Langer Deanna L, Rakaric Peter, Kirilova Anna, Jaffray David A, Damyanovich Andrei Z
Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario, Canada.
Magn Reson Med. 2007 Oct;58(4):666-73. doi: 10.1002/mrm.21351.
Intrasubject reproducibility of metabolite quantitation in three-dimensional proton magnetic resonance spectroscopic imaging (3D-MRSI) was investigated in 10 healthy volunteers over five separate sessions using two echo times (TEs): 144 and 30 ms. The use of a Gill-Thomas-Cosman (GTC) stereotactic head frame enabled precise subject repositioning and immobilization. Metabolite levels from each voxel in the volume of interest (VOI) were quantified using the Linear Combination of Model spectra (LCModel) analysis algorithm, and coefficients of variation (CVs) were calculated. Standard error estimates (%SD or Cramer-Rao lower bounds) generated by LCModel were used as a confidence filter. The 95% confidence interval (CI) was found for each metabolite, providing an indication of the normal fluctuation expected for 3D-MRSI. In vivo, median CVs at the %SD < or = 20 level were found to be (%CV for TE = 144 and 30 ms, respectively): N-acetyl-aspartate plus N-acetyl-aspartyl-glutamate (NAA): 10.2% and 13.5%; creatine plus phosphocreatine (Cr), 14.4% and 21.7%; and choline-containing compounds (Cho), 15.2% and 18.4%. Relaxing the statistical filtering criteria to %SD < or = 30 increased median CVs by less than 5% and permitted in vivo quantitation reproducibility to be evaluated for glutamine plus glutamate (Glx) and myoinositol (Ins) for TE = 30 ms, yielding CVs of 24.0% and 21.0%, respectively.
在10名健康志愿者中，通过五次独立观测，使用144和30 ms这两个回波时间（TE），研究了三维质子磁共振波谱成像（3D-MRSI）中代谢物定量的受试者内再现性。使用吉尔 - 托马斯 - 科斯曼（GTC）立体定向头架能够实现精确的受试者重新定位和固定。使用模型谱线性组合（LCModel）分析算法对感兴趣体积（VOI）中每个体素的代谢物水平进行定量，并计算变异系数（CV）。由LCModel生成的标准误差估计值（%SD或克拉美 - 罗下界）用作置信过滤器。为每种代谢物找到95%置信区间（CI），以指示3D-MRSI预期的正常波动。在体内，发现%SD≤20水平时的中位数CV分别为（TE = 144和30 ms时的%CV）：N-乙酰天门冬氨酸加N-乙酰天门冬氨酰谷氨酸（NAA）：10.2%和13.5%；肌酸加磷酸肌酸（Cr），14.4%和21.7%；以及含胆碱化合物（Cho），15.2%和18.4%。将统计过滤标准放宽至%SD≤30时，中位数CV增加不到5%，并允许对TE = 30 ms时的谷氨酰胺加谷氨酸（Glx）和肌醇（Ins）进行体内定量再现性评估，其CV分别为24.0%和21.0%。
