US6339332B1
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for the operation of a nuclear magnetic resonance tomography apparatus for separating water and fat signals
Assignee: Siemens Healthcare GmbH
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Filing: 1999-08-03
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Granted: 2002-01-15
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Expires: 2019-08-03
Abstract
Abstract In a method for the operation of a nuclear magnetic resonance tomography apparatus for separating water and fat signals a true FISP sequence is implemented with a repetition time TR, so that fat-bonded protons experience a phase rotation of approximately n.180° due to the effect of the chemical shift relative to water-bonded protons, with n being an odd number. Dependent on the further configuration of the sequence, either fat-bonded protons or water-bonded protons exhibit only a slight magnetization in the steady state condition, and thus contribute only little to the measured signal.
Inventors
- 👤 Michael Deimling
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 17:37
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/4828; G01R33/54; G01R33/56; G01R33/561; G01R33/5615; G01R33/5617
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
159 words
A method for operating a nuclear magnetic resonance tomography apparatus, which generates NMR signals comprising the steps of: emitting radio-frequency excitation pulses, with a repetition time into an examination subject containing fat-bonded protons and water-bonded protons, said radio-frequency excitation pulses exciting nuclear spins in said examination subject having a resonant frequency which exhibits a chemical shift due to said fat-bonded protons and a chemical shift due to said water-bonded protons; reading out nuclear resonance signals produced by said nuclear spins from said examination subject between successive radio-frequency excitation pulses under a readout gradient in a readout window; phase-encoding said nuclear resonance signals before said readout window and resetting said phase-encoding before a next radio-frequency excitation pulse following, said readout window; selecting said repetition time so that only nuclear spins of said fat-bonded protons experience a phase rotation of approximately n 180° due to said chemical shift compared to nuclear spins of water-bonded protons, wherein n is an odd number.
Claim 2
Independent Claim
159 words
A method for operating a nuclear magnetic resonance tomography apparatus, which generates NMR signals comprising the steps of: emitting radio-frequency excitation pulses, with a repetition time into an examination subject containing fat-bonded protons and water-bonded protons, said radio-frequency excitation pulses exciting nuclear spins in said examination subject having a resonant frequency which exhibits a chemical shift due to said fat-bonded protons and a chemical shift due to said water-bonded protons; reading out nuclear resonance signals produced by said nuclear spins from said examination subject between successive radio-frequency excitation pulses under a readout gradient in a readout window; phase-encoding said nuclear resonance signals before said readout window and resetting said phase-encoding before a next radio-frequency excitation pulse following, said readout window; selecting said repetition time so that only nuclear spins of said fat-bonded protons experience a phase rotation of approximately n 180° due to said chemical shift compared to nuclear spins of water-bonded protons, wherein n is an odd number.
Claim 3
Dependent Claim
30 words
A method as claimed in claim 1 wherein the step of emitting radio-frequency excitation pulses comprises emitting radio-frequency excitation pulses which alternate in phase from radio-frequency excitation pulse-to-radio-frequency excitation pulse.
Claim 4
Dependent Claim
74 words
A method as claimed in claim 2 wherein said radio-frequency excitation pulses have a flip angle α, and wherein at a beginning of a sequence of said radio-frequency excitation pulses at a distance which is one-half of said repetition time preceding a first of said radio frequency excitation pulses, another radio-frequency excitation pulse is emitted with a flip angle of α/2 with a phase which is inverted relative to said first radio-frequency excitation pulse.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2005-01-14 | 2005-07-16 | 2006-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2009-01-14 | 2009-07-16 | 2010-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2013-01-14 | 2013-07-16 | 2014-01-15 | $7700.00 | Window Closed / Lapsed |