Combined contrast enhanced MRI shows promise

Combined contrast enhanced (CCE) MRI, in which two contrast agents are used together, permits accurate non-invasive staging of liver fibrosis in non-alcoholic fatty liver disease (NAFLD), according to a new study by researchers from the University of California, San Diego.

For the study, the researchers reviewed 26 patients with NAFLD who underwent CCE MRI. Using a five-point scale, the researchers found that the staging of the NAFLD on CCE MRI closely matched the staging of NAFLD using conventional pathology.

According to the researchers, the prevalence of NAFLD is increasing in western nations and is a major health problem affecting both children and adults. It is a common cause of cirrhosis in American adults and the most common cause in children.

The definitive method of diagnosis and staging is liver biopsy, but it has several limitations, say the researchers. It is invasive, costly, has risks and only samples about 1/50,000th of the liver. "This sampling issue is important because the pathological processes that affect the NAFLD liver are not evenly distributed throughout, so that tiny changes in needle placement will result in potentially large changes in biopsy interpretation. Because of these limitations, alternative methods such as CCE MR need to be developed," said Claude Sirlin, MD, lead author of the study.

"Except for CCE MR, all other experimental techniques rely on surrogate or indirect markers of fibrosis. CCE MR attempts to directly visualize fibrosis by using two contrast agents with complementary mechanisms, iron particles to darken the background liver and gadolinium to brighten the fibrosis," said Dr. Sirlin, "Gadolinium alone and iron particles alone are not adequate for visualization of fibrosis, unless the fibrosis is extremely advanced. However, when given together, the agents show fibrosis with high clarity," he added.

The combined use of two or more complementary contrast agents is uncommon in radiology, according to the researchers. "Partly this is because of the prevailing radiology paradigm and partly this is because most third-party insurers refuse to pay for two contrast agents," said Dr. Sirlin.

Other potential advantages of CCE MR, say the researchers, include that CCE MRI can directly visualize the fibrosis, it has a safety profile higher than biopsy, it can detect liver cancers simultaneously, the procedure is repeatable and the possibility that CCE MRI may be more accurate than any other non-invasive method for assessing liver fibrosis.

The full results of the study will be presented on Monday, May 1, 2006 during the American Roentgen Ray Society Annual Meeting in Vancouver, BC.

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About ARRS
The American Roentgen Ray Society (ARRS) was founded in 1900 and is the oldest radiology society in the U.S Radiologists from all over the world attend the ARRS Annual Meeting to take part in instructional courses, scientific paper presentations, symposiums, new issues forums and scientific and commercial exhibits related to the field of radiology. The ARRS is named after Wilhelm Röentgen, who discovered the x-ray in 1895.


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