ELASTOGRAPHIC DYNAMIC-RANGE EXPANSION USING VARIABLE APPLIED STRAINS

In elastography, we want to image the entire range of stiffnesses of t he elastic components found in inhomogeneous tissues. In order to achi eve this, the elastographic dynamic range should equal the entire stif fness dynamic range in the target. Various sources of noise limit the dynamic range of elastography. The recently-defined strain filter conc ept offers an analytical and graphical way of observing these limitati ons. In this paper, we describe a method that achieves the expansion o f the elastographic dynamic range. It involves the application of vari able strains in combination with selective storage of strain data that have optimal elastographic signal-to-noise ratios. This expands the c urrent dynamic range of elastography by orders of magnitude when compa red to single compression elastography. The process is explained theor etically using the strain filter framework, and 1D as well as 2D tissu e simulations are used to corroborate the theory. (C) 1997 Dynamedia, Inc.