MAGNETIC RESONANCE IMAGING APPARATUS AND MAGNETIC RESONANCE IMAGING METHOD

• US 20150131884A1
• Filed: 11/12/2014
• Published: 05/14/2015
• Est. Priority Date: 11/13/2013
• 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: KIMURA, Tokunori
• Granted Patent: US 9,488,711 B2
• Time in Patent Office: Days
• US Class Current: 382/131
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/0263 using NMR
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/489 Blood vessels
• 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 33/5607 by reducing the NMR signal of a particular spin species, e.g. of a chemical species for fat suppression, or of a moving spin species for black-blood imaging
• CPC Class Codes: G01R 33/5635 Angiography, e.g. contrast-enhanced angiography [CE-MRA] or time-of-flight angiography [TOF-MRA]

Abstract

According to one embodiment, an MRI apparatus includes a data acquiring part and a data processing part. The data acquiring part acquires first and second MR signals by applying at least one IR pulse under an application condition according to a relaxation time of a fluid. The first MR signals include MR signals, having negative values, from the fluid. The second MR signals include MR signals, having positive values, from the fluid. The data processing part generates first and second image data. The first image data depict the fluid as a lower signal region than that of a tissue. The second image data depict the fluid as a higher signal region than that of the tissue. The data processing part generates the first image data with a phase correction based on the second MR signals.

Claims

1. A magnetic resonance imaging apparatus comprising:

a data acquiring part configured to acquire first magnetic resonance signals and second magnetic resonance signals from a same imaging area of an object by applying at least one inversion recovery pulse under an application condition according to a relaxation time of a fluid, the first magnetic resonance signals including magnetic resonance signals, having negative values, from the fluid, the second magnetic resonance signals including magnetic resonance signals, having positive values, from the fluid; and

a data processing part configured to generate first image data and second image data based on the first magnetic resonance signals and the second magnetic resonance signals, the first image data depicting the fluid as a lower signal region than a signal region of a tissue, the second image data depicting the fluid as a higher signal region than a signal region of the tissue;

wherein said data processing part is configured to generate the first image data with a phase correction based on the second magnetic resonance signals.

2. A magnetic resonance imaging apparatus of claim 1,

wherein said data processing part is configured to perform the phase correction of real space signals using phase data and generate the first image data by processing for imaging real parts of the real space signals after the phase correction, the real space signals being generated based on the first magnetic resonance signals, the phase data being obtained based on the second magnetic resonance signals.

3. A magnetic resonance imaging apparatus of claim 1,

wherein said data acquiring part is configured to apply the at least one inversion recovery pulse repeatedly and acquire a part of the first magnetic resonance signals and a part of the second magnetic resonance signals alternately between applications of the at least one inversion recovery pulse.

4. A magnetic resonance imaging apparatus of claim 1,

wherein said data acquiring part is configured to apply a first inversion recovery pulse in a first application region and a second inversion recovery pulse in a second application region, the first application region being larger than the imaging area, the second application region being larger than the imaging area and narrower than the first application region, the first application region being set to make magnetic resonance signals from the fluid, having flowed from an outside into the imaging area, show negative values at acquisition timing of the first magnetic resonance signals, the second application region being set to make magnetic resonance signals from the fluid, having flowed from an outside into the imaging area, show positive values at acquisition timing of the second magnetic resonance signals;

and

said data processing part is configured to generate longitudinal relaxation weighted image data as the first image data and the second image data.

5. A magnetic resonance imaging apparatus of claim 1,

wherein said data acquiring part is configured to apply a first inversion recovery pulse and a second inversion recovery pulse, the first inversion recovery pulse being applied in each of a first application region and a second application region with a predetermined time interval, the first application region being larger than the imaging area, the first application region being set to make magnetic resonance signals from the fluid, having flowed from an outside into the imaging area, show negative values at acquisition timing of the first magnetic resonance signals, the second application region being larger than the imaging area and narrower than the first application region, the second inversion recovery pulse being applied twice in a third application region with the predetermined time interval or another predetermined time interval, the third application region being larger than the imaging area and narrower than the first application region, the third application region being same as or different from the second application region, the third application region being set to make magnetic resonance signals from the fluid, having flowed from an outside into the imaging area, show positive values at acquisition timing of the second magnetic resonance signals;

and

said data processing part is configured to generate transverse relaxation weighted image data or proton density weighted image data as the first image data and the second image data.

6. A magnetic resonance imaging apparatus of claim 1,

wherein said data acquiring part is configured to apply an inversion recovery pulse in an application region outside the imaging area and acquire the second magnetic resonance signals with applying no inversion recovery pulse, the application region being set to make magnetic resonance signals from the fluid, having flowed from an outside into the imaging area, show negative values at acquisition timing of the first magnetic resonance signals;

and

said data processing part is configured to generate transverse relaxation weighted image data or proton density weighted image data as the first image data and the second image data.

