Application of Scanning Acoustic Microscopy to Pathological Diagnosis

Scanning acoustic microscopy (SAM) can obtain high-quality microscopic images of tissues and cells that are comparable with light microscopic images without staining and within only a few minutes. The speed of sound through tissues and cells is correlated with elasticity, thereby indicating their biomechanical properties. The elasticity varies according to the contents, such as collagen or elastic fibers, blood, colloids, mucin, ground substances, and cytoskeleton; therefore, SAM can follow changes in the composition of tissues and cells to determine their functions. Chemical modifications such as fixation, periodic acid-Schiff reaction, and enzymatic digestion may influence acoustic properties, and SAM can follow these changes over time in the same section to facilitate statistical comparisons based on digital values. Digital imaging using SAM is superior to analog methods for modifying images to discriminate changes, such as malignant and benign cell types. The observation ranges are shown in a colored column, and they can be manually adjusted. Thus, precise differences in acoustic properties are readily distinguished by narrowing the range. The resolution of SAM is determined by the wavelength, and it can theoretically exceed that of visible light. Combining these distinct techniques may help to elucidate the structural and functional characteristics of tissues and cells