Different forms of iron accumulation in the liver on MRI

agnetic resonance imaging (MRI) findings of iron overload, particularly in the liver, are well established (1).Hepatic iron overload is abnormal accumulation of iron in hepatocytes, Kupffer cells, or both (2, 3).Hepatic iron overload is commonly associated with hereditary hemochromatosis, transfusion-related iron overload, and chronic hepatopathies (4).MRI is mainly preferred for detection of hepatic iron.However, different forms of iron accumulation and iron sparing can make interpretation of images difficult.Knowledge of different forms of hepatic iron overload and iron sparing, and evaluation of T2* and R2* maps would allow correct diagnosis of iron-associated liver processes.In this article, we aimed to describe different forms of hepatic iron overload (diffuse, heterogeneous, multinodular, focal, hypersiderosis, segmental, intralesional, and periportal) and hepatic iron sparing (focal, geographic and nodular, and periportal) (Table ). Techniques for evaluation of hepatic iron overload UltrasonographyUltrasonography is not a suitable technique for evaluation of hepatic iron overload, as it cannot detect iron deposition (5).However, nonspecific long-term changes caused by hepatic iron overload like cirrhosis, portal hypertension, or hepatocellular carcinoma can be detected by ultrasound. Computed tomographyIron overload is presented as increased liver attenuation (72 HU or more) on unenhanced computed tomography (CT) images due to increased absorption of X-rays by iron (6).Associated hepatic steatosis, which is characterized as decreased attenuation on CT may potentially reduce sensitivity, whereas other factors increasing attenuation of hepatic parenchyma like gold storage in liver (7) and amiodarone administration (8) decrease the specificity of this technique.Therefore, CT is not a reliable technique for diagnosis and quantification of iron overload in the liver.However, CT may be of use in some patients unsuited for MRI, or to differentiate high iron content from calcifications, air, or foreign materials such as surgical clips. Magnetic resonance imagingIron causes a local distortion in the magnetic field and results in T1, T2, and T2* shortening.This effect causes signal loss on T2-weighted spin-echo/fast spin-echo and T2*-weighted gradient echo images, and is used for measurement of iron concentration.Iron-induced T2