From the Department of Radiology (R.L., G.G., M.C., K.N.V., D.O., J.S.B., A.T.) and Service of Hemato-oncology, Department of Medicine (D.S.), Centre Hospitalier de l'Université de Montréal, 1000 rue Saint-Denis, Montréal, QC, Canada H2X 0C2; MR Clinical Science, Philips Healthcare Canada, Markham, ON, Canada (G.G.); Department of Radiology and Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Tex (T.Y.); and Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada (A.T.).
Radiographics. 2018 Mar-Apr;38(2):392-412. doi: 10.1148/rg.2018170079.
Iron overload is a systemic disorder and is either primary (genetic) or secondary (exogenous iron administration). Primary iron overload is most commonly associated with hereditary hemochromatosis and secondary iron overload with ineffective erythropoiesis (predominantly caused by β-thalassemia major and sickle cell disease) that requires long-term transfusion therapy, leading to transfusional hemosiderosis. Iron overload may lead to liver cirrhosis and hepatocellular carcinoma, in addition to cardiac and endocrine complications. The liver is one of the main iron storage organs and the first to show iron overload. Therefore, detection and quantification of liver iron overload are critical to initiate treatment and prevent complications. Liver biopsy was the historical reference standard for detection and quantification of liver iron content. Magnetic resonance (MR) imaging is now commonly used for liver iron quantification, including assessment of distribution, detection, grading, and monitoring of treatment response in iron overload. Several MR imaging techniques have been developed for iron quantification, each with advantages and limitations. The liver-to-muscle signal intensity ratio technique is simple and widely available; however, it assumes that the reference tissue is normal. Transverse magnetization (also known as R2) relaxometry is validated but is prone to respiratory motion artifacts due to a long acquisition time, is presently available only for 1.5-T imaging, and requires additional cost and delay for off-line analysis. The R2* technique has fast acquisition time, demonstrates a wide range of liver iron content, and is available for 1.5-T and 3.0-T imaging but requires additional postprocessing software. Quantitative susceptibility mapping has the highest sensitivity for detecting iron deposition; however, it is still investigational, and the correlation with liver iron content is not yet established. RSNA, 2018.
铁过载是一种全身性疾病，分为原发性（遗传）或继发性（外源性铁剂给药）。原发性铁过载最常与遗传性血色素沉着症相关，而继发性铁过载与无效性红细胞生成（主要由重型β-地中海贫血和镰状细胞病引起）有关，需要长期输血治疗，导致输血性血色素沉着症。铁过载可导致肝硬化和肝细胞癌，以及心脏和内分泌并发症。肝脏是主要的铁储存器官之一，也是最早出现铁过载的器官。因此，检测和量化肝脏铁过载对于启动治疗和预防并发症至关重要。肝活检曾是检测和量化肝脏铁含量的历史参考标准。磁共振（MR）成像现在常用于肝脏铁定量，包括评估铁过载的分布、检测、分级和治疗反应监测。已经开发出几种用于铁定量的 MR 成像技术，每种技术都有其优点和局限性。肝-肌肉信号强度比技术简单且广泛可用；然而，它假设参考组织是正常的。横向磁化（也称为 R2）弛豫度测量法已得到验证，但由于采集时间长，容易受到呼吸运动伪影的影响，目前仅适用于 1.5-T 成像，并且需要额外的成本和离线分析时间。R2*技术具有快速采集时间，可显示广泛的肝脏铁含量，适用于 1.5-T 和 3.0-T 成像，但需要额外的后处理软件。定量磁化率映射对铁沉积的检测具有最高的灵敏度；然而，它仍处于研究阶段，与肝脏铁含量的相关性尚未建立。RSNA，2018 年。
