Patent US5404882A successfully refreshed from Google Patents.
US5404882A
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Adiabatic off-resonance spin-locking for enhanced tumor contrast in NMR imaging
Assignee: Wisconsin Alumni Research Foundation
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Filing: 1994-01-24
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Granted: 1995-04-11
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Expires: 2014-01-24
Abstract
Abstract Contrast between tumor and normal fat and normal fibro-glandular breast tissues is enhanced in an NMR image by a preparatory pulse sequence executed prior to the imaging pulse sequence. An off-resonance spin-locking RF pulse is employed to enhance contrast between fibro-glandular tissue and tumors and an inversion recovery sequence is employed to enhance contrast between fat and tumors.
Inventors
- 👤 Giles E. Santyr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 11:27
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/4828
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
201 words
A method for producing an NMR image, the steps comprising: a) applying a polarizing magnetic field to spins located in a region of interest to produce precession in a selected spin species at a Larmor frequency ω o ; b) applying a 180° RF inversion field pulse to the spins in the region of interest which is tuned to the Larmor frequency ω o ; c) applying an RF spin-lock field pulse to the spins in the region of interest, the frequency of said RF spin-lock field pulse being swept from far off the Larmor frequency 0 at the beginning thereof to a frequency which is offset by an amount A from the Larmor frequency ω o and the frequency of said RF spin-lock field pulse being swept far off the Larmor frequency ω o at the end thereof; d) executing an imaging pulse sequence to acquire an NMR signal by applying an RF excitation field pulse to the spins in the region of interest at a time interval TI following the application of the 180° RF inversion field pulse and which is tuned to the Larmor frequency ω o ; and e) reconstructing an image using the acquired NMR signal.
Claim 2
Independent Claim
201 words
A method for producing an NMR image, the steps comprising: a) applying a polarizing magnetic field to spins located in a region of interest to produce precession in a selected spin species at a Larmor frequency ω o ; b) applying a 180° RF inversion field pulse to the spins in the region of interest which is tuned to the Larmor frequency ω o ; c) applying an RF spin-lock field pulse to the spins in the region of interest, the frequency of said RF spin-lock field pulse being swept from far off the Larmor frequency 0 at the beginning thereof to a frequency which is offset by an amount A from the Larmor frequency ω o and the frequency of said RF spin-lock field pulse being swept far off the Larmor frequency ω o at the end thereof; d) executing an imaging pulse sequence to acquire an NMR signal by applying an RF excitation field pulse to the spins in the region of interest at a time interval TI following the application of the 180° RF inversion field pulse and which is tuned to the Larmor frequency ω o ; and e) reconstructing an image using the acquired NMR signal.
Claim 3
Dependent Claim
23 words
The method as recited in claim 1 in which the RF spin-lock field pulse has a substantially constant amplitude during its entire duration.
Claim 4
Dependent Claim
30 words
The method as recited in claim 1 in which the frequency of the spin-lock field pulse is swept as a tangential function of time at the beginning and end thereof.
Claim 5
Independent Claim
162 words
A method for producing an NMR image, the steps comprising: a) applying a polarizing magnetic field to spins located in a region of interest to produce precession in a selected spin species at a Larmor frequency ω o ; b) applying a 180° Rf inversion field pulse to the spins in the region of interest which is tuned to the Larmor frequency ω o ; c) applying an Rf spin-lock field pulse to the spins in the region of interest, said RF spin-lock field pulse being applied adiabatically at the beginning thereof and being terminated adiabatically at the end thereof; d) executing an imaging pulse sequence to acquire an NMR signal by applying an RF excitation field pulse to the spins in the region of interest at a time interval TI following the application of the 180° Rf inversion field pulse and which is tuned to the Larmor frequency ω o ; and e) reconstructing an image using the acquired NMR signal.
Claim 6
Independent Claim
162 words
A method for producing an NMR image, the steps comprising: a) applying a polarizing magnetic field to spins located in a region of interest to produce precession in a selected spin species at a Larmor frequency ω o ; b) applying a 180° Rf inversion field pulse to the spins in the region of interest which is tuned to the Larmor frequency ω o ; c) applying an Rf spin-lock field pulse to the spins in the region of interest, said RF spin-lock field pulse being applied adiabatically at the beginning thereof and being terminated adiabatically at the end thereof; d) executing an imaging pulse sequence to acquire an NMR signal by applying an RF excitation field pulse to the spins in the region of interest at a time interval TI following the application of the 180° Rf inversion field pulse and which is tuned to the Larmor frequency ω o ; and e) reconstructing an image using the acquired NMR signal.
Claim 7
Dependent Claim
40 words
The method as recited in claim 4 in which the RF spin-lock field pulse is applied adiabatically by sweeping its amplitude from zero to a value, and it is terminated adiabatically by sweeping its amplitude from said value to zero.
Claim 8
Dependent Claim
75 words
The method as recited in claim 5 in which the RF spin-lock field pulse is applied adiabatically by sweeping its frequency from far off the Larmor frequency ω o to a frequency which is offset by an amount A from the Larmor frequency ω o , and the RF spin-lock field pulse is terminated adiabatically by sweeping the frequency of said RF spin-lock field pulse far off the Larmor frequency o at the end thereof.
Claim 9
Dependent Claim
30 words
The method as recited in claim 6 in which the frequency of the spin-lock field pulse is swept as a tangential function of time at the beginning and end thereof.
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) | 1998-04-10 | 1998-10-10 | 1999-04-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-04-10 | 2002-10-10 | 2003-04-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-04-10 | 2006-10-10 | 2007-04-11 | $7700.00 | Window Closed / Lapsed |