Hepatic cirrhosis and hepatitis: MR imaging enhanced with superparamagnetic iron oxide

Article Abstract:

Diagnostic imaging is sometimes used to differentiate the liver diseases cirrhosis and hepatitis. Anatomic changes in the liver detected by imaging can indicate which disease is present, but these changes often overlap, and many are also seen with other liver diseases. An imaging technique that is more reliable in diagnosing liver disease is highly desirable. This study examined using the contrast agent superparamagnetic iron oxide in conjunction with magnetic resonance (MR) imaging, a diagnostic imaging technique that uses magnetic properties of tissues to produce images, in differentiating liver cirrhosis from hepatitis. It is thought that the contrast agent will react with liver tissue differently, depending on variations in physiology brought about by different diseases and severity of disease. The variable reactions should then be detectable on MR images. The procedure was performed on 15 patients, three with diagnosed cirrhosis, four with both cirrhosis and hepatitis, and eight with no liver disease. Results showed that on MR images, normal liver tissue and liver tissue with active hepatitis appeared homogenous, while cirrhotic liver appeared inhomogeneous. MR signal intensities decreased an average of 75 percent for normal liver tissue after iron oxide was administered, 52 percent for cirrhotic tissue, and 11 percent in liver tissue with active hepatitis after the contrast agent was given. The signal intensities appeared to decrease less in the cirrhotic tissue than in normal tissue because structural changes diminished uptake of the iron oxide. Uptake of the iron oxide was diminished to an even greater extent in liver tissue with active hepatitis. This was thought to be a result of functional changes in liver tissue caused by the disease. These results indicate that MR imaging enhanced by superparamagnetic iron oxide could be more accurate in differentiating liver cirrhosis from hepatitis than present imaging techniques. (Consumer Summary produced by Reliance Medical Information, Inc.)

Liver, Liver cirrhosis, Contrast media, Contrast media (Chemicals), Hepatitis

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Experimental lymph node metastases: enhanced detection with MR lymphography

Article Abstract:

Treatment and prognosis of cancer patients often relies on information obtained from lymph node examination. Magnetic resonance (MR) imaging in conjunction with superparamagnetic (super-magnetized) iron oxide (AMI-25) as a contrast enhancing agent was used to study the spread (metastasis) of lymph node cancer in animal subjects (rats). Metastases often occur in pelvic, abdominal, and mediastinal (a cavity separating two organs) nodes that are difficult to reach via biopsy (removal of a tissue sample from a living human). Contrast-enhanced MR allows measurement of nodal dimensions (e.g., size, volume, shape) to assess the spread of cancer via lymph node metastases. AMI-25 is a lymphographic contrast agent that selectively enhances the internal structure of normal lymph nodes, allowing normal nodes to be differentiated from abnormal nodes (particularly those that are not enlarged). AMI-25 was introduced into the subject rats via injection at various anatomic sites. Intravenous injection, which would have been the best means of introducing the contrast agent was not possible; researchers were aware that contrast agents would have been prevented from reaching lymph nodes by phagocytic cells (attack and destroy foreign matter as part of the immune response in mammals) if the material was administered intravenously. The study found that normal lymph nodes were reliably enhanced by an intramuscular injection of the superparamagnetic agent AMI-25. Lymph node uptake was recorded on MR images two hours after injection. The metastatic tumor-bearing nodes showed less uptake of AMI-25 than did normal nodes. Human studies are needed to perfect the means of detecting minimal amounts of disease, and differentiating hyperplastic (nodes enlarged due to growth of normal tissue) from malignant (cancerous) lymph nodes.

Research, Measurement, Cancer, Metastasis, Cancer metastasis, Tumors, Cancer diagnosis, Radiology, Medical, Radiology

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Hepatic iron overload: paramagnetic pathology

Article Abstract:

Hemochromatosis is a disease characterized by excessive iron levels in the body. It can be caused by genetic factors, which result in increased iron absorption, or it can be caused by excessive iron intake. The body cannot readily excrete excess iron, and high levels can cause local tissue damage. This can result in major damage to the liver. Although early diagnosis and treatment of liver iron overload has a good prognosis, diagnosis is difficult to make. The cellular distribution of excess iron varies with the underlying cause of the problem, leading to variations in severity of disease. Blood samples are not specific enough to localize problem areas. In the May 1991 issue of Radiology, Siegelman et al. report that magnetic resonance (MR) imaging can be used to verify the cause of the iron overload. MR imaging can detect relative amounts of a element in a tissue by the inherent magnetic properties unique to each element. The researchers have demonstrated the use of MR imaging to detect excess iron in tissue other than the liver, such as the pancreas and the spleen. Gomori et al., in the same issue of Radiology, report on a new MR technique for more accurately measuring iron levels in the liver. MR imaging should become a helpful tool in the early diagnosis of hemochromatosis. (Consumer Summary produced by Reliance Medical Information, Inc.)

Causes of, Physiological aspects, Liver diseases, Iron in the body, Iron (Nutrient), Hemochromatosis, editorial

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