US4876507A
Expired / Lapsed
US
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Method of and device for automatic phase correction of complex NMR spectra
Assignee: US Philips Corp
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Filing: 1988-11-14
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Granted: 1989-10-24
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Expires: 2008-11-14
Abstract
Abstract A method is proposed for the automatic correction of phase errors in NMR spectra. The phase errors are interalia due to deficiencies of the NMR hardware, the time-shifted sampling of a magnetic resonance signal after the appearance thereof. The phase correction is performed by first determining peak locations in a modulus spectrum determined from the complex spectrum and by determining the phases in the peak locations, after which the phase in the peak locations are fitted to a predetermined polynomial by means of a least-squares optimization procedure. The coefficients of the polynomial are thus defined. Subsequently, the NMR spectrum is point-wise corrected by means of the phase polynomial determined. The proposed method can be simply implemented in a NMR device; no severe requirements are imposed as regards the signal-to-noise ratio and the resolution of the spectrum. In practical situations an NMR spectrum usually comprises many spectral lines. Therefore, the method is not susceptible to the effects of overlapping spectral lines.
Inventors
- 👤 Johannes J. Van Vaals
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:23
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/46; G01R33/4625
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
109 words
A method of correcting phase errors in a complex magnetic resonance spectrum obtained by Fourier transformation from samples of at least one resonance signal excited in an object situated in a steady, uniform magnetic field by means of R.F. electromagnetic pulses, said complex magnetic resonance spectrum having peak locations and phase values in the peak locations, said method comprising: determining the coefficients of a frequency-dependent phase function extending across the complex spectrum from the phase values in selected peak locations in such a manner that said function meets a predetermined best fit criterion, and correcting phase errors in the complex spectrum by means of the frequency-dependent phase function determined.
Claim 2
Independent Claim
109 words
A method of correcting phase errors in a complex magnetic resonance spectrum obtained by Fourier transformation from samples of at least one resonance signal excited in an object situated in a steady, uniform magnetic field by means of R.F. electromagnetic pulses, said complex magnetic resonance spectrum having peak locations and phase values in the peak locations, said method comprising: determining the coefficients of a frequency-dependent phase function extending across the complex spectrum from the phase values in selected peak locations in such a manner that said function meets a predetermined best fit criterion, and correcting phase errors in the complex spectrum by means of the frequency-dependent phase function determined.
Claim 3
Dependent Claim
17 words
The method as claimed in claim 1, characterized in that the frequency-dependent phase function is a polynomial.
Claim 4
Dependent Claim
17 words
The method as claimed in claim 2, characterized in that the predetermined criterion is a least-squares criterion.
Claim 5
Dependent Claim
17 words
The method as claimed in claim 1, characterized in that the frequency-dependent phase function is a polynomial.
Claim 6
Dependent Claim
28 words
The method as claimed in claim 1, 2, 3 or 4 further comprising deriving the peak locations from a modulus spectrum which is determined from the complex spectrum.
Claim 7
Dependent Claim
29 words
The method as claimed in claim 1, 2, 3 or 4 further comprising deriving the peak locations are from a power spectrum which is determined from the complex spectrum.
Claim 8
Independent Claim
52 words
The method as claimed in any one of claims 1, 2, 3 or 4 in which peak parameters are determined in the peak locations during the determination of the peak locations, characterized in that in the case of overlapping peaks the overlapping peaks are corrected by means of the peak parameters determined.
Claim 9
Dependent Claim
28 words
The method as claimed in claim 7, characterized in that the peak parameters are the peak amplitude, the peak width at half peak amplitude, and the peak position.
Claim 10
Dependent Claim
26 words
The method as claimed in claim 7, characterized in that the peak locations are derived from a modulus spectrum which is determined from the complex spectrum.
Claim 11
Dependent Claim
26 words
The method as claimed in claim 7, characterized in that the peak locations are derived from a power spectrum which is determined from the complex spectrum.
Claim 12
Independent Claim
168 words
A device for determining a complex magnetic resonance spectrum of at least a part of an object, which device comprises means for generating a steady magnetic field, means for applying magnetic field gradients on the steady, uniform magnetic field, means for transmitting R.F. electromagnetic pulses in order to excite resonance signals in the object, means for receiving and detecting the excited resonance signals and means for generating samples from the detected resonance signals, and also comprises programmed means for determining, using Fourier transformation, the complex magnetic resonance spectrum from the samples, which programmed means are also means for determining peak locations in the complex spectrum and phase values of said complex spectrum in the peak locations, characterized in that the programmed means are also means for determining coefficients of a frequency-dependent phase function by approximation from the phase values in selected peak locations according to a predetermined best fit criterion and for subsequently correcting phase errors in the complex spectrum by means of the frequency-dependent phase function determined.
Claim 13
Independent Claim
168 words
A device for determining a complex magnetic resonance spectrum of at least a part of an object, which device comprises means for generating a steady magnetic field, means for applying magnetic field gradients on the steady, uniform magnetic field, means for transmitting R.F. electromagnetic pulses in order to excite resonance signals in the object, means for receiving and detecting the excited resonance signals and means for generating samples from the detected resonance signals, and also comprises programmed means for determining, using Fourier transformation, the complex magnetic resonance spectrum from the samples, which programmed means are also means for determining peak locations in the complex spectrum and phase values of said complex spectrum in the peak locations, characterized in that the programmed means are also means for determining coefficients of a frequency-dependent phase function by approximation from the phase values in selected peak locations according to a predetermined best fit criterion and for subsequently correcting phase errors in the complex spectrum by means of the frequency-dependent phase function determined.
Claim 14
Dependent Claim
18 words
The device as claimed in claim 11, characterized in that the frequency dependent phase function is a polynomial.
Claim 15
Dependent Claim
17 words
The device as claimed in claim 12, characterized in that the predetermined criterion is a least-squares criterion.
Claim 16
Dependent Claim
17 words
The device as claimed in claim 11, characterized in that the frequency-dependent phase function is a polynomial.
Claim 17
Dependent Claim
30 words
The device as claimed in claim 11, 12, 13 or 14, characterized in that the peak locations are derived from a modulus spectrum which is determined from the complex spectrum.
Claim 18
Dependent Claim
30 words
The device as claimed in claim 11, 12, 13 or 14 characterized in that the peak locations are derived from a power spectrum which is determined from the complex spectrum.
Claim 19
Dependent Claim
49 words
The device as claimed in claim 11, 12, 13 or 14 in which peak parameters are determined in the peak locations during the determination of the peak locations, characterized in that in the case of overlapping peaks the overlapping peaks are corrected by means of the peak parameters determined.
Claim 20
Dependent Claim
28 words
The device as claimed in claim 17, characterized in that the peak parameters are the peak amplitude, the peak width at half peak amplitude, and the peak position.
Claim 21
Dependent Claim
26 words
The device as claimed in claim 17, characterized in that the peak locations are derived from a modulus spectrum which is determined from the complex spectrum.
Claim 22
Dependent Claim
26 words
The device as claimed in claim 17, characterized in that the peak locations are derived from a power spectrum which is determined from the complex spectrum.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-10-23 | 1993-04-24 | 1993-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-10-23 | 1997-04-24 | 1997-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-10-23 | 2001-04-24 | 2001-10-24 | $7700.00 | Window Closed / Lapsed |