4530 Is higher frequency probe nessesary for determining the depth of cancer invasion

The aim of this paper is if higher frequency probe :30MHz provide better resolution and result. Equipment: 20,30MHz probes were used. The method: 1.Experiment: In order to analyze the difference between layer structure by 20MHz and one by 30MHz, 6 esophageal resected specimens were scanned by 20 or 30MHz in water tub. 2. Clinical use: Before examination, anticholinergic agent or glucagon is injected in order to suppress the peristalsis. The 2 channel scope was inserted to the lesion vicinity, the probe was inserted from the working channel, and water was irrigated from the other channel. The scan was carried out by 20 or 30MHz. Twentyone cases of superficial esophageal cancer were examined by 20 and 30MHz and each images were compared with histological findings. Result 1. Experiment: Normal esophageal wall was delineated 9 layers by 20 and 30MHz, however using 30MHz the 2nd and 4th layers became clear. 2. Clinical cases: Two epithelial cancer were delineated by 30MHz, but one of them was difficult to determine by 20MHz. The determination of cancer limited to the lamina propria was correctly determined in 78% by 30MHz, 67% by 20MHz. Cancer invading the muscularis mucosa or small invasion to the submucosa were correctly determined in 100% by 30MHz, in 67% by 20MHz. Cancer invading the submucosa was determined in 89% by 30 and 20MHz. Conclusion: 30MHz probe provide better image of the layers from the epithelium to the muscularis mucosa. Accordingly 30MHz is useful for determined indication of mucosal resection via endoscopy.