EP0209374A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
NMR phase encoding using phase-varying rf pulses
Assignee: Advanced NMR Systems Inc
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Filing: 1986-07-16
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Granted: —
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Expires: 2006-07-16
Abstract
Abstract Phase encoding of nuclear magnetic resonance (NMR) information is performed using rf pulse sequences. The rf pulse sequences produce a substantially continuous phase variation across the resonant frequency range of the atoms of an object in order to perform phase encoding. Some of the pulses may be tailored pulses, with each tailored rf pulse including frequencies which cover a bounded continuous frequency range. Either the phase or the amplitude of each tailored rf pulse varies with frequency across this continuous range. If the amplitude varies linearly across the range, the phase is constant, but if the phase varies linearly across the range, the amplitude is constant. The tailored rf pulses may be applied in the presence of pulsed magnetic gradient fields of the conventional type to produce the phase variation. Alternatively, rf pulses may be applied through rf field gradient coils providing a spatial variation which permits phase encoding of spatial information. The rf pulses may, in either case, be included in a sequence of pulses which also performs excitation of atoms in an object being imaged.
Inventors
- 👤 Andrew A. Maudsley
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 15:15
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/446; G01R33/48; G01R33/4818; G01R33/482; G01R33/54; G01R33/56; G01R33/5604
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
68 words
A method of retrieving phase-encoded NMR information from an object, characterised by phase encoding nuclei in the object to provide a phase-encoded NMR signal, the step of phase encoding comprising applying an rf pulse with a substantially continuous frequency range covering a range of resonant frequencies of the nuclei, and producing a substantially continuous phase variation across the range of resonant frequencies; and receiving the phase-encoded NMR signal.
Claim 2
Independent Claim
68 words
A method of retrieving phase-encoded NMR information from an object, characterised by phase encoding nuclei in the object to provide a phase-encoded NMR signal, the step of phase encoding comprising applying an rf pulse with a substantially continuous frequency range covering a range of resonant frequencies of the nuclei, and producing a substantially continuous phase variation across the range of resonant frequencies; and receiving the phase-encoded NMR signal.
Claim 3
Dependent Claim
46 words
A method according to claim 1, characterised in that the substep of applying an rf pulse comprises applying an rf pulse with a respective magnitude and a respective phase at each frequency of the frequency range, the respective magnitude or the respective phase varying with frequency.
Claim 4
Dependent Claim
22 words
A method according to claim 2, characterised in that the respective phases of the frequencies of the frequency range vary with frequency.
Claim 5
Dependent Claim
26 words
A method according to claim 2 or claim 3, characterised in that the respective magnitudes of the frequencies of the frequency range are all the same.
Claim 6
Dependent Claim
25 words
A method according to claim 2 or claim 3, characterised in that the respective magnitudes of the frequencies of the frequency range vary with frequency.
Claim 7
Dependent Claim
22 words
A method according to claim 5, characterised in that the respective phases of the frequencies of the frequency range are all equal.
Claim 8
Independent Claim
38 words
A method according to any preceding claim, characterised in that the substep of applying an rf pulse comprises applying an rf pulse through an inhomogeneous coil (60, 70) to produce an rf gradient field across the object (80).
Claim 9
Dependent Claim
22 words
A method according to claim 7, characterised in that the rf gradient field is zero at a point within the object (80).
Claim 10
Dependent Claim
33 words
A method according to claim 7, characterised in that the rf pulse applied through the inhomogeneous coil (60, 70) has a respective magnitude across the frequency range, the respective magnitude varying with frequency.
Claim 11
Dependent Claim
50 words
A method according to claim 1, claim 2 or claim 7, characterised in that the step of phase encoding further comprises applying an excitation pulse to bring spin axes of the nuclei into an orientation transverse to a static magnetic field, thereby producing the phase variation in the transverse orientation.
Claim 12
Dependent Claim
56 words
A method according to claim 1, claim 2 or claim 7, characterised in that the step of phase encoding nuclei comprises phase encoding spatial information about the nuclei, the phase encoded NMR signal further including spectroscopic information about the nuclei, the step of receiving the NMR signal comprising receiving both the spatial and the spectroscopic information.
Claim 13
Independent Claim
77 words
A method of retrieving phase encoded NMR information from an object, characterised by phase encoding nuclei in the object to provide a phase encoded NMR signal, the step of phase encoding comprising applying an rf pulse to the nuclei, the rf pulse including a plurality of frequencies, each frequency of the pulse having a respective magnitude and a respective phase, the respective magnitude or the respective phase varying with frequency; and receiving the phase encoded NMR signal.
Claim 14
Independent Claim
77 words
A method of retrieving phase encoded NMR information from an object, characterised by phase encoding nuclei in the object to provide a phase encoded NMR signal, the step of phase encoding comprising applying an rf pulse to the nuclei, the rf pulse including a plurality of frequencies, each frequency of the pulse having a respective magnitude and a respective phase, the respective magnitude or the respective phase varying with frequency; and receiving the phase encoded NMR signal.
Claim 15
Dependent Claim
34 words
A method according to claim 12, characterised in that the frequencies of the rf pulse cover a continuous range of frequencies, the respective phases of the frequencies in the continuous range varying with frequency.
Claim 16
Dependent Claim
21 words
A method according to claim 13, characterised in that the frequencies of the continuous range all have the same respective magnitude.
Claim 17
Dependent Claim
34 words
A method according to claim 12, characterised in that the frequencies of the rf pulse cover a continuous range of frequencies, the respective magnitudes of the frequencies in the continuous range varying with frequency.
Claim 18
Dependent Claim
20 words
A method according to claim 15, characterised in that the frequencies of the continuous range all have the same phase.
Claim 19
Dependent Claim
50 words
A method according to claim 12, characterised by defining the respective magnitudes and phases of the frequencies and transforming the defined respective magnitudes and phases to obtain time-varying real and imaginary components, the applying of the rf pulse comprising applying an rf pulse modulated by the real and imaginary components.
References Cited (Backward Citations)
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