US4498048A
Expired / Lapsed
US
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NMR Imaging apparatus
Assignee: Revvity Health Sciences Inc
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Filing: 1984-03-12
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Granted: 1985-02-05
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Expires: 2004-03-12
Abstract
Abstract An NMR imaging apparatus is described having a desired imaging volume for imaging of biological tissue, said apparatus comprising bias means for generating a bias field, means for generating gradient fields, and radio frequency means for applying a pulse of electromagnetic radiation to the biological tissue and for detecting the resultant signals emitted from said tissue; wherein said bias means comprises a plurality of dipole ring magnets, each dipole ring magnet comprising a plurality of segments, each segment comprising an oriented, anisotropic permanent magnet material arranged in a ring so that there is a substantially continuous ring of permanent magnet material; wherein the inner radius of at least one dipole ring magnet is different from the inner radius of an adjacent dipole ring magnet.
Inventors
- 👤 Denny L. Y. Lee
- 👤 Robert D. Hay
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:55
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/28; G01R33/38; G01R33/383; Y; Y10; Y10S; Y10S505/00; Y10S505/825; Y10S505/842; Y10S505/843; Y10S505/844
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
122 words
An NMR imaging apparatus having a desired imaging volume for imaging of biological tissue, said apparatus comprising bias means for generating a bias field, means for generating gradient fields, and radio frequency means for applying a pulse of electromagnetic radiation to the biological tissue and for detecting the resultant signals emitted from said tissue; wherein said bias means comprises a plurality of dipole ring magnets, each dipole ring magnet comprising a plurality of segments, each segment comprising an oriented, anisotropic permanent magnet material arranged in a ring so that there is a substantially continuous ring of permanent magnet material; wherein the inner radius of at least one dipole ring magnet is different from the inner radius of an adjacent dipole ring magnet.
Claim 2
Dependent Claim
122 words
An NMR imaging apparatus having a desired imaging volume for imaging of biological tissue, said apparatus comprising bias means for generating a bias field, means for generating gradient fields, and radio frequency means for applying a pulse of electromagnetic radiation to the biological tissue and for detecting the resultant signals emitted from said tissue; wherein said bias means comprises a plurality of dipole ring magnets, each dipole ring magnet comprising a plurality of segments, each segment comprising an oriented, anisotropic permanent magnet material arranged in a ring so that there is a substantially continuous ring of permanent magnet material; wherein the inner radius of at least one dipole ring magnet is different from the inner radius of an adjacent dipole ring magnet.
Claim 3
Dependent Claim
18 words
The NMR imaging apparatus of claim 1 wherein said bias field is generated by four dipole ring magnets.
Claim 4
Dependent Claim
26 words
The NMR imaging apparatus of claim 2 wherein the two interior dipole ring magnets have a larger inner radius than the two exterior dipole ring magnets.
Claim 5
Dependent Claim
19 words
The NMR imaging apparatus of claim 1 wherein each dipole ring magnet comprises eight segments of permanent magnet material.
Claim 6
Dependent Claim
15 words
The NMR imaging apparatus of claim 4 wherein each segment has a substantially trapezoidal shape.
Claim 7
Dependent Claim
19 words
The NMR imaging apparatus of claim 1 wherein each segment is built up from a plurality of smaller bricks.
Claim 8
Dependent Claim
26 words
The NMR imaging apparatus of claim 1 wherein the bias field within the desired imaging volume has a field variation, ΔB/B, less than 5×10 -4 .
Claim 9
Dependent Claim
88 words
The NMR imaging apparatus of claim 7 wherein said imaging volume having said field variation is at least as large as defined by the following equations: ##EQU7## where g is the height of the gap between the pole surfaces of the dipole magnet, W is the width of the pole surfaces of the dipole magnet, L is the length of the dipole magnet; ω is the width of the imaging volume; γ is the height of the imaging volume; and λ is the length of the imaging volume.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-02-05 | 1988-08-06 | 1989-02-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-02-05 | 1992-08-06 | 1993-02-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-02-05 | 1996-08-06 | 1997-02-05 | $7700.00 | Window Closed / Lapsed |