Selected Methods for Imaging Elastic Properties of Biological Tissues

For millennia, physicians have used palpation as a part of the physical examination to detect pathology. The ubiquitous presence of "stiffer" tissue associated with pathology often represents an early warning sign for disease, as in the cases of breast or prostate cancer. Very often tumors are found at surgery that were occult even with modern imaging instruments. This implies that methods for estimating "hardness" of tissues would add a weapon to the medical armamentarium. To this end, this review discusses several methods of estimating tissue hardness using internal or external means of applying stress (force per unit area) and several associated methods of detecting the resulting strain (fractional length…