Patent EP0229228A2 successfully refreshed from Google Patents.
EP0229228A2
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Contiguous slices in multi-slice magnetic resonance imaging (MRI)
Assignee: University of California Berkeley
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Filing: 1986-10-02
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Granted: —
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Expires: 2006-10-02
Abstract
Abstract In a multi-slice magnetic resonance imaging system which employs a train of plural RF NMR nutation pulses, the frequency spectrum and/or magnetic gradient employed for successive pulses is controlled so as to effect more nearly equal full-width-half-magnitude (FWHM) or other spatial dimensions of actual nuclei nutation variation versus distance curves for all of the slice selective nutation pulses. The result is a reduction of any "gap" of non-imaged volume disposed between the succession of selected MRI slice volumes.
Inventors
- 👤 Lawrence E. Crooks
- 👤 John C. Hoenninger, Iii
- 👤 David A. Tanglewood Condominium Feinberg
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 12:46
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/483; G01R33/4833; G01R33/4835
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
126 words
An improved magnetic resonance imaging method comprising: using a train of plural RF NMR nutation pulses, each occurring during imposition of a magnetic gradient pulse, to elicit NMR RF spin echo responses from a succession of selected slices or planar volumes of an object to be imaged; producing φ₁ and φ₂ RF NMR nutation pulses and controlling the time domain envelope of said φ₁ and φ₂ RF NMR nutation pulses and the magnitude of said magnetic gradient pulses to effect a succession of angular nuclei nutations within and across substantially all of each slice to elicit at least one NMR spin echo response therefrom; and controlling the frequency spectrum of said RF NMR nutation pulses to cause said succession of selected slices to be substantially contiguous.
Claim 2
Dependent Claim
126 words
An improved magnetic resonance imaging method comprising: using a train of plural RF NMR nutation pulses, each occurring during imposition of a magnetic gradient pulse, to elicit NMR RF spin echo responses from a succession of selected slices or planar volumes of an object to be imaged; producing φ₁ and φ₂ RF NMR nutation pulses and controlling the time domain envelope of said φ₁ and φ₂ RF NMR nutation pulses and the magnitude of said magnetic gradient pulses to effect a succession of angular nuclei nutations within and across substantially all of each slice to elicit at least one NMR spin echo response therefrom; and controlling the frequency spectrum of said RF NMR nutation pulses to cause said succession of selected slices to be substantially contiguous.
Claim 3
Dependent Claim
45 words
An improved magnetic resonance imaging method as in claim 1 wherein said producing step is performed with φ₁ = 90°, φ₂ = 180° and the magnetic gradient pulse employed during 180° RF pulses having a magnitude approximately 80% of that employed during 90° RF pulses.
Claim 4
Dependent Claim
35 words
An improved magnetic resonance imaging method as in claim 1 wherein the magnetic gradient pulse employed during φ₁ RF pulses has a magnitude different from that employed during φ₂ RF pulses for a given slice.
Claim 5
Dependent Claim
32 words
An improved magnetic resonance imaging method as in claim 1 wherein said φ₂ RF pulses have a shorter duration and higher magnitude envelope in the time domain than said φ₁ RF pulses.
Claim 6
Dependent Claim
56 words
An improved magnetic resonance imaging method as in claim 4 wherein φ₁ is 90°, φ₂ is 180° and wherein the time duration of the 180° RF pulse is approximately 80% of the 90° RF pulse duration and wherein the envelope magnitude of the 180° RF pulse is approximately 250% of the 90° RF pulse envelope magnitude.
Claim 7
Dependent Claim
107 words
An improved magnetic resonance imaging method comprising: sequentially transmitting φ₁ and φ₂ RF nutation pulses of RF frequency spectra Δf₁ and Δf₂ respectively into an object to be imaged in the presence of a slice-selective magnetic gradient pulse G such that corresponding first and second nuclei nutation versus displacement variations V₁, V₂ in the spatial domain are produced within a selected slice or planar volume of the object; and controlling the time-domain envelope of said φ₁ and φ₂ RF nutation pulses and/or said magnetic gradient pulse G to produce substantial width-matching of said first and second nuclei nutation versus displacement variations V₁, V₂ in the spatial domain.
