在体肝脏3．0T^1H—MR波谱匀场及抑水影响因素探讨

Exploration of factors influencing shimming and water suppression on hepatic ^1H-MR spectroscopy in vivo on 3.0 T

目的探讨受检者的自身因素对在体肝脏^1H—MRS自动预扫描中匀场和抑水效果的影响。方法回顾性分析57例行肝脏^1H—MRS检查受检者资料，其中正常受检者35名、慢性乙型肝炎5例、脂肪肝14例、脂肪肝合并慢性乙型肝炎3例。把受检者按是否抑水率（WS）≥90％及是否匀场线宽（LW）〉20Hz分别分为2组，分别采用两独立样本的t检验比较2组的一般情况如身高、体重、体质量指数（BMI），采用卡方检验比较脂肪肝组与非脂肪肝组达到较好的LW和WS效果的比率。结果抑水较好组47例和抑水不好组10例比较，平均身高[分别为（164．7±8．0）和（170．5±3．7）cm]、体重[分别为（61．8±10．4）和（73．4±5．4）kg]、BMI[分别为（22．7±3．2）和（25．2±1．3）kg／m^2]及LW[分别为（17．7±3．7）和（24．6±6．3）Hz]，差异均有统计学意义（t值分别为-3．488、-3．415、-4．002和-3．327，P值均〈0．05）。匀场较好组41例和匀场不好组16例比较，体重[分别为（62．2±11．6）和（68．1±6．1）kg]，BMI[分别为（22．8±3．4）和（24．2±1．9）kg／m^2]，WS[分别为（93．0±2．7）％和（86．1±8．5）％]，差异均有统计学意义（t值分别为-2．516、-2．024和3．213，P值均〈0．05）。脂肪肝组17例巾，7例自动匀场LW≤20Hz，无脂肪肝组40例中，34例自动匀场LW≤20Hz，2组间差异有统计学意义（Х^2=11．347，P〈0．05）。脂肪肝组17例中，WS〈90％者7例，无脂肪肝组40例中，无WS〈90％患者，两者差异有统计学意义（Х^2=28．536，P〈0．05）。结论肝脏的脂质沉积对^1H—MRS匀场及抑水存在负性影响，体重及BMI大的受检者达到良好的匀场和抑水效果预期成功率低。

Objective To characterize the clinical factors which influence water suppression and auto-shimming line width for liver 3.0 T ^1H-MRS. Methods Fifty-seven cases with liver ^1H-MR spectroscopy（^1H-MRS） were retrospectively studied, including chronic type B hepatitis （n = 5）, fatty liver （n=14）, chronic type B hepatitis combining fatty liver （n = 3） and normal situation （n ： 35）. Independent t test was used to characterize the difference of general condition （ height, weight, body mass index etc. ） between different water suppression effect groups and between different shimming effect groups. Using Chi-square test to analyze whether water suppression rate and auto-shimming line width between fatty liver groups and non-fatty liver exist significance difference . Results By comparing WS≥ 90% （ n = 47 ） group with WS 〈 90% （ n = 10） group, the former showed smaller average height [ （ 164. 7 ± 8.0） and （170.5±3.7） cm respectively], weight [（61.8± 10.4） and （73.4 ±5.4） kg respectively], BMI [（22.7±3.2） and （25.2±1.3）kg/m^2 respectively] and LW [（17.7 ±3.7）and（24.6 ±6.3） Hz respectively ] than the latter（ t = - 3. 488, - 3. 415, - 4. 002 and - 3. 327, P 〈 0. 05 ）. By comparing LW ≤ 20 Hz （ n = 41 ） group with LW 〉 20 Hz （ n = 16 ） group, the former showed better water suppression rate [ （93.0 ±2. 7）% and （86. 1 ±8.5）% respectively] than the latter（t =3. 213 ,P 〈0. 05）, whereas larger weight[（62.2 ± 11.6） and （68.1 ± 6.1） kg respectively] and BMI[（22.8 ± 3.4） and （24.2 ±1.9）kg/m^2 respectively] （t = -2. 516, -2. 024,P 〈0. 05）. LW≤20 Hz in the fatty liver and non-fatty liver group was 7/17 and 34/40, respectively （ Х^2 = 11. 347, P 〈 0. 05 ）. WS 〈 90% in the fatty liver and non-fatty liver group was 10/17 and 0/44, respectively （Х^2 = 28. 536, P 〈 0. 05 ） . Conclusion Hepatic steatosis exerts an adverse effect in water suppression and shimming.