New MRI Technology Enables Noninvasive Liver Diagnoses

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Source: Mayo Clinic

Date: May

22, 2007

New

MRI Technology Enables Noninvasive Liver Diagnoses

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 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.

The

findings will be 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. 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.

This

research was funded in part by the National Institutes of Health.

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