[Critical evaluation of preoperative instrumental staging of rectal tumors. Research on the adequate use of US, CT and MR]

Both traditional exams (rectal exploration, rectoscopy, barium enema, CEA) and advanced imaging (31 US, 40 CT and 11 MR) were performed for preoperative evaluation of rectal carcinoma in order to assess the accuracy of radiological imaging in the T and N staging. The results obtained have not been considered satisfactory and it is felt that US, CT and MR should not be employed routinely for rectal staging. Indeed accuracy of US, CT and MR is respectively 64%, 75% and 81% in the T evaluation and 64%, 70% and 64% in the N staging. In order to evaluate the effective usefulness of these three latter imaging techniques a double therapeutical choice was proposed. The first treatment option was suggested on the basis of traditional staging while a second choice was given considering US, TC and MR data also. Operatory findings subsequently allowed a definitive judgement on the influence of the different techniques on treatment selection. US has furnished useful data that could have allowed us to modify treatment in one case while in 5 other cases diagnostic error would have influenced treatment negatively. CT was useful in 5 cases while in 7 cases it would have influenced treatment choice negatively. MR would have been useful in one case and harmful in another. It is concluded that only patients with large neoplasms (stages T3 and T4) benefit from CT and MR staging with the exception of those cases that have tumors above the peritoneal fold or in strict relation with the sphincter structures. US was useful only in evaluating relations of neoplasms of the anterior rectal wall with nearby pelvic structures.