A NEW TECHNIQUE OF ENDOSCOPIC ULTRASONOGRAPHY BY WHICH THE MUSCULARIS MUCOSAE OF THE STOMACH IS VISUALIZED WITH SUBMUCOSAL-INJECTION METHOD AND SCANNING ACOUSTIC MICROSCOPE SYSTEM

Abstract

The muscularis mucosae of the stomach is thought to be included in the second layerof five layers of which the stomach wall consists by endoscopic ultrasonography (EUS) .Nevertheless the muscularis mucosae has still been impossible clearly to be visualized asacertain layer on EUS image. This study was aimed at devising a nevv scanning method to depict the layer of the muscularis mucosae of the stomach We tried to figure this layerby using high-resolution ultrasonoprobe With “ submucosal-injection method ” and scanning acoustic microscope (SAM) system. Ultrasound on this system penetrates into the tissuedependently on sound-speed of biological tissues and this scan differentiates each area onacertain tissue according to acoustic impedance. Fresh pieces of the human gastric wall were mounted on the cork hoard which were obtained surgically. Scanning line was determined by two steel needles which were picked by 15 mm distance. FUJINON sonoprobe-sytstem SP-101 (20MHz) was used through the forceps channel of an endoscope. Subsequently to ordinary scan, sonolucent echo-jelly was injected as an “ enhancer” into thesubmucosal layer. After ultrasound scanning, the resected stomach was fixed in 10% of formalin and cut along the marked pin-hales in order to compare the scanning image with the optical microscopic findings and with acoustic properties by SAM. Ordinary scan by SP-101 showed five layers. After injecting echo-jelly, a thin hypoechoic layer depictedbetween the second layer and the “ enhancer” . It revealed 1000μ m thick from the surface of the first layer to the thin hypoechoic layer of which the layer itself was 100μ m. This finding was identical to the muscularis mucosae an histalogical findings on their position.From SAM image, there might be enough differentiation of acoustic impedances to create an interface echo between the mucosal layer and muscularis mucosae as much as those between the muscularis mucosae and submucosal layer. In conclusion, as these ultrasonogram showed, the layer of the muscularis mucosae corresponds to the most superficial part of the third layer. This new technique devised here of the high-frequency ultrasonoprobe can depict the position of the muscularis mucosae, which will enable precise analysis when we are going to make a depth diagnosis of early gastric cancer which is invasive inside oroutside of this layer.