Imaging Pearls ❯ Liver ❯ Iron Overload
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- " tomography (CT) of the abdomen is a sensitive method for the evaluation of liver abnormalities, particularly when a dedicated contrast-enhanced examination is performed. However, the non-contrast CT images can also provide relevant information if the liver attenuation number deviates from the physiologic range. This measures normally between 50 and 60 Hounsfield units (HU) on multidetector CT examinations and about 10 HU higher than the spleen. A lower attenuation is typically associated with hepatic steatosis due to non-alcoholic fatty liver. In contrast, an increased attenuation exceeding 70 HU is caused by a wide spectrum of pathological conditions that lead to the deposition of high-density or radiopaque elements within the liver. ”
Computed tomography of hyper-attenuated liver: Pictorial essay.
Ghahremani GG, Hahn ME, Fishman EK
Clin Imaging. 2023 May 97:1-6. - "The most common cause of a hyper-attenuated liver is the long-term treatment with amiodarone. This drug has been used very extensively for the management of ventricular arrhythmia and atrial fibrillation. It accounted for 2.4 million prescriptions dispensed to 677,240 patients in the United States during 2020. Amiodarone has a molecular weight of 681 and contains 37.3% iodine.”
Computed tomography of hyper-attenuated liver: Pictorial essay.
Ghahremani GG, Hahn ME, Fishman EK
Clin Imaging. 2023 May 97:1-6. - "Adverse effects of amiodarone include thyroid dysfunction in 14%– 18% of patients caused by iodine content of the medication, and pulmonary changes due to interstitial fibrosis and pneumonia in about 3% of cases. Approximately 25% of patients receiving amiodarone will have a transient asymptomatic rise of their liver enzyme levels. Amiodarone-induced hepatotoxicity can develop after long-term therapy, causing abnormal liver function tests in 15% to 50% of patients, and hepatitis or cirrhosis in about 3% of cases.”
Computed tomography of hyper-attenuated liver: Pictorial essay.
Ghahremani GG, Hahn ME, Fishman EK
Clin Imaging. 2023 May 97:1-6. - “The main feature of Wilson's disease on abdominal CT is a diffusely hyper-attenuated liver. Concomitant findings include liver cirrhosis, renal calculi, premature osteoarthritis, osteopenia, and chondrocalcinosis of intervertebral discs and hip joints. Note that copper is non-ferromagnetic and invisible on MRI, but contour abnormalities and parenchymal nodules of the liver are frequently seen in patients with Wilson's disease.”
Computed tomography of hyper-attenuated liver: Pictorial essay.
Ghahremani GG, Hahn ME, Fishman EK
Clin Imaging. 2023 May 97:1-6. - “Thorotrast had been widely used as an angiographic contrast material for 3 decades until 1950s, when it was finally disapproved for clinical usage in the United States. It was produced as a colloidal suspension of thorium dioxide, a radioactive substance with biological half-life of 22 years and emitting alpha radiation. Almost 10 million patients worldwide had been examined with thorotrast, particularly while undergoing cerebral angiography. Thorotrast is retained in the liver, spleen, lymph nodes and bone marrow for prolonged time, and its radioactivity can cause various hepatosplenic malignancies such as angiosarcoma. In the surviving patients, however, the increased density of the liver and spleen is clearly recognized on abdominal radiographs and CT examinations many decades after it had been injected.”
Computed tomography of hyper-attenuated liver: Pictorial essay.
Ghahremani GG, Hahn ME, Fishman EK
Clin Imaging. 2023 May 97:1-6. - Hepatic calcifications represent a common source of increased liver density on abdominal CT images, and they are associated with a wide spectrum of pathological processes. Most of them appear as focal or clusters of radiopacity caused by granulomatous diseases (tuberculosis, histoplasmosis), parasitic infections (hydatid disease), liver abscesses, and post-traumatic hematomas. However, large multilocular and scattered punctate calcifications may occur in hepatocellular carcinoma, metastatic mucinous adenocarcinoma of the gastrointestinal tract and ovaries, or metastases from osteogenic malignancies. Shibuya et al. reported a patient with diffuse liver calcification, which had developed following a severe episode of hypotensive shock from massive gastrointestinal bleeding. Other authors have also described large areas of liver calcification due to infarct or other pathologic conditions.”
Computed tomography of hyper-attenuated liver: Pictorial essay.
Ghahremani GG, Hahn ME, Fishman EK
Clin Imaging. 2023 May 97:1-6. - “Iron deposition in the liver of patients with hemochromatosis manifests a homogenously increased liver attenuation to about 75–130 HU on non-contrast CT images. The portal and hepatic veins will appear conspicuous because of their relatively low density within the hyper-attenuated liver. This condition is usually diagnosed through blood tests, liver biopsy, and abdominal CT or MRI. The latter modality is particularly useful for quantification of the liver iron content because its superparamagnetic effect leads to a markedly reduced signal intensity on T2-weighted images."
Computed tomography of hyper-attenuated liver: Pictorial essay.
Ghahremani GG, Hahn ME, Fishman EK
Clin Imaging. 2023 May 97:1-6.
