Double-contrast barium enema and computerised tomography in the pre-operative evaluation of rectal carcinoma: are they still useful diagnostic procedures?

PURPOSE: In modern management of rectal carcinoma, the preoperative evaluation of disease parameters is important for selection of therapeutic options. Such parameters are currently defined through endorectal ultrasonography or endoscopic ultrasonography. A retrospective analysis of the parameters obtained with double-contrast barium enema (DCBE) and endorectal balloon computed tomography (CT) was conducted to verify the diagnostic reliability of the radiological techniques and to establish whether there is still an indication for their use. METHODS: 53 consecutive patients with adenocarcinoma of the distal half of the rectal ampulla underwent double contrast barium enema examination and CT of the pelvis with endorectal balloon. On the basis of the DCBE and CT assessment we evaluated: 1) the distance between the cranial extremity of the anal canal and the distal margin of the neoplasm; 2) the radial diffusion of the tumor; 3) the metastatic involvement of the perirectal and inferior mesenteric lymph nodes. RESULTS: 1) CT and DBCE measurements of the distal margin tended to coincide, but both tended to overestimate the measurement when compared to the pathologic examination; 2) in the identification of neoplastic infiltration of perirectal fat (T3) CT had 100% sensitivity, 78.7% specificity and 86.8% accuracy; 3) the CT sensitivity for detecting lymph node metastasis was 52.6%, specificity 85.3% and accuracy 73.6%. CONCLUSIONS: The diagnostic information provided by the radiological examinations is comparable to that of clinical and instrumental methods currently employed for staging of rectal carcinoma, although the latter are preferred because they are more readily accessible and less costly. DCBE and CT can therefore be usefully employed for staging of cancer of the rectum in those cases in which there are limitations of the current standard methods.