EVALUATION OF ENDOSCOPIC ULTRASONOGRAPHY (EUS) IN THE DIAGNOSIS OF COLORECTAL CANCER INVASION

Abstract

Endoscopic Ultrasonography (EUS) was performed in 46 patients with colorectal cancer with an echo-endoscope (Olympus GF-UM 2). The procedure was done by the water-filled method and it was limited to the rectum and sigmoid colon because of the instrumental problems. The colorectal wall was ultrasonographically recognized as five layers in its structure. Viewing from luminal side, the 1st hyperechoic layer corresponded histologically to the proper mucosa, the 2nd hypoechoic layer to the mucosal muscle, the 3rd hyperechoic layer to the submucosa, the 4th hypoechoic layer to the proper muscle, and the 5th hyperechoic layer to the subserosa and serosa, respectively. The ultrasonographic feature of colorectal cancer was clearly shown as a hypoechoic mass in the wall. EUS proved to have high diagnostic value for the detection of colorectal cancer invasion in comparison with histological diagnosis. From these results it is apparent that EUS of the colon is an effective method for the diagnosis of cancer invasion. Further improvements of the instruments as well as techniques may lead increasing demand for use of EUS in the diagnosis of colonic diseases.