The impact of different repetition time in quantifying normal brain metabolites concentrations by proton MR spectroscopy
- VernacularTitle:重复时间对MR氢质子波谱定量脑组织代谢物浓度的影响
- Author:
Laiyou LI
- Publication Type:Journal Article
- Keywords:
Brain;
Magnetic resonance imaging;
Magnetic resonance spectroscopy
- From:
Chinese Journal of Radiology
2008;42(5):479-483
- CountryChina
- Language:Chinese
-
Abstract:
Objective To investigate the variabihty of absolute and relative biochemical concenstrations at different repetition time(TR) in quantifying normal brain by single voxel proton MR spectroscopy.Methods Thirty normal volunteers signed informed consent were recruited for the study.Short echo time(TE=35 ms)single voxel spectroscopy of the left parieto-occipital white matter were performed on a 1.5 T MR scanner by using point-resolved selective spectroscopy(PRESS)sequence.Two spectra were obtained using the same voxel placement and acquisition parameters but at different TRs:first at TR=1500 ms then at TR=5000 ms.Raw data of spectra were processed on a commercial software Liinear combination model(LCModel)normalized to spectral date obtained from a reference phantom of known metabolite quantities.Measured metabohtes included total creatine(tCr,creatine and phosphocreatine),glutamate(Glu),myo-inositol(mI),N-acytalaspartate(NAA),glycerophosphorylcholine(GPC),glutamate and glutamine(Glx).The t test was performed by using SPSS 11.5 for windows.Results Both the absolute and relative concentrations of normal white matter were significanth different between spectra obtafined at TR=1500 ms and that at TR=5000 ms(P＜0.05).The absolute concentrations(mmol/L)at TR=1500 ms were tCr,3.0±0.2;Glu,4.4±0.7;ml,3.0±0.3;NAA,5.0±0.4;GPC,1.1±0.1:Glx,5.9±0.6;compared to concentration at TR=5000 ms,tCr,4.2±0.4;Gitu,5.3±0.5;mI.3.7±0.5;NAA,6.7±0.7;GPC,1.4±0.1;Glx,6.6±0.6;respectively.The concentrations relatively to tCr at TR=1500 ms,were Glu,1.47±0.27;mI,1.00±0.11;NAA,1.69±0.17;GPC,0.36±0.05;Glx,1.95±0.22;and relative concentrations at TR=5000 ms were Glu,1.25±0.12;mI,0.89±0.09;NAA,1.60±0.16;GPC,0.33±0.04;Glx,1.58±0.17;respectively.Conclusion Proton MR spectroscopy can accurately quantify absolute and relative concentrations of brain metabolites.Metabolites concentrations may be significant underestimated when using shorter repetition time in short TE spectroscopic study.
