James F. Greenleaf, Ph.D.

Dr. Greenleaf and his colleagues study methods of measuring tissue properties using noninvasive, simple, and high speed ultrasound scanners. Vibro-acoustography (Science 280:82-85,1998) and shear wave methods are used to assess the mechanical properties of tissue such and its stiffness and viscosity. The methods produce images or "ultrasonic biopsies" of tissues and organs. Dr. Greenleaf and his colleagues are working with several companies to build and test new scanning instruments.

Focus Areas

Dr. Greenleaf and his colleagues have tested these methods in several organ systems. They have:

• Studied variations in stiffness of muscles in patients with stroke.
• Determined that skin stiffness varies with skin disease progression and regression.
• Noted variations in viscoelastic properties of kidneys with different disease states.
• Measured variations in stiffness of the heart wall during the heart cycle.
• Measured fundamental material properties of arteries by exciting modes of vibration using radiation force of ultrasound.
• Measured tissue material properties using ultrasound detected displacements within externally vibrated tissue.

Significance to patient care

Because the stiffness of tissue is highly associated with disease, these methods should provide convenient approaches for using widely available medical devices, ultrasound scanners, to assess many maladies in most of the population of the world.

Professional highlights

Dr. Greenleaf has received the Joseph H. Holmes Pioneer Award and the William F. Fry Memorial Lecture Award from the American Institute of Ultrasound in Medicine; and the Achievement, Rayleigh, Distinguished Service, Best Paper and Distinguished Lecturer awards from the IEEE Ultrasonics, Ferroelectrics and Frequency Control Society.