Liver Imaging Group, Department of Radiology, University of California San Diego, 408 Dickinson St, San Diego, CA 92103-8226, USA.
Radiology. 2013 May;267(2):422-31. doi: 10.1148/radiol.12120896. Epub 2013 Feb 4.
To evaluate the diagnostic performance of magnetic resonance (MR) imaging-estimated proton density fat fraction (PDFF) for assessing hepatic steatosis in nonalcoholic fatty liver disease (NAFLD) by using centrally scored histopathologic validation as the reference standard.
This prospectively designed, cross-sectional, internal review board-approved, HIPAA-compliant study was conducted in 77 patients who had NAFLD and liver biopsy. MR imaging-PDFF was estimated from magnitude-based low flip angle multiecho gradient-recalled echo images after T2* correction and multifrequency fat modeling. Histopathologic scoring was obtained by consensus of the Nonalcoholic Steatohepatitis (NASH) Clinical Research Network Pathology Committee. Spearman correlation, additivity and variance stabilization for regression for exploring the effect of a number of potential confounders, and receiver operating characteristic analyses were performed.
Liver MR imaging-PDFF was systematically higher, with higher histologic steatosis grade (P < .001), and was significantly correlated with histologic steatosis grade (ρ = 0.69, P < .001). The correlation was not confounded by age, sex, lobular inflammation, hepatocellular ballooning, NASH diagnosis, fibrosis, or magnetic field strength (P = .65). Area under the receiver operating characteristic curves was 0.989 (95% confidence interval: 0.968, 1.000) for distinguishing patients with steatosis grade 0 (n = 5) from those with grade 1 or higher (n = 72), 0.825 (95% confidence interval: 0.734, 0.915) to distinguish those with grade 1 or lower (n = 31) from those with grade 2 or higher (n = 46), and 0.893 (95% confidence interval: 0.809, 0.977) to distinguish those with grade 2 or lower (n = 58) from those with grade 3 (n = 19).
MR imaging-PDFF showed promise for assessment of hepatic steatosis grade in patients with NAFLD. For validation, further studies with larger sample sizes are needed.
利用中心评分的组织病理学验证作为参考标准，评估磁共振（MR）成像估计质子密度脂肪分数（PDFF）在非酒精性脂肪性肝病（NAFLD）中评估肝脂肪变性的诊断性能。
本前瞻性设计、经横断面内部审查委员会批准、符合 HIPAA 标准的研究纳入了 77 例经肝活检证实患有 NAFLD 的患者。MR 成像-PDFF 是在 T2*校正和多频带脂肪建模后，从基于幅度的低翻转角多回波梯度回波图像中估计得出的。组织病理学评分由非酒精性脂肪性肝炎（NASH）临床研究网络病理委员会达成共识获得。采用 Spearman 相关分析、加性和回归方差稳定法来探索多种潜在混杂因素的影响，并进行受试者工作特征（ROC）分析。
肝 MR 成像-PDFF 系统性升高，与较高的组织学脂肪变性程度呈正相关（P＜0.001），与组织学脂肪变性程度显著相关（ρ=0.69，P＜0.001）。该相关性不受年龄、性别、肝小叶炎症、肝细胞气球样变、NASH 诊断、纤维化或磁场强度的影响（P=0.65）。用于区分脂肪变性程度为 0 级（n=5）与 1 级或更高（n=72）患者的 ROC 曲线下面积为 0.989（95%置信区间：0.968，1.000），用于区分脂肪变性程度为 1 级或更低（n=31）与 2 级或更高（n=46）患者的 ROC 曲线下面积为 0.825（95%置信区间：0.734，0.915），用于区分脂肪变性程度为 2 级或更低（n=58）与 3 级（n=19）患者的 ROC 曲线下面积为 0.893（95%置信区间：0.809，0.977）。
MR 成像-PDFF 有望用于评估 NAFLD 患者的肝脂肪变性程度。为了验证这一结果，还需要进一步开展具有更大样本量的研究。
