年龄对肝脏3.0 T质子MRS抑水的影响

The Effect of Age on MRS Prescan Water Suppression at 3.0 T

目的探讨年龄对在体肝脏3.0T质子磁共振波谱(MRS)预扫描抑水效果的影响。资料与方法 44名自愿者,使用GE Signa Excite HD 3.0 T超导磁共振扫描仪,8通道腹部相控阵线圈,单体素点分辨波谱(PRESS)序列采集。参数为TR1500ms,TE30ms,信号采集次数(NSA)64次,感兴趣容积(VOI)2cm×2cm×2cm。采用SAGE进行后处理分析得到代谢物峰高及峰下面积。以水峰为内参照对脂质峰高度及面积进行标准化。(1)把受检者按是否年龄<44岁分为两组,比较两组受检者一般情况包括身高、体重、体重指数(BMI);波谱预扫描匀场效果和抑水效果;脂质峰和水峰的峰高及峰下面积等计量指标是否存在统计学差异,采用两独立样本的t检验,数据为非正态分布时采用两独立样本秩和检验。(2)并计算年龄与各上述指标相关系数,数据为非正态分布时计算等级相关系数。结果 (1)年龄较轻组较年龄较长组的平均BMI较小[分别为(22.0±3.5)kg/m2,(24.7±2.7)kg/m2,t=-2.793,P=0.008],Lip2峰高[两组最小值-最大值分别为14099-634600,34480-1752600;中位数分别为90044,211375]及峰下面积[两组最小值-最大值分别为42717-1E+007,123810-5E+007;中位数分别为357605,1075300]较小(Z值分别为-2.393,-2.317;P值分别为0.017,0.020)。标准化脂质峰高度[两组最小值-最大值分别为0.00-0.27,0.02-0.70;中位数分别为0.07,0.19]及面积[两组最小值-最大值分别为0.00-0.23,0.00-0.96;中位数分别为0.01,0.03]更小(Z值分别为-2.317,-2.116;P值分别为0.020,0.034)。(2)BMI与体重高度正相关(r=0.859,P=0.000),年龄与BMI(r=0.420,P=0.004)及Lip2峰高(r=0.362,P=0.019)及标准化脂质峰高度(r=0.317,P=0.041)中度正相关;年龄与预扫描匀场效果低度负相关(r=-0.298,P=0.049),抑水效果中度负相关(r=-0.326,P=0.031)。结论年龄增加伴随肝脏脂质沉积增加,更难确定水抑制脉冲的中心频率,影响波谱预扫描抑水效果,总体来说年龄更大者更难达到良好的波谱抑水结果从而更难获得高分辨的可析性波谱。

Objective To assess the effect of age on proton hepatic MRS at 3.0 T.Materials and Methods The prospective study of hepatic proton MRS was performed with a GE Signa Excite HD 3.0 T system and eight-channel torso phased-array coils using PRESS sequence.44 individuals were enrolled in this study.Liver spectra were collected with a TR of 1500 ms,TE of 30 ms,VOI of 2 cm×2 cm×2 cm,NSA of 64 times.Areas and heights for metabolites resonances were obtained.Results young age group has lower BMI（22.0±3.5 kg / （m）2,24.7±2.7 kg / （m）2,t=-2.793,P=0.008）,smaller of integrated area of Lip2 than old age group.There were significant correlations between age and BMI（r=0.420,P=0.004）,Lip2 peak height （r=0.362,P=0.019）,shimming effect（r=-0.298,P=0.049）,water suppression（r=-0.326,P=0.031）.Conclusion Lipid accumulation in the liver could be the result of the increased fat portion of the body depending on age and hinder to achieve effective water suppression.