180 Part III – Diffuse (Depositional) Liver Diseases
85 Thalassemia with Iron Deposition
Thalassemia major is one of the most prevalent diseases caused by an abnormality in a single gene (monogenic), which results in defects in hemoglobin production of alphaor beta-chain and affects multiple organs. The worldwide birth rate of symptomatic globin disorders, including thalassemias, is no less than 240 per 100,000 births, of which 196 have sickle cell disease and 44 have thalassemias. Currently, over 2 million patients are transfusion-dependent worldwide, with the majority in Southeast Asia. Children with thalassemia usually become symptomatic between 6 and 12 months of age with symptoms of anemia and enlargement of the liver and spleen due to extramedullary hematopoiesis. Without iron chelation, iron-mediated free radical damage may cause hemosiderosis with liver fibrosis, myocardial damage with cardiac hypertrophy and dilatation (cardiomyopathy), skin pigmentation and endocrine failure including (bronze) diabetes mellitus, growth failure and delayed onset of puberty.
Literature
1.Tyler PA, Madani G, Chaudhuri R, et al. (2006) The radiological appearances of thalassemia. Clin Radiol 61:40 – 52
2.Mazza P, Giua R, De Marco S, et al. (1995) Iron overload in thalassemia: comparative analysis of magnetic resonance imaging, serum ferritin and iron content of the liver. Haematologica 80:398 – 404
3.Papakonstantinou O, Kostaridou S, Maris T, et al. (1999) Quantification of liver iron overload by T2 quantitative magnetic resonance imaging in thalassemia: impact of chronic hepatitis C on measurements. J Pediatr Hematol Oncol 21:142 – 148
4.Rund D, Rachmilewitz E (2005) Beta-thalassemia. NEJM 353:1135 – 1146
MR Imaging Findings
In thalassemia, as a result of blood transfusions, excessive iron deposition within Kupffer cells (hemosiderosis) may lead to secondary hemochromatosis (parenchymal) iron overload. Parenchymal iron deposition may also result from associated genetic hemochromatosis. At MR imaging signal loss may be observed both in organs with Kupffer cell (liver, spleen, bone marrow) and in parenchymal (pancreas and myocardium) compartments (Figs. 85.1 – 85.3).
Management
Management of the resulting anemia is through blood transfusions. Repeated transfusions result in excessive iron overload, removal of which is achieved through iron chelation therapy. Without blood transfusion, patients may develop massive bone marrow or extramedullary hematopoiesis, resulting in deformities of the facial bones, spinal cord compression and pathologic fractures. Desferrioxamine is the most widely used iron chelator.
85 Thalassemia with Iron Deposition 181
Fig. 85.1. Thalassemia with severe iron deposition. T1 TE = 2.3 ms: liver, pancreas (solid arrow) and lymph nodes (open arrow) have abnormally low signal intensity; T1 TE = 4.6 ms: note the loss of signal in the previously men-
Fig. 85.2. Thalassemia with parenchymal and Kupffer cell iron deposition, severe, MRI findings. A Axial T1 with the short TE (T1 TE = 2.3 ms): The liver, pancreas (solid arrow), and lymph nodes (open arrow) are much darker than the muscle due to parenchymal and Kupffer cell iron deposition. B Axial T1 GRE with a longer TE (T1 TE = 4.6 ms): Also one of the vertebrae is darkened indicating involvement. C Axial T1 GRE with a longer TE (T1 TE =
tioned structures as well as in one of the vertebrae; T1 TE = 12 ms: there is further loss of signal; ART: the liver appears less dark (TE of this sequence is set to a minimum of about 1.2 ms) (patient had undergone splenectomy)
12 ms) shows further decrease in signal. D Axial arterial image (ART): No enhancing nodules are present. E Coronal SSTSE image (SSTSE): The liver is as dark as the lung (*). F Coronal SSTSE image (SSTSE): The vertebra (*) is as dark as the lung. G and H Axial T1 with respectively the short (2.3 ms) and long TEs (4.6 ms) at the level of the heart: The myocardium shows loss of signal due to iron deposition (arrows)
Fig. 85.3. Various compartments with iron deposition. A Legend to the following two drawings. B The drawing shows the myocardium (parenchymal) and the vertebra (Kupffer cells) compartments. C The drawing shows the liver (parenchyma as well as Kupffer cells), the vertebra, the lymph nodes, and
the spleen (Kupffer cells), and the pancreas (parenchymal) compartments. D Photomicrograph of a different patient shows the parenchymal iron deposition in the liver. Iron Perls’, × 100
Part IV
Vascular Liver Lesions |
IV |