Hemochromatosis

Hemochromatosis is a disease caused by an increased intestinal absorption of dietary iron, bound as ferritin or hemosiderin, and is characterized by excessive parenchymal iron accumulation [29].

The primary organs affected by hemochro-matosis are the liver, pancreas and heart. Thus, liv

Fig. 9a-d. Longstanding hemochromatosis. The liver and pancreas show decreased SI on T2-weighted (a, b) and Tl-weighted (c, d) images, while the spleen demonstrates essentially normal SI. Note that the atrophy of the pancreas is displayed best on T2-weighted images (arrows). As a result of the atrophy, this patient with longstanding disease developed diabetes mellitus

Hemochromatosis Liver Mri

Fig. 9a-d. Longstanding hemochromatosis. The liver and pancreas show decreased SI on T2-weighted (a, b) and Tl-weighted (c, d) images, while the spleen demonstrates essentially normal SI. Note that the atrophy of the pancreas is displayed best on T2-weighted images (arrows). As a result of the atrophy, this patient with longstanding disease developed diabetes mellitus er cirrhosis, diabetes mellitus and cardiomyopathy frequently occur in untreated patients. Patients with longstanding disease and liver cirrhosis are significantly more at risk of developing HCC, thereby worsening their overall prognosis. Additional clinical manifestations include dermal hy-perpigmentation, decreased libido and a slightly increased incidence of extrahepatic malignancies.

In general, menstruating women tend to show only a moderate development of the disease [47].

Patients with hemochromatosis also demonstrate decreased reticuloendothelial function and thus iron storage is mainly limited to the hepatic parenchyma [40]. In contrast, patients without hereditary hemochromatosis who ingest massive amounts of iron demonstrate both parenchymal and reticuloendothelial iron overload.

Hemochromatosis should be differentiated from hemosiderosis, in which increased accumulation of iron arises due to transfusional iron overload, typically in patients with hematological diseases who need regular blood transfusions. In patients with hemosiderosis, iron accumulates primarily in the reticuloendothial cells of the liver and spleen, while hepatocytes, pancreas and other parenchymal organs are relatively excluded. This difference is of major importance since parenchy-mal overload has more toxic consequences. However, an accumulation of iron within liver cells may also be seen in certain patients after massive blood transfusions [16, 46].

Since in most cases hemochromatosis is a primary genetic disease, familial screening should be performed in order to detect early liver cirrhosis or HCC. Moreover, the prognosis of patients with hemochromatosis can be improved significantly by reducing serum iron levels by means of repeated phlebotomy [3].

As measurements of serum iron levels and ferritin are not specific and CT findings do not provide satisfactory results, a definitive diagnosis has to be obtained by means of histological examination [58].

Since iron decreases the T2 relaxation time, he-mochromatosis is seen as areas of decreased SI on T2- or T2*-weighted MR images [55]. In addition to the liver, the pancreas and heart are also affected. Therefore, the suspicion of hemochromatosis can be confirmed if each of these organs demonstrates decreased SI on MR images. Parenteral iron accumulation (e.g. in transfusional iron overload), can be excluded as the pathogenic factor in he-mochromatosis if the spleen presents with a normal SI (Fig. 9).

In normal individuals the liver parenchyma shows increased SI compared with the skeletal muscles on all sequences. As skeletal muscles are not affected by hemochromatosis, they represent a suit

Fig. 10a-d. A 74-year old male patient with longstanding hemochromatosis, significantly elevated AFP levels and HCC. The unenhanced T2-weighted (a) and Tl-weighted (b) images reveal decreased SI of the liver parenchyma and a hyperintense liver lesion (arrows) in the right liver lobe. In this case, iron deposition in the hepatocytes serves as an intrinsic contrast agent enabling the HCC to appear with high SI since iron storage does not take place in the tumor cells. With dynamic imaging after injection of Gd-BOPTA, strong hypervascularity of the lesion can be seen in the arterial phase (c) and portal-venous phase (d), clearly suggesting the presence of a HCC

Fig. 10a-d. A 74-year old male patient with longstanding hemochromatosis, significantly elevated AFP levels and HCC. The unenhanced T2-weighted (a) and Tl-weighted (b) images reveal decreased SI of the liver parenchyma and a hyperintense liver lesion (arrows) in the right liver lobe. In this case, iron deposition in the hepatocytes serves as an intrinsic contrast agent enabling the HCC to appear with high SI since iron storage does not take place in the tumor cells. With dynamic imaging after injection of Gd-BOPTA, strong hypervascularity of the lesion can be seen in the arterial phase (c) and portal-venous phase (d), clearly suggesting the presence of a HCC

able reference tissue to interpret and quantify the decreased signal of affected liver parenchyma [12].

In the early stages of the disease the SI of the pancreas remains normal, particularly in menstruating women. However, as the disease progresses, the signal within the pancreatic tissue decreases. This is particularly evident in symptomatic he-mochromatosis. Since MRI is able to demonstrate the progression of iron accumulation and the clearing of hepatic iron, it may possibly serve as a monitoring modality in place of the histological follow-up examinations performed at present.

Cirrhosis of the liver frequently occurs in patients suffering from untreated hemochromatosis. With MRI, hemochromatosis may be detected due to the fact that fibrous septa demonstrate increased SI compared to the low SI of the parenchyma. However, in many cases of hemochromatosis-induced cirrhosis, a micronodular pattern is present that is difficult to visualize on MRI [64].

As dysplastic liver cells in HCC do not tend to accumulate iron to the same extent as liver parenchyma in hemochromatosis, HCC usually appear with high SI compared to the low SI of liver tissue. However, similar high signal areas are generally seen on all sequences for most focal liver lesions in cases of hepatic iron overload (Fig. 10).

Liver transplantation is usually indicated for patients with hemochromatosis and advanced liver cirrhosis (Fig. 11). Although the transplanted organ also tends to accumulate iron, the hepato-toxic effect of the accumulation develops over a long time and so prognosis is significantly improved. Interestingly, patients suffering from he-mochromatosis may serve as donors for liver transplantation because the transplanted liver rapidly clears the accumulated iron [15].

Diabetes 2

Diabetes 2

Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...

Get My Free Ebook


Post a comment