US5627469A — Separation of fat and water magnetic resonance im…

Claim 1

Independent Claim 326 words

A method for generating a magnetic resonance image of a region comprised of a first species of nuclei having a first Larmor frequency and a second species of nuclei having a second Larmor frequency different from said first Larmor frequency, said method comprising: generating a RF excitation pulse for exciting said first species of nuclei and said second species of nuclei in said region; generating a phase-encoding magnetic gradient pulse after generating said RF excitation pulse; generating a first read-out magnetic gradient pulse after generating said RF excitation pulse and said phase-encoding magnetic gradient pulse and before generating another RF excitation pulse and another phase-encoding magnetic gradient pulse, nuclei of said first and second species having a first relative phase offset at the center of said first read-out gradient pulse; generating a second read-out magnetic gradient pulse after generating said RF excitation pulse and said phase-encoding magnetic gradient pulse and before generating another RF excitation pulse and another phase-encoding magnetic gradient pulse, nuclei of said first and second species having a second relative phase offset at the center of said second read-out gradient pulse, said second relative phase offset being different from said first relative phase offset; generating a third read-out magnetic gradient pulse after generating said RF excitation pulse and said phase-encoding magnetic gradient pulse and before generating another RF excitation pulse and another phase-encoding magnetic gradient pulse, nuclei of said first and second species having a third relative phase offset at the center of said third read-out gradient pulse, said third relative phase offset being different from said second relative phase offset; acquiring RF resonant signals emitted by excited first and second species of nuclei during said first read-out gradient pulse, said second read-out gradient pulse, and said third read-out gradient pulse; and processing RF resonant signals acquired in said acquiring step to generate a magnetic resonant image, said processing step including the substep of phase-correcting data used to generate said magnetic resonance image.

Claim 2

Independent Claim 326 words

A method for generating a magnetic resonance image of a region comprised of a first species of nuclei having a first Larmor frequency and a second species of nuclei having a second Larmor frequency different from said first Larmor frequency, said method comprising: generating a RF excitation pulse for exciting said first species of nuclei and said second species of nuclei in said region; generating a phase-encoding magnetic gradient pulse after generating said RF excitation pulse; generating a first read-out magnetic gradient pulse after generating said RF excitation pulse and said phase-encoding magnetic gradient pulse and before generating another RF excitation pulse and another phase-encoding magnetic gradient pulse, nuclei of said first and second species having a first relative phase offset at the center of said first read-out gradient pulse; generating a second read-out magnetic gradient pulse after generating said RF excitation pulse and said phase-encoding magnetic gradient pulse and before generating another RF excitation pulse and another phase-encoding magnetic gradient pulse, nuclei of said first and second species having a second relative phase offset at the center of said second read-out gradient pulse, said second relative phase offset being different from said first relative phase offset; generating a third read-out magnetic gradient pulse after generating said RF excitation pulse and said phase-encoding magnetic gradient pulse and before generating another RF excitation pulse and another phase-encoding magnetic gradient pulse, nuclei of said first and second species having a third relative phase offset at the center of said third read-out gradient pulse, said third relative phase offset being different from said second relative phase offset; acquiring RF resonant signals emitted by excited first and second species of nuclei during said first read-out gradient pulse, said second read-out gradient pulse, and said third read-out gradient pulse; and processing RF resonant signals acquired in said acquiring step to generate a magnetic resonant image, said processing step including the substep of phase-correcting data used to generate said magnetic resonance image.

Claim 3

Dependent Claim 16 words

A method as recited in claim 1 wherein said first relative phase offset is substantially zero.

Claim 4

Dependent Claim 16 words

A method as recited in claim 1 wherein said second relative phase offset is substantially 180°.

Claim 5

Dependent Claim 26 words

A method as recited in claim 1 wherein said step of acquiring RF resonant signals comprises the substeps of sampling and digitizing said RF resonant signals.

Claim 6

Dependent Claim 61 words

A method as recited in claim 4 wherein said step of acquiring RF resonant signals comprises the substep of storing digitized RF resonant signals in a first raw data matrix during said first read-out gradient pulse, in a second raw data matrix during said second read-out gradient pulse, and in a third raw data matrix during said third read-out gradient pulse.

Claim 7

Dependent Claim 24 words

A method as recited in claim 1 wherein said processing step includes the substep of time-reversing at least some of said RF resonant signals.

Claim 8

Dependent Claim 23 words

A method as recited in claim 1 wherein said processing step includes the substep of removing DC bias from said RF resonant signals.

Claim 9

Dependent Claim 25 words

A method as recited in claim 1 wherein said processing step includes the substep of Fourier transforming said RF resonant signals to generate image signals.

Claim 10

Dependent Claim 19 words

A method as recited in claim 8 wherein said processing step includes the substep of magnitude-correcting said image signals.

