1 Department of Radiology, University of Wisconsin School of Medicine and Public Health, E3/311 Clinical Science Center, 600 Highland Ave, Madison, WI 53792-3252.
AJR Am J Roentgenol. 2014 Apr;202(4):752-8. doi: 10.2214/AJR.13.11367.
Hepatic steatosis is a common incidental finding at radiologic imaging. The natural history of nonalcoholic fatty liver disease (NAFLD) and its associated risks for cardiovascular complications are not well established in this context. Our purpose was to investigate the clinical outcome of moderate-to-severe hepatic steatosis detected incidentally at CT.
Liver attenuation was measured at unenhanced CT in 4412 consecutive adults scanned over a 12-month period. Moderate-to-severe steatosis was diagnosed by liver attenuation less than or equal to 45 HU, which is essentially 100% specific for histologic grading of 30% or more fat content. The control group was defined by a high-normal liver attenuation of 60-65 HU. The main exclusion criteria were preexisting liver disease (beyond asymptomatic NAFLD), alcoholism, or less than 1 year of clinical follow-up. A medical record review assessed for the development of symptomatic liver disease (including nonalcoholic steatohepatitis and cirrhosis) and seminal cardiovascular events (myocardial infarction, cerebrovascular accident, transient ischemic attacks, or coronary bypass or stent). Data for body mass index, diabetes, and liver enzyme levels were also recorded.
Five hundred three adults (11.4%) had unenhanced CT liver attenuation of 45 HU or less, yielding a final steatosis cohort of 282 patients after exclusions; the control group consisted of 768 patients after exclusions. The mean (± SD) patient age (51.4 ± 14.7 vs 50.8 ± 17.4 years), sex (53.9% vs 54.7% female), and mean follow-up intervals (7.3 ± 3.2 vs 7.7 ± 3.2 years) were similar between groups. No patient in either group had progression of liver disease beyond incidental steatosis. Subsequent cardiovascular events were more common in the steatosis cohort (9.9% vs 5.9%; p = 0.028), but steatosis was not an independent risk factor after controlling for diabetes and body mass index in multiple logistic regression analysis.
This longitudinal study failed to show progression of moderate-to-severe hepatic steatosis to symptomatic forms of fatty liver disease over a 5- to 10-year time horizon. Aggressive workup of hepatic steatosis found incidentally on imaging does not appear to be warranted. Steatosis was a biomarker for subsequent cardiovascular events but not an independent risk factor.
肝脂肪变性是影像学检查中常见的偶然发现。非酒精性脂肪性肝病（NAFLD）的自然史及其与心血管并发症相关的风险在这种情况下尚未得到很好的确定。我们的目的是研究 CT 偶然检测到的中重度肝脂肪变性的临床结果。
在 12 个月期间对 4412 例连续成年患者进行 CT 平扫，测量肝脏衰减值。通过肝脏衰减值小于或等于 45HU 诊断为中重度脂肪变性，这对于组织学分级为 30%或更高脂肪含量的诊断具有 100%的特异性。对照组的肝脏衰减值定义为正常高值 60-65HU。主要排除标准为存在肝脏疾病（超出无症状 NAFLD 范围）、酗酒或临床随访时间少于 1 年。病历回顾评估了症状性肝病（包括非酒精性脂肪性肝炎和肝硬化）和主要心血管事件（心肌梗死、中风、短暂性脑缺血发作或冠状动脉旁路或支架置入）的发生情况。还记录了体重指数、糖尿病和肝酶水平的数据。
503 例成年人（11.4%）的 CT 平扫肝脏衰减值为 45HU 或更低，排除后得出最终脂肪变性队列为 282 例患者；对照组为 768 例患者。排除后，两组患者的平均（±标准差）年龄（51.4±14.7 岁比 50.8±17.4 岁）、性别（53.9%比 54.7%女性）和平均随访时间（7.3±3.2 年比 7.7±3.2 年）相似。两组均无患者的肝病进展超出偶然的脂肪变性。在多因素逻辑回归分析中，脂肪变性队列的心血管事件更常见（9.9%比 5.9%；p=0.028），但在控制糖尿病和体重指数后，脂肪变性并不是一个独立的危险因素。
这项纵向研究未能在 5 至 10 年的时间内显示中重度肝脂肪变性进展为有症状的脂肪性肝病。对影像学偶然发现的肝脂肪变性进行积极的检查似乎没有必要。脂肪变性是随后发生心血管事件的生物标志物，但不是独立的危险因素。
