1. A method of ultrasound strain imaging comprising the steps of: (a) acquiring first and second ultrasound echo data with an axial ultrasonic beam passing through a material subject to a first and second state of axial deformation, respectively, the echo data providing data points along axial columns and lateral rows of one or more image planes; and (b) determining displacement of elements of the material by comparing data points of the first and second echo data on a column-by column basis, wherein a determination of displacement for data points of a first column is substantially complete before a determination of displacement for data points of at least one second column to be determined is substantially begun; and (c) producing elasticity images of the material using determinations of displacement of the first and second ultrasound echo data.