Development of acoustic microscope for biological tissue and its application

Scanning acoustic microscope (SAM) is useful for tissue characterization because it is possible to obtain two-dimensional information of acoustic properties, viz., velocity and attenuation coefficient, in the microscopic region. We have studied development of SAM and its application to quantitative evaluation of biological tissue and a single cell. We developed a SAM system using a pulse signal and analytical procedure to obtain acoustic properties. Recently, we also developed an acoustic and optic hybrid system to obtain both optical and elastic images and acoustic properties for a single cell in real time. We applied the system to a 3T3-L1 mouse fibroblast cell using an acoustic lens with center frequency of 250 MHz. Measurements were conducted immediately and enough later after takeoff from the culture apparatus. Sound velocities were 1602 m/s and 1558 m/s, and thicknesses were 7.9 μm and 16 μm, respectively. Properties changes of the cell were successfully detected quantitatively.