3.0T ~1H-MRS联合梯度回波化学位移技术定量分析评估脂肪肝治疗效果

Quantification of liver fat content by 1 H-MR spectroscopy combined with chemical shift gradient-echoMR imaging at 3.0T for therapeutic evaluation of fatty liver a preliminary study

目的:探讨在3.0T MRI上联合运用氢质子波谱成像(1H-MRS)和梯度回波化学位移技术评估脂肪肝治疗效果的可行性。方法:搜集临床确诊的脂肪肝病例26例,于干预治疗前、干预治疗后3个月、6个月各行1次磁共振化学位移抑脂成像(梯度回波T1WI同/去相位双回波)和氢质子波谱成像(1 H-MRS),测得同/去相位序列的信号强度值(SIIP和SIOP),计算双回波脂变指数(FI)。测得1 H-MRS的水峰峰值(Pwater)和脂肪峰峰值(Plipid)、水峰峰下面积(Awater)、脂肪峰峰下面积(Alipid),计算肝细胞相对脂肪含量1(RLC1)及相对脂肪含量2(RLC2)。同期测量患者的血脂、谷氨酰转肽酶、腹围及身高体重指数(BMI),将其拟合成临床脂肪肝指数(FLI)。以FLI为参照标准,对不同时间点MRI所测得肝脏脂肪含量进行统计学分析。结果:FI、RLC1、RLC2与FLI进行秩相关性分析,呈正相关性(r>0,P<0.05)。干预治疗前后对照采用重复测量的方差分析,显示FI、RLC1、RLC2、FLI组间差异具有统计学意义(P=0.000),对时间(time)变化趋势的对比Polynomial检验显示time*type有统计学意义(P=0.000),提示FI、RLC1、RLC2在治疗前、治疗后3个月、治疗后6个月的变化是有差异的。可靠性分析显示,治疗前后组的FI和治疗前组的RLC1、RLC2的可重复性好,组内相关系数ICC≥0.75。结论:1H-MRS和梯度回波化学位移MRI可在一定程度上对脂肪肝进行定量测定,可作为脂肪肝动态监测、疗效评估和随访观察的有效手段。

Objective：To investigate the feasibility of proton magnetic resonance spectroscopy （1 H-MRS） and chemi cal shift gradient-echo imaging to quantitatively analyze liver fat content for therapeutic evaluation of fatty liver at 3.0T MR system. Methods..26 patients diagnosed as fatty liver were examined with proton MRS and magnetic resonance chemical shift-based fat suppression sequences（Dixon and triple-echo Dixon）at 3.0T MR system before and 3,6 months after treat ment respectively to calculate the fat index（FI）of Dixon, the water peak （Pwator）, fat peak （Plipid） and water peak area （A ）, fat peak area （Alipid） were for MRS to calculate relative lipid content 1 （RLC1）and relative lipid content 2 （RLC2）. Fatty liver index（ FL1） was referred to the standard which was calculated from triglycerides （TG）, gamma-glutamyl trans ferase （GGT）, waist circumference and body mass index（BMI）. Results：Significant positive correlation （r〉0, P〈0.05）was demonstrated between MRI measured values（F1, RLCl, RLC2） and FLI. Significant positive correlation（r〉 0, P〈0.05） was demonstrated in MRI measured values（FI, RLC1,RLC2）and FLI. Significant difference between groups was demonstrated in FI, RLC1 ,RI,C2 and FLI. Significance in statistics was demonstrated in time ＊ type in the Polynomial test for the com- parison of time change trend which point out the significant difference of FI,RLCl,RLC2 between pre treatment and pos treatment. Reliability analysis showed that FI in both pre treatment and pos-treatment groups and RLCI ,RLC2 in pre treat ment group got significant repeatability while ICC ≥0.75. Conclusion：1 H-MRS combined with chemical shift gradient echo techniques can qtmntitatively measure liver fat content. They can be reliably used for dynamic monitoring the therapeutic effects for fatty liver. Dixon technique is more stable,while 1H MRS is more accurate. Both 1H-MRS and Dixon technique have good clinical application in dynamically monitoring the progression of fatty liver and evaluating the therapeutic effects of various treatments.