New way in detecting small tumors

By Susan Milius

Washington (UPI): A new way of seeing inside living tissue or other opaque things may be able to find smaller tumors than current methods can or reveal hidden strains in industrial materials, said Mayo Clinic researchers last week.

Adding special computer software to a conventional Mri (magnetic resonance imaging) device can create images by using vibrations to detect differences in the stiffness of materials.

The method, called magnetic resonance elastograpy, does a high-tech version of what doctors' hands have been doing for centuries, said Dr. Richard Ehman. Palpation, the prodding and pushing that forms the basis for many medical diagnoses, works well. Most breast cancers are discovered this way.

"It happens every day: A surgeon will pick up tumors that we have missed with every modality of imaging we have," said radiologist Ehman.

"The property of stiffness is probably a very important property," he said. Dramatic differences in stiffness between tumors and their surrounding tissue -- sometimes 10-fold changes -- should make the property very useful for imaging, he said.

In contrast, tumors differ from their surroundings by only a few percent in the way they absorb X-rays, challenging Cat scans to create images from subtle differences.

An experimental system for measuring stiffness, developed in Ehman's lab and described in the new issue of the journal Science, is sensitive enough to catch even slight quivers of a few hundred nanometers, smaller than the wavelength of most visible light, said Ehman.

How far this sensitivity will go in detecting minuscule objects is not clear yet, the researchers said.

Ehman and colleagues tested their device on a pig's kidneys and have just begun to work on imaging organs within living beings. "Probably within a year we will have a good idea of whether it will work in vivo," he said.

"I think it has a place," predicted physicist Ronald Price, a professor of radiology at Vanderbilt Medical Center in Nashville, Tennessee. He speculated that this method might be useful in nondestructive testing, such as searching for flaws in industrial material without smashing it open.

In comparing Ehman's method to ultrasound imaging, Price suggested that the two might complement each other. Certain materials gobble up the penetrating waves of ultrasound, blinding the technology beyond certain depths. Ehman's method tracks different sorts of waves, which might be able to penetrate some of the blind spots.