Evaluation of signal processing methods for the quantification of a multi–exponential signal: the glycogen 13C-1 NMR signal
✍ Scribed by K. Overloop; P. Van Hecke; F. Vanstapel; H. Chen; S. Van Huffel; A. Knijn; D. van Ormondt
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 786 KB
- Volume
- 9
- Category
- Article
- ISSN
- 0952-3480
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✦ Synopsis
The "C-l NMR peak in proton-decoupled spectra of liver glycogen solution was quantitatively analyzed by three types of model-function fitting algorithms: iterative line-fitting in the frequency domain (MDCON); iterative least-squares fitting (VARF'RO) in the time domain; and noniterative singular value decomposition-based analysis (HTLS), also in the time domain. Quantification results were compared with manual integration values. Performance of the algorithms was tested at different signal-to-noise ratios (S/N) of the glycogen C-1 peak. This was achieved by varying the number of scans summed prior to analysis. Since T2 relaxation in glycogen has been shown to be multiexponential [Overloop, K. et ul. Mugn. Reson. Med. 36, 45-51 (19961, the exact quantification of the C-1 glycogen signal requires a model function comprising a sum of Lorentzian components, each with a different broadening at the glycogen frequency. This paper focuses on the performances of the above methods to fit such a multicomponent resonance line. In the frequency domain, line fitting with two Lorentz lines gives good results at sufficiently high S/N. In the time domain, VARPRO performs better than HTLS because fixed values can be imposed to the linewidth of the components at the common C-1 frequency, thereby reducing convergence problems at low S/N.
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