3-DIMENSIONAL ENDORECTAL ULTRASONOGRAPHY FOR STAGING OF OBSTRUCTING RECTAL-CANCER

PURPOSE: Preoperative staging of advanced carcinoma of the rectum by c onventional endorectal ultrasonography is often impossible because of the presence of obstruction, which does not allow passage of the endop robe. In a prospective study, we investigated the value of three-dimen sional endorectal ultrasonography for staging of obstructing rectal ca ncer. This technique permits examination of obstructing rectal tumours because scan planes can be chosen deliberately within a scanned volum e. METHODS: Overall obstructing tumors not accessible for conventional endoprobes were found in 26 of 94 patients who were subjected to endo rectal ultrasonography for staging of rectal cancer. Three-dimensional volume scanning was performed using a three-dimensional frontfire tra nsducer or a three-dimensional bifocal multiplane transducer (7.5/10 M Hz). Data of the three-dimemsional scans were stored on a hard disk fo r subsequent evaluation with a combison 530 processor. RESULTS: Three- dimensional transrectal endosonography enabled visualization of local tumor spread in all 26 patients. In 18 patients, obstruction was cause d by advanced primary rectal carcinoma. Endosonography accurately dete rmined the tumor infiltration depth in three T2 tumors, eight T3 tumor s, and three T4 tumors. Overall accuracy for assessment of infiltratio n depth was 78 percent. Accuracy for assessment of perirectal lymph no de involvement was 75 percent. In eight patients, the obstruction was attributable to extramural regrowth of rectal cancer after surgery. Di ameter of the lesions ranged between 3 and 6 cm. Although all lesions were clearly depicted by three-dimensional endosonography, only five l esions (62 percent) were detected by computed tomography. CONCLUSIONS: Three-dimensional endorectal ultrasonography provides previously unat tainable scan planes and enables accurate staging of obstructing recta l tumors. This technique may improve therapy planning in advanced rect al cancer by selecting patients who require preoperative adjuvant ther apy.