多回波化学位移编码水／脂MRI评估骨髓脂肪的可行性研究  

Quantitative chemical shift-encoded MRI is an accurate method to quantify marrow fat

作　　者：祝乐群[1] 李冠武[1] 施丹[2] 史晓[2] 王炳新[2] 李雪峰[1] 常时新[1] 

机构地区：[1]上海中医药大学附属岳阳中西医结合医院医学影像科,上海200437 [2]上海中医药大学附属岳阳中西医结合医院老年科,上海200437

出　　处：《实用放射学杂志》2018年第2期283-286,295,共5页Journal of Practical Radiology

摘　　要：目的 以多回波T2校正磁共振波谱成像（MRS）为参考，证实化学位移编码8回波3D扰相梯度回波序列水/脂分离MRI（CSE-MRI）定量椎体骨髓脂肪含量的可行性。方法 83例绝经后妇女按骨密度分为正常骨量组（n=41）、低骨量组（n=26）及骨质疏松组（n=16）。8例受试者做3次CSE-MRI重复扫描，以均方根绝对精度误差及均方根变异系数评价CSE-MRI定量质子密度脂肪分数（PDFF）的可重复性。组内相关系数（ICC）评估观察者内及观察者间测定CSE-MRI PDFF值的一致性。采用Linear regression、Bland-Altman分析及Lin’s一致性相关系数法评价CSE-MRI与MRS定量PDFF的可代替性。结果 CSE-MRI 重复扫描，均方根绝对误差为1.45%。MRS及CSE-MRI定量83例受试者骨髓PDFF，PDFF值分别为62.1%±11.1%、60.4%±10.1%，无统计学差异。协方差分析校正年龄、绝经年数及体质量指数，正常骨量组、低骨量组、骨质疏松（OP）组PDFF值存在统计学差异（P均〈0.001）。观察者内及观察者间测定受试者CSE-MRI PDFF均具有实质性的一致性，ICC均≥0.993。MRS、CSE-MRI定量83例受试者PDFF的线性回归分析，相关系数为0.979，Lin’s一致性相关系数为0.962。 所有的MRS PDFF与CSE-MRI PDFF差值的点均落在Bland-Altman分析法95%可信区间内。各组受试者CSE-MRI PDFF与腰椎骨密度（BMD） （r=-0.560^-0.710） 及MRS PDFF与腰椎BMD（r=-0.539^-0.706）均呈中度正相关性。结论 CSE-MRI应用多脂峰模型及T2＊校正定量椎体骨髓脂肪含量其准确性可等同于多回波T2校正MRS。Objective To validate a chemical shift-encoded MRI（CSE-MRI） water-fat imaging for quantifying vertebral marrow fat content using MRS as the reference standard.Methods MRS and CSE-MRI were performed to calculate proton density fat fraction （PDFF） in 83 subjects, including 41 normal bone mass, 26 osteopenia and 16 osteoporosis. Eight participants were scanned three times with repositioning to assess the repeatability of CSE-MRI PDFF measurements. Agreements of intra-observer and inter-observer were evaluated by intraclass correlation coefficient （ICC）.Linear regression, Bland-Altrnan 95 % limit of agreement and Lin＇s concordance correlation coefficient were calculated.Results The repeatability for CSE-MRI PDFF measurements expressed as absolute precision error was 1.45%.PDFF was 62.1 %-11.1% by MRS and 60.4 %±10.1% by CSE-MRI in 83 subjects. There were significant differences in PDFF among the normal bone mass, osteopenia and osteoporosis groups after adjusting for age,years since menopause and body mass index （all P〈 0.001 ）. The intra-and inter-rater reliability for duplicate measurements at CSE-MRI PDFF were more than 0.993.Pearson correlation coefficient was 0.979 and Lin＇s concordance correlation coefficient was 0.962. All data points calculated using the Bland-Airman method were within the limits of agreement. Inverse associations were observed between BMD （ r = - 0.560- - 0. 710 ） and CSE- MRI-based PDFF, and between BMD ~ r=-3. 539- -0.706 ） and MRS-based PDFF in various groups.Conclusion CSE-MRI with multiple lipids peak model and T2 -correction is equally accurate in characterizing marrow fat content as MRS.

关 键 词：化学位移编码 水/脂分离 磁共振波谱成像 骨髓脂肪 

分 类 号：R445.2[医药卫生—影像医学与核医学] R322.71[医药卫生—诊断学]