1. An apparatus comprising: an imaging processing machine having a processor and a memory, wherein the processor is configured to execute instructions that when executed cause the imaging processing machine: to receive ultrasound images of a two-dimensional area corresponding to the target sample, where a first ultrasound image is taken at a first time period and a second ultrasound image is taken at a second time period after the first time period; to determine a change in strain value of the target sample over the two-dimensional area, wherein the strain value is determined from comparing the first ultrasound image to the second ultrasound image; to determine from the change in strain value, an xy-plane change in area of the target sample between the first time period and the second time period; to determine an approximate physical z-axis displacement over the two-dimensional area by approximating a change in local curvature of the two-dimensional area between the first time period and the second time period; and to determine a volume displacement of the target sample from the approximate physical z-axis displacement and the change in strain value.