Dr. Jensen has written a lay-language paper that describes this research in greater detail. It is available upon request and will be posted to ASA's virtual press room shortly before the meeting.
4) Sounding Out Ruptured Livers
The human liver, a highly vascularized vital organ, is the largest visceral organ and as such is vulnerable to traumatic injury. Blunt force can easy rupture the liver's capsule (the parenchyma) resulting in bleeding fractures.
Imaging these fractures non-invasively is difficult. Unlike tumors, which contain tissues of varying density that provide good contrast, the homogenous soft tissue of liver lacks contrast.
Traditional ultrasound imaging doesn't do that well with livers. That's because sound waves are pressure waves; they pulsate in the direction as the motion of the wave. Such sound waves probe the bulk modulus of the material -- its elasticity in the forward-backward direction.
By contrast, a shear wave moving through a medium imposes a pulsation of the atoms transverse to the movement of the wave. Shear waves probe the shear modulus, the stiffness, of the medium and can provide a much sharper image of the kinds of fractures that occur in livers.
Jiao Yu of the University of Washington in Seattle and her colleagues produced such shear waves by aiming a series of ultrasound pulses with successively deeper focal points in the material to be imaged. This, in effect, creates the desired shear waves. Their new studies look at liver tissue outside the body; the method is therefore at an early stage and not yet in clinical trials.
"We are investigating this method for imaging damaged livers," says Jiao Yu. "There is
|Contact: Jason S. Bardi|
American Institute of Physics