7. A magnetic resonance imaging apparatus of claim 1,

wherein said data acquiring part is configured to acquire the first magnetic resonance signals by applying the at least one inversion recovery pulse and the second magnetic resonance signals with applying no inversion recovery pulse, the second magnetic resonance signals including magnetic resonance signals from the tissue and magnetic resonance signals from the fluid having flowed into the imaging area, intensities of the magnetic resonance signals from the tissue being suppressed by repeatedly applying a radio frequency excitation pulse to the imaging area with a repetition time shorter than a longitudinal relaxation time of the tissue, the magnetic resonance signals from the fluid having positive values.

8. A magnetic resonance imaging apparatus of claim 1,

wherein said data acquiring part is configured to acquire at least multiple sets of the first magnetic resonance signals, the sets corresponding to at least one of different inversion times and different echo times;

and

said data processing part is configured to generate at least one of image data showing a distribution of a longitudinal relaxation time, image data showing a distribution of a transverse relaxation time, image data showing a distribution of a permeability of the fluid to the tissue and blood dynamic state image data, based on at least the multiple sets of the first magnetic resonance signals.

9. A magnetic resonance imaging apparatus of claim 1,

wherein said data acquiring part is configured to acquire the first magnetic resonance signals and the second magnetic resonance signals with inversion times which can be considered to be same;

and

said data processing part is configured to generate the second image data as image data, in which a depiction of the tissue is suppressed and the fluid is depicted, by data processing including subtraction processing between image data generated based on the first magnetic resonance signals and image data generated based on the second magnetic resonance signals.

10. A magnetic resonance imaging apparatus of claim 1,

wherein said data acquiring part is configured to acquire the first magnetic resonance signals and the second magnetic resonance signals after applying a common inversion recovery pulse.

11. A magnetic resonance imaging apparatus comprising:

a data acquiring part configured to acquire magnetic resonance signals from an imaging area of an object by applying at least one inversion recovery pulse under an application condition according to relaxation times of a first component to be a suppression target and a second component to be a weighted target, the magnetic resonance signals including signals, having negative values, from the first component and signals, having positive values, from the second component, the magnetic resonance signals corresponding to an asymmetric sampling region in at least one direction in a k-space; and

a data processing part configured to generate image data by data processing including a phase correction of real space signals generated based on the magnetic resonance signals and processing for imaging real parts of the real space signals after the phase correction, the image data depicting the first component as a lower signal region than a signal region of the second component.

12. A magnetic resonance imaging apparatus of claim 11,

wherein said data acquiring part is configured to acquire the magnetic resonance signals by a spin echo series of a pulse sequence.

13. A magnetic resonance imaging apparatus of claim 12,

wherein said data acquiring part is configured to acquire the magnetic resonance signals with applying refocus pulses having at least two different flip angles.

14. A magnetic resonance imaging apparatus of claim 11,

wherein said data processing part is configured to perform the phase correction using phase data obtained based on the magnetic resonance signals.

15. A magnetic resonance imaging apparatus of claim 14,

wherein said data processing part is configured to obtain the phase data based on magnetic resonance signals in a narrow region in a lower frequency side in at least one direction than a symmetric low frequency region out of the sampling region.

16. A magnetic resonance imaging apparatus of claim 14,

wherein said data processing part is configured to obtain the phase data based on magnetic resonance signals in a symmetric low frequency region out of the sampling region.

17. A magnetic resonance imaging apparatus of claim 14,

wherein said data processing part is configured to obtain the phase data by processing which inverts a phase of a real space signal determined to have shifted by 180 degrees from a phase of a real space signal corresponding to the second component, the real space signal corresponding to the second component being obtained based on the magnetic resonance signals, the processing which inverts the phase being performed for each voxel.

18. A magnetic resonance imaging apparatus of claim 14,

wherein said data processing part is configured to obtain the phase data by an interpolation based on a phase distribution of real space signals corresponding to the second component, the real space signals corresponding to the second component being obtained based on the magnetic resonance signals.

19. A magnetic resonance imaging apparatus of claim 11,

wherein said data processing part is configured to perform the phase correction using phase data obtained based on reference image data, the reference image data being generated using original data which are magnetic resonance signals different from the magnetic resonance signals acquired from the imaging area.

20. A magnetic resonance imaging apparatus of claim 11,

wherein said data acquiring part is configured to acquire magnetic resonance signals including signals, having the negative values, from blood as the first component and signals, having the positive values, from a tissue as the second component.

21. A magnetic resonance imaging method comprising:

acquiring first magnetic resonance signals and second magnetic resonance signals from a same imaging area of an object by applying at least one inversion recovery pulse under an application condition according to a relaxation time of a fluid, the first magnetic resonance signals including magnetic resonance signals, having negative values, from the fluid, the second magnetic resonance signals including magnetic resonance signals, having positive values, from the fluid; and

generating first image data and second image data based on the first magnetic resonance signals and the second magnetic resonance signals, the first image data depicting the fluid as a lower signal region than a signal region of a tissue, the second image data depicting the fluid as a higher signal region than a signal region of the tissue;

wherein the first image data are generated with a phase correction based on the second magnetic resonance signals.