Abstract

In recent years, many new treatment methods and new medications have been developed in the biomedical field. Obviously, their effects and side effects need to be studied qualitatively and quantitatively. Conventional optical microscopes are often used for obtaining such data from cells or tissues taken from patients as specimens. However, in most of the cases, the tissues or the cells need to be chemically stained and/or fixed for optical microscopic observation. Staining and/or fixation usually kills cells. Therefore, when those techniques are applied, it is difficult to understand the real effects of the medication or the treatment, because the transformation in the tissue may only be visible in living cells.

An ultrasonic image is formed by reflected ultrasonic waves which are based on elastic properties of the living cells and/or the tissues. Therefore, staining is not required for scanning acoustic microscope (hereinafter called simply “SAM”). Hence, living cells and tissues can be observed. Furthermore, SAM can observe not only the surface but also the internal structure of the specimen with sub-micrometer resolution. Scanned images from the surface and internal structures can be combined to form a 3D image for better visualization. The SAM also has capabilities to measure mechanical properties (e.g., attenuation, velocity or the like) of the cells and/or tissues. Several investigators, including our group, have described the clinical applications of scanning acoustic microscopy. Subsurface imaging of thin and thick biological specimens is critical to the potential in VIVO application of this technique. However, conventional SAM has not optimized those capabilities for biomedical, especially clinical applications. High-frequency imaging (frequency ranging from 100MHz to 1.0GHz) would provide a powerful tool that would permit high-resolution imaging to visualize cellular interactions in complex microenvironments.