Magnetic resonance imaging apparatus

• US 9,791,533 B2
• Filed: 08/28/2014
• Issued: 10/17/2017
• Est. Priority Date: 09/05/2013
• Status: Active Grant

• Current Assignee: Toshiba Medical Systems Corporation (Canon Inc.)
• Original Assignee: Toshiba Medical Systems Corporation (Canon Inc.)
• Inventors: Sakashita, Naotaka, Kimura, Tokunori
• Primary Examiner(s): Lindsay, Jr., Walter L
• Assistant Examiner(s): Wenderoth, Frederick
• Application Number:
  US14/471,865
• Publication Number:
  US 20150061675A1
• Time in Patent Office: 1,146 Days
• Field of Search: 324318
• CPC Class Codes: G01R 33/5602 by filtering or weighting based on different relaxation times within the sample, e.g. T1 weighting using an inversion pulse
• CPC Class Codes: G01R 33/56366 Perfusion imaging
• 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 according to an embodiment includes an execution unit and a generation unit. The execution unit executes first data collection after a predetermined inversion time elapses from a time when a labeling pulse is applied to a fluid flowing into an imaging region of a subject and a second data collection without application of the labeling pulse. The generation unit generates a differential image by using the first data and the second data. Here, the generation unit generates the differential image by a different differential method according to a relationship between the inversion time and a longitudinal relaxation time of the fluid.

Claims

1. A magnetic resonance imaging apparatus comprising:

execution circuitry configured to execute first data collection after a predetermined inversion time elapses from a time when a labeling pulse is applied to a fluid flowing into an imaging region of a subject and second data collection without application of the labeling pulse; and

generation circuitry configured to generate a differential image by using the first data and the second data,

wherein the generation circuitry is configured to generate the differential image by (i) a first differential method when the inversion time and a longitudinal relaxation time of the fluid have a first relationship, and (ii) a second differential method, differing from the first differential method, when the inversion time and a longitudinal relaxation time of the fluid have a second relationship differing from the first relationship.

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

wherein the execution circuitry is configured to execute data collection after the inversion time elapses from a time when a control pulse similar to the labeling pulse is applied to a position where the fluid is not influenced as the second data collection.

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

wherein the execution circuitry is configured to execute data collection without an application of a control pulse as the second data collection.

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

wherein the generation circuitry is configured to generate the differential image in a different differential method according to whether the inversion time is shorter than the elapsed time taken until the longitudinal magnetization of the fluid becomes zero after application of the labeling pulse or is equal to or longer than the elapsed time.

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

wherein the generation circuitry is configured to generate a differential data by differentiating the first data and the second data and generates the differential image by executing a Fourier transform on the generated differential data when the inversion time is shorter than the elapsed time, and

wherein the generation circuitry is configured to generate a first absolute value image by executing a Fourier transform on the first data, to generate a second absolute value image by executing a Fourier transform on the second data, and generates the differential image by differentiating the first absolute value image and the second absolute value image when the inversion time is equal to or longer than the elapsed time.

6. The magnetic resonance imaging apparatus according to claim 1,

wherein the generation circuitry is configured to generate a first complex image by executing a Fourier transform on the first data, to generate a second complex image by executing a Fourier transform on the second data, and to generate the differential image by differentiating the first complex image and the second complex image when the inversion time is shorter than the elapsed time, and

wherein the generation circuitry is configured to generate a first absolute value image by executing a Fourier transform on the first data, to generate a second absolute value image by executing a Fourier transform on the second data, and to generate the differential image by differentiating the first absolute value image and the second absolute value image when the inversion time is equal to or longer than the elapsed time.

7. The magnetic resonance imaging apparatus according, to claim 1,

wherein the generation circuitry is configured to generate a first real image by executing a Fourier transform on the first data, to generate a second real image by executing a Fourier transform on the second data, and to generate the differential image by differentiating the first real image and the second real image when the inversion time is shorter than the elapsed time, and

wherein the generation circuitry is configured to generate a first absolute value image by executing a Fourier transform on the first data, to generate a second absolute value image by executing a Fourier transform on the second data, and to generate the differential image by differentiating the first absolute value image and the second absolute value image when the inversion time is equal to or longer than the elapsed time.

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

wherein the generation circuitry is configured to generate the first real image by performing a phase correction for the first data, and to generate the second real image by performing a phase correction for the second data.

