US4713616A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Nuclear magnetic resonance imaging apparatus
Assignee: GE Healthcare Japan Corp
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Filing: 1986-05-16
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Granted: 1987-12-15
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Expires: 2006-05-16
Abstract
Abstract An NMR imaging apparatus, wherein a 180° RF pulse is applied shortly after the termination of the 90° RF pulse, and wherein after such 180° pulse application, to collection of spins and after collection of spins to dispersion of spins are sampled asymmetrically, whereby Fourier transformation takes place by interpolating missing data on a Fourier plane, and by operating on the data, image is accurately reconstructed. The novel pulse sequence improves the S/N ratio and reduces deterioration of images.
Inventors
- 👤 Toru Shimazaki
- 👤 Hiroyuki Matsuura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 10:34
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/54; G01R33/56; G01R33/561
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
218 words
A method of obtaining an NMR image of a plane section of an object to be examined, comprising the steps of concurrently impressing a 90° RF exciting pulse to excite said object and a negative Z gradient magnetic field to selectively excite only the spins in the plane section under examination; after termination of said 90° RF pulse, concurrently impressing a positive X gradient magnetic field, a Y gradient magnetic field and changing the negative Z gradient magnetic field to a positive Z gradient magnetic field, thereby to phase encode and prepare for observation of the echo spins; concurrently terminating said X gradient magnetic field, said Y gradient magnetic field, and said Z gradient magnetic field, and concurrently therewith impressing a 180° RF exciting pulse on said object to invert the spins; terminating said 180° RF exciting pulse; impressing an X gradient magnetic field to generate an echo signal on a receiving coil; detecting the phase and amplitude of said echo signal; storing said echo signal in a memory and obtaining a two dimensional Fourier transform thereof; generating a signal to substitute for data issing during a negative time from the detected phase and amplitude continuity conditions; and operating on said Fourier transform and said generated signal substituting for the missing data, to thereby produce a reconstructed image.
Claim 2
Independent Claim
218 words
A method of obtaining an NMR image of a plane section of an object to be examined, comprising the steps of concurrently impressing a 90° RF exciting pulse to excite said object and a negative Z gradient magnetic field to selectively excite only the spins in the plane section under examination; after termination of said 90° RF pulse, concurrently impressing a positive X gradient magnetic field, a Y gradient magnetic field and changing the negative Z gradient magnetic field to a positive Z gradient magnetic field, thereby to phase encode and prepare for observation of the echo spins; concurrently terminating said X gradient magnetic field, said Y gradient magnetic field, and said Z gradient magnetic field, and concurrently therewith impressing a 180° RF exciting pulse on said object to invert the spins; terminating said 180° RF exciting pulse; impressing an X gradient magnetic field to generate an echo signal on a receiving coil; detecting the phase and amplitude of said echo signal; storing said echo signal in a memory and obtaining a two dimensional Fourier transform thereof; generating a signal to substitute for data issing during a negative time from the detected phase and amplitude continuity conditions; and operating on said Fourier transform and said generated signal substituting for the missing data, to thereby produce a reconstructed image.
Claim 3
Dependent Claim
65 words
The method of claim 1, wherein the 90° and 180° pulses are applied and terminated so that time t is the time period from the time the 90° pulse is terminated to the time the 180° pulse is terminated, and said time t is equal to the time period from the time of termination of the 180° pulse to the peak of the echo signal.
References Cited (Backward Citations)
US4573014A
Cited
US4583044A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-12-14 | 1991-06-15 | 1991-12-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-12-14 | 1995-06-15 | 1995-12-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-12-14 | 1999-06-15 | 1999-12-15 | $7700.00 | Window Closed / Lapsed |