US5227725A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Nuclear magnetic resonance imaging with short gradient pulses
Assignee: United States Department of the Navy
•
Filing: 1990-11-29
•
Granted: 1993-07-13
•
Expires: 2010-11-29
Abstract
Abstract An improved method and apparatus for nuclear magnetic resonance (NMR) imaging are provided by intercalating a magnetic field gradient in the form of short pulses into an NMR line-narrowing sequence. By inserting the short pulses into predetermined windows in the line-narrowing pulse sequence, the resolution of NMR images obtained thereby is increased and image artifacts from homogenous contributions to the natural linewidth are reduced. Furthermore, the short gradient pulses may be intercalated into known multiple pulse sequences or new multiple pulse sequences for specific imaging purposes which allows far more freedom in designing efficient and improved pulse cycles for NMR imaging.
Inventors
- 👤 David G. Cory
- 👤 Joel B. Miller
- 👤 Allen N. Garroway
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 01:27
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/46; G01R33/4608; G01R33/48; G01R33/54; G01R33/56; G01R33/565; G01R33/56527; G01R33/4816; G01R33/56536
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
125 words
A method for imaging an object by nuclear magnetic resonance, comprising the steps of: (a) intercalating a sequence of magnetic field gradient pulses into a predetermined number of windows in a RF pulse sequence having at least one window, each of said windows being positioned between each RF pulse of said RF pulse sequence, to form an intercalated pulse sequence; (b) exposing said object to said intercalated pulse sequence to excite nuclear spins within said object, thereby phase and frequency encoding spatial positions of said excited nuclear spins; (c) detecting NMR signals corresponding to the nuclear procession during said RF pulse sequence; (d) repeating said steps (b)-(c) as required for imaging the object; and (e) processing said NMR signals as an image of the object.
Claim 2
Independent Claim
125 words
A method for imaging an object by nuclear magnetic resonance, comprising the steps of: (a) intercalating a sequence of magnetic field gradient pulses into a predetermined number of windows in a RF pulse sequence having at least one window, each of said windows being positioned between each RF pulse of said RF pulse sequence, to form an intercalated pulse sequence; (b) exposing said object to said intercalated pulse sequence to excite nuclear spins within said object, thereby phase and frequency encoding spatial positions of said excited nuclear spins; (c) detecting NMR signals corresponding to the nuclear procession during said RF pulse sequence; (d) repeating said steps (b)-(c) as required for imaging the object; and (e) processing said NMR signals as an image of the object.
Claim 3
Dependent Claim
29 words
The method of claim 1, wherein said RF pulse sequence comprises a multiple pulse cycle having said at least one window for coherently averaging homonuclear dipolar couplings to zero.
Claim 4
Dependent Claim
31 words
The method of claim 1, wherein said RF pulse sequence comprises a multiple pulse cycle having said at least one window for coherently averaging time independent I z interactions to zero.
Claim 5
Dependent Claim
34 words
The method of claim 1, wherein said RF pulse sequence comprises a multiple pulse cycle having said at least one window for coherently averaging homonuclear dipolar couplings and time independent Iz interactions to zero.
Claim 6
Dependent Claim
22 words
The method of claim 2, further comprising the step of performing a second averaging interaction for removing time independent I z interactions.
Claim 7
Dependent Claim
19 words
The method of claim 5, wherein said second averaging interaction is performed by applying said magnetic field gradient pulses.
Claim 8
Dependent Claim
19 words
The method of claim 5, wherein said second averaging interaction is performed by phase varying said RF pulse sequence.
Claim 9
Dependent Claim
19 words
The method of claim 5, wherein said second averaging interaction is performed by amplitude varying said RF pulse sequence.
Claim 10
Dependent Claim
25 words
The method of claim 5, wherein said second averaging interacting is performed by varying the lengths of the RF pulses in said RF pulse sequence.
Claim 11
Dependent Claim
25 words
The method of claim 5, wherein said second averaging interaction is performed by varying the spacings of the RF pulses in said RF pulse sequence.
Claim 12
Dependent Claim
14 words
The method of claim 1, wherein said RF pulse sequence comprises a MREV-8 sequence.
Claim 13
Dependent Claim
14 words
The method of claim 1, wherein said RF pulse sequence comprises a 48-pulse sequence.
Claim 14
Dependent Claim
20 words
The method of claim 1, wherein said nuclear spins are initially excited at said step (b) by a slice selection.
