New Mayo Clinic MRI Technology

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Noninvasive Liver Diagnoses Possible With New Mayo Clinic MRI

Technology

Article Date: 24 May 2007 - 4:00 PDT

Two recent Mayo Clinic studies have found that magnetic resonance

elastography (MRE), a new imaging technique invented at Mayo Clinic,

is an accurate tool for non-invasive diagnosis of liver diseases. The

findings were presented this week at the International Society for

Magnetic Resonance in Medicine Annual Meeting in Berlin, Germany, and

Digestive Disease Week 2007 in Washington, D.C.

The liver responds to many diseases that damage its cells by

developing scar tissue or fibrosis. MRE uses a modified form of

magnetic resonance imaging (MRI) to accurately measure the hardness

or elasticity of the liver. By applying vibrations to the liver, MRE

obtains pictures of the mechanical waves passing through the organ.

The wave pictures are then processed to generate a quantitative image

of tissue stiffness.

" Healthy liver tissue is very soft, while a liver with fibrosis is

firmer, and a liver with cirrhosis is almost rock-hard, " says

Ehman, M.D., lead researcher on the MRE project. " If detected early,

fibrosis of the liver can be treated, but once the disease has

progressed to cirrhosis, the condition is irreversible. "

Dr. Ehman and his imaging research team collaborated with Mayo Clinic

gastroenterologists to study whether MRE could provide reliable and

accurate diagnoses in patients with varying degrees of liver disease.

One study involved MRE examinations of 57 individuals with chronic

liver disease and 20 healthy volunteers. The researchers confirmed

that MRE accurately detects fibrosis with high sensitivity and

specificity. Researchers also found that steatosis, which is deposits

of fatty acids and triglycerides in liver cells and a common

condition in patients with liver disease, did not interfere with

detection of fibrosis with MRE.

" Based on this research, we are now using MRE examinations in select

patients to determine liver stiffness and assess the need for liver

biopsies, " says Jayant Talwalkar, M.D., a Mayo Clinic

gastroenterologist and an investigator on the MRE studies. " More than

170 million people in the world are known to have hepatitis C, and

nearly one-fourth of those will develop severe liver fibrosis. MRE

can help us noninvasively identify fibrosis in this large patient

population. "

A second study looked at whether MRE can accurately measure portal

hypertension, or high blood pressure in the portal vein that carries

blood from the digestive track to the liver, usually as a result of

cirrhosis of the liver. This study involved 35 individuals with

varying degrees of chronic liver disease and 12 healthy volunteers.

Researchers studied MRE examinations of liver and spleen stiffness

and found that a highly significant correlation exists between liver

and spleen stiffness in patients with portal hypertension. However,

the validity of spleen stiffness as a noninvasive measure of portal

venous pressure requires further study.

According to Dr. Ehman, many diseases cause the properties of tissue

to change and will be likely candidates for diagnosis using MRE in

the future. His research team is exploring the use of MRE in

detecting breast cancer and Alzheimer's disease.

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This research was funded in part by the National Institutes of

Health. Co-authors of these studies include Meng Yin; Grimm;

Rossman; Manduca, Ph.D.; Kamath, M.D. and Dr.

Ehman; all from Mayo Clinic's campus in Rochester; and

Romano, Ph.D., of the Naval Research Laboratory in Washington, D.C.

Contact: Rice

Mayo Clinic