Fat Quantification in the Abdomen.
Fat Quantification in the Abdomen.
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DOI：
10.1097/rmr.0000000000000141
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发表时间：
2017-12
期刊：
影响因子：
--
通讯作者：
Sirlin CB
中科院分区：
文献类型：
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作者：
Hong CW;Fazeli Dehkordy S;Hooker JC;Hamilton G;Sirlin CB
脂肪肝在组织学上的特征是肝脂肪变性，即肝细胞内脂质异常积聚。它分为酒精性脂肪肝和非酒精性脂肪肝，是慢性肝病和肝硬化日益重要的病因。在这些情况下评估肝脂肪变性的严重程度对于诊断和预后目的很重要，因为如果早期诊断，肝脂肪变性有可能是可逆的。评估肝脂肪变性的金标准是肝活检，但它受取样误差、侵入性以及相关发病率的限制。因此，需要基于非侵入性成像的评估肝脂肪变性的方法。
超声和CT能够根据成像特征提示肝脂肪变性的存在，但无法准确量化肝脏脂肪含量。自1984年迪克森的开创性工作以来，磁共振成像（MRI）已被用于通过化学位移编码成像计算信号脂肪分数，通常采用反相位和正相位成像来实现。然而，信号脂肪分数受到几个因素的干扰，限制了其准确性和可重复性。最近，已经开发出先进的化学位移编码MRI方法，这些方法解决了这些干扰因素，能够测量质子密度脂肪分数（PDFF），这是一种标准化、准确且可重复的脂肪含量生物标志物。本文将讨论这些方法在肝脏以及其他腹部器官（如胰腺、肾上腺和脂肪组织）中的应用。
Fatty liver disease is characterized histologically by hepatic steatosis, the abnormal accumulation of lipid in hepatocytes. It is classified into alcoholic fatty liver disease and non-alcoholic fatty liver disease, and is an increasingly important cause of chronic liver disease and cirrhosis. Assessing the severity of hepatic steatosis in these conditions is important for diagnostic and prognostic purposes, as hepatic steatosis is potentially reversible if diagnosed early. The gold standard for assessing hepatic steatosis is liver biopsy, which is limited by sampling error, its invasive nature, and associated morbidity. As such, non-invasive imaging-based methods of assessing hepatic steatosis are needed. Ultrasound and CT are able to suggest the presence of hepatic steatosis based on imaging features, but are unable to accurately quantify hepatic fat content. Since Dixon’s seminal work in 1984, MRI has been used to compute the signal fat fraction from chemical-shift-encoded imaging, commonly implemented as out-of-phase and in-phase imaging. However, signal fat fraction is confounded by several factors that limit its accuracy and reproducibility. Recently, advanced chemical-shift-encoded MRI methods have been developed that address these confounders and are able to measure the proton density fat fraction (PDFF), a standardized, accurate, and reproducible biomarker of fat content. The use of these methods in the liver, as well as in other abdominal organs such as the pancreas, adrenal glands, and adipose tissue will be discussed in this review.