein a difference between the second phase encode amount and a third phase encode amount included in the zeroth region is a minimum value among values of differences between phase encode amounts include in the (n−

1)th region and phase encode amounts included in the zeroth region.

7. The data collection method of claim 5, wherein a difference between the first phase encode amount and a third phase encode amount included in the zeroth region is a minimum value among values of differences between phase encode amounts included in one of the first regions and phase encode amounts included in the zeroth region, and a difference between the second phase encode amount and the third phase encode amount included in the zeroth region is a minimum value among values of differences between phase encode mounts included in one of the second regions and the phase encode amounts included in the zeroth region.

8. The data collection method of claim 5, further comprising generating images of a blood stream from data that fills the k space.

9. The data collection method of claim 5 wherein I is at least equal to 3.

10. The data collection method of claim 5, wherein said dividing comprises dividing, when I equals 3, the k-space into seven regions including a zeroth region, the two first regions, two second regions, and two third regions.

11. The data collection method of claim 5 wherein said repeating the MR data collection from the nth region comprises repeating the MR data collection from the nth region while successively selecting n from 1 to 3 to fill the k space.

12. The data collection method of claim 11 wherein said inserting comprises at least one of:

inserting a third pulse sequence for two times to collect data between the MR data collection for one of the first two regions and the MR data collection for the zeroth region, wherein the third pulse sequence corresponds to the first phase encode amount that is included in one of the first regions;

inserting the third pulse sequence for two times to collect data between a data collection for one of the second regions and the MR data collection for the zeroth region;

inserting the third pulse sequence once to collect data between a data collection for one of the third regions and the MR data collection for the zeroth region; and

inserting a fourth pulse sequence once to collect data between the MR data collection for one of the two third regions and the MR data collection for the zeroth region, wherein the fourth pulse sequence corresponds to a third phase encode amount that is included in one of the second regions.

13. A data collection method comprising:

collecting magnetic resonance (MR) data applying a first phase encode amount after each successive change in n ranging from 1 to I in a k-space divided into 2I+1 regions; and

inserting a pulse sequence, for at least one time, between said collecting MR data by applying the first phase encode amount and each successive change in n, wherein the pulse sequence corresponds to a second phase encode amount between the first phase encode amount and a third phase encode amount within the I^th region, and the first, second, and third phase encode mounts correspond to polarities and magnitudes along a phase encode axis.

14. An MRI system comprising:

a magnet configured to apply a magnetic field to a subject;

a transmitting coil configured to excite spins within nuclei of the subject;

a gradient coil configured to apply at least one gradient to the magnetic field;

a receiving coil configured to receive an NMR signal generated from the spins to fill a k space;

a data collection device configured to divide the k space into (2I+1) regions, wherein the (2I+1) regions include a zeroth region positioned in a center of a phase encode axis, two first regions, and two Ith regions lying along the phase encode axis, wherein one of the first regions lies between the zeroth region and one of the Ith regions, a remaining region of the first regions lies between the zeroth region and a remaining region of the Ith regions, wherein said data collection device is configured to repeat a data collection from an nth region while changing n successively to fill the k, space and perform an intermittent collection of MR data corresponding to the zeroth region after each successive change in n, and n from 1 to I; and

a buffer pulse sequence inserting device configured to insert a pulse sequence for at least one time to collect data between the data collection from the nth region and the intermittent collection of the MR data corresponding to the zeroth region, wherein the pulse sequence corresponds to a phase encode amount that is included in one of the first regions, and the phase encode amount is represented by a polarity and a magnitude along the phase encode axis.

15. The MRI system of claim 14, wherein a difference between the phase encode amount included in one of the first regions and a phase encode amount included in the zeroth region is a minimum value among values of differences between phase encode amounts included in one of the first regions and phase encode amounts included in the zeroth region.

16. The MRI system of claim 14, wherein said data collection device generates images of a blood stream from data that fills the k space.

