An approach to tissue acoustic impedance imaging by utilizing adjacent near-field formed at an end of fused quartz fiber as an acoustic transmission line

A fused quartz fiber as an ultrasonic transmission line can be a promising tool to expand the advanced capability of ultrasonic clinical application. Quantitative acoustic impedance of living tissue surface could be measured by utilizing adjacent near-field from the fiber end with excellent lateral resolution which overcome the diffraction limit in ordinary beam-forming controlled by a transducer aperture. The proposed imaging method based on the near-field optical nanotechnology is the frequency-domain version of our previously reported measurement method for tissue acoustic impedance. Thus the principle and performance of this method were experimentally evaluated and proved to be a practical approach to realize the real-time imaging of local tissue acoustic impedance for the conventional endoscopic ultrasonography without any moving adjustment of liquid layer coupling between fiber end and tissue surface.