Magnetic resonance imaging apparatus and magnetic resonance imaging method

• US 7,613,496 B2
• Filed: 09/21/2006
• Issued: 11/03/2009
• Est. Priority Date: 09/22/2005
• Status: Active Grant

• Current Assignee: Toshiba Medical Systems Corporation (Canon Inc.)
• Original Assignee: Toshiba Medical Systems Corporation (Canon Inc.), Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Kanazawa, Hitoshi, Miyazaki, Mitsue
• Primary Examiner(s): Winakur; Eric F
• Assistant Examiner(s): Laryea; Lawrence N
• Application Number:
  US11/524,309
• Publication Number:
  US 20070083105A1
• Time in Patent Office: 1,139 Days
• Field of Search: 600/410, 600/411, 600/419, 324/306, 324/309
• US Class Current: 600/419
• 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 33/5608 Data processing and visualization specially adapted for MR, e.g. for feature analysis and pattern recognition on the basis of measured MR data, segmentation of measured MR data, edge contour detection on the basis of measured MR data, for enhancing measured MR data in terms of signal-to-noise ratio by means of noise filtering or apodization, for enhancing measured MR data in terms of resolution by means for deblurring, windowing, zero filling, or generation of gray-scaled images, colour-coded images or images displaying vectors instead of pixels image data processing or generation, in general G06T
• CPC Class Codes: G01R 33/5617 using RF refocusing, e.g. RARE
• CPC Class Codes: G01R 33/56316 involving phase contrast techniques
• CPC Class Codes: G01R 33/5635 Angiography, e.g. contrast-enhanced angiography [CE-MRA] or time-of-flight angiography [TOF-MRA]
• 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 magnetic resonance imaging apparatus includes a blood flow velocity acquiring unit that acquires a flow velocity of the blood flow of an object, a capturing condition setting unit that, on the basis of the flow velocity of the blood flow acquired by the blood flow velocity acquiring unit, sets at least one of a transmitting phase of a transmitted exciting pulse, a transmitting phase of a refocusing pulse, a shift amount of the relative phase difference between the transmitted exciting phase and the refocusing pulse, and an intensity of a gradient pulse in a readout direction as a capturing condition, and a blood flow image capturing unit that creates a blood flow image of the object by performing an imaging scan on the basis of the capturing condition set by the capturing condition setting unit.

Claims

1. A magnetic resonance imaging apparatus comprising:

a blood flow velocity acquiring unit that acquires a flow velocity of the blood flow of an object;

an imaging condition setting unit configured to set on the basis of the flow velocity of the blood flow acquired by the blood flow velocity acquiring unit, at least one of (a) a transmitting phase of a transmitted exciting pulse, (b) a transmitting phase of a refocusing pulse, (c) a shift amount of the relative phase difference between the transmitted exciting phase and the refocusing pulse, and (d) an intensity of a gradient pulse in a readout direction as an imaging condition;

said capturing condition setting unit is configured to perform the setting such that (i) intensities of magnetic resonance signals generated from a vein in a diastole and a systole of the cardiac muscle of the object are equal to each other, and (ii) the difference between intensities of magnetic resonance signals generated from an artery in a diastole and a systole of the cardiac muscle of the object increases; and

a blood flow image capturing unit that creates a blood flow image of the object by performing an imaging scan on the basis of the imaging condition set by the imaging condition setting unit.

2. The magnetic resonance imaging apparatus according to claim 1, wherein:

the imaging condition setting unit sets the at least one of (a) the transmitting phase of the transmitted exciting pulse, (b) the transmitting phase of the refocusing pulse, and (c) the shift amount such that an intensity of a magnetic resonance signal generated from a vein of the object increases.

3. The magnetic resonance imaging apparatus according to claim 1, wherein:

the imaging condition setting unit sets the intensity of the gradient pulse such that an intensity of a magnetic resonance signal generated from an artery of the object is larger than a predetermined intensity.

4. The magnetic resonance imaging apparatus according to claim 1, wherein:

the blood flow image capturing unit creates a blood flow image so as to display at least one of a vein and an artery in recognizable colors.

5. The magnetic resonance imaging apparatus according to claim 1, wherein:

the blood flow image capturing unit detects vein data by performing a threshold process, which uses an upper limit and a lower limit, on data except for artery data among three-dimensional image data in a diastole obtained by the imaging scan.

