1 Department of Internal Medicine, Division of Gastroenterology and Hepatology, University of California, Davis, 4150 V St, PSSB 3500, Sacramento, CA 95817.
2 Department of Radiology, University of California, Davis, Sacramento, CA.
AJR Am J Roentgenol. 2019 Mar;212(3):529-537. doi: 10.2214/AJR.18.20012. Epub 2019 Jan 23.
Nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) are major causes of chronic liver disease characterized by steatosis, inflammation, and fibrosis. Diagnosis of inflammation is limited by the need for liver biopsy. Dynamic PET with the widely used radiotracer F-FDG provides a novel method for evaluating spatial and temporal changes in liver inflammation.
Patients with NAFLD or NASH underwent dynamic FDG PET and MRI within 6 months of undergoing liver biopsy. Liver time-activity curves were extracted to estimate kinetic parameters representing various rate constants of FDG transport using tracer kinetic modeling. Liver biopsy specimens were scored on the basis of NASH Clinical Research Network criteria.
This pilot study included 22 patients, 14 of whom were women. Patient age ranged from 18 to 70 years, and the mean body mass index (weight in kilograms divided by the square of height in meters) was 33.2 (range, 24-43.1). The K value, which represents the rate of FDG transport from blood to hepatic tissue, was significantly correlated with inflammation (r = -0.7284; p = 0.0001) and the overall NAFLD activity score (NAS; r = -0.6750; p = 0.0006). K values were inversely related to the hepatic inflammation score and NAS. Although heterogeneity in K values across eight liver segments was noted, distinct segregation existed among segmental K values dependent on the histologic inflammation score (p = 0.022) or NAS (p = 0.0091). K had a strong association with both inflammation (ROC AUC value, 0.88) and the NAS (ROC AUC value, 0.89), with K = 1.02 (mL/min/mL) corresponding to a sensitivity and specificity of 93% and 88%, respectively, for the NAS.
Dynamic FDG PET with tracer kinetic modeling has the potential to determine liver inflammation in patients with NAFLD and NASH and can fill an essential gap in diagnosis.
非酒精性脂肪性肝病（NAFLD）和非酒精性脂肪性肝炎（NASH）是导致慢性肝病的主要原因，其特征为脂肪变性、炎症和纤维化。炎症的诊断受到肝活检的限制。使用广泛应用的放射性示踪剂 F-FDG 的动态 PET 提供了一种评估肝脏炎症时空变化的新方法。
NAFLD 或 NASH 患者在肝活检后 6 个月内行 FDG PET 动态检查和 MRI。提取肝脏时间-活性曲线，使用示踪动力学模型来估计代表 FDG 转运各种速率常数的动力学参数。根据 NASH 临床研究网络标准对肝活检标本进行评分。
本研究为前瞻性试点研究，共纳入 22 例患者，其中 14 例为女性。患者年龄 1870 岁，平均体重指数（体重/身高 2，kg/m 2 ）为 33.2（范围，2443.1）。K 值代表 FDG 从血液向肝组织的转运速率，与炎症（r=-0.7284，p=0.0001）和总体 NAFLD 活动评分（NAS；r=-0.6750，p=0.0006）显著相关。K 值与肝炎症评分和 NAS 呈负相关。尽管在 8 个肝段的 K 值存在异质性，但在依赖组织学炎症评分（p=0.022）或 NAS（p=0.0091）的各肝段的 K 值之间存在明显的分离。K 值与炎症（ROC 曲线下面积，0.88）和 NAS（ROC 曲线下面积，0.89）具有很强的相关性，K 值为 1.02（mL/min/mL）时，NAS 的敏感性和特异性分别为 93%和 88%。
使用示踪动力学模型的 FDG PET 动态检查具有确定 NAFLD 和 NASH 患者肝脏炎症的潜力，可以填补诊断上的重要空白。
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