| [ Summary ] |
We reviewed reports on a basic study to elucidate the relationship between the depth of invasion of gastrointestinal cancer and its hardness using a newly developed ultrasound tactile sensor, capable of digitally representing the hardness of objects. All objects possess a unique vibration frequency that depends on their hardness (resonance frequency), and when a probe tip oscillator that vibrates at a resonance frequency of fO comes into contact with tissue, the frequency decreases to fx. There is a strong correlation between the change in frequency (delta f=fx-f0) and tissue hardness : the higher the absolute value of the change, the softer the tissue is, and the smaller the change, the harder it is. In gastric cancer specimens, the more deeply the tumor had invaded, the harder cancerous areas tended to be, as compared to normal areas. However, the hardness of gastric cancer areas was influenced not only by the depth of invasion, but also by the presence of associated fibrosis within the lesion, the tumor stroma quantity, and the tumor size. Similar results are reported where cancerous areas tended to be harder than norma1 areas in other gastrointestinal cancers. Improvements and innovations in instrumentation are necessary to obtain stable data when the ultrasound tactile sensor probe is inserted through the endoscope and applied clinically to the diagnosis of depth of invasion of gastrointestinal cancers. |