超声筛检肥胖儿童脂肪肝的价值评估

Diagnostic value of ultrasonographic examination for hepatic steatosis in obese children

摘要:

目的 评价常规超声在筛检肥胖儿童脂肪肝中的灵敏度和特异度。方法 162 例肥胖儿童（年龄 10.5±2.2 岁，体重指数 28±4）纳入该研究，均进行肝脏超声和磁共振氢谱（¹H MRS）检查。¹H MRS 直接检测到的肝脏脂肪信号百分数通过相应的校准程序换算成甘油三酯重量百分数（mg/g 湿重），表示肝脏脂肪含量（LFC）。以¹H MRS 结果为参考标准，计算超声筛检肥胖儿童脂肪肝的灵敏度、特异度、阳性预测值和阴性预测值。结果 根据 LFC>5% 的量化诊断标准，¹H MRS 确定 58.6%（95/162）的肥胖儿童患有脂肪肝，超声筛检脂肪肝的灵敏度为 91.6%（87/95），特异度为 50.7%（34/67），阳性预测值为 72.5%（87/120），阴性预测值为 81.0%（34/42）。不同超声等级的脂肪肝分组与 LFC 四分位数分组间存在明显的交互重叠。结论 常规超声筛检肥胖儿童脂肪肝的灵敏度高，而特异度较低，提示常规超声可应用于肥胖儿童的脂肪肝筛检，必要时进行¹H MRS 检查加以明确。

Abstract:

Objective To evaluate the sensitivity and specificity of hepatic ultrasonography（US) for the diagnosis of hepatic steatosis in obese children, using ¹H magnetic resonance spectroscopy（¹H MRS) as the reference standard.Methods A total of 162 obese children with age of 10.5±2.2 years and BMI of 28±4 were enrolled in this study. They accepted hepatic US and ¹H MRS examinations. The sensitivity, specificity, positive predictive value（PPV) and negative predictive value（NPV) of US were calculated for the overall presence of hepatic steatosis by comparison with ¹H MRS results. Results Using quantitative criteria of liver fat content（LFC) >5% determined by ¹H MRS, 95 children(58.6%) were diagnosed as having hepatic steatosis. The sensitivity and specificity of US in diagnosing steatosis were 91.6%（87/95) and 50.7%（34/67) respectively, with PPV of 72.5%（87/120), and NPV of 81.0%（34/42). Considerable overlap in LFC measured by ¹H MRS was observed between different grades from US findings: absent（LFC interquartile range:1.3%-3.9%), mild（2.4%-10.7%), moderate（7.1%-20.2%) and severe（7.6%-28.8%) steatosis. Conclusion The US can yield a high sensitivity and low specificity in the diagnosis of hepatic steatosis in obese children, suggesting it can be used as a screening tool for hepatic steatosis. To improve diagnostics, ¹H MRS is needed to determine LFC.