US5016637A
Expired / Lapsed
US
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MRI method
Assignee: Hitachi Healthcare Manufacturing Ltd
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Filing: 1989-05-25
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Granted: 1991-05-21
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Expires: 2009-05-25
Abstract
Abstract An MRI method is disclosed, by which, when liquid moving in a body to be examined stays in a predetermined region, this region is excited by using the nuclear magnetic resonance phenomenon and when the liquid thus excited moves from that excited region, a nuclear magnetic resonance signal produced by the excited spin and emitted during the relaxation time thereof is detected.
Inventors
- 👤 Hideaki Koizumi
- 👤 Ryuzaburo Takeda
- 👤 Koichi Sano
- 👤 Tetsuo Yokoyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 12:33
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/54; G01R33/56; G01R33/567; G01R33/5673; G01R33/563
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
368 words
An MRI method comprising the steps of: (a) locating a body to be examined in a space defined by a Cartesian coordinate system of X, Y, and Z directions and in which a direction of a static magnetic field is in the Z-direction; (b) monitoring movement of a first region of interest of said body including detecting movement of liquid in said first region of interest; (c) exciting said first region in which said liquid moving in said body is present, by using a nuclear magnetic resonance phenomenon, when said liquid is temporarily nonmovable in said first region so that said liquid becomes excited; (d) detecting a nuclear magnetic resonance signal which is produced from said excited liquid at a second region different from said first region, when said excited liquid moves through said second region; and (e) reconstructing an image of a flow path of said excited liquid on the basis of said detected nuclear magnetic resonance signal; wherein said step of exciting comprises the steps of: (1) applying a high frequency 90° pulse and at the same time a gradient magnetic field in the Z-direction after a predetermined period of time measured from a specified movement of said first region; (2) applying a first high frequency 180° pulse and at the same time a gradient magnetic field pulse in the Y-direction after a period of time of T E /2, T E representing two times of a period of time from the application of said high frequency 90° pulse to said first high frequency 180° pulse; (3) applying said gradient magnetic field pulse in the Y-direction as a phase encoded pulse after said Step (2); and (4) applying a second high frequency 180° pulse and at the same time a gradient magnetic field pulse in the X-direction after a period of time of T E measured from the application of said first high frequency 180° pulse; and said step of detecting the nuclear magnetic resonance signal comprises the step of applying a gradient magnetic field pulse in said Z-direction and detecting said nuclear magnetic resonance signal after a period of time of T E /2 measured from the application of said second high frequency 180° pulse.
Claim 2
Dependent Claim
368 words
An MRI method comprising the steps of: (a) locating a body to be examined in a space defined by a Cartesian coordinate system of X, Y, and Z directions and in which a direction of a static magnetic field is in the Z-direction; (b) monitoring movement of a first region of interest of said body including detecting movement of liquid in said first region of interest; (c) exciting said first region in which said liquid moving in said body is present, by using a nuclear magnetic resonance phenomenon, when said liquid is temporarily nonmovable in said first region so that said liquid becomes excited; (d) detecting a nuclear magnetic resonance signal which is produced from said excited liquid at a second region different from said first region, when said excited liquid moves through said second region; and (e) reconstructing an image of a flow path of said excited liquid on the basis of said detected nuclear magnetic resonance signal; wherein said step of exciting comprises the steps of: (1) applying a high frequency 90° pulse and at the same time a gradient magnetic field in the Z-direction after a predetermined period of time measured from a specified movement of said first region; (2) applying a first high frequency 180° pulse and at the same time a gradient magnetic field pulse in the Y-direction after a period of time of T E /2, T E representing two times of a period of time from the application of said high frequency 90° pulse to said first high frequency 180° pulse; (3) applying said gradient magnetic field pulse in the Y-direction as a phase encoded pulse after said Step (2); and (4) applying a second high frequency 180° pulse and at the same time a gradient magnetic field pulse in the X-direction after a period of time of T E measured from the application of said first high frequency 180° pulse; and said step of detecting the nuclear magnetic resonance signal comprises the step of applying a gradient magnetic field pulse in said Z-direction and detecting said nuclear magnetic resonance signal after a period of time of T E /2 measured from the application of said second high frequency 180° pulse.
Claim 3
Dependent Claim
99 words
An MRI method according to claim 1, wherein said first region includes the left ventricle of a heart; said step of applying a high frequency 90° pulse includes the step of counting a predetermined period of time, starting from the systole of the left ventricle; said step of exciting said first region includes a step of controlling the generation of said gradient magnetic fields in the X-, Y- and Z-directions, the waveform of said high frequency 90° pulse and the waveform of said high frequency 180° pulse so that said first region is an aortic sinus of the heart.
Claim 4
Dependent Claim
54 words
An MRI method according to claim 2, wherein said step of detecting the nuclear magnetic resonance signal includes a step of: applying a step of detecting by means of a band pass filter said nuclear magnetic resonance signal having a frequency component corresponding to a position adjacent in the Z-direction to said first region.
Claim 5
Dependent Claim
39 words
An MRI method according to claim 3, wherein said step of applying said high frequency 90° pulse and said first and second 180° pulses includes the step of: generating said pulses in waveforms of SINC or SINC like function.
Claim 6
Dependent Claim
80 words
An MRI method according to claim 4, wherein said step of applying said gradient magnetic field in the Z-direction includes the step of: applying compensating uses, the polarity of which is opposite to that of said gradient magnetic field in the Z-direction, whose intensity is equal to that of the latter and the application duration of which is a half of that of the latter, just before or just after the application of said gradient magnetic field in the Z-direction.
Claim 7
Dependent Claim
160 words
An MRI method comprising the steps of: (a) locating a body to be examined in a space defined by a Cartesian coordinate system of X, Y, and Z directions and in which a direction of a static magnetic field is in the Z- direction; (b) monitoring movement of a first region of interest of said body including detecting movement of liquid in said first region of interest; (c) exciting said first region in which said liquid moving in said body is present, by using a nuclear magnetic resonance phenomenon, when said liquid is temporarily nonmovable in said first region so that said liquid becomes excited; (d) detecting a nuclear magnetic resonance signal which is produced from said excited liquid at a second region different from said first region, when said excited liquid moves through said second region; and (e) reconstructing an image of a flow path of said excited liquid on the basis of said detected nuclear magnetic resonance signal.
Claim 8
Dependent Claim
160 words
An MRI method comprising the steps of: (a) locating a body to be examined in a space defined by a Cartesian coordinate system of X, Y, and Z directions and in which a direction of a static magnetic field is in the Z- direction; (b) monitoring movement of a first region of interest of said body including detecting movement of liquid in said first region of interest; (c) exciting said first region in which said liquid moving in said body is present, by using a nuclear magnetic resonance phenomenon, when said liquid is temporarily nonmovable in said first region so that said liquid becomes excited; (d) detecting a nuclear magnetic resonance signal which is produced from said excited liquid at a second region different from said first region, when said excited liquid moves through said second region; and (e) reconstructing an image of a flow path of said excited liquid on the basis of said detected nuclear magnetic resonance signal.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-05-20 | 1994-11-19 | 1995-05-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-05-20 | 1998-11-19 | 1999-05-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-05-20 | 2002-11-19 | 2003-05-21 | $7700.00 | Window Closed / Lapsed |