中文摘要：

目的评价化学位移成像（chemical shift imaging，CSI）和MRS两种方法在脂肪研究中的作用，为进一步活体实验提供定量标准。方法在7．0TMR成像仪上运用CSI和MRS方法对体外水脂模型进行水脂定量分析。体外水脂模型的脂肪含量从0～100％平均分成11个组，各组间浓度相差10％，分别应用水、脂肪选择性CSI和1H—MRS对体外水脂模型进行图像和波谱数据采集，对2种方法所得结果分别与实际水脂含量进行单样本t检验及相关分析并比较两种方法间的相关性。MRS计算100％油模型饱和脂肪酸（fraction of saturatedfattyacids，FS）、不饱和脂肪酸（fraction of unsaturatedfattyacids，FU）的相对含量及多聚不饱和程度（polyunsaturation degree，PUD）。结果CSI法测定实际脂肪含量为50％-100％的测量值分别为（48．0±1．0）％、（57．0±0．5）％、（67．3±0．6）％、（77．3±0．6）％、（83．3±0．6）％和（91．0±1．0）％；MRS测定实际脂肪含量为10％-60％的测量值分别为（8．3±0．6）％、（16．3±0．7）％、（27．7±0．6）％、（36．0±1．0）％、（43．5±0．6）％和（56．5±1．0）％，均轻度低估了脂肪含量，差异均有统计学意义（P值均〈0．05）。CSI与MRS计算的脂肪含量与实际脂肪含量间均呈线性相关（CSI：r=0．998，MRS：r=0．996；P值均〈0．01）；两种方法间也呈线性相关（r=0．992，P〈0．01），两种方法定量脂肪含量差异无统计学意义（t=-0．125，P=0．903）。MRS计算橄榄油的FS和FU相对含量分别为0．15和0．85，PUD为0．0325，与实际含量一致。结论在7．0TMR成像仪上，体外水脂模型证实CSI和MRS定量脂肪的准确性及在脂肪研究上的可行性。

英文摘要：

Objective To evaluate the accuracy of chemical shift imaging （CSI） and MR spectroscopy （MRS） for fat quantification in phantom model. Methods Eleven phantoms were made according to the volume percentage of fat ranging from 0 to 100% with an interval of 10% . The fat concentration in the phantoms were measured respectively by CSI and MRS and compared using one-sample t test. The correlation between the two methods was also analyzed. The concentration of saturated fatty acids （FS）, unsaturated fatty acids （FU） and the polyunsaturation degree （PUD）were calculated by using MRS. Results The fat concentration was （48.0 ±1.0）%, （57.0 ±0.5）%, （67.3 ±0.6）%, （77.3 ± 0. 6） %, （83.3 ±0.6） % and （91.0 ±1.0） % respectively with fat volume of 50% to 100% by CSI. The fat concentration was （ 8.3 ± 0. 6） %, （ 16. 3± 0. 7 ） %, （ 27. 7 ±0. 6 ） %, （ 36. 0 ± 1.0 ） %, （43.5 ± 0. 6）% and （56. 5± 1.0）% respectively with fat volume of 10% to 60% by MRS, the fat concentration were underestimated by CSI and MRS （P 〈 0.05 ）, and had high linear correlation with the real concentration in phantoms （ CSI： r = 0. 998, MRS： r = 0. 996, P 〈 0. 01 ） . There was also a linear correlation between two methods （ r = 0. 992, P 〈 0. 01 ） but no statistically significant difference （ pairedsamples t test, t = -0. 125,P =0. 903）. By using MRS, the relative ratio of FS and FU in fat were 0. 15 and 0. 85, the PUD was 0. 0325, respectively, and highly consistent with these in phantoms. Conclusion Both CSI and MRS are efficient and accurate methods in fat quantification at 7.0 TMR.