6. A magnetic resonance imaging apparatus comprising:

a pre-scanning unit that performs a pre-scan that collects a plurality of reference blood flow images by varying at least one of (a) a transmitting phase of a transmitted exciting pulse, (b) a transmitting phase of a refocusing pulse, (c) a shift amount of the relative phase difference between the transmitted exciting phase and the refocusing pulse, and (d) an intensity of a gradient pulse in a readout direction;

an imaging condition setting unit configured to set an imaging condition using (a) the transmitting phase of the transmitted exciting pulse, (b) the transmitting phase of the refocusing pulse, (c) the shift amount of the relative phase difference between the transmitted exciting phase and the refocusing pulse, and (d) the intensity of a gradient pulse in a readout direction that are used for an image selected from the plurality of the reference blood flow images;

said capturing condition setting unit is configured to perform the setting such that (i) intensities of magnetic resonance signals generated from a vein in a diastole and a systole of the cardiac muscle of the object are equal to each other, and (ii) the difference between intensities of magnetic resonance signals generated from an artery in a diastole and a systole of the cardiac muscle of the object increases; and

a blood flow image capturing unit that creates a blood flow image of the object by performing an imaging scan on the basis of the imaging condition set by the imaging condition setting unit.

7. A magnetic resonance imaging apparatus, comprising:

a storage unit that stores at least one of (a) a transmitting phase of a transmitted exciting pulse, (b) a transmitting phase of a refocusing pulse, (c) a shift amount of the relative phase difference between the transmitted exciting phase and the refocusing pulse, and (d) an intensity of a gradient pulse in a readout direction so as to be associated with at least one of an imaging condition and a blood flow velocity;

an imaging condition determining unit configured to determine on the basis of the at least one of (a) the transmitting phase of the transmitted exciting pulse, (b) the transmitting phase of the refocusing pulse, (c) the shift amount, and (d) the intensity of the gradient pulse that are stored in the storage unit, determines the at least one of (a) the transmitting phase of the transmitted exciting pulse, (b) the transmitting phase of the refocusing pulse, (c) the shift amount of the relative phase difference between the transmitted exciting phase and the refocusing pulse, and (d) the intensity of the gradient pulse in the readout direction corresponding to the blood flow velocity of the object as an imaging condition;

said capturing condition determining unit is configured to perform the determining such that (i) intensities of magnetic resonance signals generated from a vein in a diastole and a systole of the cardiac muscle of the object are equal to each other, and (ii) the difference between intensities of magnetic resonance signals generated from an artery in a diastole and a systole of the cardiac muscle of the object increases;

an imaging unit that performs a three-dimensional imaging scan for obtaining a multi-phase MRA image by synchronizing a signal representing a heart phase collected by a time phase detecting unit on the basis of the imaging condition determined by the imaging condition determining unit; and

a data processing unit that obtains a differential image by differentiating the multi-phase MRA image obtained by the three-dimensional imaging scan.

8. The magnetic resonance imaging apparatus according to claim 7, wherein:

the data processing unit differentiates an MRA image in the diastole and an MRA image in the systole as a multi-phase MRA image and acquires an MRA image in which the vein and the artery are distinguished as the differentiated image.

9. The magnetic resonance imaging apparatus according to claim 7, wherein:

the imaging unit controls a gradient magnetic field on the basis of the imaging condition and performs the scan by encoding a frequency in a moving direction of the blood vessel of the object.

10. The magnetic resonance imaging apparatus according to claim 7, wherein:

the storage unit stores the at least one of (a) the transmitting phase of the transmitted exciting pulse, (b) the transmitting phase of the refocusing pulse, (c) the shift amount, and (d) the intensity of the gradient pulse so as to be associated with at least one imaging condition; and

the imaging condition determining unit includes a graphical user interface to select at least one of the imaging condition and the blood flow velocity.

11. A magnetic resonance imaging method comprising:

acquiring a flow velocity of the blood flow of an object;

setting, on the basis of the acquired flow velocity of the blood flow, at least one of (a) a transmitting phase of a transmitted exciting pulse, (b) a transmitting phase of a refocusing pulse, (c) a shift amount of the relative phase difference between the transmitted exciting phase and the refocusing pulse, and (d) an intensity of a gradient pulse in a readout direction as an imaging condition such that (i) intensities of magnetic resonance signals generated from a vein in a diastole and a systole of the cardiac muscle of the object are equal to each other and (ii) the difference between intensities of magnetic resonance signals generated from an artery in a diastole and a systole of the cardiac muscle of the object increases; and

creating a blood flow image of the object by performing an imaging scan on the basis of the set imaging condition.