Claim 11

Dependent Claim 19 words

A method as recited in claim 8 wherein said image signals are the data subjected to said phase-correcting substep.

Claim 12

Dependent Claim 23 words

A method as recited in claim 10 wherein said processing step includes the substep of locating echo centers in said RF resonant signals.

Claim 13

Dependent Claim 22 words

A method as recited in claim 11 wherein said image signals are phase-corrected in accordance with the locations of said echo centers.

Claim 14

Dependent Claim 19 words

A method as recited in claim 10 wherein said image signals are phase-corrected in accordance with magnetic field inhomogeneities.

Claim 15

Dependent Claim 18 words

A method as recited in claim 10 wherein said image signals are phase-corrected in accordance with time-artifact inhomogeneities.

Claim 16

Dependent Claim 23 words

A method as recited in claim 1 wherein said magnetic resonance image is substantially free of depictions of said second species of nuclei.

Claim 17

Dependent Claim 27 words

A method as recited in claim 15 wherein said processing step generates a second magnetic resonance image substantially free of depictions of said first species of nuclei.

Claim 18

Dependent Claim 21 words

A method as recited in claim 1 wherein said first read-out gradient pulse is generated before said second read-out gradient pulse.

Claim 19

Dependent Claim 22 words

A method as recited in claim 1 wherein said third relative phase offset is substantially equal to said first relative phase offset.

Claim 20

Dependent Claim 16 words

A method as recited in claim 1 wherein said third relative phase offset is substantially zero.

Claim 21

Dependent Claim 345 words

Apparatus for generating a magnetic resonance image of a region comprised of a first species of nuclei having a first Larmor frequency and a second species of nuclei having a second Larmor frequency different from said first Larmor frequency, said apparatus comprising: means for generating a RF excitation pulse for exciting said first species of nuclei and said second species of nuclei in said region; means for generating a phase-encoding magnetic gradient pulse after generating said RF excitation pulse; means for generating a first read-out magnetic gradient pulse after said RF excitation pulse and said phase-encoding magnetic gradient pulse are generated and before another RF excitation pulse and another phase-encoding magnetic gradient pulse are generated, nuclei of said firsthand second species having a first relative phase offset at the center of said first read-out gradient pulse; means for generating a second read-out magnetic gradient pulse after said RF excitation pulse and said phase-encoding magnetic gradient pulse are generated and before another RF excitation pulse and another phase-encoding magnetic gradient pulse are generated, nuclei of said first and second species having a second relative phase offset at the center of said second read-out gradient pulse, said second relative phase offset being different from said first relative phase offset; means for generating a third read-out magnetic gradient pulse after said RF excitation, pulse and said phase-encoding magnetic gradient pulse are generated and before another RF excitation pulse and another phase-encoding magnetic gradient pulse are generated, nuclei of said first and second species having a third relative phase offset at the center of said third read-out gradient pulse, said third relative phase offset being different from said second relative phase offset; means for acquiring RF resonant signals emitted by excited first and second species of nuclei during said first read-out gradient pulse, said second read-out gradient pulse, and said third read-out gradient pulse; and means for processing RF resonant signals acquired by said acquiring means to generate a magnetic resonant image, said means for processing including a means for phase-correcting data used to generate said magnetic resonance image.

Claim 22

Dependent Claim 345 words

Apparatus for generating a magnetic resonance image of a region comprised of a first species of nuclei having a first Larmor frequency and a second species of nuclei having a second Larmor frequency different from said first Larmor frequency, said apparatus comprising: means for generating a RF excitation pulse for exciting said first species of nuclei and said second species of nuclei in said region; means for generating a phase-encoding magnetic gradient pulse after generating said RF excitation pulse; means for generating a first read-out magnetic gradient pulse after said RF excitation pulse and said phase-encoding magnetic gradient pulse are generated and before another RF excitation pulse and another phase-encoding magnetic gradient pulse are generated, nuclei of said firsthand second species having a first relative phase offset at the center of said first read-out gradient pulse; means for generating a second read-out magnetic gradient pulse after said RF excitation pulse and said phase-encoding magnetic gradient pulse are generated and before another RF excitation pulse and another phase-encoding magnetic gradient pulse are generated, nuclei of said first and second species having a second relative phase offset at the center of said second read-out gradient pulse, said second relative phase offset being different from said first relative phase offset; means for generating a third read-out magnetic gradient pulse after said RF excitation, pulse and said phase-encoding magnetic gradient pulse are generated and before another RF excitation pulse and another phase-encoding magnetic gradient pulse are generated, nuclei of said first and second species having a third relative phase offset at the center of said third read-out gradient pulse, said third relative phase offset being different from said second relative phase offset; means for acquiring RF resonant signals emitted by excited first and second species of nuclei during said first read-out gradient pulse, said second read-out gradient pulse, and said third read-out gradient pulse; and means for processing RF resonant signals acquired by said acquiring means to generate a magnetic resonant image, said means for processing including a means for phase-correcting data used to generate said magnetic resonance image.