Claim 8
Dependent Claim
107 words
An improved magnetic resonance imaging method comprising: sequentially transmitting φ₁ and φ₂ RF nutation pulses of RF frequency spectra Δf₁ and Δf₂ respectively into an object to be imaged in the presence of a slice-selective magnetic gradient pulse G such that corresponding first and second nuclei nutation versus displacement variations V₁, V₂ in the spatial domain are produced within a selected slice or planar volume of the object; and controlling the time-domain envelope of said φ₁ and φ₂ RF nutation pulses and/or said magnetic gradient pulse G to produce substantial width-matching of said first and second nuclei nutation versus displacement variations V₁, V₂ in the spatial domain.
Claim 9
Dependent Claim
33 words
An improved magnetic resonance imaging method as in claim 6 wherein φ₁ is 90°, φ₂ is 180° and G during each 180° pulse is approximately 80% of the G magnitude during 90° pulses.
Claim 10
Dependent Claim
25 words
An improved magnetic resonance imaging method as in claim 6 wherein G during said φ₂ pulses is of different magnitude than during said φ₁ pulses.
Claim 11
Dependent Claim
30 words
An improved magnetic resonance imaging method as in claim 6 wherein the center frequency of said Δf₁ frequency spectrum is different than the center frequency of said Δf₂ frequency spectrum.
Claim 12
Dependent Claim
49 words
An improved magnetic resonance imaging method as in claim 9 wherein φ₁ is 90°, φ₂ is 180°, wherein Δf₂ is substantially equal to Δf₁ in width but where increments in the center frequency of Δf₂ are approximately 80% of the increments in the center of frequency of Δf₁ .
Claim 13
Dependent Claim
39 words
An improved magnetic resonance imaging method as in claim 6 wherein φ₁ is 90°, φ₂ is 180° and wherein Δf₂ is approximately 125% of Δf₁ in width but where said Δf₁ and Δf₂ spectra have substantially equal center frequencies.
Claim 14
Dependent Claim
32 words
An improved magnetic resonance imaging method as in claim 6 wherein said φ₂ RF pulses have a shorter duration and higher envelope magnitude than said φ₁ RF pulses in the time domain.
Claim 15
Dependent Claim
56 words
An improved magnetic resonance imaging method as in claim 12 wherein φ₁ is 90°, φ₂ is 180° and wherein the time duration of the 180° RF pulse is approximately 80% of the 90° RF pulse duration and wherein the envelope magnitude of the 180° RF pulse is approximately 250% of the 90° RF pulse envelope magnitude.
Claim 16
Dependent Claim
33 words
An improved magnetic resonance imaging method as in claim 6 further comprising successively incrementing the center frequencies of Δf₁ and Δf₂ to select substantially contiguous successive slices of said object to be imaged.
Claim 17
Dependent Claim
141 words
An improved magnetic resonance imaging apparatus of the type which uses a train of plural RF NMR nutation pulses, each occurring during imposition of a magnetic gradient pulse, so as to elicit NMR RF spin echo responses from a succession of selected slices or planar volumes of an object to be imaged, said improvement comprising: means for producing φ₁ and φ₂ RF NMR nutation pulses and for controlling the time domain envelope of said φ₁ and φ₂ RF NMR nutation pulses and the magnitude of said magnetic gradient pulses so as to effect a succession of angular nuclei nutations within and across substantially all of each slice to elicit at least one NMR spin echo response therefrom; and means for controlling the frequency spectrum of said RF NMR nutation pulses to cause said succession of selected slices to be substantially contiguous.
Claim 18
Dependent Claim
141 words
An improved magnetic resonance imaging apparatus of the type which uses a train of plural RF NMR nutation pulses, each occurring during imposition of a magnetic gradient pulse, so as to elicit NMR RF spin echo responses from a succession of selected slices or planar volumes of an object to be imaged, said improvement comprising: means for producing φ₁ and φ₂ RF NMR nutation pulses and for controlling the time domain envelope of said φ₁ and φ₂ RF NMR nutation pulses and the magnitude of said magnetic gradient pulses so as to effect a succession of angular nuclei nutations within and across substantially all of each slice to elicit at least one NMR spin echo response therefrom; and means for controlling the frequency spectrum of said RF NMR nutation pulses to cause said succession of selected slices to be substantially contiguous.
Claim 19
Dependent Claim
47 words
An improved magnetic resonance imaging apparatus as in claim 15 wherein said first-mentioned means includes means causing φ₁ to be 90°, φ₂ to be 180° and the magnetic gradient pulse employed during 180° RF pulses having a magnitude approximately 80% of that employed during 90° RF pulses.
