3.0T 1H-MRS测定大鼠肝内脂肪含量的可行性

目的 探讨利用3.0T临床型MR仪行¹H-MRS测定非酒精性脂肪肝（NAFLD）大鼠模型肝内脂肪含量的可行性。方法 将75只SD大鼠随机分为高脂饲养实验组（n=50）与正常对照组（n=25）；分别在第2、4、6、8、10周时行肝脏¹H-MRS扫描及组织病理学检查。将¹H-MRS原始数据导入LC model软件进行分析，并对各代谢物浓度行T1、T2纠正；将¹H-MRS结果与组织病理学结果加以对照，将肝内饱和脂肪酸含量、总非不饱和脂肪酸含量及组织病理学检测含量分别记为Lip_MRS1、Lip_MRS2和FI。结果 大鼠肝脏同一部位相同参数（r₁）及同一部位不同时间点（r₂）¹H-MRS测量结果（r₁=0.99，r₂=0.96，P均<0.01）呈高度正相关；Lip_MRS1、FI呈高度正相关，回归方程为：LogY=0.37+1.21LogX（r=0.95，P<0.01），NAFLD大鼠模型中Lip_MRS1及Lip_MRS2含量无明显相关性（r=－0.11，P=0.66）；Bland & Altman曲线分析显示Lip_MRS1与FI的一致性好。结论 采用3.0T临床型MR仪行¹H-MRS可作为在体评价NAFLD大鼠模型肝内脂肪含量的无创的影像学方法；LC model软件能区分肝内脂肪组分并精确定量。

Assessment of hepatic lipid in steatoic liver rat models using 1H-MRS on 3.0T

Objective To investigate the feasibility of in vivo assessment of hepatic lipid content using clinical 3.0T ¹H-MRS in a nonalcoholic fatty liver disease (NAFLD) rat models. Methods Totally 75 healthy Sprague-Dawle rats were randomly divided into NAFLD group (n=50) and control group (n=25). ¹H-MRS of the liver was performed, and then rats were sacrificed for histopathological assessment of the liver after 2, 4, 6, 8, 10 weeks. The raw data of ¹H-MRS was exported to LC model software. The metabolite concentration of H₂O and Lipid was measured and corrected for T1 and T2 decay. The ratio of Lip/(Lip_corr+H₂O_corr)×100% was noted as Lip_MRS1, of unsaturated fatty acid (UFA)/(UFA+H₂O)×100% was noted as Lip_MRS2, the lipid content estimated by histopathology was noted as FI. Results The reproducibility of ¹H-MRS was validated by showing that duplicate ¹H-MRS measurements on different occasions (r₁) and different sites (r₂) of the liver were highly correlated (r₁=0.99, r₂=0.96, all P<0.01). Lip_MRS1 and FI were high positively correlated, and the regression equation was LogY=0.37+1.21LogX (r=0.95, P<0.01), while Lip_MRS1 and Lip_MRS2 had no correlation (r=-0.11, P=0.66). With Bland-Altman method plot, all data points of Lip_MRS1 and FI were within the limits of agreement. Conclusion High quality and reproducible ¹H-MRS of NAFLD rat model can be achieved using clinical 3.0T MR scanner. The saturated fatty acid and the polyunsaturated fatty acid can be discriminated by LC model software. ¹H-MRS can be used as a noninvasive and in vivo method in assessing hepatic lipid content and composition for NAFLD rat models.