MAGNETIC RESONANCE DEVICE

• US 20120049845A1
• Filed: 02/03/2010
• Published: 03/01/2012
• Est. Priority Date: 03/30/2009
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Bito, Yoshitaka, Hirata, Satoshi, Ochi, Hisaaki, Hirata, Koji, Shirai, Toru, Otake, Yosuke
• Granted Patent: US 9,097,778 B2
• Time in Patent Office: Days
• US Class Current: 324/309
• CPC Class Codes: G01R 33/485 based on chemical shift information [CSI] or spectroscopic imaging, e.g. to acquire the spatial distributions of metabolites
• CPC Class Codes: G01R 33/56341 Diffusion imaging

Abstract

In the diffusion spectroscopic imaging, in which intensity of molecular diffusion is imaged with separating chemical substances, with suppressing artifacts resulting from object motion of an object, spatial resolution, spectral band and SNR are maintained, and measurement accuracy is enhanced. A measurement for acquiring diffusion SI data is repeated a plurality of times with changing acquisition timing, phase variation of each measurement result is corrected, and a diffusion SI image is reconstructed from the corrected measurement results. In addition, the phase variation is calculated for every point in the space from the diffusion SI data acquired by each measurement or navigation data obtained by each measurement. The phase correction is independently performed for every point in the space.

Claims

1. A magnetic resonance device comprising a static magnetic field generating means for generating a static magnetic field, a radio frequency magnetic field transmitting means for irradiating a radio frequency magnetic field on an object placed in the static magnetic field, a radio frequency magnetic field receiving means for receiving nuclear magnetic resonance signals from the object, a gradient magnetic field adding means for spatially modulating the nuclear magnetic resonance signals from the object, a control means for controlling operations of the radio frequency magnetic field transmitting means, the gradient magnetic field adding means, and the radio frequency magnetic field receiving means, and a data processing means for calculating diffusion spectroscopic imaging data of the object by using the nuclear magnetic resonance signals received by the radio frequency magnetic field receiving means, wherein:

the control means comprises;

a radio frequency magnetic field pulse adding means for making the radio frequency magnetic field transmitting means add a radio frequency magnetic field pulse for inducing a nuclear magnetic resonance phenomenon in the object,

a diffusion gradient adding means for, after the addition of the radio frequency magnetic field pulse, making the gradient magnetic field adding means add a diffusion gradient, and

a nuclear magnetic resonance signal acquisition means for making the radio frequency magnetic field receiving means acquire nuclear magnetic resonance signals with making the gradient magnetic field adding means add an oscillating gradient, after the addition of the diffusion gradient,

a shot consisting of a series of operations of the radio frequency magnetic field pulse adding means, the diffusion gradient adding means, and the nuclear magnetic resonance signal acquisition means is repeated with changing time intervals from the addition of the radio frequency magnetic field pulse to start of the addition of the oscillating gradient and start of the acquisition of the nuclear magnetic resonance signals, and

the data processing means comprises;

a phase variation calculating means for calculating phase variation for each position in the real space for every shot,

a phase correction means for correcting phase of each of the nuclear magnetic resonance signals of the shot at a position by using the phase variation calculated above for the position in the real space for every shot, and

a diffusion SI calculating means for calculating diffusion spectroscopic imaging data from the nuclear magnetic resonance signals after the phase correction.

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

the nuclear magnetic resonance signal acquisition means further comprises;

a navigator signal acquisition means for making the radio frequency magnetic field receiving means acquire navigator magnetic resonance signals with making the gradient magnetic field adding means add a navigator oscillating gradient for every shot, after the addition of the diffusion gradient and after a certain duration from the addition of the radio frequency magnetic field pulse, and

the phase variation calculating means calculates phase variation for each position in the real space for every shot by using the navigator magnetic resonance signals for the shot.

3. The magnetic resonance device according to claim 2, wherein:

the radio frequency magnetic field receiving means uses different center frequencies as reference of detection at the time of the acquisition of the navigator magnetic resonance signals and at the time of the acquisition of the nuclear magnetic resonance signals.

4. The magnetic resonance device according to claim 2, wherein:

the data processing means comprises a position correction means for correcting a position of a navigation image reconstructed from the navigator magnetic resonance signals by using difference between the center frequency set in the radio frequency magnetic field receiving means and used as reference of the detection and a resonance frequency of a signal showing the maximum signal intensity among the navigator magnetic resonance signals, before the calculation of phase variation.

5. The magnetic resonance device according to claim 2, wherein:

the navigator signal acquisition means acquires the navigator magnetic resonance signals before the nuclear magnetic resonance signal acquisition means acquires the nuclear magnetic resonance signals, and

the control means further comprises a suppression pulse adding means for making the radio frequency magnetic field pulse adding means and the diffusion gradient adding means add a radio frequency pulse and a gradient magnetic field pulse, respectively, for suppressing signals of a frequency band of a part of the nuclear magnetic resonance signals between the acquisition of the navigator magnetic resonance signals and the acquisition of the nuclear magnetic resonance signals.

6. The magnetic resonance device according to claim 1, wherein:

the phase variation calculating means corrects the nuclear magnetic resonance signals acquired for every shot according to starting time of addition of the shot, and calculates phase variation for each position in the real space for every shot.

7. The magnetic resonance device according to claim 1, wherein:

the oscillating gradient added by the nuclear magnetic resonance signal acquisition means is an oscillating gradient for scanning a two-dimensional space,

the phase variation calculating means calculates phase variation for every point in the two-dimensional space, and

the phase correction means independently corrects the phase for every point in the two-dimensional space by using the phase variation of each point in the two-dimensional space.

8. The magnetic resonance device according to claim 1, wherein:

the oscillating gradient added by the nuclear magnetic resonance signal acquisition means is an oscillating gradient for scanning a three-dimensional space,

the phase variation calculating means calculates phase variation for every point in the three-dimensional space, and

the phase correction means independently corrects the phase for every point in the three-dimensional space by using the phase variation of each point in the three-dimensional space.