Claim 20
Dependent Claim
41 words
An improved magnetic resonance imaging apparatus as in claim 15 wherein said first- mentioned means causing the magnetic gradient pulse employed during φ₁ RF pulses to have a magnitude different from that employed during φ₂ RF pulses for a given slice.
Claim 21
Dependent Claim
38 words
An improved magnetic resonance imaging apparatus as in claim 15 wherein said first-mentioned means includes means causing said φ₂ RF pulses have a shorter duration and higher magnitude envelope in the time domain than said φ₁ RF pulses.
Claim 22
Dependent Claim
56 words
An improved magnetic resonance imaging apparatus as in claim 18 wherein φ₁ is 90°, φ₂ is 180° and wherein the time duration of the 180° RF pulse is approximately 80% of the 90° RF pulse duration and wherein the envelope magnitude of the 180° RF pulse is approximately 250% of the 90° RF pulse envelope magnitude.
Claim 23
Dependent Claim
114 words
An improved magnetic resonance imaging apparatus of the type which sequentially transmits φ₁ and φ₂ RF nutation pulses of RF frequency spectra Δf₁ and Δf₂ respectively into an object to be imaged in the presence of a slice-selective magnetic gradient pulse G such that corresponding first and second nuclei nutation versus displacement variations V₁, V₂ in the spatial domain are produced within a selected slice or planar volume of the object, said improvement comprising: means for controlling the time-domain envelope of said φ₁ and φ₂ RF nutation pulses and/or said magnetic gradient pulse G to produce substantial width-matching of said first and second nuclei nutation versus displacement variations V₁, V₂ in the spatial domain.
Claim 24
Dependent Claim
114 words
An improved magnetic resonance imaging apparatus of the type which sequentially transmits φ₁ and φ₂ RF nutation pulses of RF frequency spectra Δf₁ and Δf₂ respectively into an object to be imaged in the presence of a slice-selective magnetic gradient pulse G such that corresponding first and second nuclei nutation versus displacement variations V₁, V₂ in the spatial domain are produced within a selected slice or planar volume of the object, said improvement comprising: means for controlling the time-domain envelope of said φ₁ and φ₂ RF nutation pulses and/or said magnetic gradient pulse G to produce substantial width-matching of said first and second nuclei nutation versus displacement variations V₁, V₂ in the spatial domain.
Claim 25
Dependent Claim
33 words
An improved magnetic resonance imaging apparatus as in claim 20 wherein φ₁ is 90°, φ₂ is 180° and G during each 180° pulse is approximately 80% of the G magnitude during 90° pulses.
Claim 26
Dependent Claim
25 words
An improved magnetic resonance imaging apparatus as in claim 20 wherein G during said φ₂ pulses is of different magnitude than during said φ₁ pulses.
Claim 27
Dependent Claim
30 words
An improved magnetic resonance imaging apparatus as in claim 20 wherein the center frequency of said Δf₁ frequency spectrum is different than the center frequency of said Δf₂ frequency spectrum.
Claim 28
Dependent Claim
47 words
An improved magnetic resonance imaging apparatus as in claim 23 wherein φ₁ is 90°, φ₂ is 180°, wherein Δf₁ is substantially equal to Δ₂ in width but where increments in the center frequency of Δf₂ are approximately 80% of the increments in the center frequency of Δf₁.
Claim 29
Dependent Claim
39 words
An improved magnetic resonance imaging apparatus as in claim 20 wherein φ₁ is 90°, φ₂ is 180° and wherein Δf₂ is approximately 125% of Δf₁ in width but where said Δf₁ and Δf₂ spectra have substantially equal center frequencies.
Claim 30
Dependent Claim
32 words
An improved magnetic resonance imaging apparatus as in claim 20 wherein said φ₂ RF pulses have a shorter duration and higher envelope magnitude than said φ₁ RF pulses in the time domain.
Claim 31
Dependent Claim
56 words
An improved magnetic resonance imaging apparatus as in claim 26 wherein φ₁ is 90°, φ₂ is 180° and wherein the time duration of the 180° RF pulse is approximately 80% of the 90° RF pulse duration and wherein the envelope magnitude of the 180° RF pulse is approximately 250% of the 90° RF pulse envelope magnitude.
Claim 32
Dependent Claim
35 words
An improved magnetic resonance imaging apparatus as in claim 20 further comprising means for successively incrementing the center frequencies of Δf₁ and Δf₂ to select substantially contiguous successive slices of said object to be imaged.
References Cited (Backward Citations)
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