Endorectal ultrasonography for the assessment of rectal wall invasion in intrapelvic tumor: A preliminary report

Background: The purpose of the present study was to determine the usefulnes s of endorectal ultrasonography (ERUS) in assessing rectal wall involvement in intrapelvic tumors. Methods: Rectal wall invasion was assessed in 16 patients; 14 with deeply i nvasive bladder tumors, one with prostatic leiomyosarcoma, and one with pro static leiomyoma. Computed tomography (CT), magnetic resonance (MTR) imagin g and ERUS with a flexible-type radial scanner (7.5 MHz) were used and the results were compared with the histopathologic findings in surgical specime ns. Results. The normal rectum was shown by ERUS to be a five- or seven-layer s tructure. Characteristic abnormal ERUS findings included disappearance of t he perirectal fat tissue layer with or without disruption of the propria mu scle layer. Endorectal ultrasonography accurately assessed rectal wall invo lvement in all four patients who had two bladder tumors, plus the one patie nt with prostatic leiomyoma and the one with prostatic leiomyosarcoma. Howe ver, ERUS overstaged one of 12 bladder tumors with no rectal wall involveme nt, which was strongly adhesive to the rectum because of an inflammatory ch ange but had no tumor invasion. There were no cases of understaging by ERUS . In comparison, CT accurately assessed rectal wall involvement in two pati ents, but overstaged in three and understaged in two. Magnetic resonance im aging, which was performed in 14 patients, accurately assessed rectal wall involvement in two patients, but overstaged in three and understaged in one . Conclusion: This preliminary study suggests that ERUS more accurately asses ses rectal wall involvement in intrapelvic tumor than CT or MRI.