Magnetic resonance imaging needing a long waiting time between pre-pulses and imaging pulse train

• US 20040049106A1
• Filed: 09/12/2003
• Published: 03/11/2004
• Est. Priority Date: 11/15/2001
• Status: Active Grant

• Current Assignee: Toshiba Medical Systems Corporation (Canon Inc.)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Kanazawa, Hitoshi
• Granted Patent: US 7,623,901 B2
• Time in Patent Office: Days
• US Class Current: 600/410
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/7285 for synchronising or triggering a physiological measurement or image acquisition with a physiological event or waveform, e.g. an ECG signal A61B6/5205, A61B6/541, A61B8/5207, A61B8/543 take precedence
• CPC Class Codes: G01R 33/563 of moving material, e.g. flow contrast angiography
• CPC Class Codes: G01R 33/56308 Characterization of motion or flow; Dynamic imaging
• CPC Class Codes: G01R 33/567 gated by physiological signals , i.e. synchronization of acquired MR data with periodical motion of an object of interest, e.g. monitoring or triggering system for cardiac or respiratory gating

Abstract

In the black blood method using a double inversion pulse, images in the systole of the cardiac cycle can be captured in a reliable manner even in the presence of a cycle-to-cycle variance in the heart beat cycle. A pulse sequence of the black blood method composed of a double inversion pulse DIV and an imaging pulse train SEQ_ima is used. This sequence is applied in sync with an ECG signal of a subject to be imaged, and magnetic resonance imaging is thereby performed. The double inversion DIV is applied in sync with an R-wave:R1 appearing on the ECG signal at a given timing, with a first delay time td1 (fixed value), and the imaging pulse train SEQ_ima is applied in sync with the following R-wave:R2 with a second delay time td2 (fixed value: set in accordance with the systole). A variance of the cardiac cycle is absorbed in an inversion time BBTI.

Claims

1. A magnetic resonance imaging apparatus that applies a pre-pulse to a subject to be imaged, and then performs scanning by applying an imaging pulse train to a desired region of said subject to be imaged when a desired standby time has elapsed since said pre-pulse was applied, said apparatus comprising:

acquiring means for acquiring a signal representing cardiac temporal phases of said subject to be imaged;

pre-pulse applying means for applying said pre-pulse in sync with a specific waveform appearing on the signal acquired by said acquiring means at a given timing, with a first delay time; and

scanning means for performing scanning by applying said imaging pulse train in sync with said specific waveform appearing on the signal detected by said acquiring means at a timing at least one cardiac cycle later than said timing, with a second delay time.

2. The magnetic resonance imaging apparatus according claim 1, wherein said pre-pulse is a double inversion pulse that forms part of a pulse sequence through a black blood method.

3. The magnetic resonance imaging apparatus according to claim 1, wherein said signal representing the cardiac temporal phases is an ECG signal, and said specific waveform is an R-wave of said ECG signal.

4. The magnetic resonance imaging apparatus according to claim 1, wherein said timing at least one cardiac cycle later at which said scanning means starts the scanning is a timing at which one cardiac cycle has elapsed.

5. The magnetic resonance imaging apparatus according to claim 1, wherein said timing at least one cardiac cycle later at which said scanning means starts the scanning is a timing at which two cardiac cycles have elapsed.

6. The magnetic resonance imaging apparatus according to claim 1, wherein said predetermined standby time is long enough to account for approximately a half or more than the half of one cycle of heart beat.

7. The magnetic resonance imaging apparatus according to claim 1, wherein said second delay time is a time set in accordance with a systole of heart beat, and said first delay time is a time calculated using said second delay time, a desired value of said standby time, and an average cycle of heart beat.

8. A magnetic resonance imaging apparatus that applies a pre-pulse to a subject to be imaged, and then performs scanning by applying an imaging pulse train to a desired region of said subject to be imaged when a predetermined standby time has elapsed since said pre-pulse was applied, said apparatus comprising:

means for synchronizing applications of said pre-pulse and said imaging pulse train respectively with two waveforms of the same kind appearing at different timings on a signal representing cardiac temporal phases of said subject to be imaged.

9. A scanning synchronization method of magnetic resonance imaging for applying a pulse sequence for magnetic resonance imaging, composed of a pre-pulse and an imaging pulse train whose application is started at a time instant at which a desired standby time has elapsed since said pre-pulse was applied, to a subject to be imaged in sync with a signal representing cardiac temporal phases of said subject to be imaged, said method comprising:

applying said pre-pulse in sync with a specific waveform appearing on said signal at a given timing, with a first delay time; and

performing scanning by applying said imaging pulse train in sync with said specific waveform appearing on said signal at a timing at least one cardiac cycle later than said timing, with a second delay time.

10. The scanning synchronization method according to claim 9, wherein said pre-pulse is a double inversion pulse that forms part of a pulse sequence through a black blood method.

11. The scanning synchronization method according to claim 9, wherein said signal representing the cardiac temporal phases is an ECG signal, and said specific waveform is an R-wave of said ECG signal.

12. The scanning synchronization method according to claim 9, wherein said timing at least one cardiac cycle later at which said scanning is started is a timing at which one cardiac cycle has elapsed.

13. The scanning synchronization method according to claim 9, wherein said timing at least one cardiac cycle later at which said scanning is started is a timing at which two cardiac cycles have elapsed.

14. The scanning synchronization method according to claim 9, wherein said standby time is long enough to account for approximately a half or more than the half of one cycle of heart beat.

15. The scanning synchronization method according to claim 9, wherein said second delay time is a time set in accordance with a systole of heart beat, and said first delay time is a time calculated using said second delay time, a desired value of said standby time, and an average cycle of heart beat.

16. A computer-readable recoding medium used for magnetic resonance imaging for applying a pulse sequence for magnetic resonance imaging composed of a pre-pulse and an imaging pulse train to a subject to be imaged in sync with a signal representing cardiac temporal phases of said subject to be imaged, said recording medium recording a program that causes a computer to perform:

a function of applying said pre-pulse in sync with a specific waveform appearing on said signal at a given timing, with a first delay time; and

a function of performing scanning by applying said imaging pulse train in sync with said specific waveform appearing on said signal at a timing at least one cardiac cycle later than said timing, with a second delay time.

17. A program for magnetic resonance imaging for applying a pulse sequence for magnetic resonance imaging composed of a pre-pulse and an imaging pulse train to a subject to be imaged in sync with a signal representing cardiac temporal phases of said subject to be imaged, said program causing a computer to perform:

a function of applying said pre-pulse in sync with a specific waveform appearing on said signal at a given timing, with a first delay time; and

a function of performing scanning by applying said imaging pulse train in sync with said specific waveform appearing on said signal at a timing at least one cardiac cycle later than said timing, with a second delay time.