12. The magnetic resonance imaging method according to claim 11, wherein:

the at least one of (a) the transmitting phase of the transmitted exciting pulse, (b) the transmitting phase of the refocusing pulse, and (c) the shift amount is set such that an intensity of a magnetic resonance signal generated from a vein of the object increases.

13. The magnetic resonance imaging method according to claim 11, wherein:

the intensity of the gradient pulse is set such that an intensity of a magnetic resonance signal generated from an artery of the object is equal or larger than a predetermined intensity.

14. The magnetic resonance imaging method according to claim 11, wherein:

a blood flow image is created so as to display at least one of a vein and an artery in recognizable colors.

15. The magnetic resonance imaging method according to claim 11, wherein:

vein data is detected by performing a threshold process, which uses an upper limit and a lower limit, on data except for artery data among three-dimensional image data in a diastole obtained by the imaging scan.

16. A magnetic resonance imaging method comprising:

performing a pre-scan that collects a plurality of reference blood flow images by varying at least one of (a) a transmitting phase of a transmitted exciting pulse, (b) a transmitting phase of a refocusing pulse, (c) a shift amount of the relative phase difference between the transmitted exciting phase and the refocusing pulse, and (d) an intensity of a gradient pulse in a readout direction such that (i) intensities of magnetic resonance signals generated from a vein in a diastole and a systole of the cardiac muscle of the object are equal to each other, and (ii) the difference between intensities of magnetic resonance signals generated from an artery in a diastole and a systole of the cardiac muscle of the objects increases;

setting an imaging condition using (a) the transmitting phase of the transmitted exciting pulse, (b) the transmitting phase of the refocusing pulse, (c)the shift amount of the relative phase difference between the transmitted exciting phase and the refocusing pulse, and (d) the intensity of a gradient pulse in a readout direction that are used for an image selected from the plurality of the reference blood flow images such that (i) intensities of magnetic resonance signals generated from a vein in a diastole and a systole of the cardiac muscle of the objects are equal to each other and (ii) the difference between intensities of magnetic resonance signals generated from an after in a diastole and a systole of the cardiac muscle of the objects increases; and

creating a blood flow image of the object by performing an imaging scan on the basis of the imaging condition set by the imaging condition setting unit.

17. A magnetic resonance imaging method comprising:

storing at least one of (a) a transmitting phase of a transmitted exciting pulse, (b) a transmitting phase of a refocusing pulse, (c) a shift amount of the relative phase difference between the transmitted exciting phase and the refocusing pulse, and (d) an intensity of a gradient pulse in a readout direction so as to be associated with at least one of an imaging condition and a blood flow velocity;

determining, on the basis of the at least one of (a) the transmitting phase of the transmitted exciting pulse, (b) the transmitting phase of the refocusing pulse, (c) the shift amount, and (d) the intensity of the gradient pulse that are stored in the storage unit, the at least one of (a) the transmitting phase of the transmitted exciting pulse, (b) the transmitting phase of the refocusing pulse, (c) the shift amount of the relative phase difference between the transmitted exciting phase and the refocusing pulse, and (d) the intensity of the gradient pulse in the readout direction corresponding to the blood flow velocity of the object as an imaging condition such that (i) intensities of magnetic resonance signals generated from a vein in a diastole and a systole of the cardiac muscle of the objects are equal to each other and (ii) the difference between intensities of magnetic resonance signals generated from an artery in a diastole and a systole of the cardiac muscle of the objects increases;

performing a three-dimensional imaging scan for obtaining a multi-phase MRA image by synchronizing a signal representing a heart phase collected by a time phase detecting unit on the basis of the determined imaging condition; and

acquiring a differential image by differentiating the multi-phase MRA image obtained by the three-dimensional imaging scan.

18. The magnetic resonance imaging method according to claim 17, wherein:

an MRA image in the diastole and an MRA image in the systole are differentiated as a multi-phase MRA image and an MRA image in which the vein and the artery are distinguished is acquired as the differentiated image.

19. The magnetic resonance imaging method according to claim 17, wherein:

a gradient magnetic field is controlled on the basis of the imaging condition and the scan is performed by encoding a frequency in a moving direction of the blood vessel of the object.

20. The magnetic resonance imaging method according to claim 17, wherein:

the at least one of (a) the transmitting phase of the transmitted exciting pulse, (b) the transmitting phase of the refocusing pulse, (c) the shift amount, and (d) the intensity of the gradient pulse is stored to be associated with at least one imaging condition; and

at least one of the imaging condition and the blood flow velocity is selected by using a graphical user interface.