Magnetic resonance imaging apparatus and magnetic resonance imaging method

Patent metadata

Field	Value
Publication number	US-9488711-B2
Application number	US-201414539584-A
Country	US
Kind code	B2
Filing date	Nov 12, 2014
Priority date	Nov 13, 2013
Publication date	Nov 8, 2016
Grant date	Nov 8, 2016

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.

First claim

What is claimed is:

1. A magnetic resonance imaging (MRI) apparatus comprising:
at least one radio frequency (RF) coil disposed within static and gradient magnetic field generators, an RF transmitter and an RF receiver coupled to said at least one RE coil, and at least one control computer connected to control said gradient magnetic field generators, said RF transmitter, said RF transmitter and said RF receiver to execute MRI data acquisition sequences and to process acquired MRI signals; said at least one control computer being configured to
acquire first and second magnetic resonance signals from a flowing fluid within same imaging area of an object using at least one inversion recovery pulse related to a MR relaxation time of a flowing fluid within the object, the first magnetic resonance signals, from the fluid including negative values, the second magnetic resonance signals from the fluid including positive values, and
generate first and second image data based, respectively, on the first and second magnetic resonance signals, the first image data depicting the fluid as a lower signal region than a signal region of surrounding tissue, the second image data depicting the fluid as a higher signal region than a signal region of the surrounding tissue;
the first image data being generated with a phase correction based on the second magnetic resonance signals.

2. The magnetic resonance imaging apparatus of claim 1 , wherein:
phase correction of real space signals is performed using phase data and the first image data is generated by 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. The magnetic resonance imaging apparatus of claim 1 , wherein:
the at least one inversion recovery pulse is applied repeatedly and a part of the first magnetic resonance signals and a part of the second magnetic resonance signals are alternately acquired between repeated applications of the at least one inversion recovery pulse.

4. The magnetic resonance imaging apparatus of claim 1 , wherein:
a first inversion recovery pulse is applied in a first application region and a second inversion recovery pulse is applied 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 smaller 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
longitudinal relaxation weighted image data is generated as the first image data and the second image data.

5. The magnetic resonance imaging apparatus of claim 1 , wherein:
a first inversion recovery pulse is applied and a second inversion recovery pulse is applied, the first inversion recovery pulse being applied in each of a first application region and a second application region after 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 smaller 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 smaller 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
transverse relaxation weighted image data or proton density weighted image data is generated as the first image data and the second image data.

6. The magnetic resonance imaging apparatus of claim 1 , wherein:
an inversion recovery pulse is applied in an application region outside the imaging area and the second magnetic resonance signals are acquired with no inversion recovery pulse being applied, 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
transverse relaxation weighted image data or proton density weighted image data is generated as the first image data and the second image data.

7. The magnetic resonance imaging apparatus of claim 1 , wherein:
the first magnetic resonance signals are acquired by applying the at least one inversion recovery pulse and the second magnetic resonance signals are acquired without applying an 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. The magnetic resonance imaging apparatus of claim 1 , wherein:
at least multiple sets of the first magnetic resonance signals are acquired, the sets respectively corresponding to at least one of (a) different inversion times and (b) different echo times; and
image data is generated showing at least one of a distribution of a longitudinal relaxation time, a distribution of a transverse relaxation time, 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. The magnetic resonance imaging apparatus of claim 1 , wherein:
the first magnetic resonance signals and the second magnetic resonance signals are acquired using inversion times which are effectively the same; and
the second image data is generated as image data, in which a depiction of the tissue is suppressed and the fluid is depicted, by 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. The magnetic resonance imaging apparatus of claim 1 , wherein:
the first magnetic resonance signals and the second magnetic resonance signals are acquired after applying a common inversion recovery pulse.

11. The magnetic resonance imaging (MRI) apparatus comprising:
at least one radio frequency (RF) coil disposed within static and gradient magnetic field generators, an RE transmitter and an RF receiver coupled to said at least one RF coil, and at least one control computer connected to control said gradient magnetic field generators, said RF transmitter, said RF transmitter and said RF receiver to execute MRI data acquisition sequences and to process acquired MRI signals; said at

Assignees

• Toshiba Medical Sys Corp

Inventors

• Kimura Tokunori

Classifications

• G01R33/5602

  by filtering or weighting based on different relaxation times within the sample, e.g. T1 weighting using an inversion pulse · CPC title

• A61B5/489

  Blood vessels · CPC title

• G01R33/5607

  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 title

• A61B5/055

  involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging · CPC title

• A61B5/02007

  Evaluating blood vessel condition, e.g. elasticity, compliance · CPC title