- Iron overload (hemosiderosis) in Thalassemia
Iron overload secondary to repeated transfusions (such as in beta-thalassaemia major) and increased intestinal absorption (such as in beta-thalassaemia intermedia), is a major cause of morbidity and mortality. Although multiorgan siderosis occurs, the liver is the main storage organ. Sequential liver iron quantification provides the best estimate of total body iron stores, hence can be used to tailor chelation therapy. - “Iron overload secondary to repeated transfusions (such as in beta-thalassaemia major) and increased intestinal absorption (such as in beta-thalassaemia intermedia), is a major cause of morbidity and mortality. Although multiorgan siderosis occurs, the liver is the main storage organ. Sequential liver iron quantification provides the best estimate of total body iron stores, hence can be used to tailor chelation therapy.”
Imaging features of thalassaemia.
Gosselin M, Maharaj P, Balkaransingh P, et al.
Br J Radiol. 2019;92(1095):20180658. doi:10.1259/bjr.20180658 - “The clinical management of Cooley anemia depends on repeated blood transfusions to prevent cardiac morbidity and mortality and on chelation therapy to alleviate the total body iron burden which results from the transfusions. While the CT findings of hemochromatosis of the liver, spleen, and other organs have recently been described in the literature, deposition of iron in upper abdominal lymph nodes has not been emphasized. We observed this and other CT findings in a series of nine patients with Cooley anemia who received transfusions and chelation therapy. Opportunity to relate CT density to iron deposition was provided in three individuals who underwent splenectomy and hepatic and lymph node biopsy.”
CT in B-Thalassemia: Iron Deposition in the Liver, Spleen, and Lymph Nodes
Julie S. Mitnick, Morton A. Bosniak, Alec J. Megibow et al.
AJR136:1191-1194,June1981 - “Computed tomography on the other hand, because of its sensitivity to tissue densities, clearly demonstrates the increased attenuation of the iron pigment in the reticuloendothelial system. Lymph node attenuation coefficients measured 145-205H in our series. Since the atomic number of calcium is close to that of iron, the lymph nodes do appear calcified. However, absorption spectrophotometry data showed iron as the only significant element present in the excised nodes.”
CT in B-Thalassemia: Iron Deposition in the Liver, Spleen, and Lymph Nodes
Julie S. Mitnick, Morton A. Bosniak, Alec J. Megibow et al.
AJR136:1191-1194,June1981 - “CT examination revealed increased density of lymph nodes in all patients . This was determined by visual evaluation of the scans and was confirmed by tissue attentuation measurements in Hounsfield units (H). The youngest patient in the series (age 6) had only faintly in creased density in periportal nodes. Attenuation coefficients of liver, spleen, and lymph nodes for the nine patients are recorded in table 1.”
CT in B-Thalassemia: Iron Deposition in the Liver, Spleen, and Lymph Nodes
Julie S. Mitnick, Morton A. Bosniak, Alec J. Megibow et al.
AJR136:1191-1194,June1981 - “An unenhanced CT liver attenuation threshold of 75 HU was sensitive (83.3%) for hereditary hemochromatosis while maintaining an acceptably low screening test positive rate (1.2%). An unexplained liver attenuation of 75 HU or more on unenhanced CT should trigger appropriate laboratory investigation for iron overload; early intervention with phlebotomy can limit or prevent organ damage in patients with hemochromatosis.”
Opportunistic Screening for Hereditary Hemochromatosis With Unenhanced CT: Determination of an Optimal Liver Attenuation Threshold
Edward M. Lawrence et al.
AJR 2018; 211:1206–1211 - “In conclusion, an unenhanced CT liver attenuation threshold of 75 HU (scanned at 120 kV) was reasonably sensitive (83%) in a cohort of patients with HH, was associated with elevated serum ferritin, and had an acceptably low test-positive rate in a screening cohort (1.2%). Therefore, an unexplained liver attenuation of 75 HU or more should be considered an opportunistic screening threshold that can provide added value by triggering appropriate laboratory investigation and lead to early intervention with phlebotomy that could limit or prevent organ damage.”
Opportunistic Screening for Hereditary Hemochromatosis With Unenhanced CT: Determination of an Optimal Liver Attenuation Threshold
Edward M. Lawrence et al.
AJR 2018; 211:1206–1211 - Hemochromatosis: Causes
- primary hemochromatosis (hereditary)
- Anemia
- Blood transfusions.
- Iron pills or injections.
- Kidney dialysis over a long period of time.
- Liver disease, such as hepatitis C infection or fatty liver disease. - “However, high liver density seen on CT scans, which is secondary to increased iodine content of amiodarone and reflects the tissue level of amiodarone, may be useful to detect the toxicity .In this regard, it is important to evaluate elevations of liver enzymes, liver CT imaging (high attenuation of the liver parenchyma), and histology, and discontinuation should be considered when amiodarone induced hepatotoxicity is suspected.”
Amiodarone-induced reversible and irreversible hepatotoxicity: two case reports
Toyonobu Tsuda et al.
Journal of Medical Case Reports (2018) 12:95 - “Amiodarone is an amphiphilic iodinated compound that is used as a treatment for refractory ventricular arrhythmias. During evaluation for possible pulmonary toxicity, a patient receiving amiodarone was noted to have an increase in the density of his liver as seen on computed tomographic (CT) scanning of the abdomen. Six additional patients who were receiving amiodarone were subsequently evaluated to ascertain the frequency of this finding. The CT density of the liver was increased in all patients. Values obtained varied from 95 to 145 H, with a mean of 117 +/- 8.9 (normal, 30-70). The alkaline phosphatase was elevated in four patients, but only one had an elevation of either the alanine or aspartate aminotransferase.”
Increased hepatic density and phospholipidosis due to amiodarone.
Goldman IS et al.
AJR Am J Roentgenol. 1985 Mar;144(3):541-6.