Noninvasive and precise motion detection for micromachines using high-speed digital subtraction echography (high-speed DSE)

To detect the very precise motion of a micromachine in a human body noninvasively, the authors have developed a high-speed digital subtraction echocardiography system. The principle of this system is real-time digital subtraction of high-speed (high frame-rate) B-mode echograms. Serial image subtraction of successive frames of B-mode echograms (with a subtraction interval of less than 10 msec) enables one to detect fine differences in the mechanical motion of a micromachine between a mask image and the consecutive live image. The potential of this system in the area of medical micromachines is demonstrated with particular reference to the two-dimensional tracking of microparticles in a cardiac cavity and the visualization of fine tissue motion caused by an artificial actuator