Division of Internal Medicine, Department of Medicine, University of California, San Diego, USA.
Aliment Pharmacol Ther. 2012 Jul;36(1):22-9. doi: 10.1111/j.1365-2036.2012.05121.x. Epub 2012 May 3.
Conventional magnetic resonance imaging (MRI) techniques that measure hepatic steatosis are limited by T1 bias, T(2)* decay and multi-frequency signal-interference effects of protons in fat. Newer MR techniques such as the proton density-fat fraction (PDFF) that correct for these factors have not been specifically compared to liver biopsy in adult patients with non-alcoholic fatty liver disease (NAFLD).
To examine the association between MRI-determined PDFF and histology-determined steatosis grade, and their association with fibrosis.
A total of 51 adult patients with biopsy-confirmed NAFLD underwent metabolic-biochemical profiling, MRI-determined PDFF measurement of hepatic steatosis and liver biopsy assessment according to NASH-CRN histological scoring system.
The average MRI-determined PDFF increased significantly with increasing histology-determined steatosis grade: 8.9% at grade-1, 16.3% at grade-2, and 25.0% at grade-3 with P ≤ 0.0001 (correlation: r(2) = 0.56, P < 0.0001). Patients with stage-4 fibrosis, when compared with patients with stage 0-3 fibrosis, had significantly lower hepatic steatosis by both MRI-determined PDFF (7.6% vs. 17.8%, P < 0.005) and histology-determined steatosis grade (1.4 vs. 2.2, P < 0.05). NAFLD patients with grade 1 steatosis were more likely to have characteristics of advanced liver disease including higher average AST:ALT (0.87 vs. 0.60, P < 0.02), GGT (140 vs. 67, P < 0.01), and INR (1.06 vs. 0.99, P < 0.01), higher stage of fibrosis and hepatocellular ballooning.
MRI-determined proton density-fat fraction correlates with histology-determined steatosis grade in adults with NAFLD. Steatosis is non-linearly related to fibrosis progression. In patients with NAFLD, a low amount of hepatic steatosis on imaging does not necessarily indicate mild disease.
传统的磁共振成像（MRI）技术测量肝脂肪变性受 T1 偏倚、T(2)*衰减和脂肪质子的多频信号干扰的影响。新的磁共振技术，如质子密度脂肪分数（PDFF），可以校正这些因素，但尚未在非酒精性脂肪性肝病（NAFLD）的成年患者中与肝活检进行专门比较。
检查 MRI 测定的 PDFF 与组织学测定的脂肪变性程度之间的相关性，以及它们与纤维化的相关性。
共 51 例经活检证实的 NAFLD 患者接受代谢生化特征分析、MRI 测定的肝脂肪变性 PDFF 测量和根据 NASH-CRN 组织学评分系统进行的肝活检评估。
MRI 测定的 PDFF 随组织学测定的脂肪变性程度的增加而显著增加：1 级为 8.9%，2 级为 16.3%，3 级为 25.0%，P≤0.0001（相关性：r(2) = 0.56，P<0.0001）。与纤维化分期 0-3 期的患者相比，纤维化分期 4 期的患者通过 MRI 测定的 PDFF（7.6%比 17.8%，P<0.005）和组织学测定的脂肪变性程度（1.4 比 2.2，P<0.05）明显更低。1 级脂肪变性的 NAFLD 患者更有可能具有晚期肝病的特征，包括更高的平均 AST:ALT（0.87 比 0.60，P<0.02）、GGT（140 比 67，P<0.01）和 INR（1.06 比 0.99，P<0.01），更高的纤维化分期和肝细胞气球样变。
MRI 测定的质子密度脂肪分数与 NAFLD 成人组织学测定的脂肪变性程度相关。脂肪变性与纤维化进展呈非线性关系。在 NAFLD 患者中，影像学上肝脏脂肪变性量少不一定表明疾病轻微。
