Endorectal ultrasonography with a 7.5 MHz linear array scanner for the assessment of invasion of rectal carcinoma.

An endorectal 7.5 MHz linear array scanner was used for the assessment of invasion in rectal tumours. As a preliminary study normal rectal wall of the resected specimen was scanned with the 7.5 MHz linear array scanner. The rectal wall was depicted in seven layers. The anatomical identification of these seven layers was made. Forty nine patients with rectal tumours were examined by endorectal ultrasonography with the 7.5 MHz linear array scanner. The sensitivities for T1, T2 and T3 tumours using the UICC TNM classification were 81%, 100% and 90% respectively, and the specificities were 100%, 85% and 100% respectively. Definite discrimination of lesions confined to the mucosa from those invading submucosa was difficult, even using this kind of high frequency ultrasonography. When the sonographic assessment was mucosal, or mucosal or submucosal involvement, local excision was performed. When the assessment was invasion in the muscularis propria or invasion penetrating the muscularis propria, bowel resection was performed. Except in one case, the histology of the resected specimens of the 49 cases confirmed the adequacy of the operation methods selected. Although there was some difficulty in making the distinction between mucosal and submucosal lesions, endorectal ultrasonography with the 7.5 MHz linear array scanner was considered to provide useful information in deciding on the type of operation offered to the patient.