Combining multiple MRI data acquisitions having different B1 inhomogeneities

Patent metadata

Field	Value
Publication number	US-10429480-B2
Application number	US-201213438141-A
Country	US
Kind code	B2
Filing date	Apr 3, 2012
Priority date	May 27, 2010
Publication date	Oct 1, 2019
Grant date	Oct 1, 2019

Abstract

A magnetic resonance imaging apparatus according to an embodiment includes a first acquiring unit, a second acquiring unit, and a combining unit. The first acquiring unit is configured to acquire data by executing a pulse sequence based on a first radio-frequency pulse transmission condition. The second acquiring unit is configured to acquire data by executing a pulse sequence based on a second radio-frequency pulse transmission condition that is different from the first radio-frequency pulse transmission condition. The combining unit is configured to perform a combining process either on the data acquired by the first acquiring unit and the data acquired by the second acquiring unit or on data obtained by reconstructing the data acquired by the first acquiring unit and data obtained by reconstructing the data acquired by the second acquiring unit.

First claim

What is claimed is:

1. A magnetic resonance imaging apparatus comprising:
a first acquiring unit configured to acquire data by executing a first pulse sequence based on a first radio-frequency (RF) pulse transmission condition having a first B1 inhomogeneity condition;
a second acquiring unit configured to acquire data by executing a second pulse sequence based on a second RF pulse transmission condition having a second B1 inhomogeneity condition different from the first B1 inhomogeneity condition; and
a combining unit configured to perform a combining process, after execution of said first and second pulse sequences, either (a) on the data acquired by the first acquiring unit and the data acquired by the second acquiring unit or (b) on data obtained by reconstructing a first image based on the data acquired by the acquiring unit and data obtained by reconstructing a second image based on data obtained by reconstructing the data acquired by the second acquiring unit,
wherein the first and second acquiring units independently control a plurality of electric-power transmitting systems that are configured to supply an RF pulse to a transmission coil so as to change a distribution of B1 strength and B1 inhomogeneity between data acquisition by the first acquiring unit and data acquisition by the second acquiring unit by differentiating at least one of an amplitude, a phase, and a waveform of the RF pulse between the first RF pulse transmission condition and the second RF pulse transmission condition.

2. The magnetic resonance imaging apparatus according to claim 1 , wherein
the first acquiring unit controls a phase encoding amount in such a manner that the acquired data corresponds to odd-numbered echo positions in a k space,
the second acquiring unit controls a phase encoding amount in such a manner that the acquired data corresponds to even-numbered echo positions in the k space, and
the combining unit reconstructs an image by treating the data acquired by the first acquiring unit as data corresponding to the odd-numbered echo positions in the k space and treating the data acquired by the second acquiring unit as data corresponding to the even-numbered echo positions in the k space.

3. The magnetic resonance imaging apparatus according to claim 1 , wherein the combining unit performs the combining process by comparing signal intensities for each set of pixels that are in a mutually same spatial position between the first image and the second image and further selecting a maximum value among the signal intensities.

4. The magnetic resonance imaging apparatus according to claim 1 , wherein the combining unit performs the combining process by comparing signal intensities for each set of pixels that are in a mutually same spatial position between the first image and the second image and further either adding together values of the signal intensities or calculating a sum of squares of the signal intensities.

5. The magnetic resonance imaging apparatus according to claim 2 , wherein
one of the first and the second acquiring units acquires data in an entirety of the k space, whereas the other of the first and the second acquiring units acquires data in a partial region of the k space, and
the combining unit supplements data in a region from which no data is acquired by the other of the first and the second acquiring units that acquired the data in the partial region of the k space, by performing an estimating process based on the data acquired by the one of the first and the second acquiring units that acquired the data in the entirety of the k space.

6. The magnetic resonance imaging apparatus according to claim 1 , wherein the first pulse sequence executed by the first acquiring unit and the second pulse sequence executed by the second acquiring unit are of a mutually same type and are performed under a mutually same condition except for the first RF pulse transmission condition and the second RF pulse transmission condition, and
with respect to the first RF pulse transmission condition and the second RF pulse transmission condition, the first acquiring unit and the second acquiring unit change at least one of the amplitude, the phase, and the waveform of the RF pulse radio supplied to the transmission coil.

7. The magnetic resonance imaging apparatus according to claim 1 , wherein
the first acquiring unit acquires data in an entirety of a k space,
the second acquiring unit acquires data in a partial region of the k space, and
the combining unit supplements data in a region from which no data is acquired by the second acquiring unit by performing a copying process or an estimating process based on the data acquired by the first acquiring unit.

8. The magnetic resonance imaging apparatus according to claim 1 , wherein
the first acquiring unit acquires data in an entirety of a k space while thinning out the data,
the second acquiring unit acquires data in a partial region of the k space while thinning out the data, and
the combining unit supplements data thinned by the first acquiring unit by performing an estimating process while using a linear combination of sensitivity distributions of coils, and also, supplements data in a region from which no data is acquired by the second acquiring unit and data thinned by the second acquiring unit by performing an estimating process based on the data acquired by the first acquiring unit.

9. The magnetic resonance imaging apparatus according to claim 1 , wherein
the first acquiring unit acquires data in an entirety of a k space while thinning out the data,
the second acquiring unit acquires data in a partial region of the k space while thinning out the data, and
the combining unit supplements data in a region from which no data is acquired by the second acquiring unit by performing an estimating process based on the data acquired by the first acquiring unit, and also, supplements data thinned by the first acquiring unit and the second acquiring unit by performing an estimating process while using a linear combination of sensitivity distributions of coils.

Assignees

• Yamashita Yuichi
• Yui Masao
• Toshiba Medical Sys Corp

Inventors

• Yamashita Yuichi
• Yui Masao

Classifications

• G01R33/5659 Primary

  caused by a distortion of the RF magnetic field, e.g. spatial inhomogeneities of the RF magnetic field (G01R33/56509, G01R33/56518, G01R33/56536 take precedence) · CPC title

• G01R33/4818

  MR characterised by data acquisition along a specific k-space trajectory or by the temporal order of k-space coverage, e.g. centric or segmented coverage of k-space · CPC title

• G01R33/5619

  by temporal sharing of data, e.g. keyhole, block regional interpolation scheme for k-Space [BRISK] · CPC title