[Transrectal ultrasonography for the assessment of invasion in rectal carcinoma].

Transrectal ultrasonography is an effective method in visualizing the tomographical view of rectal tumors. The advantage of this method over computed tomography is that with this method it is possible to visualize the layered structure of the bowel wall. The invasion was assessed as whether or not the tumor has penetrated the muscularis propria which was visualized in low echoic layer. With 5.0 MHz linear array scanner, it was possible to make relatively accurate diagnosis of depth of cancer invasion. The new 7.5 MHz linear probe visualized the rectal wall in five to seven layers, and the resolution with this probe was far better than that with the 5.0 MHz linear probe.