Histological Imaging of Gastric Tumors by Scanning Acoustic Microscope

Background: Human body tissues have their own speed-of-sound (SOS) by which sound travels through them. Harder materials exhibit greater SOS; thus, SOS through each tissue can provide information regarding its elasticity. For tumor discrimination in clinical medicine, palpation provides important information. However, manual palpation is subjective, whereas SOS data are objective and can be directly used to compare lesions.
Methods: A scanning acoustic microscope (SAM) uses ultrasound to image an object from SOS through tissues. We investigated the utility of SAM in imaging gastrointestinal lesions.
Results: We visualized the digestive tract as a layered structure and discriminated tumors to a degree comparable with that observed by light microscopy. Areas with greater SOS corresponded to those with higher collagen or muscle fiber concentrations. Cell-poor areas or regions with degeneration demonstrated less SOS than surrounding tissues. Gastric tumors displayed appropriate SOS similar to their original tissues and showed significant differences in SOS between scirrhous carcinomas and well-differentiated medullary carcinomas, scirrhous carcinomas and malignant lymphomas, and leiomyomas and leiomyosarcomas.
Conclusions: SAM offered the following benefits over LM: (1) images are acquired in a few minutes without special staining; (2) repeated observations of the same section are possible; (3) high-resolution digital imaging from SOS is comparable to LM; (4) SAM analysis could be helpful in understanding endoscopic ultrasonography imaging; and (5) digitized SOS data could be statistically compared among different stomach lesions.