9. The magnetic resonance imaging apparatus according to claim 1,

wherein the generation circuitry is configured to generate a first absolute value image by executing a Fourier transform on the first data, and to generate a second absolute value image by executing a Fourier transform on the second data,

wherein the generation circuitry is configured to generate the differential image by adding the first absolute value image and the second absolute value image when the inversion time is shorter than the elapsed time, and

wherein the generation circuitry is configured to generate the differential image by differentiating the first absolute value image and the second absolute value image when the inversion time is equal to or longer than the elapsed time.

10. The magnetic resonance imaging apparatus according to claim 9,

wherein the first absolute value image and the second absolute value image are set so that background signals are negligible or are small compared to a fluid element.

11. The magnetic resonance imaging apparatus according to claim 9,

wherein the generation circuitry is configured to generate the differential image by separating a background part and a fluid part from each other by a mask processing in each of the first absolute value image and the second absolute value image, differentiating an absolute value regardless of the inversion time as for the background part, and adding an absolute value when the inversion time is shorter than the elapsed time or differentiating an absolute value when the inversion time is equal to or longer than the elapsed time as for the fluid part.

12. The magnetic resonance imaging apparatus according to claim 1, further comprising:

setting circuitry configured to calculate a time until the longitudinal magnetization of the fluid becomes zero after the application of the labeling pulse based on a value T1 of a fluid of an imaging object,

wherein the generation circuitry is configured to use the time calculated by the setting circuitry as the elapsed time.

13. The magnetic resonance imaging apparatus according to claim 12, further comprising:

setting circuitry configured to calculate a time until the longitudinal magnetization of the fluid becomes zero after the application of the labeling pulse based on a data obtained by a pre-scan of executing plural times the data collection of collecting the data after the predetermined inversion time elapses from a timing in which the labeling pulse is applied while changing the inversion time,

wherein the generation circuitry is configured to use the time calculated by the setting circuitry as the elapsed time.

14. A magnetic resonance imaging (MRI) method comprising:

using an MRI system to effect

collecting first MRI data after a predetermined inversion time elapses from a time when a labeling pulse is applied to a fluid flowing into an imaging region of a subject and collecting second MRI data without application of the labeling pulse; and

generating a differential image by using the first MRI data and the second MRI data,

wherein the differential image is generated by (i) a first differential method when the inversion time and a longitudinal relaxation time of the fluid have a first relationship, and (ii) a second differential method, differing from the first differential method, when the inversion time and a longitudinal relaxation time of the fluid have a second relationship differing from the first relationship.

15. The magnetic resonance imaging method according to claim 14,

wherein the second MRI data is collected after the inversion time elapses from a time when a control pulse similar to the labeling pulse is applied to a position where the fluid is not influenced.

16. The magnetic resonance imaging method according to claim 14,

wherein the second MRI data is collected without application of a control pulse.

17. The magnetic resonance imaging method according to claim 14,

wherein the differential image is generated using a different differential method according to whether the inversion time is shorter than the elapsed time taken until the longitudinal magnetization of the fluid becomes zero after application of the labeling pulse or is equal to or longer than the elapsed time.

18. The magnetic resonance imaging method according to claim 14,

wherein differential data is generated by differentiating the first MRI data and the second MRI data and the differential image is generated by executing a Fourier transform on the generated differential data when the inversion time is shorter than the elapsed time, and

wherein a first absolute value image is generated by executing a Fourier transform on the first MRI data, a second absolute value image is generated by executing a Fourier transform on the second MRI data, and the differential image is generated by differentiating the first absolute value image and the second absolute value image when the inversion time is equal to or longer than the elapsed time.

19. The magnetic resonance imaging method according to claim 14,

wherein a first complex image is generated by executing a Fourier transform on the first MRI data, a second complex image is generated by executing a Fourier transform on the second MRI data, and the differential image is generated by differentiating the first complex image and the second complex image when the inversion time is shorter than the elapsed time, and

wherein a first absolute value image is generated by executing a Fourier transform on the first MRI data, a second absolute value image is generated by executing a Fourier transform on the second MRI data, and the differential image is generated by differentiating the first absolute value image and the second absolute value image when the inversion time is equal to or longer than the elapsed time.

20. The magnetic resonance imaging method according to claim 14,

wherein a first real image is generated by executing a Fourier transform on the first MRI data, a second real image is generated by executing a Fourier transform on the second MRI data, and the differential image is generated by differentiating the first real image and the second real image when the inversion time is shorter than the elapsed time, and

wherein a first absolute value image is generated by executing a Fourier transform on the first MRI data, a second absolute value image is generated by executing a Fourier transform on the second MRI data, and the differential image is generated by differentiating the first absolute value image and the second absolute value image when the inversion time is equal to or longer than the elapsed time.