USE OF VOIGT LINESHAPE FOR QUANTIFICATION OF IN-VIVO H-1 SPECTRA

Quantification of NMR visible metabolites by spectral modeling usually assumes a Lorentzian or Gaussian lineshape, despite the fact that exp erimental lineshapes are neither, To minimize systematic fitting error s, a mixed Lorentzian-Gaussian (Voigt) lineshape model was developed, When tested with synthetic FIDs, the Voigt lineshape model gave more a ccurate results (maximum error 2%) than either Lorentzian (maximum err or 20%) or Gaussian models (maximum error 12%), The three lineshape mo dels gave substantially different peak areas in an in vitro experiment , with the Voigt model having a much lower chi(2) (2.1 compared with 5 .2 for the Lorentzian model and 6.2 for the Gaussian model), In a grou p of 10 healthy volunteers, fitting of H-1 spectra from cerebral white matter gave significantly different peak areas between the methods, E ven when area ratios were taken, the Lorentzian model gave higher valu es (+5% for NAA/choline and +2% for NAA/creatine) than the Voigt lines hape model, whereas the Gaussian model gave lower values (-2% and -1%, respectively).