17. An MRI system comprising:

a magnet configured to apply a magnetic field to a subject;

a transmitting coil configured to excite spins within nuclei of the subject;

a gradient coil configured to apply at least one gradient to the magnetic field;

a receiving coil configured to receive an NMR signal generated from the spins to fill a k space;

a data collection device configured to divide the k space into (2I+1) regions, wherein the (2I+1) regions include a zeroth region positioned in a center of a phase encode axis, two first regions, and two Ith regions lying along the phase encode axis, wherein one of the first regions lies between the zeroth region and one of the Ith regions, a remaining region of the first regions lies between the zeroth region and a remaining region of the Ith regions, wherein said data collection device is configured to repeat a data collection from an nth region while changing n successively to fill the k, space and perform an intermittent collection of MR data corresponding to the zeroth region after each successive change in n, wherein n ranges from 1 to I; and

a buffer pulse sequence inserting device configured to insert;

when n equals one of 1 and 2, a first pulse sequence for (I−

1) times to collect data between the data collection from the nth region and the intermittent collection of the MR data corresponding to the zeroth region, wherein the first pulse sequence corresponds to a first phase encode amount that is included in one of the first regions, and the first phase encode amount is represented by a polarity and a magnitude along the phase encode axis; and

when n is at least equal to 3, a second pulse sequence for (I−

1) times to collect data between the data collection from the nth region and the intermittent collection of the MR data corresponding to the zeroth region, wherein the second pulse sequence corresponds to a second phase encode amount that is included in an (n−

1)th region, and the second phase encode amount is represented by a polarity and a magnitude along the phase encode axis.

18. The MRI system of claim 17, wherein a difference between the second phase encode amount and a third phase encode amount included in the zeroth region is a minimum value among values of differences between phase encode amounts included in the (n−

1)th region and phase encode amounts included in the zeroth region.

19. The MRI system of claim 17, wherein to divide the k space said data collection device configured to divide, when I equals 3, the k-space into seven regions including a zeroth region, the two first regions, two second regions, and two third regions.

20. The MRI system of claim 17 wherein to repeat the MR data collection from the nth region and the MR data collection for the zeroth region said data collection device configured to repeat the MR data collection from the nth region and the MR data collection for the zeroth region while successively selecting n from 1 to 3 to fill the k space.

21. The claim 20 wherein to insert said buffer pulse sequence inserting device configured to perform at least one of:

inserting a third pulse sequence for two times to collect data between the data collection for one of the first two regions and the data collection for the zeroth region, wherein the third pulse sequence corresponds to the first phase encode amount that is included in one of the first regions; and

inserting the third pulse sequence for two times to collect data between a data collection for one of the second regions and the data collection for the zeroth region;

inserting the third pulse sequence once to collect data between a data collection for one of the third regions and the data collection for the zeroth region; and

inserting a fourth pulse sequence once to collect data between the data collection for one of the two third regions and the data collection for the zeroth region, wherein the fourth pulse sequence corresponds to a third phase encode amount that is included in one of the second regions.

22. The MRI system of claim 17, wherein a difference between the first phase encode amount and a third phase encode amount included in the zeroth region is a minimum value among values of differences between phase encode amounts included in one of the first regions and phase encode amounts included in the zeroth region, and a difference between the second phase encode amount and the third phase encode amount included in the zeroth region is a minimum value among values of differences between phase encode amounts included in one of the second regions and phase encode amounts included in the zeroth region.

23. The MRI system of claim 17, wherein said data collection device generates images of a blood stream from data that fills the k space.

24. An MRI system comprising:

a magnet configured to apply a magnetic field to a subject;

a transmitting coil configured to excite spins within nuclei of the subject;

a gradient coil configured to apply at least one gradient to the magnetic field;

a receiving coil configured to receive an NMR signal generated from the spins to fill a k space;

a data collection device configured to collect data by applying a first phase encode amount after each successive change in n ranging from 1 to I in a k-space divided into 2I+1regions; and

a buffer pulse sequence inserting device configured to insert a pulse sequence, for at least one time, between collecting the data obtained by using the first phase encode amount and each successive change in n, wherein the pulse sequence corresponds to a second phase encode amount between the first phase encode amount and a third phase encode amount within the I^th region, and the first, second, and third phase encode amounts correspond to polarities and magnitudes along a phase encode axis.