Elastography imaging: the 30 year perspective

From the development of x-ray imaging in the late 19th century, the field of medical imaging developed an impressive array of modalities. These can measure and image a variety of physical parameters from absorption coefficients to spin-spin relaxations. However, throughout most of the 20th century, the intrinsic biomechanical properties of tissues remained hidden from conventional radiology. This changed around 1990 when it was demonstrated that medical ultrasound systems with their fast pulse repetition rate and high sensitivity to motion could create images related to the stiffness of tissues and their shear wave properties. From there, vigorous development efforts towards imaging the elastic properties of tissues were launched across different modalities. These progressed from the research phase, through implementation on clinical scanners, through extensive clinical trials of selected diagnostic tasks, to government approvals, payer approvals, international standards statements, and into routine clinical practice around the globe. This review covers highlights of some major topics of the technical and clinical developments over the last 30 years with brief pointers to some of the remaining issues for the next decade of development.