Parenchymal versus reticuloendothelial iron overload in the liver: distinction with MR imaging

Article Abstract:

Iron overload occurs when excessive amounts of iron are present in the body. The body does not have a mechanism for excreting this excess iron, which is deposited in and causes damage to various tissues. There are a number of underlying causes of this condition, such as hemochromatosis (an inherited disease that causes increased iron absorption) and blood transfusion. Tissue damage can be prevented or minimized if the cause is diagnosed early, and proper treatment is initiated. However, accurate diagnosis is difficult to make. Iron will accumulate in different types of cells of the liver and other abdominal organs, depending on the cause of the excess iron. For example, parenchymal cells are affected by hemochromatosis or cirrhosis. Reticuloendothelial (RE) cells are affected when the cause is multiple blood transfusions. The latter is usually not a problem, but the former can lead to major damage. Magnetic resonance (MR) imaging has been reported to be capable of detecting excess iron in abdominal tissues. This study examined the usefulness of MR imaging in differentiating the cell types affected by the overload. Abdominal MR images from 87 cases of iron overload were reviewed for characteristics that distinguished the cell types involved, and the underlying cause. Five patients suffered from hemochromatosis. MR images in all five showed low signal intensities for the pancreas, but only one showed decreased intensities for the spleen. Fifteen out of 16 patients who were diagnosed with RE iron overload had undergone multiple blood transfusions. In 14 patients, splenic signal intensities were decreased. The spleens in the other two subjects had been removed. These results indicate MR imaging can be useful in detecting iron deposition patterns and in determining the cell types involved in case of iron overload. This can be helpful in diagnosing the underlying cause, which may lead to more effective treatment. (Consumer Summary produced by Reliance Medical Information, Inc.)

Physiological aspects, Hemochromatosis, Iron, Iron (Metal)

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Comparison of Kaopectate with barium for negative and positive enteric contrast at MR imaging

Article Abstract:

Computed tomography (CT) continues to be the diagnostic imaging technique of choice for evaluating the upper abdominal region. Magnetic resonance (MR) imaging, thought to be a prime candidate for replacing CT in this role, is still rarely used. A suitable contrast agent, which is a chemical that is ingested or injected to increase the quality of images, for use with MR imaging has not yet been found. Barium is the contrast agent most frequently used for CT examinations, which utilize X-rays. It provides high tissue contrast for imaging and is both safe and inexpensive. These are the qualities needed by a MR imaging contrast agent as well. This study evaluated both the new (attapulgite) and old formulas (kaolin-pectate) for Kaopectate, a clay compound with diamagnetic properties, and barium, for use as contrast agents for MR imaging of the upper abdominal area. The imaging studies were performed on 10 volunteer subjects and five patients, four of whom were suffering from pancreatic cancer and one from pancreatitis. Relaxation times after giving the various agents were measured; a shorter relaxation time improves imaging quality. Relaxation times were slightly shorter for attapulgite than for kaolin-pectate at all concentrations, and were significantly shorter for attapulgite than for barium at all concentrations. Even when attapulgite was diluted - a problem likely to occur when intestinal secretions are present - relaxation continued to be shorter. Subjects were able to drink attapulgite, but disliked its taste. It caused stomach distension following ingestion, but the only side effect resulting from its ingestion was loose stools in some patients. Attapulgite improved MR imaging of the pancreas in the five patients with pancreatic disease. The results indicated that attapulgite was both safe and effective for use with MR imaging of the upper abdomen, particularly for imaging the pancreas. (Consumer Summary produced by Reliance Medical Information, Inc.)

Methods, Evaluation, Pectin, Barium, Silicates, Contrast media, Contrast media (Chemicals), Kaolin

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Temporomandibular joint dysfunction: correlation of MR imaging, arthrography, and arthroscopy

Article Abstract:

The temporomandibular joint (TMJ) is the point where the temporal bone and the mandible, or jawbone, meet in the lower jaw. TMJ dysfunction caused by abnormalities in the joint is a common problem, affecting up to a third of the population. It is characterized by abnormal jaw clicking and movements which often result in pain in the neck, head, and face. Various diagnostic imaging techniques are used to diagnose the underlying problem. Arthrography, X-raying of joints, is the most commonly used imaging technique. Magnetic resonance imaging (MRI), a technique that uses the inherent magnetic properties of tissues to produce images of them, is a more recent addition to the diagnostic tools used to examine TMJ dysfunction. This study compared MRI with arthrography and arthroscopy, an imaging technique that uses a scope to examine the inside of joints, to determine which was best in diagnosing TMJ dysfunction. Imaging results were correlated to results found with surgery. The three imaging techniques were performed on 36 joints in 27 patients with suspected TMJ dysfunction. Surgery was performed on 12 joints. The position of the joint disks as seen in surgery was accurately demonstrated by MRI imaging in 11 joints (92 percent), by arthrography in 9 joints (75 percent), and in all cases when arthroscopy was used. Arthroscopy was more accurate in detecting abnormalities or tears in the disks than either of the other two techniques. MRI imaging was found to be very useful for initial diagnostic purposes, because it requires no entry into the body, unlike arthroscopy. It cases where surgery is thought necessary, arthroscopy may be needed to further characterize the problem. (Consumer Summary produced by Reliance Medical Information, Inc.)

Temporomandibular joint disorders, Arthroscopy, Temporomandibular joint, Arthrography

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