METHOD AND APPARATUS FOR MEASURING T1 RELAXATION

• US 20080150532A1
• Filed: 12/21/2006
• Published: 06/26/2008
• Est. Priority Date: 12/21/2006
• Status: Abandoned Application

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Gupta, Sandeep Narendra, Slavin, Glenn Scott
• Application Number:
  US11/614,593
• Publication Number:
  US 20080150532A1
• Time in Patent Office: Days
• US Class Current: 324/318
• CPC Class Codes: G01R 33/50 based on the determination of relaxation times , e.g. T1 measurement by IR sequences; T2 measurement by multiple-echo sequences
• CPC Class Codes: G01R 33/56509 due to motion, displacement or flow, e.g. gradient moment nulling G01R33/567 takes precedence
• CPC Class Codes: G01R 33/5673 Gating or triggering based on a physiological signal other than an MR signal, e.g. ECG gating or motion monitoring using optical systems for monitoring the motion of a fiducial marker

Abstract

A method for rapid measurement of T1 relaxation comprises a gated, multi-time-point saturation-recovery experiment. Each saturation-recovery experiment may include multiple gating intervals to increase dynamic range of the T1 measurement. Multiple saturation-recovery experiments may also be used to improve accuracy and signal-to-noise of the T1 measurement.

Claims

1. A method for measuring T1 relaxation, the method comprising:

applying a magnetic field to a subject, the subject comprising a plurality of tissues, each tissue characterized by a T1 relaxation time, wherein the magnetic field causes a net longitudinal magnetization in the plurality of tissues;

receiving a first trigger signal;

in response to the first trigger signal, generating a first saturation radio frequency pulse configured to saturate the longitudinal magnetization from the plurality of tissues;

acquiring a first set of magnetic resonance imaging data at a predetermined time delay after the first trigger signal;

receiving a second trigger signal;

acquiring a second set of magnetic resonance imaging data at the predetermined time delay after the second trigger signal; and

calculating at least one T1 relaxation time based on at least the first and second sets of magnetic resonance imaging data.

2. A method according to claim 1, further comprising:

receiving a third trigger signal;

generating a second saturation radio frequency pulse configured to saturate the longitudinal magnetization from the plurality of tissues;

acquiring a third set of magnetic resonance imaging data at the predetermined time delay after the third trigger signal; and

calculating at least one T1 relaxation time based on at least the first, second, and third sets of magnetic resonance imaging data.

3. A method according to claim 1, wherein the trigger signals are derived from electrocardiograph data.

4. A method according to claim 1, further comprising calculating a T1 map.

5. A method according to claim 1, wherein acquiring a first set of magnetic resonance imaging data and acquiring a second set of magnetic resonance imaging data comprises performing a fast gradient-recalled echo pulse sequence.

6. A method according to claim 5, wherein the fast gradient-recalled echo pulse sequence is a steady-state free precession pulse sequence.

7. A method according to claim 1, wherein the method for measuring T1 relaxation is performed during a breath-hold time associated with the subject.

8. A method according to claim 1, wherein the at least one T1 relaxation time is for myocardial tissue.

9. A computer-readable medium having computer-executable instructions for performing a method for measuring T1 relaxation, the computer-readable medium comprising:

program code for receiving a first trigger signal;

program code for generating a first saturation radio frequency pulse in response to the first trigger signal, the first radio frequency pulse configured to saturate a longitudinal magnetization in a subject;

program code for acquiring a first set of magnetic resonance imaging data at a predetermined time delay after the first trigger signal;

program code for receiving a second trigger signal; and

program code for acquiring a second set of magnetic resonance imaging data at the predetermined time delay after the second trigger signal.

10. A computer-readable medium according to claim 9, further comprising:

program code for receiving a third trigger signal;

program code for generating a third saturation radio frequency pulse in response to the third trigger signal, the third saturation radio frequency pulse configured to saturate the longitudinal magnetization in the subject; and

program code for acquiring a third set of magnetic resonance imaging data at the predetermined time delay after the third trigger signal.

11. An apparatus for generating a magnetic resonance image, the apparatus comprising:

a magnetic resonance imaging assembly comprising a magnet, a plurality of gradient coils, a radio frequency coil, a radio frequency transceiver system, and a pulse generator module; and

a computer system coupled to the magnetic resonance imaging assembly and programmed to perform a first pulse sequence segment comprised of;

a first saturation radio frequency pulse configured to saturate a longitudinal magnetization in a subject, the first saturation radio frequency pulse performed in response to receipt of a first trigger signal;

a first data acquisition block configured to acquire magnetic resonance imaging data for a first image at a predetermined time delay after the first trigger signal; and

a second data acquisition block configured to acquire magnetic resonance imaging data for a second image at the predetermined time delay after a second trigger signal.

12. An apparatus according to claim 11, wherein the computer system coupled to the magnetic resonance imaging assembly is programmed additionally to perform a second pulse sequence segment comprised of:

a second saturation radio frequency pulse configured to saturate the longitudinal magnetization in the subject, the second saturation radio frequency pulse performed in response to receipt of a third trigger signal; and

a third data acquisition block configured to acquire magnetic resonance imaging data for a third image at the predetermined time delay after the third trigger signal.

13. An apparatus according to claim 11, wherein the first data acquisition block and the second data acquisition block comprise a fast gradient-recalled echo pulse sequence.

14. An apparatus according to claim 13, wherein the fast gradient-recalled echo pulse sequence is a steady-state free precession pulse sequence.

15. An apparatus according to claim 11, wherein the first trigger signal and the second trigger signal are derived from electrocardiograph data.