Magnetic resonance imaging device and method therefor
First Claim
Patent Images
1. A magnetic resonance imaging apparatus comprising:
- static magnetic field generation means for applying a static magnetic field to an object to be examined, gradient magnetic field generation means for applying a slice direction gradient magnetic field, a frequency encode gradient magnetic field and a phase encode gradient magnetic field to said object to be examined, high frequency pulse generation means for generating a high frequency pulse to cause a magnetic resonance phenomenon to a nucleus composing said object, detecting means for detecting a nuclear magnetic resonance signal emitted from said object, image reconstruction means for image-reconstructing said nuclear magnetic resonance signal, display means for displaying said reconstructed image, and control means for performing controlling said static magnetic field generation means, said gradient magnetic field generation means, said high frequency pulse generation means, said detecting means, said image reconstruction means, and said display means, wherein said control means measures a spatial phase distribution including temperature information at different measuring times, and calculates a complex difference of spatial phase distribution between said different measuring times, and searches a reference phase in said spatial phase distribution, and calculates a difference between said reference phase and said spatial phase distribution applied to said difference calculation, and searches a temperature change distribution from said spatial phase distribution applied to said phase difference calculation.
1 Assignment
0 Petitions
Accused Products
Abstract
Variations in spatial phase distribution due to static magnetic field changes are corrected based on phase variations at points, specifically, at three points or a plurality of points selected by ROI, in an area where no temperature change is encountered. And a temperature distribution image is determined by using a spatial phase distribution reflecting only temperature changes after the correction, thereby high-accuracy temperature distribution image information is provided.
66 Citations
18 Claims
-
1. A magnetic resonance imaging apparatus comprising:
-
static magnetic field generation means for applying a static magnetic field to an object to be examined, gradient magnetic field generation means for applying a slice direction gradient magnetic field, a frequency encode gradient magnetic field and a phase encode gradient magnetic field to said object to be examined, high frequency pulse generation means for generating a high frequency pulse to cause a magnetic resonance phenomenon to a nucleus composing said object, detecting means for detecting a nuclear magnetic resonance signal emitted from said object, image reconstruction means for image-reconstructing said nuclear magnetic resonance signal, display means for displaying said reconstructed image, and control means for performing controlling said static magnetic field generation means, said gradient magnetic field generation means, said high frequency pulse generation means, said detecting means, said image reconstruction means, and said display means, wherein said control means measures a spatial phase distribution including temperature information at different measuring times, and calculates a complex difference of spatial phase distribution between said different measuring times, and searches a reference phase in said spatial phase distribution, and calculates a difference between said reference phase and said spatial phase distribution applied to said difference calculation, and searches a temperature change distribution from said spatial phase distribution applied to said phase difference calculation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. A magnetic resonance imaging apparatus comprising:
-
static magnetic field generation means for applying a static magnetic field to an object to be examined, gradient magnetic field generation means for applying a slice direction gradient magnetic field, a frequency encode gradient magnetic field and a phase encode gradient magnetic field to said object to be examined, high frequency pulse generation means for generating a high frequency pulse to cause a magnetic resonance phenomenon to a nucleus composing said object, detecting means for detecting a nuclear magnetic resonance signal emitted from said object, image reconstruction means for image-reconstructing said nuclear magnetic resonance signal, display means for displaying said reconstructed image, and control means for performing controlling said static magnetic field generation means, said gradient magnetic field generation means, said high frequency pulse generation means, said detecting means, said image reconstruction means, and said display means, in which said control means measures a phase at different measuring times at a specified region including temperature information, and searches a reference phase from said specified region, and calculates a difference between said reference phase and said measured phase, and outputs said difference in phase to said display means as corrected temperature information.
-
-
11. A magnetic resonance imaging apparatus comprising:
-
static magnetic field generation means for applying a static magnetic field to an object to be examined, gradient magnetic field generation means for applying a slice direction gradient magnetic field, a frequency encode gradient magnetic field and a phase encode gradient magnetic field to said object to be examined, high frequency pulse generation means for generating a high frequency pulse to cause a magnetic resonance phenomenon to a nucleus composing said object, detecting means for detecting a nuclear magnetic resonance signal emitted from said object, image reconstruction means for image-reconstructing said nuclear magnetic resonance signal, display means for displaying said reconstructed image, and control means for performing controlling said static magnetic field generation means, said gradient magnetic field generation means, said high frequency pulse generation means, said detecting means, said image reconstruction means, and said display means, in which said control means measures a spatial phase distribution at different measuring times including temperature information, and searches a reference phase in said spatial phase distribution, and calculates a difference between said reference phase and said spatial phase distribution, and searches a distribution of temperature change from said spatial phase distribution applied to said difference calculation.
-
-
12. A magnetic resonance imaging method comprising the steps of:
-
applying a static magnetic field to an object to be examined, applying a gradient magnetic field to said object in three direction, transmitting a high frequency pulse for causing a magnetic resonance phenomenon to an atomic nucleus composing said object, detecting a nuclear magnetic resonance signal emitted from said object, reconstructing an image from said nuclear magnetic resonance signal, and displaying said reconstructed image, further including;
a step for measuring a spatial phase distribution including temperature information from said nuclear magnetic resonance signal in a first time, a step for measuring the spatial phase distribution including temperature information from said nuclear magnetic resonance signal in a second time, a step for correcting a change of spatial phase distribution due to a static magnetic field change between said first time and said second time, and a step for calculating a temperature change distribution from said corrected spatial phase distribution. - View Dependent Claims (13, 14, 15)
a step for calculating a reference phase in said spatial phase distribution, and a step for calculating a difference between said reference phase and said spatial phase distribution.
-
-
14. A magnetic resonance imaging method according to claim 12, further including a step for displaying simultaneously an image of said temperature change distribution and said reconstructed image.
-
15. A magnetic resonance imaging method according to claim 12, further including a step for superimposing said temperature change distribution image upon'"'"' said reconstructed image.
-
16. A magnetic resonance imaging method comprising the steps of:
-
applying a static magnetic field to an object to be examined, applying a gradient magnetic field to said object in three direction, transmitting a high frequency pulse for causing a magnetic resonance phenomenon to an atomic nucleus composing said object, detecting a nuclear magnetic resonance signal emitted from said object, reconstructing an image from said nuclear magnetic resonance signal, and displaying said reconstructed image, further including;
a step for measuring a spatial phase distribution including temperature information from said nuclear magnetic resonance signal at two different times t1 and t2 in a measurement region, a step for calculating a temperature change distribution at the different times t1 and t2 from said spatial phase distribution, a step for displaying an image corresponding to said temperature change distribution, a step for selecting at least 3 points from said image corresponding to said temperature change distribution, a step for calculating a change of spatial phase distribution at at least said 3 points between the different times t1 and t2, a step for subtracting a change amount of said spatial phase distribution from spatial phase distribution measured in said measurement region, a step for recalculating a temperature change distribution from said subtracted spatial phase distribution, and a step for displaying as image corresponding to the recalculated temperature change distribution. - View Dependent Claims (17, 18)
-
Specification