A Scanning Acoustic Microscope ‐ A Novel Tool for Cytological Discrimination

Abstract

A scanning acoustic microscope (SAM) uses ultrasound to make cell images on the slide by plotting the data of cell thickness, speed of sound (SOS), and attenuation of sound (AOS) through cells without staining. We have applied this microscope to discriminate various free cells in the fluid for cytological diagnosis.PurposeHow different are SAM images of various free cells from optical ones? Is SAM image analysis applicable to cytological diagnosis?Materials and MethodsResidual cells of cytology specimen from body cavity were prepared to make single cell‐layer slides by liquid‐based cytology method. The slides were fixed in ethanol and kept dry until observation. The slide were soaked in distilled water and observed with SAM. Cells from squamous cell carcinomas, adenocarcinomas, reactive mesothelial cells, mesotheliomas, malignant lymphomas, and neutrophils /macrophages were compared of their SOS, AOS, and thickness.ResultsSAM could visualize not only SOS, AOS and thickness of each cell portion but also cell sizes, thicknesses, borders, contents, cell clusters and structures. Various free cells showed their own characteristic acoustic images that was equivalent to optic ones. Obtained data with SAM was statistically comparable among different cell types.imageimage Cytological analysis SAM LM Nucleus Size △ ◎ Irregularity/groove X ◎ chromatin density X ◎ Cytoplasm Size ◎ ○ Border ◎ ○ Content ◎ ○ Irregularity ◎ △ Cell connection/Cluster ◎ ◎ Structure ◎ ◎ Statistical analysis ◎ ○ DiscussionEach acoustic property of different cell types was distinct to make characteristic acoustic images. Statistical difference in SOS, AOS and thickness of each cell type may help discriminate cell types. SAM can be a novel diagnostic tool for cytological diagnosis.