Claim 15
Dependent Claim
142 words
A nuclear magnetic resonance imaging apparatus comprising: RF pulse developing means for developing a line narrowing RF pulse sequence having at least one window, each of said windows being positioned between each RF pulse of said RF pulse sequence; magnetic field gradient developing means for developing a sequence of magnetic field gradient pulses; intercalating means for intercalating said sequence of magnetic field gradient pulses into a predetermined number of said windows in said RF pulse sequence to develop an intercalated pulse sequence; excitation means for exposing an object to be imaged to said intercalated pulse sequence to excite nuclear spins within said object and thereby phase and frequency encode said nuclear spins; detecting means for detecting NMR signals corresponding to the nuclear procession during said RF pulse sequence; and processing means for processing said NMR signals as an image of the object.
Claim 16
Dependent Claim
142 words
A nuclear magnetic resonance imaging apparatus comprising: RF pulse developing means for developing a line narrowing RF pulse sequence having at least one window, each of said windows being positioned between each RF pulse of said RF pulse sequence; magnetic field gradient developing means for developing a sequence of magnetic field gradient pulses; intercalating means for intercalating said sequence of magnetic field gradient pulses into a predetermined number of said windows in said RF pulse sequence to develop an intercalated pulse sequence; excitation means for exposing an object to be imaged to said intercalated pulse sequence to excite nuclear spins within said object and thereby phase and frequency encode said nuclear spins; detecting means for detecting NMR signals corresponding to the nuclear procession during said RF pulse sequence; and processing means for processing said NMR signals as an image of the object.
Claim 17
Dependent Claim
38 words
The apparatus of claim 14, wherein said RF pulse developing means comprises means for developing a RF pulse sequence having a multiple pulse cycle and said at least one window for coherently averaging homonuclear dipolar couplings to zero.
Claim 18
Dependent Claim
40 words
The apparatus of claim 14, wherein said RF pulse developing means comprises means for developing a RF pulse sequence having a multiple pulse cycle and said at least one window for coherently averaging time independent I z interactions to zero.
Claim 19
Dependent Claim
42 words
The apparatus of claim 14, wherein said RF pulse sequence developed by said RF pulse developing means comprises a multiple pulse cycle having said at least one window for coherently averaging homonuclear dipolar couplings and time independent I z interactions to zero.
Claim 20
Independent Claim
83 words
A method for slice selection in nuclear magnetic resonance imaging, comprising the steps of: (a) intercalating a sequence of magnetic field gradient pulses into a predetermined number of windows in a line narrowing RF pulse sequence having at least one window, each of said windows being positioned between each RF pulse of said RF pulse sequence, to develop an intercalated pulse sequence; (b) selecting a slice of an object by exposing said object to said intercalated pulse sequence; (c) imaging said selected slice.
Claim 21
Independent Claim
83 words
A method for slice selection in nuclear magnetic resonance imaging, comprising the steps of: (a) intercalating a sequence of magnetic field gradient pulses into a predetermined number of windows in a line narrowing RF pulse sequence having at least one window, each of said windows being positioned between each RF pulse of said RF pulse sequence, to develop an intercalated pulse sequence; (b) selecting a slice of an object by exposing said object to said intercalated pulse sequence; (c) imaging said selected slice.
Claim 22
Dependent Claim
29 words
The method of claim 18, wherein said RF pulse sequence comprises a multiple pulse cycle having said at least one window for coherently averaging homonuclear dipolar couplings to zero.
Claim 23
Independent Claim
86 words
A method for volume selection in nuclear magnetic resonance imaging, comprising the steps of: (a) intercalating a sequence of magnetic field gradient pulses into a predetermined number of windows in a line narrowing Rf pulse sequence having at least one window, each of said windows being positioned between each RF pulse of said RF pulse sequence, to develop an intercalated pulse sequence; selecting a volume of an object by exposing said object to said intercalated pulse sequence; (c) detecting the nuclear signal from said selected volume.
Claim 24
Independent Claim
86 words
A method for volume selection in nuclear magnetic resonance imaging, comprising the steps of: (a) intercalating a sequence of magnetic field gradient pulses into a predetermined number of windows in a line narrowing Rf pulse sequence having at least one window, each of said windows being positioned between each RF pulse of said RF pulse sequence, to develop an intercalated pulse sequence; selecting a volume of an object by exposing said object to said intercalated pulse sequence; (c) detecting the nuclear signal from said selected volume.
References Cited (Backward Citations)
US4549140A
Cited
US4542343A
Cited
US4710718A
Cited
US4789832A
Cited
US5045790A
Cited
US5001427A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-07-12 | 1997-01-11 | 1997-07-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-07-12 | 2001-01-11 | 2001-07-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-07-12 | 2005-01-11 | 2005-07-13 | $7700.00 | Window Closed / Lapsed |