Claim 23

Independent Claim 292 words

A method for generating a magnetic resonance image of a region comprised of fat nuclei having a Larmor frequency of f f in Hertz and water nuclei having a Larmor frequency of f w in Hertz, said method comprising: generating a first RF excitation pulse for exciting said fat and water nuclei in said region, said first RF excitation pulse having an center; generating a phase-encoding magnetic gradient pulse after generating said first RF excitation pulse; generating a first read-out magnetic gradient pulse after generating said first RF excitation pulse and said phase-encoding magnetic gradient pulse and before generating another RF excitation pulse and another phase-encoding magnetic gradient pulse, fat and water nuclei being substantially in-phase with respect to one another at the center of said first read-out gradient pulse; generating a second read-out magnetic gradient pulse after generating said first read-out gradient pulse and before generating another RF excitation pulse and another phase-encoding magnetic gradient pulse, fat and water nuclei being substantially 180° out-of-phase with respect to one another at the center of said second read-out gradient pulse; generating a third read-out magnetic gradient pulse after generating said second reed-out gradient pulse and before generating another RF excitation pulse and another phase-encoding magnetic gradient pulse, fat and water nuclei being substantially in-phase with respect to one another at the center of said third read-out gradient pulse; acquiring RF resonant signals emitted by excited first and second species of nuclei during said first read-out gradient pulse, said second read-out gradient pulse, and said third read-out gradient pulse; transforming said RF resonant signals to generate image data; phase-correcting at least some of said image data; and generating a magnetic resonant image from at least some of said image data after said phase-correcting step.

Claim 24

Independent Claim 292 words

A method for generating a magnetic resonance image of a region comprised of fat nuclei having a Larmor frequency of f f in Hertz and water nuclei having a Larmor frequency of f w in Hertz, said method comprising: generating a first RF excitation pulse for exciting said fat and water nuclei in said region, said first RF excitation pulse having an center; generating a phase-encoding magnetic gradient pulse after generating said first RF excitation pulse; generating a first read-out magnetic gradient pulse after generating said first RF excitation pulse and said phase-encoding magnetic gradient pulse and before generating another RF excitation pulse and another phase-encoding magnetic gradient pulse, fat and water nuclei being substantially in-phase with respect to one another at the center of said first read-out gradient pulse; generating a second read-out magnetic gradient pulse after generating said first read-out gradient pulse and before generating another RF excitation pulse and another phase-encoding magnetic gradient pulse, fat and water nuclei being substantially 180° out-of-phase with respect to one another at the center of said second read-out gradient pulse; generating a third read-out magnetic gradient pulse after generating said second reed-out gradient pulse and before generating another RF excitation pulse and another phase-encoding magnetic gradient pulse, fat and water nuclei being substantially in-phase with respect to one another at the center of said third read-out gradient pulse; acquiring RF resonant signals emitted by excited first and second species of nuclei during said first read-out gradient pulse, said second read-out gradient pulse, and said third read-out gradient pulse; transforming said RF resonant signals to generate image data; phase-correcting at least some of said image data; and generating a magnetic resonant image from at least some of said image data after said phase-correcting step.

Claim 25

Dependent Claim 39 words

A method as recited in claim 21 wherein said center of said first read-out gradient pulse occurs substantially N/(f f -f w ) seconds after said center of said first RF excitation pulse, where N is a positive integer.

Claim 26

Dependent Claim 39 words

A method as recited in claim 21 wherein said center of said second read-out gradient pulse occurs substantially (M+1/2)/(f f -f w ) seconds after said center of said first RF excitation pulse, where M is a positive integer.

Claim 27

Dependent Claim 39 words

A method as recited in claim 23 wherein said center of said third read-out gradient pulse occurs substantially (P+1/2)/(f f -f w ) seconds after said center of said second read-out gradient pulse, where P is a positive integer.

Claim 28

Dependent Claim 39 words

A method as recited in claim 21 wherein said center of said third read-out gradient pulse occurs substantially Q/(f f -f w ) seconds after said center of said first RF excitation pulse, where Q is a positive integer.

Claim 29

Dependent Claim 43 words

A method as recited in claim 1 wherein said processing step includes the substep of processing RF resonant signals acquired in said acquiring step in accordance with said first relative phase offset, said second relative phase offset, and said third relative phase offset.

Claim 30

Dependent Claim 27 words

A method as recited in claim 1 wherein said first species of nuclei comprise water hydrogen nuclei, and said second species of nuclei comprise fat hydrogen nuclei.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2000-05-05	2000-11-04	2001-05-06	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2004-05-05	2004-11-04	2005-05-06	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2008-05-05	2008-11-04	2009-05-06	$7700.00	Window Closed / Lapsed

Separation of fat and water magnetic resonance images

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag