Displacement and strain imaging for an elasticity microscope

An elasticity microscope images tissue stiffness at fine resolution. We have constructed an elasticity imaging system based on a single element, 50 MHz ultrasound transducer. Displacement tracking outside of the focal region is subject to speckle decorrelation, so a multi-focus, composite B-scan image is desired. The scanning must be performed while the object is held in a static deformed position; this is accomplished by scanning the element crosswise over a narrow slit in the deforming plate. We use phase sensitive complex correlation techniques between subsequent deformations to calculate displacement and strain images both lateral and axial to the scanning plane. Experimental results from a homogeneous tissue mimicking phantom well match simulations. Results from a layered phantom demonstrate significantly higher normal axial strain in the region corresponding to the softer layer. Resolution of the strain image is 90 /spl mu/m.